Panel Discussion on Motors:
Permanent Magnet, Induction,
Switched Reluctance
Dave Fulton, Remy International
Prof. Chris Mi, University of Michigan – Dearborn
Prof. Zi-Qiang Zhu, University of Sheffield
William Cai, Jing-Jin Electric Technologies Co., Ltd.
November 16, 2011
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
1
Overview
•
•
•
•
Construction and Functional Differences (Dave Fulton)
System and Cost Considerations (Prof. Chris Mi)
Application Considerations and Recent Developments (Z.Q. Zhu)
System Issues and Control Strategies for Different HEV/EV Motors
(William Cai)
• Discussion
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
2
Construction and Functional Differences
David Fulton, P.E.
Director, Advanced Engineering
Remy International
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
3
Construction Differences
Permanent Magnet
Induction
Switched Reluctance
Permanent Magnet
Induction
Switched Reluctance
Rotor
- Interior PM
- Surface PM
(PM’s usually rare earth)
- Aluminum Bars
- Copper Bars
Only steel laminations
Stator
- Distributed Wind
- Concentrated Wind
(1 coil/tooth)
Distributed Wind
Concentrated Wind
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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PM Motor Types
Interior Permanent Magnet (IPM) Rotor
Distributed Wind (DW) Stator
Surface Permanent Magnet (SPM) Rotor
Concentrated Wind (CW) Stator
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
5
PM Motor Types
Interior Permanent Magnet (IPM) Rotor
Distributed Wind (DW) Stator
Surface Permanent Magnet (SPM) Rotor
Concentrated Wind (CW) Stator
• There are many types of PM motors, each with different strengths and weaknesses.
• PM machines can have distributed or concentrated stator windings.
• PM machines can have interior or surface PM rotors.
• Surface PM rotors can tolerate the largest air gap without substantial torque loss (no
reluctance torque contribution, as in interior PM rotors)
• Concentrated windings have shortest end turns, but also have less cooling surface area than
distributed windings.
• Concentrated windings have no phase overlaps, reducing chance of phase-to-phase shorts.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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PM Motors Advantages & Disadvantages
•
•
•
•
•
•
•
Currently, PM motors are the most popular
choice for HEV and EV applications
PM allows for highest torque density and
peak efficiency
Allows for wide range of constant power in
field weakening
Good designs have both low torque ripple
and low audible noise
Current designs use rare earth magnets for
highest torque density
Always has back-emf voltage present when
spinning
Efficiency drops in field weakening, due to
stator ohmic losses from negative d-axis
current
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
7
Induction (Asynchronous) Motors
Rotor Bars
(Cu or Al)
Distributed
Stator Winding
End Rings
(Cu or Al)
(image courtesy of Infolytica)
• No magnets
• Robust design
• Lower material and sensor cost than PM
• Relatively mature technology
• Induction machines can provide high power density with low torque ripple and
noise.
• IM’s use distributed stator windings, like IPM motors – offer possible contingency
plan for IPM to IM rotor change, if rare earth PM’s are no longer an economical
solution
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
8
Induction Motors
Stator ohmic losses
Rotor ohmic losses
I2
I1
V1
Part of stator ohmic
loss is due to
magnetizing current
IM
Per phase equivalent circuit
Not present in
PM motors
• Current is generated in rotor due to slip (difference in rotor speed and stator field
speed)
• Torque is generated by stator and rotor fields trying to align
• Compared to PM motors, induction motors have extra ohmic rotor and stator loss
• Magnetizing current increases with increasing air gap, so IM’s usually have smaller air
gaps than PM machines
• Medium constant power speed ratio (CPSR)
• Cooling an induction motor can be more difficult, due to its rotor heat generation.
Induction rotor itself is more tolerant of higher temperature than PM rotor, but heat
transferred from the rotor to stator or bearings must still be managed. Spray oil cooling
is well-suited for induction machines.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Performance Comparison: IPM vs. IM Rotor
Using same battery, inverter, cooling system, and stator.
Torque comparison between IPM, copper & aluminum IM rotors
400
Tp copper rotor
Peak
350
Tc copper rotor
Torque (Nm)
300
Tp IPM
250
Tc IPM
200
Tp aluminum
rotor
Tc aluminum
rotor
150
100
Continuous
50
0
0
1000
2000
3000
4000
5000
6000
Speed (rpm)
7000
8000
9000
10000
• Comparable low speed performance. At high speed, IM performance
dropped off faster than IPM.
• Depending on application needs, could boost system voltage to
maintain high speed performance.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Full Load Efficiency Comparison
Using same battery, inverter, cooling system, and stator.
Full load efficiency comparison: IPM, copper & aluminum IM rotors
1
0.9
0.8
Efficiency
0.7
0.6
0.5
0.4
IPM rotor
0.3
Copper rotor
0.2
Aluminum rotor
0.1
0
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Speed (rpm)
• Some compromise in efficiency at low speeds, but slight improvement
at high speeds.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
11
High Efficiency Zone Comparison
Using same battery, inverter, cooling system, and stator.
• As expected, induction rotors had a smaller “sweet spot” of high
efficiency. This may require a plan for increasing cooling system capacity.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Switched Reluctance – Pro’s
• Rugged and low cost design
• No magnets or bars in rotor, just laminations
• Concentrated wind has low end turn length and
no phase overlaps
• Peak efficiency is lower than PM motor, but
efficiency curve is flatter than PM’s, allowing high
efficiency over wider operating range
Stator and rotor of 3-phase SR motor
(courtesy SR Drives Ltd.)
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
13
Switched Reluctance – Con’s
Stator and rotor of 3-phase SR motor
(courtesy SR Drives Ltd.)
• For largest reluctance torque, need largest
difference between aligned and unaligned
inductance
• Noise from torque ripple, uneven radial forces,
and stator flexure
• Small air gap needed to give highest torque
density (aligned/unaligned inductance) and low
magnetizing current (highest efficiency)
• Higher windage loss due to rotor saliency
(unless rotor spaces are filled in – difficult at high
speeds, and adds cost)
• Independent phases require two motor cables
and connections per phase
• Higher phase count can reduce torque ripple,
but this requires more cables and connections
• Increasing stator yoke thickness (beyond
magnetic requirement) can reduce audible noise,
but at the expense of extra size and weight
• Can improve noise, but at expense of cost and
power density
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
14
Comparing Possible Failure Modes
Failure Mode
Distributed Wind
PM
Concentrated Wind
PM
Induction
Rotor burst
x
x
x
Demagnetization
x
x
Phase-to-Phase Short
x
Switched
Reluctance
x
Pole rub due to hot
rotor
x
x
Pole rub due to shock
loading or vibration
x
x
Uncontrolled generation
x
x
Fractured rotor bars
Noise
x
x
Vibration
x
x
Added possible failure modes do not necessarily mean the motor will
have lower reliability. It simply means that these must be properly
addressed in the design phase.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
15
System and Cost Considerations
Electric Motors for Electric Drive Vehicles
Chris Mi, Ph.D.
Associate Professor, Department of Electrical and Computer Engineering
Director, DTE Power Electronics Laboratory
University of Michigan-Dearborn
4901 Evergreen Road, Dearborn, MI 48128 USA
email: chrismi@umich.edu, Tel: (313) 583-6434, Fax: (313)583-6336
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Major Requirements of EDV Motors
• High instant power and a high power density
• High torque at low speeds for starting and climbing, as
well as high power at high speed for cruising
• Wide speed range, including constant-torque and
constant-power regions
• Fast torque response
• High efficiency over the wide speed and torque ranges
• High efficiency for regenerative braking
• High reliability and robustness for various vehicle
operating conditions
• Reasonable cost
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Types of EDV Motors
• DC motor
• IM
• PM brushless
motor
• SRM
"Electric Motor Drive Selection Issues for HEV Propulsion Systems: A
Comparative Study,“ Vehicular Technology, IEEE Transactions on 2006.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
18
Comparison of EDV Motors
"Electric Motor Drive Selection Issues for HEV Propulsion Systems: A
Comparative Study,“ Vehicular Technology, IEEE Transactions on 2006.
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Comparison Study
8 pole IPM motor
8 pole IM
18/12 SRM (3-phase)
"Comparison of different motor design drives for hybrid electric vehicles,"
Energy Conversion Congress and Exposition (ECCE), 2010 IEEE. 2010
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Efficiency Comparison
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Cost Comparison
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Weight Comparison
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Prius IPM motor
a) Structure
b) Flux line
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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2.5
2
1.5
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
Cogging torque (Nm)
Tp-p =3.7Nm
0
3
6
9
12
2.5
2
1.5
1
0.5
0
-0.5
-1
-1.5
-2
-2.5
15
Tp-p =4.3Nm
0
6
12
Time
(deg) (deg.)
Mechanical
angle
18
24
30
36
Mechanical angle (deg.)
FSPM
Prius - IPM
Torque (Nm)
Cogging torque (N·m)
Cogging Torque
25
20
15
10
5
0
-5
-10
-15
-20
-25
Tp-p =32.23Nm
0
60
120
180
240
300
360
Elec. degree (º)
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
25
T_avg (Nm)
450
400
350
300
250
200
150
100
50
0
I_250A
I_200A
I_100A
I_50A
0
Torque (Nm)
a) The output torque
versus inner power
angle at different
current (1200 rpm)
I_150A
10
20
500
450
400
350
300
250
200
150
100
50
0
30
40
50
ψ, deg
60
70
80
90
b) The output torque
versus electrical
angle(Ipeak=250A,Ψ=
50°)
Tavg =383.25Nm
Tripple =80.5Nm
0
60
120
180
240
300
360
Elec. degree (º)
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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FSPM Motor
PM
Stator
Rotor
Armature
winding
a) Structure
b) Flux line
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
27
300
T_250A
T_150A
T_50A
Torque (Nm)
250
200
150
100
50
0
-90
-60
-30
0
30
60
90
ψ (deg)
300
a) The output
torque versus inner
power angle at
different current
(1200 rpm)
Torque (Nm)
250
Tavg =268.78Nm
200
b) The output torque
versus electrical
angle(Ipeak=250A,Ψ
=0°)
Tripple =26.8Nm
150
100
50
0
0
60
120
180
240
300
360
Elec. degree (º)
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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DSPM Motor
Stator
PM
Armature
winding
Rotor
a) Structure
b) Flux line
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Torque (Nm)
250
200
150
100
50
10deg
0
-90
-60
-30
0
30
60
90
ψ (deg)
a) The output
torque versus inner
power angle at
different current
(1200 rpm)
300
Torque (Nm)
250
200
Tavg =236.5Nm
150
Tripple =82.13Nm
100
50
0
0
60
120
180
240
300
360
b) The output torque
versus electrical
angle(Ipeak=250A,Ψ
=10°)
Elec. degree (º)
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Primary Comparison Results
mass of stator iron
mass of rotor iron
Iron total mass
mass of PM
EMF(RMS)
Torque
Torque ripple
Cogging torque
Inner power angle
Input current (peak)
Prius
19.05
11.5793028
30.6293028
1.23881974
71.5
383.35
80.5
3.7
50
250
kg
kg
kg
kg
V
Nm
Nm
Nm
deg
A
FSPM_12/8
9.79283715
17.65089
27.4437271
2.47591237
71.2
268.78
26.8
4.3
0
250
kg
kg
kg
kg
V
Nm
Nm
Nm
deg
A
DSPM_12/10
20.04312165
14.01540744
34.05852908
3.24169202
70.5
236.5
82.13
32.23
10
250
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
kg
kg
kg
kg
V
Nm
Nm
Nm
deg
A
31
DOE GATE Center for Electric Drive Transportation
(Cedrive)
EV, PHEV,
EREV
Charger
V2G
Battery
management
Power
management
Silicon
carbide
devices
Applied
Research
Fundamental Transmission
Research shift dynamics
Electric
Drive
Vehicles
Interdisciplinary
Research
and fuzzy
based control
Vehicle
control
development
Reliability, diagnostics, prognostics, NVH, thermal management
Fund: DOE $1M; Automotive OEM/Supplier Consortium Membership
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Acknowledgement
Thanks to Mr. Ruiwu Cao for
his help with the presentation
and the simulation
Thanks to Authors of papers
referred to in this presentation
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Application Considerations
and Recent Innovations
Professor Z. Q. Zhu, PhD, CEng, Fellow IEEE
Head of Electrical Machines and Drives Research
Group Department of Electronic and Electrical
Engineering University of Sheffield
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Design Compromise of PM Brushless Machines
High speed
Low speed
High torque and high power over wide operation speed range often conflict
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Mismatch between Machine High Efficiency and Driving Cycles
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Motor Torque-speed Requirement for FUDS Driving Cycles
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Concerns of Rare-earth PM Machines
Advantages:
•
High torque density
•
High efficiency
Disadvantages:
•
Expensive magnet and limited resources
•
Irreversible demagnetisation
•
Not adjustable flux
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Variable Flux PM Machines
Means for varying flux:
•
Mechanical
•
Electric
Excitation flux path topology:
•
Series
•
Parallel
Coil excitation location:
•
Stator
•
Rotor
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Various Hybrid PM and Coil Excited Machines
Based on consequent-pole PMM
Based on hybrid stepper PMM
Based on claw-pole PMM
Based on switched flux
PMM
F2
B2
C1
A1
F1
C2
B1
F4
A1
Based on doublysalient PMM
B1
C2
F3
A2
F6
C1
B2
A2
F5
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
40
Based on SFPM machine
F2
C1
A1
A1
F1
F3
B1
Magnitude of fundamental back-emf (V)
An Example of Hybrid PM and Coil Excited Machine
7
6
5
4
3
10-rotor poles
11-rotor poles
2
13-rotor poles
1
14-rotor poles
0
-60
-40
-20
0
20
40
60
F6
F4
DC excitation current (A)
1.2
B1
1
C1
Torque (Nm)
F5
0.8
0.6
11-rotor poles, 2D FE
0.4
13-rotor poles, 2D FE
11-rotor poles, measured
0.2
13-rotor poles, measured
0
-20
-15
-10
-5
0
5
10
15
20
DC excitation current (A)
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Hybrid PM and Coil Excited Machines
Advantages:
 Easy to achieve constant power operation (flux weakening)
 Potentially enhanced low speed torque
 Reduced risk of high open-circuit back-emf at high speed during flux
weakening
 High efficiency operation possible
Disadvantages:
 Complicated structure
 Torque capability likely reduced
 Limited flux enhancing capability due to magnetic saturation
 Extra DC source required, or
 Extra mechanical means required
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Torque/Power, Speed, & Efficiency Requirements
• High torque/power density;
• High torque for starting, at
low speeds and hill
climbing, and high power for
high speed cruising;
• Wide operating speed
range;
• High efficiency over wide
speed and torque ranges,
particularly at low torque
operation (partial load);
• Intermittent overload
capability for short durations
PM brushless machines are inherently high efficient and high
torque dense, and is eminently suitable for EV/HEV applications
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Magnetless Machines
Switched reluctance machines:
•
•
•
Simple rotor
High torque ripple and acoustic noise
3-phase bipolar excitation – low torque
ripple and noise
Induction machines:
•
•
•
•
Mature technology
Excellent flux-weakening
performance
Copper rotor – high efficiency
Aluminum winding – low cost
Traditional magnetless machines are high
torque density machines and should be
reviewed !
SR machine with integrated flywheel and clutch for mild-hybrid
vehicle. Cranking: 45Nm (0-300rpm), continuous motoring:
200Nm (300-1000rpm), transient motoring: 20kW (10002500rpm), continuous generating: 15kW (600-2500rpm),
transient generating: 25kW (800-2500rpm).
120 Nm, 11.5kW at maximum speed of 7600 rpm,
26kW at base-speed of 2020rpm
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Comparison of IM, PM, and SR Machines
Induction
SR
PM
1. Specific Power and Power Density
kw/kg
1.0
0.93
kw/m3
1.0
0.95
1.33
1.26
2. Efficiency: Impact on EV Range
FUDS Range %
100
ECE Range %
100
93
105
100-105
105-110
3. Cost
1.0
1.1
1.2
4. Reliability
High
Higher
Lower
5. Major
advantages
Mature
technology
Simple
motor
High torque density
High efficiency
6. Major
disadvantages
Low
efficiency
Noisy
Torque ripple
High cost
Limited PM
resource
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Recent Development of Magnetless Machines
 Price for NdFeB magnets is soaring!
Synchronous reluctance machines and PM assisted
synchronous reluctance machines become attractive and under
extensive investigation
ABB have developed synchronous reluctance machine for industrial
applications. It shows improved efficiency over conventional induction
machines
(ABB)
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Recent Development of Magnetless Machines
Synchronous Reluctance Machine
 PM free machine
 Utilising reluctance torque
 Inherently failure safe and no need to protect
converters from over voltage
 Possible lower torque density
 Potentially lower efficiency and power factor
PM Assisted Synchronous Reluctance Machine
= Synchronous reluctance motor + Ferrite magnet
or a small amount of rare earth magnet
 IPM machine technology
 With added ferrite magnets or a small amount of rare
earth magnets, power density, efficiency and power
factor improved, but may be lower than conventional
IPM machine employing rare earth magnets (e.g. 75%)
 Excellent high speed power capability
 Ferrite magnets may experience demagnetisation
problem which can be solved by improving the design of
flux barriers and iron bridges
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Continental in series development of a SM axle drive system
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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Continental in series development of a SM axle drive system
240
short term (10s):
226 Nm
220
T / Nm
200
180
160
short term (60s):
180Nm ; 70kW
140
120
100
80
60
continuous (60min):
60Nm ; 35kW
40
20
0
0
2000
4000
6000
8000
10000
12000
n / rpm
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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System Issues and Control Strategies for
Different HEV/EV Motors
William Cai
Chief Technical Officer
Jing-Jin Electric
SAE 2011 Powertrain Electric Motors Symposium - Shanghai
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1. IPM Machines and Their Control Strategies
Torque/Current Control
SAE 2011
Electric
Motors
- Shanghai
SAE Powertrain
2011 Powertrain
Electric
MotorsSymposium
Symposium - Shanghai
51
Motoring Peak Torque & Power Performance
Power Factor
Power Factor
200
100
100
6000
8000
Speed(rpm)
0.99
0.95
0.96
0.97
0.98
0.88
0.93
0.9
0.82
0.84
0.86
0.8
0.75
0.7
0.6
10000
0
12000
0.88
0.45
20
5
0.3 0.3
00..
0.25
0.25 0.65
0.35
0.3
87
0.4
0.5
0.55
0.6
0.7
0.8
0.82
0.75
0.9950.45
0.86
0.88
0.84
0.9
0.95
0.96
0.97
0.98
0.99
0.93
0 1425
1
0
2000
4000
0.35
0.3
0.25
0.25 0.65
0.35
0.3
0.4
0.55
0.5
0.6
0.7
0.8
0.82
0.75
0.86
0.88
0.84
0.9
0.9950.45
0.95
0.96
0.97
0.98
0.99
0.93
1
6000
8000
Speed(rpm)
0.3
0.25 0.65
0.35
0.3
0.40.5
0.6
0.7
0.8
0.9
0.9950.45
1
10000
12000
Power factor with no PM
300
High Grade PM
Low Grade PM
NO PM
300
200
0.4
0.35
300
Power(kW)
300
4000
Torque(Nm)
0.4
40
Power factor at Low Grade PM
400
2000
60
0. 0
0.9
98 .9
95
0.93
0.93
0.93 0.95
0.9
0.960.95
0.960.95
9
0.96
0.97
0.97
0.97
0.98
0.98
0.98
0.93
0.95
0.96
0.97
0.98
0.98
0.93
0.95
0.96
0.97
0.93
0.95
0.96
0.97
0.98
0.82
0.84
0.86
0.88
0.9
0.82
0.84
0.86
0.88
0.9
0.82
0.84
0.86
0.88
0.9
0.75
0.8
0.75
0.8
0.75
0.8
0.65
0.7
0.65
0.7
0.65
0.7
0.55
0.6
0.55
0.6
0.55
0.6
0.45
0.5
0.45
0.5
0.45
0.5
0.35
0.4
0.35
0.4
0.35
0.4
0.25
0.3
0.25
0.3
0.25
0.3
0.15
0.2
0.15
0.2
0.15
0.2
0.05
0.1
0.05
0.1
0.05
0.1
2000
4000
6000
8000
10000
12000
Speed(rpm)
High Grade PM
Low Grade PM
NO PM
0
0
80
45
0.
0.995
0.65
0.4
5
0.4
Torque(Nm)
0.99
0.86
0.99
0.93
0.86
0.84
0.9
0.93
0.
9
0.995
0.88
0.9
400
Torque(N.m)
Torque(Nm)
0.86
0.99
0.97
0.96
Power factor at High Grade PM
0
0.8
8
0.45
100
0.45
12000
0.86
0.95
0.96
0.97
0.98
0.99
3658
0.5
.5
0
0000...65.87.98997
0
0.84
120
1
9
0.9
0.99
0.96
0.95
0.995
0.97
0.98
0.86
0.88
0.93
0.82
0.84
0.9
0.75
0.8
0.7
0.65
0.6
0.55
0.5
0.45
0.35
0.4
0.25
0.3
0.15
0.2
0.05
0.1
8000
10000
0.84
7
0.9
0.98
50
1
0.95
0.96
0.97
0.98
0.99
0.995
0.95
0.96
0.995
0.97
0.98
0.99
0.86
0.88
0.93
0.82
0.84
0.9
0.75
0.8
0.7
0.65
0.6
0.55
0.5
0.45
0.35
0.4
0.25
0.3
0.15
0.2
0.05
0.1
4000
6000
Speed(rpm)
5
99
0.
0.95
0.96
0.97
0.99
0.95
0.96
0.995
0.97
0.98
0.99
0.86
0.88
0.93
0.82
0.84
0.9
0.75
0.8
0.7
0.65
0.6
0.55
0.5
0.45
0.35
0.4
0.25
0.3
0.15
0.2
0.05
0.1
0
0
2000
0.995
0.93
0.9
3
150
100
0.99
8
0.9
0..9967
0 .95
0 .93
0 0.98
0.8
140
0.9
0.82
0.86
0.995
0.9
3
8
0.9
.967
00.95
0..993
0
8
0.95
0.96
0.97 0.995
0.99
0.9 1
0.9
100
160
0.96
0.95
0.93
8
0.90.8
0.9
0.9959
200
0.86 0.9
0.93
0.96
0.99
1 0.97
0.98
0.88
150
0.82
45
0.
0.98
0.5
0.55
1
0.86
0.88
0.8
250
95
0. .96
0
0.97
0.84
0.82
0.8
200
2
0.80.84
0.88
0.9
0.95
0.97
0.96
0.98
0.9
0.93
0.98 1
0.995
250
1
300
180
300
0.86
0.88
0.95
1
0.82
0.84
200
0.95
350
50
Power Factor
350
0.99
0.93
0.95
0.96
0.97
0.98
0.995
0.86
0.88
0.9
0.82
0.84
0.8
0.75
0.7
0.65 0.65
0.5
0.5
400
200
200
100
100
0
0
2000
4000
6000
8000
10000
0
12000
Speed(rpm)
Comparison among Strong PM, Weak PM and No PM
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375
250
300
200
225
150
150
100
Torque VS Speed Using SVPWM
Power VS Speed Using SVPWM
Torque VS Speed Using Six Step
Power VS Speed Using Six Step
75
0
0
2000
4000
6000
Power(kW)
Torque(N.m)
Impact of Voltage & Control Strategies on IPM Performance
50
0
8000 10000 12000
Speed(rpm)
SPWM vs. Six –step Controls at 120C & 320VDC
Motoring Power vs Speed@0~450V& Iphrms=690A,Winding Temp 120℃
Motoring Torque vs Speed@0~450V& Iphrms=690A,Winding Temp 120℃
350
450
400
350
300
45
0
40
0
0
25
40 0
0
30
30
0
25
0
20
0
300
30 0
200
250
150
250
200
200
22303
5400450
05000
Battery Voltage(VDC)
Torque@MaxVoltage
350
3445
0500
0
0
20
Torque(Nm)
250
40
0
35
0
200
150
Battery Voltage(VDC)
Power@MaxVoltage
45
0
0
25
250
45 0
300
0
35
0
20
300
Power(W)
200
0
00
300
250
35
5
350 440
100
50
50
22303
5400450
05000
100
0
0
2000
4000
6000
Speed(rpm)
8000
10000
12000
0
0
2000
4000
6000
Speed(rpm)
8000
10000
12000
Performance at different DC bus voltages
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Impact of characteristic current on IPM performance
1
2
3
(1)Characteristic current > Current circle
(2) Characteristic current = Current circle
(3) Characteristic current < Current circle
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2. Induction Machines and Their Control Strategies
0cos(2)1
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Speed and Torque Control Loops
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Compensation of Voltage & Frequency
Motoring
Braking
Sm
-Sm
ns
Generating
Kf = f / fN
Kf<1
Kf >1
Total compensation U/f
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Avoid frequency & optimal operating
Avoid Frequency area
I
1
Optimal Operation Point
i.e. T/I = min
Lower Kf to meet torque requirement
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A) P adjustment
B) Oscillating
C) I adjustment
D) PID adjustment
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3. Switch Reluctance Machine (SRM) Control
T ( , i ) 
1 2 L
1 2 dL
i

i
2

2
d
(a)
(b)
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Three Phase SRM Position Control & Chopping Control
Traditional Position Control
At 1500rpm and on = 38
Chopping Control
At 450rpm and c ≠360/qNr
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System Design ：Battery, Motor & Power Electronics
电池
Inverter fed three
phase brushless
DC motor drive
Motor design should be performed systematically, instead of component independent
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