2020 IEEE 13th International Conference on Developments in eSystems Engineering (DeSE)
2020 13th International Conference on Developments in eSystems Engineering (DeSE) | 978-1-6654-2238-3/20/$31.00 ©2020 IEEE | DOI: 10.1109/DeSE51703.2020.9450773
The Development of a Charger for the Formula
Student Electric Race Car
Alexander Gritsenko
Vladimir Shepelev
Alexander Lopukhov
South Ural State University
Chelyabinsk, Russia
South Ural State Agrarian University,
Troitsk, Russia
gritcenkoav@susu.ru
South Ural State University
Chelyabinsk, Russia
shepelevvd@susu.ru
South Ural State University
Chelyabinsk, Russia
lav2807@yandex.ru
Irina Makarova
Polina Buyvol
Gleb Parsin
Kazan Federal University
Naberezhnye Chelny, Russia
kamivm@mail.ru
Kazan Federal University
Naberezhnye Chelny, Russia
skyeyes@mail.ru
Kazan Federal University
Naberezhnye Chelny, Russia
Inf801.parsin@gmail.com
Abstract— Industry 4.0. with its inherent complexity of
technologies, digitalization and intellectualization encourages
universities to look for new innovative approaches in education to
provide students with advanced professional competencies. Formula
Student Electric is an international student competition consisting in
the development of racing cars followed by competitive races.
However, accidents can happen not only on the track, but also in the
garage. A big problem is charging batteries due to the complexity of
controlling such a long process. The market lacks ready-made
solutions meeting the requirements of the regulations. We developed
a schematic diagram of the charger and designed a simplified model
of the CC / CV charging process in Simulink. Theoretical
calculations show that the charging time of a battery with a capacity
of 100 Ah and a maximum voltage of 42 V, in the case of 30 A, took
3 hours 32 minutes to 100% and 1 hour 47 minutes to 50%, at in the
case of 20 A - 5 hours 15 minutes and 2 hours 40 minutes,
respectively. We selected the charger components. We designed a 3D
model of the rack in the SolidWorks software for the safe use of the
charger.
Keywords — electric race car, charger, model, energy transfer,
regulations.
I. INTRODUCTION
The accelerating growth of technologies, digitalization
and intellectualization characteristic of Indstria 4.0 prompts
universities to meet the challenge of providing students with the
knowledge necessary to solve complex, new and unpredictable
future challenges. All this requires adding an innovative
approach to the educational process. In contrast to traditional or
didactic teaching, the acquisition of engineering skills in
design, production and the ability to solve problems is
becoming more relevant than ever [1, 2]. In this sense, longterm project-based student activities are an example of effective
teaching in engineering education.
The SAE Formula, better known in Europe as
"Formula Student" (FS), is a student engineering competition
originally organized in 1978 by the Society of Automotive
Engineers (SAE) and a part of the SAE Collegiate Design
Series in the USA. According to the concept of the competition,
a team of university students is an engineering company that
should develop, build and test a prototype of a formula-class car
for the non-professional racing car market [3-6]. The vehicle
should have a very high performance in terms of acceleration,
braking and handling and be durable enough to successfully
compete in FSAE competitions. Additional design factors, such
as
aesthetics,
cost,
ergonomics,
maintainability,
manufacturability and reliability, should also be considered.
During this process, students will acquire competencies related
to the study of material structure, aerodynamics, suspension
dynamics, internal combustion engine, material selection and
manufacturing requirements [7]. Students are actively studying
and applying such promising areas as the use of carbon fiber to
lighten the structure to improve environmental and economic
indicators, additive technologies for the production of
individual components [8]. This becomes essential with the
growth of environmental requirements to vehicles and the
transition to alternative fuels [9, 10].
Since 2010, they were joined by the Formula Student
Electric series [6, 11-14]. At the moment, only 4 teams from
Russia develop in this direction [15-17]. An important task in
the development of vehicles with an electric drive is the design
of a charger combining a high level of safety and an acceptable
charging time [18]. In the student series, almost complete
freedom is given to designers, which translates into the
development of batteries of their own designs, i.e., there are no
standard solutions for solving the indicated problems. Fires
occur not only at the charging stage, but also during the race.
However, when the car is on the track, the situation is controlled
by several marshals with fire extinguishers ready to use, and the
pilot himself can de-energize the car in case of emergency. In
the case of charging the battery, the car is in the closed paddock
mode, that is, access to the car is limited and safety depends
only on the charger and security systems.
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363
2020 IEEE 13th International Conference on Developments in eSystems Engineering (DeSE)
The importance of the developments presented in the
article lies in the practical implementation of the charger for the
developed race car, the adaptability of the battery charging
modes, and the selection of protection system elements. This
race car will serve as a prototype for the manufacture of similar
race cars of analogous or larger power. The presented diagrams
of electronic components and devices can be adapted and
applied in common electric vehicles. Currently, most
mechanical engineering leaders seek to advance their
developments in the field of automotive electronics, circuitry
engineering, and automation. The timeliness of the presented
topic considered in the article lies in the essential need for the
practical implementation of electronic charging control circuits,
their widespread commercialization, and subsequent
improvement. This area of research is the most relevant in the
coming years of the transfer of transport from diesel and
gasoline ICEs to electric motors as a drive.
II. METHODS
The main requirements to be met are contained in the
annual set of competition rules - regulations [16]. In total, there
are 8 points related to the charger:
EV.10.3.1 Only chargers presented and sealed during the
technical inspection are permitted.
EV.10.3.2 All chargers shall meet one of the following
requirements:
• The device is accredited according to a recognized
standard (eg CE);
• Chargers manufactured by the team shall meet all
electrical requirements for the vehicle's traction system.
EV.10.3.3 All charger connections shall be insulated and
free from open areas that could pose a hazard in case of contact.
EV.10.3.4 The charger connector shall be interlocked so
that neither side of the connector is live, unless it is properly
connected to the battery.
EV.10.3.5 High voltage charging wires shall be orange.
EV.10.3.6 The charger shall be equipped with two TSMP
(traction measuring points) connected to the positive and
negative outputs of the charger, and be accessible when
charging any battery.
EV.10.3.7 During charging, the AMS (Battery
Management System) shall be energized and able to disconnect
the charger if a fault is detected.
EV.10.3.8 When charging the battery, the isolation monitor
shall be switched on and able to disconnect the charger.
Either the charger shall include an active IMD in its
design, or the active IMD shall be in the battery container.
The development of the memory begins with the
accumulation of all the information on the car: battery
characteristics, data of auxiliary systems, types of connectors
and their number [19-22].
The Project N0 electric bumper has two battery containers
with a total maximum voltage of 84 V and a capacity of 100 Ah.
Each of the containers is equipped with 24 LiFePO4
batteries with a total maximum voltage of 42 V. EVE LF5073103 LiFePO4 battery is used as a battery.
The battery is connected to the traction system through
special connectors that are designed for electric vehicles and
can withstand continuous loads. In our case, the
HVSL800022A1H6 connector is used, it is designed for a rated
current of 180 A and a register diameter of 35 to 50 mm2.
Also, according to the rules of the competition, two
insulation control relays (contactors) are installed in the
container for the positive and negative wires of the battery
power supply. In our case, we use JQX-200-12HD contactors
with a supply voltage of 12 V. When the insulation monitoring
device is triggered, they break the circuit, thereby disconnecting
the battery from the traction system.
The contactors are powered by the low voltage system, so
other connectors are used for them, in our case it is SP2113 / P9.
The schematic diagram will give a general understanding
of the operation, device and connection diagram of the charger.
Simulation is performed in the sPlan program.
Different voltages can be supplied either through the use
of two power sources, or one power source and a voltage
converter. The process of transferring energy from the power
sources to the battery is carried out separately. Also, according
to the regulations, the insulation monitoring device shall be
powered from a separate power source - therefore, the charging
scheme is permissible only through the use of two power
sources [23-25].
Figure 1 - Schematic diagram
CC / CV charging type consists in the initial supply of a
constant high current, with a gradual increase in the supply
voltage. After reaching the maximum voltage, charging
continues with a constant voltage and a gradual decrease in the
current value to zero.
To simulate the charging process, we developed a charger
model in the Matlab Simulink program. Two situations were
simulated: charging with a current of 30 A and 20 A. The
charging time in the case of 30 A took 3 hours 32 minutes to
100% and 1 hour 47 minutes to 50%, in the case of 20 A - 5
hours 15 minutes and 2 hours 40 minutes, respectively.
Charging simulation charts are shown in Figures 2 and 3.
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2020 IEEE 13th International Conference on Developments in eSystems Engineering (DeSE)
wide variation of the current and charging voltage; the
presented model allows us to ensure the battery charging time
specified in the regulations and the completeness of charging;
we presented the practical implementation of the race car
charger and means to automate its operation and security.
The presented article is a structurally elaborated
material set forth strictly according to the work stages, from
analyzing the well-known scientific works in this area of
research to the practical implementation of the battery charging
systems, their protection, and reliable operation. The quality of
presenting the article is confirmed by the logical structure, the
thoroughly elaborated text, figures, and tables. The analysis of
the materials following the graphic objects fully reveals the
essence of the above studies. The standard of written English
corresponds to the technical level of the article and meets the
requirements of the international rules for writing and
formatting printed materials.
Figure 2 - Charging graph at a current of 20 A
III. RESULTS
Figure 3 - Charging graph at a current of 30A
The resulting necessary data on the device and the
characteristics of the charger allows us to select components.
The technical content of the materials presented in the
article includes a detailed description of the charger
implementation schemes, elements of its automation, and
protection means. The scientific rigor is ensured by the
adequacy of the applied statistical methods for calculating
electrical quantities in theoretical modeling, practical
calculations, and engineering experiment. In the calculations
made during simulation, we took into account statistical and
data calculation errors, which are in the range of 1-3%,
depending on the combination of charging conditions. The
reliability of the presented data was assessed by comparing the
probabilities of a correct and false estimated result. The
calculated reliability was 0.92-0.96, depending on the recorded
parameter of the battery charging process in operation.
The validity of the used models is explained by a
considerable convergence of the simulation results with the real
measurements. The convergence of the theoretical and practical
(experimental) data was 0.9-0.96. The completeness of the
above analysis of the graphic and table material proves and
reveals the main results of the article. The thoroughness of
studying the scientific treatise is confirmed by the logic of its
presentation and the completeness of disclosing the material,
which is consistent with the existing works of this area of
research.
The novelty and originality of the ideas presented in
the materials of the article lie in the following: we developed a
charger model in the Matlab Simulink program, which allows
us to simulate the operation of system components in the entire
range of the possible operating conditions of a race car; we
developed and graphically presented a model for the
implementation of the battery charger in an adaptive mode at a
According to the proposed scheme, you need two power
supplies with a minimum possible voltage of 12 V and a
maximum voltage of at least 42 V. The PS6030 model is
suitable as per these requirements. For the developed charger,
two similar devices are needed to power the low-voltage and
high-voltage lines.
TABLE I.
PS6030 POWER SUPPLY SPECIFICATIONS
Supply voltage, V
220 V
Output voltage, V
0-60 V
Output current, A
0-30 A
The next mandatory component needed according to the
requirements of the regulations is the insulation monitoring
device (IMD). In our case, this is a Bender A-ISOMETER ®
iso-F1 IR155-3203 device.
TABLE II.
CHARACTERISTICS OF THE INSULATION MONITORING DEVICE
TABLE TYPE STYLES
Supply voltage, V
12/24 V
Consumption current, mA
150 mA
The size of the measured
resistance, MOhm
0…10 MOhm
Also, according to the requirements of the regulation, the
presence of two measuring points (TSMP) is mandatory, there
are no requirements for the design or type of connectors. The
following connectors were matched: SEB6452-SW (black) and
SEB6452 / RT (red). From the technical point of view, the
connectors are identical.
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2020 IEEE 13th International Conference on Developments in eSystems Engineering (DeSE)
TABLE III.
CHARACTERISTICS OF TSMP CONNECTORS
Rated voltage, V
1000 V (constant pressure)
Connector type
«Banana», 4 mm
Rated current, A
32 A
Contact resistance, mOhm
7
The contactor installed on the low-voltage positive line is
IMD-controlled. The peculiarity of its use is that it is actually a
backup for contactors installed on the positive and negative
outputs of the high-voltage system of battery containers. Thus,
only 3 units of JQX-200-12HD contactors are needed, but only
one is needed for the charger to operate.
The following are the indication and emergency shutdown
systems: an indicator, an audio speaker and a power button. The
indicator is a red LED signal lamp, the supply voltage is 36V.
The sound speaker is an ordinary beep with a supply voltage of
36-72 V. The power button is actually an emergency shutdown
button with latching, similar buttons are used in the electric car
for emergency shutdown of the power system, the supply
voltage is up to 220 V.
For a wired charger, it is important to choose the right
charging connectors, in our case, these are mating parts to the
connectors described in the review of the battery container.
To transfer energy to the batteries, you can use the
HVSL800062A150 connector, with a fixing bracket that allows
you to firmly fix the resulting connection, and also prevents
incorrect connection to the battery container. One item is
required.
TABLE IV.
POWER CONNECTOR SPECIFICATIONS
Maximum voltage, V
1000 V
Rated current, A
180 A
For connection to a low-voltage system, a female
connector SP1310 / S9I is suitable. Also only one item is
needed.
TABLE V.
CONNECTOR CHARACTERISTICS
Rated voltage, В
125 V
Rated current, А
3A
The power wires of the traction system must be shielded,
and in order to increase safety during maintenance, they must
be orange.
The most common conductor materials are aluminum and
copper. Therefore, the choice of wire material will be based on
a general analysis of the following parameters: density of
metals, resistivity of metals, tensile strength, thermal
conductivity, permissible continuous current for wires.
Despite the fact that, with the same cross-section, the
density, and, accordingly, the mass of aluminum wires is 3.26
times less than that of copper wires, the latter surpass them in
all other parameters. The tensile strength of copper wires is 2.17
times higher, which is important in conditions of repair work in
a box.
The selected power source can supply a maximum of 30 A,
with a margin of more than 50% in terms of the current value, a
wire with a cross section of 6 squares is suitable, however, the
minimum possible cross section for a wire that meets all the
requirements of the regulations is 10 mm2 [18, 26-28].
The ÖLFLEX® FD 90 CY wire from LappGroup is
suitable for these requirements, it is a shielded single-core
power cable for universal use in power circuits, UL / CSA
AWM certified (Canada and USA). The charger requires 16
meters of cable. The maximum operating voltage of the wire is
up to 1000 V.
For the wires supplying the contactors and the insulation
monitoring device, such strict requirements are not provided,
therefore, simple single-core wires ПУГВ 1х0.75 of red and
black colors, cross-section 0.75 mm2 were chosen. For the
charger to function, you need 10 meters of each of the wires.
TABLE VI.
CHARACTERISTICS OF CONTACTOR POWER WIRES
Maximum voltage, V
750 V
Rated current, A
15 A
The total cost of the charger was 134,400 rubles.
The battery charging process of the electric race car takes
place in a paddock or garage, that is, in a potentially hazardous
work area. To optimize the charging process and minimize
possible accidents, it is necessary to design a special rack that
allows you to comfortably charge the batteries of the electric
car.
The rack should ensure convenient movement of the
charger, as well as securely fix it and have a separate display
panel with emergency indication. You can also bring tools and
accessories to the electric car on the rack.
In SolidWorks 2018, we designed a sketched 3D model of
a rack with three shelves. The dimensions of the resulting rack
are 600x420x725 mm. The appearance of the product with an
installed indication panel and power supplies is shown in Fig.
4.
The power supplies are installed on the middle shelf, a
warning lamp, an emergency shutdown button, an emergency
warning speaker and two measuring points are displayed on the
display panel.
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2020 IEEE 13th International Conference on Developments in eSystems Engineering (DeSE)
Figure 4 - Sketch of a rack with an installed charger
IV. CONCLUSION
The rules of the competition were analyzed and the points
relating to the development of the charger were highlighted.
We developed a schematic diagram of a charger based on
two power sources 42 V and 12 V has. We built a simplified
model showing the charging process according to the CC / CV
combined type. Two charging options are simulated: with a
current of 30 A and 20 A, the theoretical charging time was in
the case of 30 A, it took 3 hours 32 minutes to 100% and 1 hour
47 minutes to 50%, in the case of 20 A - 5 hours 15 minutes and
2 hours 40 minutes, respectively.
We selected optimal components for assembling the
charger. The total cost of the charger is 134,440 rubles. We
designed a 3D model of the rack for the safe movement of the
charger around the garage.
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