Modelling and Simula on of EHV
Q1] Explain a Motor Control Unit in electric vehicle with its func onal features?
Q18] Explain A Motor Control Unit in electric vehicle with its func onal features?
• A Motor Control Unit (MCU) is an electronic module that interfaces between the pack of ba eries
and Motor to control the electric vehicle’s speed and accelera on based on the thro le input.
• The main func on of MCU is to transform the ba ery’s direct current into alterna ng current using
a Voltage Source Inverter (VSI) by applying pulse width modulated (PWM) waveforms to the gates of
VSI switches/MOSFETs.
• PWM pulses are generated according to the posi on sensors (Hall/Encoder/Resolver) feedback and
the ON Time/Duty Cycle of these pulses varies according to the required Speed/Torque command.
• To achieve efficient closed loop control of Motor drive, Vector Control methods/Field Oriented
Control (FOC) are adopted.
• In Field Oriented Control, torque and flux can be controlled separately which results in a fast and
efficient control of Motor drive.
• In addi on, Vector Control methods reduce the harmonic content of the Motor current by using a
fixed frequency PWM switching, which also helps to minimize the Motor temperature rise and noise.
• This Motor control unit (MCU) can fulfil the following func ons irrespec ve of the Motor used.
- Control the Motor torque and speed
- Start/Stop the Motor
- Prevent from electrical faults
- Provide overload protec on
- Change the motor rota on direc on
- Regenera ve Braking
Explain the following concepts related to modes of BMS control,
i) Centralized BMS Architecture ii) Modular BMS Topology iii) Primary/Subordinate BMS iv)
Distributed BMS Architecture
i) Centralized BMS Architecture
Centralized BMS Architecture has one central BMS in the ba ery pack assembly. All the ba ery
packages are connected to the central BMS directly. The centralized BMS has some advantages. It is
more compact, and it tends to be the most economical since there is only one BMS. However, there
are disadvantages of a centralized BMS. Since all the ba eries are connected to the BMS directly, the
BMS needs a lot of ports to connect with all the ba ery packages. This translates to lots of wires,
cabling, connectors, etc. in large ba ery packs, which complicates both troubleshoo ng and
maintenance.
ii) Modular BMS Topology
Similar to a centralized implementa on, the BMS is divided into several duplicated modules, each with
a dedicated bundle of wires and connec ons to an adjacent assigned por on of a ba ery stack. In
some cases, these BMS submodules may reside under a primary BMS module oversight whose
func on is to monitor the status of the submodules and communicate with peripheral equipment.
Thanks to the duplicated modularity, troubleshoo ng and maintenance is easier, and extension to
larger ba ery packs is straigh orward. The downside is overall costs are slightly higher, and there may
be duplicated unused func onality depending on the applica on.
iii) Primary/ Subordinate BMS
Conceptually similar to the modular topology, however, in this case, the slaves are more restricted to
just relaying measurement informa on, and the master is dedicated to computa on and control, as
well as external communica on. So, while like the modular types, the costs may be lower since the
func onality of the slaves tends to be simpler, with likely less overhead and fewer unused features.
iv) Distributed BMS Architecture
Considerably different from the other topologies, where the electronic hardware and so ware are
encapsulated in modules that interface to the cells via bundles of a ached wiring. A distributed BMS
incorporates all the electronic hardware on a control board placed directly on the cell or module that
is being monitored. This alleviates the bulk of the cabling to a few sensor wires and communica on
wires between adjacent BMS modules. Consequently, each BMS is more self-contained, and handles
computa ons and communica ons as required. However, despite this apparent simplicity, this
integrated form does make troubleshoo ng and maintenance poten ally problema c, as it resides
deep inside a shield module assembly. Costs also tend to be higher as there are more BMSs in the
overall ba ery pack structure.
Q2] Explain Electronic Control Unit of electric vehicle with its types and working principal?
Q39] Explain Electronic Control Unit of electric vehicle with its types and working principal?
• An electronic control unit (ECU), also known as an electronic control module (ECM), is an embedded
system in automo ve electronics that controls one or more of the electrical systems or subsystems in
a car or other motor vehicle.
• Quite simply put ECU is a device that controls all the electronic features in a car. This may range from
fuel injec on to maintaining perfect cabin temperature to controlling braking and suspension.
• Modern vehicles have many ECUs, and these can include some or all of the following:
1) Engine Control Module: With its sensors, the ECM ensures the amount of fuel and igni on ming
necessary to get the most power and economy out of the engine.
2) Brake Control Module: Used in vehicles with ABS, the BCM makes sure that the wheels are not
skidding and determine when to trigger braking and let go of the brake to ensure the wheels don’t
lock up.
3) Transmission Control Module: Used on an automa c vehicle, the TCM ensures you get the
smoothest shi s possible by assessing the engine RPM and accelera on of the car.
4) Telema c Control Module: Another one with the same abbrevia on this TCU ensures the car
onboard services are up and running. It controls the satellite naviga on and Internet and phone
connec vity of the vehicle.
5) Suspension Control Module: Present in Cars with ac ve suspension systems, the SCM ensures the
correct ride height and op mal changes to suspension depending on the driving condi on.
Working Principal:
• Each ECU typically contains a dedicated chip that runs its own so ware or firmware, and requires
power and data connec ons to operate.
• An ECU has an applica on so ware which is a set of algorithms. ECU gets inputs from other ECUs
and sensors. These inputs are assessed and used in the algorithms to calculate or determine the
output. These outputs then control a specific func on.
• An ECU receives inputs from different parts of the vehicle, depending on its func on. For example, a
door lock ECU would receive input when a passenger pushes the door lock/unlock bu on on a car
door or on a wireless key fob.
• An airbag ECU would receive inputs from crash sensors and from sensors that detect when someone
is si ng in a par cular seat. And an automa c emergency braking ECU would receive inputs from
forward-facing radars that detect when the vehicle is approaching an obstacle too quickly.
• The ECU would then communicate to actuators to perform an ac on based on the inputs. In our
examples, the door lock ECU would ac vate an actuator that locks or unlocks the corresponding door.
• The airbag ECU would choose which airbags to deploy, depending on the loca on of the passengers,
and then direct the actuators to deploy them. And the automa c emergency braking ECU would
engage the brakes to prevent a collision.
Q36] Explain the Electric Machine Control System (EMCS) and The Stability Control System (SCS) with
its important features?
• It is basically the inverter. It is called electric machine because it can be a motor (posi ve torque) or
a generator (nega ve torque), depending on the driver inputs (accelerator and brake pedal posi on).
• The EMCS receives the torque request from the vehicle control system (VCS) and the modulates the
stator phases (for permanent magnet electric machine) in order to obtain the required torque.
• The EMCS also performs diagnos cs on the electric machines and sends out the status. • For
example, in case of thermal protec on, the electric machine control system (EMCS) informs the vehicle
control system (VCS) that it cannot apply the requested torque and sends out the torque limit (derated
torque).
• An example of EMCS is the Rinehart Mo on Systems PM100 and PM150 family of propulsion
inverters. They are suitable for a range of applica ons like high-performance vehicles, professional
motor sport, heavy vehicle hybrid propulsion, sta c energy conversion, hybrid range extender or
integrated starter generator (ISG) controller.
• The PM family of propulsion inverters are designed for on-road and off-road electric (EV) or hybrid
vehicle (HEV) applica ons. Their main purpose is to convert DC power from a high voltage ba ery to
3-phase AC power required by the electric machine.
1) cooling circuit connec ons (input/output)
2) communica on and input-output ports
3) high voltage ba ery connec ons (DC)
4) 3-phase output connec ons (AC)
• The analog inputs can be used for various sensors (posi on, pressure, etc.).
• The RTD (Resistance Temperature Detector) inputs are used for temperature sensors connec on.
The resolver, quadrature encoder and sin-cos encoder are inputs from posi on/speed sensors
(rota on).
• The CAN (Controller Area Network) is used as a communica on protocol with other modules (e.g.
VCS). The programming port is used to flash the module with a different so ware algorithm or
so ware calibra on.
Q3] What is Ba ery/Cell Control System in EV? Explain with its func ons and working principal?
Q20] What is Ba ery/Cell Control System in EV? Explain with its func ons and working principal?
Q35] Explain Ba ery Management System along with its main features?
Q37] What is Ba ery/Cell Control System in EV? Explain with its func ons and working principal?
• A ba ery management system (BMS) is any electronic system that manages a rechargeable ba ery
(cell or ba ery pack), such as by protec ng the ba ery from opera ng outside its safe opera ng area,
monitoring its state, calcula ng secondary data, repor ng that data, controlling its environment,
authen ca ng it and / or balancing it.
• A ba ery pack built together with a ba ery management system with an external communica on
data bus is a smart ba ery pack. A smart ba ery pack must be charged by a smart ba ery charger.
• Func ons:
1) A BMS may monitor the state of the ba ery as represented by various items, such as voltage,
temperature, coolant flow, current, state of charge and health.
2) The BMS will also control the recharging of the ba ery by redirec ng the recovered energy (i.e.,
from regenera ve braking) back into the ba ery pack (typically composed of a number of ba ery
modules, each composed of a number of cells).
3) a BMS may calculate values of working parameters of ba ery cells like SOC, SOH, SOP, DOD, SOS etc.
4) The central controller of a BMS communicates internally with its hardware opera ng at a cell level,
or externally with high level hardware such as laptops or an HMI.
5) A BMS may protect its ba ery by preven ng it from opera ng outside its safe opera ng area, i.e.,
overcharging / over-discharging. 6) A BMS may also feature a pre-charge system allowing a safe way
to connect the ba ery to different loads and elimina ng the excessive inrush currents to load
capacitors.
Working of BMS:
• The ba ery management system monitors individual cells in the ba ery pack. It then calculates how
much current can safely go in (charge) and come out (discharge) without damaging the ba ery.
• The current limits prevent the source (usually a ba ery charger) and the load (such as an inverter)
from overdrawing or overcharging the ba ery. This protects the ba ery pack from cell voltages ge ng
too high or low, which helps increase the ba ery’s longevity.
• The BMS also monitors the remaining charge in the ba ery. It con nually tracks the amount of energy
entering and exi ng the ba ery pack and monitors cell voltages. It uses this data to know when the
ba ery is drained and shut the ba ery down. This is why lithium-ion ba eries don’t show signs of
dying like a lead-acid, but just shut off.
• Ba ery management systems are cri cal in protec ng the ba ery’s health and longevity but even
more important from a safety perspec ve. The liquid electrolyte in lithium-ion ba eries is highly
flammable. So, these ba eries need to be opera ng op mally and within safety limits at all mes to
prevent a fire.
Q4] Explain Torque and speed coupling in electric vehicle?
Q21] Explain Torque and speed coupling in electric vehicle?
Q38] Explain Torque and speed coupling in electric vehicle?
• A coupling is a mechanical element part that connects two sha s together to accurately transmit the
power from the drive side to the driven side while absorbing the moun ng error (misalignment), etc.
of the two sha s.
• In speed and torque coupling drivetrain, the generator/ motor is used to adjust the engine speed
and the trac on motor to adjust the engine torque. In this way, the engine can be operated in its
op mal speed and torque region.
• Torque and speed coupling is a method of connec ng the wheels and the engine in a Hybrid Electric
Vehicle (HEV) in which a planetary gear system is used to decouple the engine speed and a sha fixed
gear unit is used to decouple torque from that of the wheels (vehicle). This allows the engine to work
in narrow range of speed and torque where is most efficient. This is used in series - parallel hybrid
vehicles.
• In torque coupling mechanical-hybrid and parallel hybrid-electric vehicles, the mechanical power
outputs from different power sources are combined using various devices that can be generically called
"torque couplers." These include three-sprocket gears driven by belts or chains or direct coupling on
the same sha .
• In speed coupling, a variable speed drive is installed between the motor and the driven load. This
drive may be an eddy current clutch or a fluid clutch (some mes called a fluid coupling). Use of such a
drive allows the motor to accelerate without accelera ng the driven load.
• A er the motor is up to speed, the variable speed drive is ac vated and the load brought up to
opera ng speed.
• In this process, the losses that would have otherwise occurred in the motor rotor now occur in the
drive, and must be dissipated from the drive. Usually, the drive has more effec ve cooling than the
motor, and also the rate of accelera on of the load can be controlled so that the rate of heat genera on
in the drive can be controlled.
• It Allows higher star ng iner as and very low star ng current using reduced voltage starter.
• Usually used with high iner a condi ons where the motor is incapable of absorbing the hea ng. Also
used where very low inrush is required. Also used where variable load speed is required.
Q22] Explain following motor Control methods (any three)
i) Phase flux linkage ii) Phase Inductance iii) Modulated Signal Injec on iv) Mutually Induced Voltage
v) Observer based Theory
i) Phase flux linkage:
• Flux linkage is the linking of the magne c field with the conductors of a coil when the magne c field
passes through the loops of the coil, expressed as a value. The flux linkage of a coil is simply an
alterna ve term for total flux, used for convenience in engineering applica ons.
• Its formula is, emf = dλ/dt. If the current i created the magne c flux density B, then the flux linkage
is given by λ = Li. In this case, emf = L di/dt. L is the self-inductance of the coil.
• Flux linkage occurs when a magne c field interacts with a material such as what would happen when
a magne c field goes through a coil of wire. Flux linkage is determined by the number of windings and
flux, where ϕ is used to indicate the instantaneous value of a me-varying flux.
ii) Phase Inductance:
• Inductance is the tendency of an electrical conductor to oppose a change in the electric current
flowing through it.
• Phase inductance is the key parameter in designing current controllers. Addi onally, the rotor
posi on is essen al for coordinate transforma on during the motor startup.
• E = N(dϕ/dt) The number of turns in the coil is N, and the induced EMF across the coil is E. Using
Lenz's law, rewrite the above equa on, E = -N(dϕ/dt) The previous equa on is modified to compute
the value of inductance.
• Use the formula L = R * sqrt (3) / (2 * pi * f). L is the inductance, so you need the resistance (R) and
the frequency (f)
iii) Modulated Signal Injec on
• Modula on is defined as the process of superimposing a low-frequency signal on a high-frequency
carrier signal.
• Injec on modula on is the effect observed when laser oscilla on is perturbed by an injected signal
below the threshold of locking. In this regime the oscilla on becomes a wave modulated in frequency
as well as in amplitude. The modula on envelope has a characteris c waveform which depends on the
amplitude and phase of the injected signal.
iv) Mutually Induced Voltage
• Mutual induc on is defined as the property of the coils that enables it to oppose the changes in the
current in another coil. With a change in the current of one coil, the flow changes too thus inducing
EMF in the other coil. This phenomenon is known as mutual induc on.
• E.g. Two inductors whose self-inductances are given as 75mH and 55mH respec vely, are posi oned
next to each other on a common magne c core so that 75% of the lines of flux from the first coil are
cu ng the second coil.
• When two coils are brought in proximity with each other the magne c field in one of the coils tend
to link with the other. This further leads to the genera on of voltage in the second coil. This property
of a coil which affects or changes the current and voltage in a secondary coil is called mutual
inductance. • The formula of two coils is given as M= (μ0. μr. N1. N2. A) / L. Where μ0= permeability
of free space = 4π10-2, μ = permeability of the so iron core, N1= turns of coil 1, N2= turns of coil 2,
A= cross-sec onal area in m2, L = length of the coil in meters. The unit of mutual inductance is kg. m2.
s-2. A-2
• A device that produces the effect of mutual induc on is called a transformer. However, a very
interes ng property of the device is its ability to change voltage and current ra o only according to a
simple ra o, which is determined by the input, and the output of the coil turns.
v) Observer based Theory:
• In control theory, a state observer or state es mator is a system that provides an es mate of the
internal state of a given real system, from measurements of the input and output of the real system.
It is typically computer-implemented, and provides the basis of many prac cal applica ons.
• Knowing the system state is necessary to solve many control theory problems; for example,
stabilizing a system using state feedback. In most prac cal cases, the physical state of the system
cannot be determined by direct observa on. Instead, indirect effects of the internal state are observed
by way of the system outputs. A simple example is that of vehicles in a tunnel: the rates and veloci es
at which vehicles enter and leave the tunnel can be observed directly, but the exact state inside the
tunnel can only be es mated. If a system is observable, it is possible to fully reconstruct the system
state from its output measurements using the state observer.
• Typical observer models are, 1) Discrete- me case 2) Con nuous- me case 3) Peaking and other
observer methods
• State observers for nonlinear systems 1) Linearizable error dynamics 2) Sliding mode observer
• Mul -observer
• Bounding observers
Q5] Explain EV and EHV configura on based on power electronics?
Q7] Explain EV configura on and list out the components involved in it?
Ba eries are one of the most important components for electromobility and must be combined with
a ba ery charger. In addi on to ba ery packs and chargers, the following components are essen al
for vehicle electrifica on:
• The electric machine(s) – used as a trac on motor and some mes as a generator.
• Propulsion power converters – such as DC/DC and DC/AC converters, opera ng both in inver ng and
rec fying mode.
• DC/DC converter – with 12V output for auxiliary equipment (windshield wipers, hea ng, radio, lights
etc). Replaces the alternator in an ordinary car. The DC/ DC converter is connected to a 12V ba ery.
• Safety equipment – to break high currents and to monitor the ba ery, for instance.
• High voltage cables – DC cables between ba ery and power electronics and cables between power
electronics and the electric machine (unless those components are placed adjacent to each other).
May have a total weight of around 10kg in hybrid vehicles but may be lower for a pure electric vehicle
since the ba ery, motor and converter can be placed closer to one other.
• Electric cooling compressor – to keep the ba eries from overhea ng, may also be used to cool the
passenger compartment.
• Hybrid electric vehicles (HEVs) can be classified into four kinds: series hybrids, parallel hybrids,
series–parallel hybrids (dual mode), and complex hybrids. These classifica ons refer to the way in
which electric drive systems (ba ery, power electronic converter, and electric motor) are connected
with mechanical drive systems (fuel tank, Internal Combus on Engine (ICE), transmission and
differen al).
• The series hybrid configura on has various benefits. For example, the working point of the ICE can
be chosen freely to be that which gives the best efficiency and lowest emissions. The ICE can also be
turned off so that the vehicle can be driven in a purely electric mode giving zero emissions (for a
limited range). Furthermore, the ICE and generator set can be placed in a separate loca on to that of
the trac on motor, allevia ng the packaging issue. However, the series hybrid configura on has low
system efficiency due the number of energy conversions. Addi onally, the electric motor and the
ba ery pack need to be of a high ra ng, and the generator adds extra weight and cost compared to
the parallel configura on, which only requires one electric machine.
• The series configura on is par cularly advantageous for PHEVs, as the electric motor and the
ba ery pack are already of a high ra ng. However, the pure series hybrid is rare for the first
genera on of plug-in vehicles, which are to be rolled out between 2012 and 2014. The mechanical
drive train of the series configura on is different to an ordinary drive train (where the ICE is
mechanically connected to the transmission system), and most first-genera on PHEVs are configured
to allow conven onal mechanical drive train designs, such as parallel or series-parallel
configura ons.
• In parallel HEVs the opera ng point of the ICE may also be chosen rela vely freely to give the best
efficiency. Both the ICE and the electric drive system (ba ery and electric motor) can be used at the
same me to cope with peak loads and to provide extra accelera on. Parallel configura ons require
fewer electrical components than series configura ons – the generator is no longer needed since the
trac on motor can also be used to generate electricity (charging the ba ery via regenera ve
braking). Less power electronics is needed, and the rated values of the electric motor and ba ery can
be lower.
• Combina ons of the series and parallel configura ons are o en used to create systems that derive
advantages from both configura ons, but with higher complexity and cost. In the series– parallel
hybrid, the series and parallel systems could. either be used independently with a clutch that
switches between the two systems or simultaneously (a split system). Figure shows a schema c
diagram of a dual mode PHEV.
• Complex hybrids are similar to series–parallel hybrids but with addi onal power electronics.
Complex hybrids allow for versa le opera ng modes that cannot be offered by the series–parallel
hybrid, such as electric or ICE-assisted four-wheel opera on. Similar to series–parallel HEVs, complex
hybrids suffer from higher complexity and cost. In sum, the size and rated values of vehicle system
components and the power value ra o between motor types can be altered in many different ways.
Similarly, vehicle weight and differences in drive cycles should be considered. There is no single
system configura on that is suitable for all circumstances.
Q6] Explain the importance of Sensor Management and Integra on for electric vehicle with
func onal and applica on point of view?
Q23] Explain the importance of Sensor Management and Integra on for electric vehicle with
func onal and applica on point of view?
Q40] Explain the importance of Sensor Management and Integra on for electric vehicle with
func onal and applica on point of view?
It contributes to address problems such as: (1) traffic conges on and parking difficul es, (2) longer
commu ng mes, (3) higher levels of CO2 emissions, and (4) increase in the number of road
accidents, among others is of cri cal importance for improving a vehicle’s performance as well
enhancing the driving experience.
Func ons:
• Sensors are required to monitor the ba ery and power train system, and ensure that the demands
of drivers can be met over a sustained period of me.
• Monitor cell voltage and temperature
• Es mate ba ery state-of-charge (SOC) and state-of-health (SOH)
• Limit power input and output for thermal and overcharge protec on
• Control the ba ery charging profile
• Balance the state-of-charge of individual cells
• Isolate the ba ery pack from source and load when necessary. Applica ons for In-Vehicle Sensors
• Tire-pressure monitoring is an applica on that is required for the Na onal Highway Traffic
Administra on of the U.S. to alert drivers using acous c, light or vibra on warning if the re air
pressure is low.
• Proximity, ultrasonic and electromagne c sensors are used in parking assistance and reverse
warning applica ons. Proximity sensors can detect when a vehicle gets close to an object. Ultrasonic
sensors use a type of sonar to iden fy how far the vehicle is from an object, aler ng the driver when
the vehicle gets closer than a set threshold. Electromagne c sensors alert the driver when an object
enters an electromagne c field created around the front and back bumpers. Proximity sensors have
been used to develop a system based on a rectangular capaci ve proximity-sensing array for
occupant head posi on quan fica on to meet the guidelines of the Insurance Ins tute for Highway
Safety (IIHS). However, these types of sensors are frequently affected by temperature and humidity,
reducing their accuracy.
• Radio Detec on and Ranging (RADAR) and laser sensors constantly scan the road for frontal, side
and rear collisions and allow safety applica ons to adjust thro le and ac vate brakes to prevent
poten al collisions or risk situa ons by using radio waves to determine the distance between
obstacles and the sensor. The applica on no fies the driver if something close to the vehicle is
detected and automa cally ac vates the brakes to avoid a collision.
• The gyroscope and accelerometer sensors are used in Iner al Naviga on Systems (INS) to
determine the vehicle’s parameters such as vehicle posi on, orienta on, and velocity. INS are used in
conjunc on with Global Posi oning Systems (GPS) to improve accuracy. • Radar and speed sensors
are used in applica ons that warn the driver of poten al danger if changing lanes or wandering out
of the lane is detected. The driver is usually warned through vibra on in the seat or steering wheel
or acous cally using an alarm.
• Cameras are used to: (1) monitor the driver’s body posture, head posi on and eye ac vity to
detect abnormal condi ons such as signs of fa gue or the vehicle behaving erra cally (driving out of
a straight line on the road or pedestrians crossing suddenly in front of the vehicle) and (2) execute
night vision assistance applica ons to help drivers see farther down the road and detect objects such
as animals, people or trees in the path that can cause a poten al risky situa on or an accident.
• LIDAR (Light Detec on and Ranging) has become in a key component for the evolu on of
autonomous vehicles. LIDAR enables a self-driving car (or any robot) to observe the world with a few
special characteris cs such as con nuous 360-degree visibility and highly accurate depth
informa on. LIDAR sensors con nually fire off beams of laser light, and then measure how long it
takes for the light to return to the sensor.
• Although more sensors are in each vehicle, their integra on with other components and the lack of
widely accepted standards among different brands is a huge drawback in their adop on. In contrast,
current automated systems are limited in their capaci es. For example, Volvo’s city safety speed limit
is 50 km/h or less to avoid collisions with other vehicles or hi ng motorcycles or cyclists. A city
safety system is based on a laser unit, so in darkness condi ons, the it can only detect a vehicle if its
headlights and taillights are on and are clearly visible.
Q8] Explain the important feature of following (any four),
i) Unicycle ii) Bicycle iii) Dicycle iv) Tricycle v) Quadracycle
i) Unicycle:
An electric unicycle is a self-balancing personal transporter with a single wheel. The rider controls
speed by leaning forwards or backwards, and steers by twis ng or l ng the unit side to side. The
self-balancing mechanism uses accelerometers, gyroscopes, and a magnetometer.
• Commercial units are self-balancing in a forward and backward direc on, with side-to-side (lateral)
stability being provided by the steering mo ons of the rider, similar to Bicycle and motorcycle
dynamics.
• An electric unicycle (EUC) is a personal transporta on device that works on the principle of selfbalancing like a Segway but only has one wheel. The rider controls the direc on and speed of the
EUC by leaning backward or forwards.
• An electric unicycle is a bike with one wheel that is propelled via an electric motor instead of your
muscles. The motor is the main thing that drives the unicycle, and there is no pedalling required.
• A motherboard inside the unicycle reads the angle of the vehicle when it's in mo on. These angles
include front and back as well as le and right, which are moved and adjusted by the gyroscopes.
• As the gyroscopes sense the angle of mo on, it changes the speed of the motor to keep you in an
upright posi on as you move forward. The changes in speed are what helps to keep you in balance
so you can ride your electric unicycle without pping over.
• You can stop the unit by leaning backward, which will tell the motor to slow down based on the
angle. Electric unicycles have rugged wheels that can handle rain, snow, and even rough terrain. It
takes a bit of prac ce, but these personal transporta on vehicles are quite easy to master with a bit
of prac ce.
• When your motor needs a recharge, you simply plug it in to recharge the ba ery and then con nue
to enjoy it for hours at a me. Ba ery life depends on a variety of factors, but most electric unicycles
can operate for several hours on a single charge.
ii) Bicycle:
The electric bicycle is an electrical-assisted device that is designed to deliver the electromagne c
momentums to a present bicycle therefore relieving the user of producing the energy essen al to
run the bicycle. It contains a strong motor and enough ba ery power that just needs charging to help
in hill climbing, generate greater motoring speeds and provide completely free electric
transporta on. Electric vehicles price more and perform poorer than their gasoline Counterparts.
ADVANTAGES
• Easy to commute with low fa gue.
• Less maintenance cost.
• Normal Drag/Pedal is possible when power is not in use.
• Deployable ba eries – can be taken inside house.
• Cost of the unit is very low.
• Easy to carry since it is portable.
• Less energy consumed.
• High efficiency can be obtained if inverter is used.
• If using solar panel, free u liza on of energy can be done.
DISADVANTAGES
• High intensity of wind load.
• High centre of gravity.
• Cannot tolerate dras c changes in environment.
• Needs Periodic Monitoring.
iii) Dicycle:
It is a vehicle with two parallel wheels, side by side, unlike single-track vehicles such as motorcycles
and bicycles, which have two wheels inline. Originally used to refer to devices with large wheels and
pedals, the term is now used in rela on to powered self-balancing scooters with smaller wheels and
no pedals such as the Segway PT and the self-balancing hoverboard.
• In more recent usage, "dicycle" has been used for both pedalled and motorised vehicles with
wheels of varying sizes, as long as they share a common axis, though not necessarily a common axle.
• The Segway PT is a two-wheeled self-balancing personal transporter which uses computers,
sensors, and electric motors to keep the device upright. The rider commands the PT to go forward or
backward by shi ing their weight forward or backward on the pla orm. The maximum speed of the
Segway PT is 12.5 miles per hour (20.1 km/h) with a range of 24 mi (39 km) on a fully charged
lithium-ion ba ery, depending on terrain, riding style, and the condi on of the ba eries. Invented by
Dean Kamen, it is produced by Segway Inc.
• The self-balancing scooter is a category of personal transporter which includes all self-balancing
powered portable devices with two parallel wheels that includes the Segway PT, the Segway miniPRO
and the self-balancing hoverboard.
Di wheel design:
• The diwheel design has the two large outer wheels completely encompassing an inner frame. The
inner frame is free to rotate within the wheels, and is typically supported by a common axle or idlers
which roll on the wheels (see figure). Diwheel, like their more popular cousins the monowheel, have
been around for almost one and a half centuries. All of these pla orms suffer from two common
issues affec ng driver comfort; slosh and tumbling (also known as gerbilling). Sloshing is when the
inner frame oscillates, and it occurs in all monowheel and diwheel where the centre of gravity of the
inner frame is offset from the centre line of the wheels. It is very prevalent as these pla orms
typically have low damping between the wheel and the frame, to minimize power consump on
during locomo on. In addi on, during severe braking or accelera on the inner frame will tumble
rela ve to the earth centred frame, which affects the ability of the driver to control the pla orm.
Both the sloshing and tumbling issue can be controlled through feedback control, and has been
demonstrated successfully. The equa ons of mo on for the diwheel have been published
iv) Tricycle:
A tricycle has a low risk of falling over because it always has three wheels on the ground, which
provides a secure sensa on. You can either pedal with electric pedal support or use 100 percent
electric power assist to ride it. The main advantage of a tricycle is small children or adults who have
never ridden a tricycle before simply ride it. it can use as both bicycle as well as a tricycle.
• A tricycle, some mes abbreviated to trike, is a human-powered (or gasoline or electric motor
powered or assisted, or gravity powered) three wheeled vehicle. Some tricycles, such as cycle
rickshaws (for passenger transport) and freight trikes, are used for commercial purposes.
• Adult-sized tricycles are used primarily for recrea on, shopping, and exercise. Tricycles are
favoured by children and senior adults for their apparent stability versus a bicycle; however, a
conven onal trike has poor dynamic lateral stability, and the rider must take care when cornering to
avoid pping the trike over. Unconven onal designs such as recumbents have a lower centre of
gravity so require less care.
Wheel configura ons:
• Delta: A delta tricycle has one front wheel and two rear wheels.
• Tadpole: A tadpole tricycle has two front wheels and one rear wheel. Rear wheel steering is
some mes used, although this increases the turning circle and can affect handling (the geometry is
similar to a regular tricycle opera ng in reverse, but with a steering damper added).
• Other: Some early pedal tricycles from the late 19th century used two wheels in tandem on one
side and a larger driving wheel on the other. An in-line three-wheeled vehicle has two steered
wheels, one at the front and the other in the middle or at the rear.
v) Quadracycle:
It is a four-wheeled human-powered land vehicle. It is also referred to as a quadricycle, quad cycle,
pedal car or four-wheeled bicycle amongst other terms. In addi on, there are single manufacturers
who call them Go kart, Car, Car-Bike, Ecological car, Human Powered Vehicle, Pedal Kart, Quadri
bent, Qua ro cycle, Surrey and Twin bike.
• Quadracycles have been in use since 1853 and have grown into several families of vehicles for a
variety of purposes, including tourist rentals, pedal taxis, private touring, mountain and industrial
use.
• Tourist des na on rental: Quadracycles can o en be found at tourist a rac ons where they are
available to rent by the hour or day. Modern tourist Quadracycles usually feature open sea ng for
two or more riders in a sociable configura on. They are o en designed to look like early 20th century
automobiles with a bench seat, rack-and-pinion steering, and a canopy top. They are commonly
called "surreys", due to their resemblance to horse-drawn wagons of similar appearance and the
same name. Examples of this type include: Interna onal Surrey Company Surrey, Quadricycle
Interna onal Quad-3, Rhoades Car 4W4P, Sirene a.
Q9] Explain front and rear wheel drive for electric vehicle with its advantages and disadvantages?
A) Front Wheel Drive:
The FWD is the most common arrangement in the auto industry, u lizing the front wheels to drive
the car. It is the most prac cal choice for the majority of today’s drivers. The idea behind the frontwheel-drive arrangement is to save space inside the cabin which is why you don’t see a hump on the
floor on most modern front-wheel-drive cars. We can say that the FWD is the busiest and most task
involved layout out of the four as it has to do three things all along at the same me, i.e., Steering,
Driving the wheels and Braking.
ADVANTAGES
• The front-wheel-drive configura on offers some advantages over Rear-wheel drive, as the gross
weight of the car is set-up on the front, this, in turn, provides more trac on to the front wheel which
is being powered hence more grip on the road.
• FWD also stands tall when it comes to manufacturing point of view as it’s significantly cheaper to
build and as ge ng popular day by day, it is only ge ng more cost-effec ve.
• Front-Wheel Drive setup is also lighter and in turn, helps with the fuel economy. FWD is commonly
deployed in city cars and economy hatches
DISADVANTAGES
There is a demerit for the popular FWD, which is known as Torque Steering. Due to the nature of the
setup that burdens it with three tasks, FWD can suffer from some severe Torque Steering, which
means that the power from the engine overwhelms the front wheels which is felt when the car
undergoes hard accelera on and the steering goes haywire. Torque Steering causes the vehicle to
steer le or right on its own, under the influence of the torque transmi ed from the engine. But with
the ever-developing modern technology, FWDs are ge ng smarter and agiler.
B) Rear Wheel Drive:
It is the most revered of all the four set-ups. The RWD or what we like to call it the” Right Wheel
Drive” is the most tried and true drivetrain setup of all. In this geometry, the rear wheel does the
driving part whereas the front wheel takes up the steering. As Thanos says “Perfectly Balanced”.
ADVANTAGES
• RWD does wonders for the car and if you observe there is a perfect symphony between the front
and the rear wheels as the rear pushes and the front steers hence there is no Torque Steering which
allows for a more engaged and dynamic driving experience, therefore, RWD can handle more
horsepower compared to an FWD.
• This also provides engineering to tweak the suspension and the overall vehicle configura on. RWD
is commonly employed in SUVs, premium luxury sedans and sports cars.
DISADVANTAGES
• There are issues with the RWD though. It provides less trac on when it encounters slippery and
tread-unfriendly road surfaces. RWD is also rela vely expensive to manufacture and service.
Q10] Explain Propulsion and Power distribu on system in electric vehicle with its main
components?
Q26] Explain Propulsion and Power distribu on system in electric vehicle with its main
components?
Q44] Explain Propulsion and Power distribu on system in electric vehicle with its main
components?
Q27] Explain Design and repair ps for frame of vehicles?
1) Surfaces should be smooth and contoured without strain concentrators such as notches and sharp
steps.
2) Avoid pu ng holes in highly stressed loca ons. In par cular, avoid holes in the flanges of the rails.
3) Avoid pu ng holes or sec on changes where the rails or cross members experience significant
flex or twis ng. For example, when a rigid body is installed on a truck the two front mounts should
be flexible.
4) Use medium grade steel (grade 350 or higher) rather than mild steel. This will help achieve an
adequate Factor of Safety.
5) Use steel that has a surface hardness. Because cracks start on the surface, hardness here will
hinder crack development. Nitriding or Carburising, for which the metal is exposed to a Nitrogen-rich
or Carbon-rich environment at high temperature will produce a surface layer that is hardened.
6) Use gradual changes to the sec on proper es. Sharp changes will cause stress risers and this will
promote crack propaga on at these loca ons.
7) Tensile stresses open cracks whilst compressive stresses close them. The most vulnerable regions
are in tension.
8) The fa gue life of a welded part is independent of the material proper es. The quality of the weld
is the important factor. Undercu ng and discon nui es in the weld are risk factors. Prehea ng and
tempering of the weld can be important.
Q28] Explain the types and components of ba ery pack in electric vehicle?
A ba ery pack is a set of any number of (preferably) iden cal ba eries or individual ba ery cells.
They may be configured in a series, parallel or a mixture of both to deliver the desired voltage,
capacity, or power density. The term ba ery pack is o en used in reference to cordless tools, radiocontrolled hobby toys, and ba ery electric vehicles.
The Components of a Ba ery Pack
A ba ery pack is the most expensive part in an electric vehicle. It is a complex system made of a wide
range of components. Here are some of the important components.
• Cells are the most important components of a ba ery pack. The mixture of materials comprising
the cell is known as its chemistry. Different ba ery chemistries can achieve different performances
and specifica ons. There are two common types of cells: energy cells and power cells. There are also
many variants to provide the perfect trade-off depending on the applica on. In the EV industry, the
lithium-ion cell (li-ion cell) is the most common chemistry. Alterna ve chemistries are some mes
used, such as Nickel-Metal Hydride (NiMH), which offers a slightly be er lifecycle.
• Electrical connectors such as busbars, wires, or other distribu on conductors are used to make
series or parallel connec ons between cells and groups of cells. These connec ons are typically done
using ultrasonic bonding or laser welding. Busbar connec ons between modules can also be done
mechanically using fasteners.
• Thermal interface materials (TIMs) such as pastes, adhesives and gap fillers are inserted between
ba ery components to join them mechanically while improving thermal proper es between
surfaces. With the rise of the structural ba ery pack, TIMs are becoming essen al components.
• The Ba ery Management System (BMS) protects cells by monitoring key parameters such as
voltages, currents, and temperatures. It is responsible for cell balancing (to maintain the op mal
performance of the cells at the right voltage) and communicates with several systems such as engine
management and temperature control. It also includes protec on devices that can shut down the
ba ery if needed.
• The Ba ery Thermal Management System (BTMS) controls the thermal energy in the electric
vehicle’s powertrain and cabin, providing cooling or hea ng as needed to meet the ba ery’s thermal
needs and protect the cells. The BTMS includes several components such as a heat exchanger, tubes,
hoses, cold plates, pumps, valves, and temperature sensors.
• The Contactor System is a switch controlled by the ba ery management system. It can cut off the
electrical connec on between the main ba ery and the high voltage bus, which delivers current to
the trac on motor and other high-voltage components.
• The Housing is a rigid enclosure that protects the ba ery from environmental factors such as water,
dust, and salt. It helps maintain a precise temperature and electrical insula on in the ba ery, and it
prevents damages like rust and slow shorts.
• The Communica ons System ensures communica on with other components in the electric
vehicle. The most used protocol is CAN bus.
The 4 Main Types of Ba ery Pack Designs:
12V Ba ery Packs for Accessories
• 12V ba ery pack with their low voltage, 12V ba eries are used for low energy applica ons such as
headlights, radio systems, and other accessories. In hybrid and petrol cars, they are used to start the
engine.
• In electric vehicles, they are used as an energy source that can func on without the main electric
ba ery (trac on ba ery). For example, it is used to ac vate the trac on ba ery and provide power
to some vital components if power has been cut off for safety reasons.
• Tradi onally, the most known type of 12V ba eries were made using the lead acid cell chemistry
and were hence referred to as lead-acid ba eries. The number of cells in these packs was limited to
6.
• The most recent 12V ba eries are lithium-ion ba ery packs whose lithium cells offer be er
performance and lighter weight.
• 12V ba eries are small and are typically placed under the hood. More recently, manufacturers
have started placing them inside the trunk to improve safety, as it minimizes chances of short circuits
during crashes. Since more collisions occur at the front, the ba ery is be er protected from impacts
when it is posi oned at the back.
Hybrid Ba ery Packs
• Hybrid ba eries contain a smaller amount of energy than EV ba eries and are much smaller.
• S ll, today’s hybrid ba eries typically have a range between 30 and 50 miles (50 and 80 km). •
They can be used for most short-distance trips without having to fall back on the internal combus on
engine (ICE). That’s a major improvement compared to the very first models, which offered a mere
0.6 miles of autonomy (1 km).
• Hybrid ba ery packs are built to complement the combus on engine when it is least efficient, such
as when accelera ng.
• The goal is to diminish petrol consump on as much as possible. The ba ery can also recharge itself
by recovering wasted energy when braking (regen braking).
EV Ba ery Packs
• EV structural ba ery pack Unlike other ba ery pack designs, EV ba eries are full-sized ba eries
made to supply the en re range of the vehicle, including the trac on motor and accessories. Current
EV ba eries offer between 20 and 130 kWh of energy and can use between 90% and 95% of that
energy—a much higher percentage than other types of ba eries. The Mercedes EQS is the electric
car with the highest range, offering 485 miles of autonomy (780 km).
• EV ba eries represent a significant por on of the vehicle’s weight and volume. They can weigh up
to 450 kg (1000 lbs), represen ng one-fourth of the car’s total weight. Different designs come with
high voltage going from 400V to 900V. In the most recent designs, they are being integrated as part
of the vehicle’s structure.
High Performance Ba ery Packs
• High performance ba ery packs are ba eries designed for Formula E races. They are divided in two
categories: hybrid and pure EV.
• They are made with composite materials to obtain an ultra-light structure. Some high-performance
ba eries are removable so they can be replaced during races.
• Even though they are small, these ba eries can deliver ultra-high power. More precisely, they can
deliver several hundred kW of power, which is enough to output power for an en re neighbourhood.
Their cooling system is oversized due to the aggressive power demand.
• High-performance ba ery packs are more energy efficient than other types of ba eries. For
example, they can recover a larger por on of lost energy during braking (regen braking)
Q11] Explain Frame building Problems? Also list out Types of Frame Damage & How to Spot it?
Defects in frames and body generally occur due to severe impacts on rough roads and collision with
other objects or vehicles. Depending upon the nature of collision, the defects of the following kinds
may occur.
• Misalignment in horizontal and/or ver cal plane. • Twis ng of main frame and/or sub-frames. •
Buckled main frame and/or sub-frames. • Bent side members and/or dumb iron. • Broken or loose
gusset plates and rivets.
Types of Frame Damage & How to Spot Them
1) Sagging Frame: You may no ce gaps in the body of your car if your frame is sagging. When parts of
the frame are uneven, the vehicle tends to lean towards and create these gaps. Sagging causes stress
to res and coils, and without frame repair, they will wear out faster.
2) Twisted Frame: A twisted frame causes similar damage as a sagging frame. However, it is harder to
spot. If your car feels unstable at high speeds or experiences difficulty in turns, this may indicate that
your vehicle has a twisted frame. To find the source of damage, you will need a thorough inspec on.
3) Sway Damage: Sway damage occurs when something hits any corner of your vehicle. This type of
damage is more no ceable since the car will significantly lean in one direc on. You will have difficulty
keeping the car driving straight and may feel vibra ons while driving. Sway damage not only
compromises the vehicle’s alignment but can also lead to transmission issues and even a full
breakdown if not dealt with in me.
4) Mashed Frame: These types of accidents can cause the frame to crumple in on itself, making it
effec vely shorter than the appropriate specifica ons. Deformi es in the hood, fenders, or rails may
indicate damage to the frame. A mashed frame can also cause a chain reac on, extending to other
parts of the car and resul ng in sags, twists, and sway damage.
Q12] What do you mean by the term “DFMEA”? Explain the objec ve feature that can achieve the
in the process of system or equipment design?
DFMEA (Design Failure Mode Effect Analysis) failure mode impact analysis is to analyze the poten al
failure modes of each component unit of the product and the func onal impact on the product in
the process of system or equipment design.
• DFMEA can achieve the following objec ves in the process of system or equipment design:
1) Find out what is important to system func on and performance. All kinds of affected components
and their failure modes are found out and their influence degree analyzed.
2) Be able to ensure that all failure modes and effects of all components of the system are carefully
considered and relevant measures are taken, which can help designers and decision makers to select
the best scheme to meet the system reliability requirements from various design schemes.
3) Make objec ve and scien fic evalua on of relevant measures, tes ng equipment, etc. in design
review.
4) Be able to provide basis and implementa on condi ons for quan ta ve analysis of system
reliability design and provide system reliability evalua on results.
5) Provide data, technology, and condi ons for further improvement of system design.
6) Accumulate technical data for the next similar new product design scheme selec on and decisionmaking.
Q24] Explain, “Placement of Motors” in electric vehicle system?
Q41] Explain, “Placement of Motors” in electric vehicle system?
• In conven onal EV models, the motor is installed in the posi on of the engine in gasoline engine
vehicles, and it transfers power to the wheels via a drive sha . This method allows EVs to make use
of the automo ve technology already exis ng in cars with engines, and excels in terms of sound and
vibra on.
• Generally, it is Mounted between the engine and transmission, the Electric Drive Motor is used for
vehicle propulsion. During decelera on or braking, it acts as an alternator and charges the HV ba ery
by conver ng the vehicle's kine c energy into electrical energy.
• On most electric cars, there will be just one electric motor found on either the rear or front axle,
depending on whether the car is rear wheel or front-wheel drive. On an all-wheel drive electric car,
there will be two motors—one for each axle.
• The proper es of the vehicle such as size, weight, overload and aerodynamics are crucial vehicle
characteris cs that will ul mately determine speed, torque and power requirements of the electric
motor. In cases where the vehicle was designed for electric motors, they are generally located at the
front and/or rear between the wheels. There are short half-sha s connec ng the output of the
motors to the wheels. In a few cases, there is an a empt to have the motors incorporated in the
wheels. This may have advantages in a few cases, but generally not. Finally, there are cases,
especially in conversions, where the electric motor is placed where the ICE would have been to make
the change over easy. But this results in far more complica on than necessary.
Q25] Explain, “Ba ery and Mo on Transmission Systems” in electric vehicle system?
Q42] Explain, “Ba ery and Mo on Transmission Systems” in electric vehicle system?
• An electric car transmission doesn’t func on the same as a standard transmission on a gaspowered vehicle. That’s because an electric motor produces nearly instantaneous torque, unlike an
internal combus on engine. As such, there’s no need to rev the engine to create peak power during
Springfield drives.
• A transmission control system for an electric vehicle, includes a motor for directly conver ng
electric energy to usable mechanical energy and a transmission connected to the motor without
clutch. A motor speed sensor detects motor speed and a wheel speed sensor detects wheel speed. A
shi fork sensor detects shi fork movement. An inverter controls the motor and a control unit
controls the inverter in accordance with the motor speed sensor signal and the wheel speed sensor
signal.
• An electric vehicle powertrain works below.
1) Upon stepping on the accelerator, electricity is sent from the ba ery to the electric motor.
2) The spinning motor then spins the gearbox (aka electric car transmission).
3) As the motor and gearbox spin, your vehicle will begin to move. Some electric motors have the
capacity to rotate up to 20,000 rpm. By contrast, the majority of internal combus on engines only
rotate up to 7,000 rpm.
4) When you transi on to reverse, the electric motor spins backward. In a standard vehicle, there is a
separate gear in the transmission that allows you to move in reverse
Q13] Explain Chassis frame layout with suitable sketch? Also list out various types of Loads on the
Chassis frame?
Q48] Explain Chassis frame layout with suitable sketch? Also list out various types of Loads on the
Chassis frame?nois
The automobiles such as cars, buses and trucks, etc. are generally considered to be consis ng of two
major assemblies, The frame is the main part of the chassis on which remaining parts of chassis are
mounted.
• The automobiles such as cars, buses and trucks, etc. are generally considered to be consis ng of
two major assemblies, chassis and Frame.
• A chassis consists of an internal framework that supports a manmade object in its construc on and
use. A chassis is usually rectangular steel frame, supported on springs and a ached to the axles, that
holds the body and motor of an automo ve vehicle.
• The frame is the main part of the chassis on which remaining parts of chassis are mounted. The
frame should be extremely rigid and strong so that it can withstand shocks, twists, stresses and
vibra ons to which it is subjected while vehicle is moving on road. It is also called underbody. The
frame is supported on the wheels and re assemblies. The frame is narrow in the front for providing
short turning radius to front wheels. It widens out at the rear side to provide larger space in the
body.
Loads on the Chassis frame:
• Weight of the vehicle and the passengers, which causes ver cal bending of the side members.
• Ver cal loads when the vehicle comes across a bump or hollow, which results in longitudinal
torsion due to one wheel li ed with other wheels at the usual road level.
• Loads due to road camber, side wind, cornering force while taking a turn, which result in lateral
bending off side members.
• Load due to wheel impact with road obstacles may cause that par cular wheel to remain
obstructed while the other wheel tends to move forward, distor ng the frame to parallelogram
shape.
• Engine torque and braking torque tending to bend the side members in the ver cal plane.
• Sudden impact loads during a collision, which may result in a general collapse.
Various Loads Ac ng on Frame
1. Short Dura on Loads These loads are acts when vehicle passes through broken patches of roads
and feels a sudden shock. Due to this ac on vehicle will experience a reac on force which is further
acts on the frame of the vehicle.
2. Momentary Dura on Loads When body takes a curve or during cornering body will experience a
centrifugal force. This force is transmi ed to the frame. This force also acts on the frame.
3. Impact Loads When vehicle experience an accident then the chassis frame experiences a high
impact load which is directly transferred to frame. The frame has to sustain these impact loads.
4. Iner a Loads These loads are because of the weight of the vehicle itself. When brakes are applied
and vehicle comes to rest and experiences huge iner a force due to the vehicle mo on on the front
side of the chassis, this is called iner al loads. Similarly, when vehicle accelerates the complete
vehicle weight is transferred to the back side of the frame. Basically, iner a loads are due to braking
and accelera on.
5. Sta c Loads These are because of the weight of the vehicle or the weight of the chassis
components viz. transmission system, braking system, suspension system, body, accessories of
vehicle, and passengers in the vehicle etc.
6. Overhead Loads These loads are those which are used by engineer to take the factor of safety to
sustain the overloading condi ons. For example, two wheelers are designed to carry loads of two
passengers but in actual the vehicle is designed to carry much more load than two passengers to
provide the factor of safety.
Q29] Explain the types of chassis on basis of following, i) Engine Loca on ii) Assembly iii) Frame
Types of Chassis
Based on Engine Loca on:
1. Conven onal Chassis
In this type of chassis engine is fi ed in front of driver cabin making the driver sit quiet far from the
front axle. Due to this driver is unable to see the road just in front of tyres. The por on of the chassis
where engine is fi ed can’t be u lized for carrying passengers or goods.
2. Semi Forward Chassis
Here engine is fi ed in such a way that half of it is in driver’s cabin and remaining half is in front of
drivers’ cabin. This por on of chassis where engine is fi ed inside drivers’ cabin can be u lized.
3. Full forward or Bus Chassis
Here complete engine is mounted inside the driver’s cabin and driver sits just above the front wheels
and is able to see the road just in front of the tyres completely.
4. Centre Engine Chassis
It is also known as mid-engine chassis. In this engine is mounted between front wheels and rear
wheels. Since the weight of the cars shi s under the accelera on this arrangement further improves
wheel grip and curved body can be designed with greater aerodynamic efficiency.
5. Rear Engine Chassis
Here engine’s Centre of gravity is behind the rear wheels. This is mostly seen in low floor buses
wheels remaining space can be used for passengers and luggage.
B) Based on Assembly:
1. Conven onal Chassis
In conven onal chassis the longitudinal members or side members are joined by four or five cross
members over which all the body and all the components are installed.
2. Integral Chassis
This is also called as frameless chassis. The body shell and under body are welded into a single unit
which helps in decreasing the overall weight. Due to the elimina on of longer frame it is cheaper.
The only disadvantage is its difficulty to repair.
3. Semi Integral Chassis
In the semi-integral chassis, the engine is installed on a frame. The remaining por on is frameless.
This is because when the vehicle suffers from any accident then only the front por on can be
repaired.
C) Based on Frame:
1. Ladder Frame
This frame is similar to the shape of a ladder. It has two longitudinal members also called as side
members joined by four or five lateral members or cross members.
2. Backbone Frame
In this frame instead of two-dimensional ladder, it consists of strong tubular backbone which bears
most of the loads.
3. Tubular Space Frame Space
frames are all about tubes held together in compression and tension using 3D pyramid style
structure and diagonally brace tube boxes. A tube space frame is capable of holding its shape even if
the joints between tubes are hinges.
4. Monocoque Frame
In Greek mono means single and in French coque means shell. It is a construc on technique that
supports structural loads by using objects external skin.
5. Aluminium Space Frame
As tradi onal steel monocoque chassis is heavier. Hence, car makers turned to replace steel with
aluminium and everything is same as monocoque.
6. ULASAB Frame
Aluminium space frame is heavier, so American steel manufacturers hide Porsche engineering
services to develop a new kind of steel monocoque technology called ultra-light steel body
monocoque frame.
7. Carbon Fibre Frame
Carbon Fiber monocoque frame is a monocoque type frame made of carbon fibre. It has superior
rigidity to weight ra o
Q14] Explain Durability along with Factors Affec ng Electric Car Durability?
• Durability is the ability of a physical product to remain func onal, without requiring excessive
maintenance or repair, when faced with the challenges of normal opera on over its design life me.
• There are several measures of durability in use, including years of life, hours of use, and number of
opera onal cycles. In economics, goods with a long usable life are referred to as durable goods.
• Crashworthiness criteria such as energy absorp on & fracture, collapse mode, reac on force, and
mean load is evaluated to provide reference data for car design. With these tests, designer is able to
provide dynamic material data to its customers in order to propose the most appropriate material
solu ons that maximize safety for passengers.
• The durability of parts is a cri cal factor to consider in vehicle design as their complicated
components are subject to a wide array of complex stresses. In cars, material fa gue due to repeated
mechanical loading can lead to the damage of cri cal components.
• Also, as vehicles are mobile machines, they are subject to even more unpredictable degrees of
loading that can amplify the effects of fa gue on their parts. Moreover, because fa gue failure is
o en abrupt and difficult to detect, material providers must work to improve durability and ensure
longer fa gue life.
• EVs are more reliable than vehicles with internal combus on engines, which means they have
fewer parts. The average engine incorporates hundreds of moving parts that need to get maintained
and replaced, whereas your electric vehicle relies on a ba ery, transmission, and motor.
• Factors Affec ng Electric Car Durability
1) Electric Car Ba ery Type 2) Temperature 3) Ba ery Charging 4) Types of Vehicles
• Electric Car Ba ery Type: The ba ery life of electric vehicles, especially cars, varies depending on
the type and se ngs of the vehicle. However, in general, the average lifespan of an electric car
ba ery is between 10-15 years, or the equivalent of 200 thousand kilometres. In addi on, the life of
an electric car ba ery is also influenced by the type of ba ery used. Originally, the most widely used
type of electric car ba ery was lithium-ion (Li-ion). Li-ion ba eries will undergo a cycle of discharge
when driving and charging when plugged into the SPKLU. The cycle will have an impact on how much
power the ba ery can hold. Therefore, you must know how far the electric car can go before
recharging.
• Temperature: The ba ery life of an electric car is also affected by temperature. Temperatures that
are too cold or too hot can affect EV ba ery life. Hot temperatures have the poten al to make
electric car ba eries reduce their lifespan faster. Meanwhile, temperatures that are too cold can
make the mileage of electric cars shorter than warmer temperatures.
• Ba ery Charging: If overcharging will affect the efficiency of energy storage so that the ba ery
tends to run out faster. causing chemical changes in the ba ery itself. On the other hand, emptying
an electric car ba ery before charging is also not a good idea, considering that most li ion ba eries
work best when their capacity is between 50-80 percent. Charging the last 20 percent of the ba ery
also takes longer than the first 80 percent. The average electric car has a ba ery that can be used up
to 1000 mes fully recharged. However, every year, the ba ery life will decrease even though it can
s ll be used.
• Types of Vehicles: The ba ery life of electric cars is also affected by the type of vehicle. Therefore,
several types of electric car ba eries sold by manufacturers have a free ba ery replacement
warranty. It's just that, you have to pay a subscrip on fee to get these facili es. As addi onal
informa on, the durability of a good electric car can be seen from its power storage capacity. A good
endurance electric car has a high number of kilowa -hours (kWh). A high number of kWh is likened
to a larger gas tank. The larger the tank capacity or kilowa -hour, the more distance we can drive
without needing to stop.
Q15] Explain Fa gue analysis. List out the factors which affect the fa gue behaviour?
• Fa gue Analysis is the structural analysis of failure tendency of systems when subjected to cyclical
loads.
• Fa gue is the progressive and localized structural damage that occurs when a material is subjected
to cyclic loading.
• Con nued cycling of high-stress concentra ons may eventually cause a crack that propagates and
results in leakages. This failure mechanism is called fa gue.
• Damage once done during the fa gue process is cumula ve and normally unrecoverable.
• Fa gue analysis is performed to find out the sa sfactory performance level of a structural member
under cyclic loading. It es mates the performance of the member under all three stages of fa gue
failure. Means fa gue analysis will give data related to crack ini a on, crack propaga on, and finally
failure probability for a specific material.
• The factors which affect the fa gue behaviour are listed below:
1) Type and Nature of Loading.
2) Size of Component and stress or strain Distribu on.
3) Surface finish and Direc onal Proper es.
4) Stress or Strain Concentra on.
5) Mean stress or Strain.
6) Environmental Effects.
7) Metallurgical Factors and Material Proper es.
8) Strain Rate and Frequency Effects.
Q16] Explain the phases involved in Crashworthiness Design along with its important features?
Q50] Explain the phases involved in Crashworthiness Design along with its important features?
• For impact tests which influence the overall vehicle structure, these standard tests may be
categorized into four major groups: front impact, side impact, rear impact, and roll-over resistance.
• Crashworthiness is defined as the ability of materials to absorb impact energy by means of
controlled failure mechanisms and modes.
• The core idea of crashworthiness structure design is to preset a crumple zone, which can absorb
the kine c energy of vehicles during crashes, possibly lowering the accelera on. In a frontal crash,
for example, the s ffness of the front structure determines the accelera on pulse during a crash.
This pulse should have a specific shape, to minimize the risk for the occupant. During a massive
collision, there are three essen al phases, as follows:
• Crash ini a on phase: In this phase the sensor triggering for the belt pretensioner and the airbag
must take place. For op mal sensor triggering the front end of the car should be sufficiently s ff to
generate within a short me interval a velocity change that lies above the trigger value of about 6
km/h.
• Airbag deployment phase: In this phase the airbag is inflated, and the occupant ghtens the belts
while moving forward with a rela ve velocity with respect to the car. To minimize the injuries due to
the impact with the airbag, the decelera on of the car should be sufficiently low in this phase,
implying that the s ffness must be rela vely low.
• Occupant contact phase: In this phase the occupant has hit the airbag and there is a s ff contact
between the occupant and the car. In this phase, high decelera ons may occur because the occupant
will not be subjected to further shock loads caused by contacts with the interior. The frontal car
structure should be s ff enough to decelerate substan ally in the remaining me.
• Factors affect crashworthiness involves
1) Strength of the container (cockpit and cabin)
2) Adequacy of seats and restraint systems
3) Adequacy of energy a enua on systems
4) Injurious objects in the local environment of occupants
5) Post-crash factors, principally fire preven on and adequacy of escape routes
Q17] What do you mean by Topology and Topography Op miza on, explain with suitable
example?
• Topology op miza on is performed to iden fy the density of the required elements, whereas
topography op miza on is u lized to strengthen the structure of the lower seat by applying bead
parameters in the model.
• Topology op miza on is the mathema cal method which op mizes the structural layout of the
design space with the given load criteria, material, degree of freedom, constraints, and objec ve
func ons. This op miza on is limited only to linear sta c analysis for the simplifica on purpose;
however, it can also solve non-linear sta c simula on.
• The goal of topology op miza on is achieving the op mal performance of the structure, including
objec ves such as strength, s ffness and stability by using the least amount of material, the simplest
process, low cost. Depending on the simula on experiment and the experience of the tradi onal
op miza on design method is difficult to solve the design problems such as plane, automobile, ship,
mould and other large-scale complex structure parts and bridge, tunnel and other large engineering.
Topology op miza on method is becoming one of the key means to solve such problems.
• Topography op miza on is an advanced form of shape op miza on which u lize sheet structure
and changes it by adding stamped beads. In this way, s ffness is maximized without adding mass.
This approach is used for sheet metals only which has a thickness of 0.5 to 6mm. the cross-sec on is
an important parameter which is used as a design variable. Addi onal changes to the layout of the
design model cannot be made, however stress concentra on, displacement, compliance can be
minimized by modifying the shape of the design model.
• Topography op miza on helps manufacturers to design and op mize any thin-walled part. Like a
drum skin, these thin sheet structures can be easily excited, causing undesirable noise, vibra on and
even damage under certain condi ons.
• To improve the vibra on characteris cs, local shape modifica ons such as beads are added for
s ffness. Most of the me, the loca on, shape, and orienta on of these beads is based on the
natural geometry of the part and the designer’s experience. Topography op miza on enables
designers to define spaces where beads can and cannot be added, the width of the beads, as well as
the draw direc on, angle, and height. This means only prac cal designs are generated, with op mal
pa erns.
Q30] Explain the following parameters related to vehicle dynamics in detail,
i) Aerodynamic drag ii) Aerodynamic li iii) Side force iv) Rolling movement
i) Aerodynamic drag:
• Aerodynamic means the behaviour of the air moving rela ve to the car body. Aerodynamic drag is
also called air resistance.
• Air drags force acts in the direc on of vehicle mo on.
• The total aerodynamic drag of a vehicle includes many factors such as profile drag (57%), induced
drag (8%), skin fric on (10%), interference drag (15%) and cooling and ven la on drag (10%).
• The streamline of airflow around the vehicle should be con nuous and separa on of the boundary
layer with its a endant ver ces should be avoided. The skin drag coefficient should be decreased by
smooth and well-polished of the body surface.
• The accessories such as mirror, door handle aerials and badges which project outward from normal
surface of the body produce interference drag and projec on below the vehicle such as axle,
propeller sha , tow bar also contribute interference drag hence such projec on should be avoided.
ii) Aerodynamic li :
• It is the ver cal component of the resultant force caused by the pressure distribu on on the
vehicle body.
• The aerodynamic li and pitching moment are undesirable effects. The aerodynamic li tends to
reduce the pressure between the re and the ground. This causes the loss of steering on the front
axle and loss of trac on on the rear axle.
• Pitching causes rear wheel li off the ground and reduces available trac on. It is the rocking chair
or rota ng ac on about the transverse axis through the vehicle parallel to the ground. Due to
pitching, the front suspension moves out of phase with the rear resul ng in rocking effect in a
vehicle.
iii) Side force:
• The imbalance of the wheel due to centrifugal force acts on the vehicle during turning which
produces a side thrust.
• To sustain that force, the plane of the wheel makes some angle with the direc on of the mo on of
the vehicle. This is achieved by the direc on of the re which is flexible.
• The angled form during taking a turn to sustain the side thrust is known as slip angle and the force
produces to counteracts the side thrust is called a cornering force.
iv) Yawing movement (Bouncing):
• It is a ver cal movement of the complete body. When a complete body of the vehicle goes up and
down which is known as bounce or bouncing. Depending upon the movement of the front end or
rear end the bounce is known as front end bounce or rear-end bounce.
v) Rolling movement:
• It is the movement of a vehicle about its longitudinal axis produced due to centrifugal force act
during cornering.
• The retarding and cornering forces are applied at road levels but the center of gravity of a vehicle is
at a certain height. During cornering, a turning couple is produced about the longitudinal axis of the
vehicle owing to centrifugal force ac ng at the center of gravity and forces ac ng at the point of
contact of road and re patch. This results in a mo on known as rolling.
• A combina on of rolling and pitching is called diagonal pitch.
Q31] List out the feature of Electric Vehicle Dashboard considering suitable example of
2W/3W/4W.
Hour Meter + Speedometer + Voltmeter + Ampere Meter + Turning + Brake + Forward / Reverse
• instruments assemblages are designed for electric vehicles informa on indica on, integra ng
indica ng light, ampere meter, voltage meter, ba ery meter, hour meter, speed meter and odometer
into a single device panel.
• Features include:
1) A rac ve, easy-to-read, 8-character dot matrix Liquid Crystal Display enhances the look of any
vehicle.
2) Two display versions available: – Three LEDs: Green to indicate that hour meter is being displayed;
Amber to indicate that ba ery state-of-charge is being displayed; and Red to indicate that a fault has
occurred. – Six LEDs: Five Green to indicate ba ery state-of-charge; and one Red to indicate that a
fault has occurred.
3) Standard models display hours of use, ba ery state-of-charge and messages from a CURTIS motor
controller.
4) Interfaces directly to CURTIS motor controllers and displays various system parameters.
5) Moulded-in rear Molex style connector provides a low-cost, rugged and reliable installa on.
6) Front sealed (IP65) for use in harsh environments
Q32] What do you mean by ergonomics and aesthe cs aspects of EV? Explain in detail with
important features?
Ergonomics is a mul disciplinary science involving fields that have informa on about people (e.g.,
psychology, anthropometry, biomechanics, anatomy, physiology, psychophysics).
• It involves studying human characteris cs, capabili es, and limita ons and applying this
informa on to design and evaluate the equipment and systems that people use.
• The basic goal of ergonomics is to design equipment that will achieve the best possible fit between
the users (drivers) and the equipment (vehicle) such that the users’ safety (freedom from harm,
injury, and loss), comfort, convenience, performance, and efficiency (produc vity or increasing
output/input) are improved.
• The field of ergonomics is also called “human engineering,” “human factors engineering,”
“engineering psychology,” “man– machine systems,” or “human–machine interface design.”
Ergonomics Engineer’s Responsibili es in Vehicle Design
• Provide the vehicle design teams with needed ergonomics design guidelines, informa on, data,
analyses results, scorecards, and recommenda ons for product decisions at the right me (called the
“gateways” or “milestones”) in front of the right level of decision makers (involving design teams,
program managers, chief engineers, senior management, etc.).
• Apply available methods, models, and procedures (e.g., Society of Automo ve Engineers Inc. [SAE,
2009] and company prac ces) to address issues raised in the vehicle development process.
• Conduct quick-react studies (i.e., experiments) to answer ques ons raised during the vehicle
development process.
• Evaluate product/program assump ons, concepts, sketches, drawings, CAD models, physical
models/mock-ups/bucks, mechanical prototypes (called “mules” in the auto industry), prototype
vehicles, and produc on vehicles made by the manufacturer and its compe tors.
• Par cipate in the design and data collec on phases of drive clinics and market research clinics
involving concept vehicles and exis ng leading products as comparators (or controls).
• Obtain, review, and act on the customer feedback data from complaints, warranty, customer
sa sfac on surveys, market research data (e.g., J. D. Power survey data [J. D. Power and Associates,
2010]), inspec on surveys with owners, automo ve magazines, press, etc.
• Create ergonomics scorecards at selected program milestones during the vehicle development
process.
• Provide ergonomics consulta ons to members of the vehicle development teams.
• Perform long-term tasks: conduct research, translate research results into design guidelines, and
develop design tools.
Aesthe c aspects in electric vehicle
• The car aesthe c designer is responsible for the overall form and design of the vehicle but no just
so that it is beau ful to look at, they must consider the func onality and ease of use of their design
when the final vehicle is assembled.
• It is also known that aesthe cs has a major influence on a vehicle's desirability and subsequent
commercial success. Similarly, brand percep on of the vehicle manufacturer greatly influences
desirability and judgments of quality and is shown to be closely linked to aesthe c features.
• Aesthe cs is a core design principle that defines a design's pleasing quali es. In visual terms,
aesthe cs includes factors such as balance, colour, movement, pa ern, scale, shape and visual
weight. Designers use aesthe cs to complement their designs' usability, and so enhance func onality
with a rac ve layouts
Q33] Explain Noise Factors & Failure Modes in electric vehicle?
Q51] Explain Noise Factors & Failure Modes in electric vehicle?
• The noise factor, usually of an amplifier, is defined as the ra o of the signal to noise ra o at the
input to the signal to noise ra o at the output of the amplifier stage. It indicates the “noisiness” of
the amplifier.
• When moving at higher speeds, electric vehicles, or E.V.s, produce roughly the same wind and road
noise that I.C.E. vehicles do, but at lower speeds they operate in near-silence: electricity flows from
the ba ery to the motor, which spins with a barely audible hum.
• Most of an EV's life is spent opera ng between 25 and 50 miles per hour. At this speed, wind noise
is s ll minimal and motor noise is mostly masked by road and tyre noise. That means that the most
dominant noise experienced by drivers and passengers of EVs will mostly be road and tyre noise.
• When a motor runs, the commutator switches the direc on of the electricity that flows in the
windings. Though the system keeps the motor running, occasional spark occurs between brushes and
commutator at the ming of the commuta on. The spark is one of the causes of the electrical noise.
• Noise Factor is the measure of degrada on of the signal to noise ra o in a device. It is the ra o of
the Signal to Noise Ra o at the input to the Signal to Noise Ra o at the output. Since the signal to
noise ra o at the output will always be lower than the Signal to Noise ra o at the input, the Noise
Factor is always less than 1. The Lower Noise Factors results in be er performance of a devices.
• When categorizing noise, there are generally four main types: con nuous, intermi ent, impulsive,
and low-frequency. The main differen a ng factor between these types is how the noise changes
with me.
• The noise factor can be derived simply by taking the SNR at the input and dividing it by the SNR
(signal to noise ra o) at the output. As the SNR at the output will always be worse, i.e., lower, this
means that the noise factor is always greater than one.
• Noise figure (NF) and noise factor (F) are figures of merit that indicate degrada on of the signal-tonoise ra o (SNR) that is caused by components in a signal chain. These figures of merit are used to
evaluate the performance of an amplifier or a radio receiver, with lower values indica ng be er
performance.
Q34] Explain the important features of FMEA analysis in electric vehicle?
Lithium-ion ba ery failure may be due to several reasons. The below list provides some of the most
significant causes for safety-related failure.
Electrical over-stress
Thermal over-stress
Mechanical over-stress
Cell internal fault
• FMEA is “a systema c methodology to iden fy poten al failure mechanisms and models for all
poten al failure modes, and to priori ze failure mechanisms” and is the cornerstone of the physics
of failure approach to reliability assessment of systems, subsystems, and components.
• Failure mechanisms are iden fied as the “processes by which physical, electrical, chemical, and
mechanical stresses induce failures”, These mechanisms describe the fundamental manner in which
a device or component can fail.
• Failure modes, on the other hand, are defined as the manner by which a failure is physically
observed. The mode may not be easily observed in-situ; however, a complete failure analysis would
reveal the source of the failure.
• The failure cause is the driving force behind the failure mechanism, and can be the result of either
internal or external stresses. Finally, the failure effect is how the failure mechanism impacts the
usability of the device or component.
• It provides a comprehensive list of the parts within a lithium-ion ba ery that can fail or degrade,
the mode by which the failure is observed, the poten al causes of the failure, whether the failure is
brought on by progressive degrada on (wear out) or abrupt overstress, the frequency of occurrence,
the severity of failure, and the ease of detec on of the failure mechanism.
• Using this tool, we can find and evaluate the poten al failure modes of products or processes,
point out the weaknesses and possible defects judged according to experience as early as possible,
analyse the failure consequences and risks caused, and finally find measures to avoid or reduce these
poten al failures in the decision-making process.
Q43] List and explain with suitable sketches, the configura ons of possible drivetrain systems in
electric vehicle?
The choices of drivetrain systems in an EV include mainly: propulsion mode, such as front-wheel
drive, rear-wheel drive, or four-wheel drive; number of electric motors in a vehicle; drive
approach, for instance, indirect or direct drive; and number of transmission gear levels.
Hence, the possible drivetrain systems in EVs have the following six configura ons. 1) Conven onal
Type 2) Transmission-less Type 3) Cascade Type 4) In-wheel Type with Reduc on Gears and Directdrive Type 5) Four- wheel Direct-drive Type 6) Planetary gear type
Q45] What are Requirements of body structural system for a road vehicle?
• Space availability: There must be adequate space inside the body for the passenger & luggage
both.
• S ffness: The car body may be considered a rigid beam which is supported on wheels at each end.
The car body must have sufficient to prevent excessive sagging or bending in the middle.
• Strength: The body must be strong enough to withstand all tyres of forces to which the car is
subjected, which include the weight of car, passengers & luggage iner a & side forces. It should able
to cope with bad impacts of reasonable magnitude.
• Protec on against weather: The design of the body must be such that the occupants & luggage are
protected from bad weather.
• Tensional s ffness: The body should be sufficiently rigid to resist twis ng movement on rough
roads.
Q46] Explain causes for safety-related failure for lithium-ion ba ery?
Lithium-ion ba ery failure may be due to several reasons. The below list provides some of the most
significant causes for safety-related failure.
Electrical over-stress
Various components (e.g., transient suppressors and ba ery cells) are sensi ve to electrical
overstress and may fail thermally. An element can heat or ignite adjacent surfaces, crea ng electrical
product hazards such as fire. Overhea ng is possible to occur during the charge or discharge of the
lithium-ion cell. Installing a control circuit in the ba ery pack can help avoid such hazards and ensure
the cell’s correct opera on.
Thermal over-stress
Lithium-ion ba eries are sensi ve to temperature. Because of that, the ba ery cell must always
operate within a specific temperature range. When the temperature is below the recommended,
undesirable lithium pla ng may occur. Furthermore, ven ng of the ba ery cell can cause the
electrolyte to migrate to the circuit board of the ba ery pack or the product device. Consequently,
the electrolyte may cause propaga ng circuit board failures, leading to external hea ng of the cell
and forcing the cell into thermal runaway.
Mechanical over-stress
Safety issues can occur when the ba ery cell or the circuit is mechanically stressed or damaged.
Damage to any of these two components may lead to immediate ba ery failure or induce a defect
before the failure occurs. The cell’s failure mode depends on factors such as the extent of mechanical
damage, age of the cell, ambient temperature, and the state of charge. If there is mechanical stress
on the cell, the separator within the cell may fail, resul ng in an anode-to-cathode short circuit. If the
damage is to the circuit board, the result could be malfunc oning.
Cell internal fault
An internal cell fault can occur due to manufacturing defects, contaminated raw materials, improper
cell design and failed separators, among many. To minimize internal cell faults, the cell’s design and
manufacturing need to pass conformity evalua on. The cell design must comply with the technical
specifica ons of the relevant ba ery safety standards and receive safety cer fica on. The cell’s
manufacturing needs to be managed by safety audits and cer fica on. Implemen ng a quality
management system will help ensure the consistency of the manufacturing process
Q47] What do you mean by dynamics of motor vehicle? List out various force and performance
parameters consider in it?
• It is a combine study of interac on between driver, vehicle, road and environment.
• It mainly deals with, the improvement of ac ve safety and driving comfort and the reduc on of
road destruc on.
• The accelera on of the vehicle depends upon the power delivered by the propulsion unit, road
condi ons, aerodynamics shape and mass of the vehicle.
• General descrip on of the vehicle movement like trac ve force, rolling resistance, aerodynamic
drag and uphill (grading and accelera on) resistance.
• Longitudinal vehicle dynamics, Forces and mo ons in longitudinal direc on, smooth road surface
Predic ng top speed, accelera on and braking performances, gradeability, fuel consump on.
• Lateral vehicle dynamics, Forces and mo ons mainly in lateral direc on Predic ng cornering
performances, handling, stability.
• Ver cal vehicle dynamics, Forces and mo ons mainly in ver cal direc on Ride, vibra on behaviour,
er/road contact.
Forces ac ng on the vehicle
• Gravity effects
• Aerodynamic forces
• Tyre-road interac on
• Tyre behaviour (longitudinal and side slip)
• The dynamic equa on of vehicle mo on along the longitudinal direc on
Performance parameters
• Accelera on
• Top speed
• Gradeability
• Breaking performances
• Adhesion, Dynamic wheel radius and slip
Q49] Explain Vehicle Structure design against Noise and Vibra on exposure with suitable sketches?
Sources of NVH in Electric Vehicles Without an engine vibra ng and genera ng noise that would
normally cancel out certain squeaks and ra les, engineers are having to improve upon or create from
scratch solu ons to prevent or at least reduce NVH. Some of the sources of NVH that need to be
addressed include:
• Cooling Fans • Transmission • Road Noise • Brakes • Fluid Rou ng Lines • Wind • Actuators •
Alternator • Doors • Panel Holes • Moun ng Brackets
Solu ons Used to Reduce NVH
Non-Conduc ve A/C Line Grommets
• Custom rubber tube grommets reduce NVH by preven ng metal-to metal contact and limi ng the
movement of metal tubing. The custom designed internal ribs give the fluid rou ng line assembly
the ability to be flexible, while significantly reducing the amount of vibra on that occurs. And they’re
made with a custom EPDM rubber formula on that is non-conduc ve (developed by pulling out the
carbon black), aiding in the preven on of galvanic corrosion.
Metal Bracket Rubber Inserts
• Similar to the A/C line grommets, rubber inserts are designed specifically to prevent metal-to-metal
contact with the bracket and metal tubing, and reduce vibra on with it's ribbed design.
Butyl Patches
• Panel holes found throughout a vehicle’s body are typically covered with butyl foil patches (foil
backed with butyl adhesive). These work as a great way of sealing out liquids, as well as reducing the
amount of noise that enters a vehicle's cabin. In NVH applica ons, manufacturers typically go with a
thicker amount of butyl.
Rubber Panel Plugs
• Rubber panel plugs are another great way of covering a vehicle's panel openings. The ideal panel
plug is a small component that does three major things – it reduces noise transmission into the
cabin, it is water ght, and it installs with ease. Rubber panel plugs accomplish all three tasks, a feat
that is not easily duplicated.
• The general nature of plugs supplies an improved installa on quality, compared to butyl foil
patches, as they eliminate the tendency toward human error of not completely covering the hole.
EPDM panel plugs are also rubber, rather than plas c, which seals out moisture be er than plas c
and provides superior noise reduc on.
Rubber - An Ideal NVH Material
• Usage of rubber in NVH applica ons con nues to grow as the Electric Vehicle market climbs. Due
to its versa lity, high density, and consistency, rubber is an ideal NVH material. The high density of
rubber materials like EPDM gives it the ability to be er absorb sound and vibra ons compared to
plas cs, while its consistency allows sound and vibra on to be evenly distributed throughout the
material.
Retrofi ng and its associated Problems.
• EV retrofi ng means replacing the petrol engine with an electric powertrain. An electric motor
gets fixed in the rear wheel and engine parts get removed.
• Electric Vehicle Retro-fitment means to convert exis ng petrol or diesel run vehicles into an electric
vehicle. The process involves changing the original engine and other related components and a new
alterna ve energy source to be transplanted into the exis ng vehicle body. The retrofi ng will allow
people to con nue to use their costly vehicles rather than ge ng them scrapped, and will also be
beneficial for the environment.
• It can either be an addi onal system added to the exis ng vehicle motor or to completely replace
the exis ng engine with a new motor and drivetrain. All other components remain the same on the
vehicle, which makes it easier to replace or repair parts like suspension, brakes, headlights, etc.
• benefits of EV retrofi ng,
1) Zero Pollu on,
2) Less number of parts needed to produce the drivetrain as compared to a petrol or diesel fuel
which are made from nearly 350 parts, it is cost effec ve,
3) zero sound pollu on, heat is not generated, no vibra ons, reduc on of noise pollu on.
4) With the recent rule of scrapping 10-15 year old vehicles, the main benefit of retrofi ng is
increasing the lifespan of your vehicle especially if the vehicle is in good running condi on so there is
no need to compulsory re re your vehicle.
5) When the consump on of fossil fuel has reduced, the imports of fuel will be stopped, which will
automa cally control the air pollu on, and with the vehicles being retrofi ed new job opportuni es
are being generated for the EV industry.
6) From the customer’s point of view, retrofi ng reduces the running cost of the vehicle, prolongs
the life of the vehicle, and gives the pride of taking a step towards sustainability.
7) From society’s point of view, electric/hybrid vehicles are good for public health and cause less
harm to the global climate.
8) From the government’s point of view, retrofi ng reduce crude oil consump on, vehicular
emissions, and expenditure on oil imports
Q52] What are Human Characteris cs and Capabili es in ergonomics design of electric vehicle?
The human characteris cs and capabili es used in equipment design can be classified as follows:
A) Physical Capabili es
These can be measured by use of physical instruments (e.g., measuring tapes, rulers, calipers,
weighing scales, strength/force measuring gauges).
• Anthropometric characteris cs (which involve measurements of human body dimensions). The
measurements made when a human subject is sta onary (not moving) are called “sta c”
dimensions, which generally are taken when a subject is standing erect or si ng in an
anthropometric measurement chair (with ver cal torso and lower legs and horizontal upper legs).
The human body dimensions measured when a subject is in a work posture (e.g., si ng in a car seat
and performing a task) are called “func onal” anthropometric dimensions. Other measurements of
human body (and body segments) such as surface areas, volumes, center of gravity, and weights are
also considered to be part of anthropometry (science of human body dimensions; see Chapter 2 for
more details).
• Biomechanical characteris cs (e.g., ability to produce forces/strength and body movements.
B) Informa on-Processing Capabili es
• These are mental (cogni ve) capabili es involving the acquisi on of informa on through various
sensors (eye, ear, joint, ves bular ssues, etc.), transmi ng this sensed informa on to the brain,
recalling informa on stored in the memory, processing the informa on to make decisions (detec ng,
recognizing, comparing, selec ng, etc.), and making responses (e.g., motor ac on—genera ng a
body movement, ac va ng a control, or making a verbal response