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

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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

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Construction and Functional Differences David Fulton, P.E. Director, Advanced Engineering Remy International

SAE 2011 Powertrain Electric Motors Symposium - Shanghai

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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

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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

• 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

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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

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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

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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.)

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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

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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

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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: [email protected], 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

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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

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Cost Comparison

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Weight Comparison

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Prius IPM motor

a) Structure

b) Flux line

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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

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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

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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

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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

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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

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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

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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

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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

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System Issues and Control Strategies for Different HEV/EV Motors William Cai Chief Technical Officer Jing-Jin Electric

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1. IPM Machines and Their Control Strategies

Torque/Current Control

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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 SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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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 SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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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 SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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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

Kf1

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

SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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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)

SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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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

SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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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 SAE 2011 Electric Motors - Shanghai SAE Powertrain 2011 Powertrain Electric MotorsSymposium Symposium - Shanghai

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