We acknowledge the support of the NaturalSciences and Engineering Council of Canada(NSERC), which invests annually over $1billion in people, discovery and innovation.

EECOMOBILITY (ORF) &HEVPD&D CREATE

We acknowledge the support ofthe Ontario Research Fund:Research Excellence Program.

Multiphase Drives for EV ApplicationsCentre for Mechatronics and Hybrid TechnologyElectrical and Computer Engineering, McMaster UniversityAhmed Salem

Why Multiphase Drives

Modulation Techniques1. Space Vector Modulation (SVPWM) Based on

Vector Space Decomposition (VSD):Pros:• Full control of voltage vectors in different subspaces• Compensation of non-torque production harmonics.Cons:• Requires high computational power.• Requires additional controllers to compensate the effects ofmachine back EMF’s.

Sa1

Sa2

Sa3Sa4

Sa5

Sa6

Sa1

Sa2

Sa3Sa4

Sa5

Sa6

—

A

— —

— —

—

-

+

Vdc

Multiphase Drives Features:1. Lower Power/Current Rating per Phase.2. Fault-tolerance operation.3. Torque density improvement.4. Lower Dc-Link Current Ripples.

Calculate Ixy0+0-*

Calculate Loss function

Min(Loss) using global

Optimization A

Increase Tref & evaluate Iαβ*

Possible global Minima

No

A

Applying constraints

Calculating Ia1b1c1a2b2

Yes

Record Values of K in look up table against

the Tref

End

Il <= In (l = a1, b1, c1, a2, b2)& Ic2 =0

Start

Project StatementObjectives:• Develop a six-phase

inverter based on the requirements of the drive.

• Reduce the size of the DC-link bank of capacitors.

Tasks:• Literature review on multiphase

drives.• Build up a scaled down prototype

of six-phase inverter.• Developing new control technique.• Developing new switching

technique for the capacitor sizing.

The figure shows a schematic of one phase-leg of the inverterused in Tesla Model S which has for the upper part 6 switchesconnected in parallel. The inverter comprises of 36 IGBT in total.The multiphase concept overcomes the problems associatedwith paralleling IGBT’s.

c2 b1c1b2 a2

30º

120º 120º n

C2 B1C1B2 A2

N

- +Vdc

A1

a1

3-Phase Inverter

3-Phase Inverter

T1

Fault-Tolerance Capability

8, 42

27

10

3 , 59

1714

24, 31

19

26

18

302, 58

51

16, 23

28

5022

6, 62

20

54 48, 55

38

56

60, 4

53

36

39, 32

44

37

61, 5

494621

3412

35

29

47

16,

27

52922

45

26

36

1154

41

18

37

45,

3534

42

46

14 44

10

38

43 50

59, 339, 32

58, 2

47, 40

6, 62

8, 15

30

12

4, 60

13 20

5, 6124, 31

2928

0+

0-

0, 9, 10, 12, 17, 18, 20, 27, 29, 30, 33, 33, 32, 36, 43, 45, 46, 51, 53, 54, 63

8, 16, 25, 26, 28, 32, 41, 42, 44, , 49, 50, 52, ,59, 61, 62

24, 40, 48, 57, 58, 60

56

1, 2, 4, 11, 13, 14, 19, 21, 22, 31, 35, 37, 38, 47, 55

7

3, 5, 6, 15, 23, 39

2. SVPWM based on voltage classification method

Using two references Using one reference

Pros: Simple technique in implementationCons: Unable to eliminate the xy subspace harmonics.

• Unlike Three-phase drives, Multiphase drives operates with hightorque range under faulty conditions.• Three-phase drives has 29% maximum output torque withoutput torque ripples under optimal current control.• Six-phase Drives under one-phase loss can operate up till69.5% under optimal current control with no torque ripples andminimum losses..Remedial Solution to increase the torque range under single-phase faults:• The proposal is to provide a neutral connection to the dc-linkmidpoint and by applying global optimization the torque rangereaches 81.6% which represents 11% increasement.

Results:

0 10 20 30 40 50 60 70 80 90 100

Torque Range %

0

20

40

60

80

100

Stat

or C

oppe

r Los

s %

Without Neutral

With Neutral

Healthy