Mojgan Nikouei Harnefors| SHC 1

Mojgan Nikouei-Harnefors, Funding period: 2013-08-01 – 2015-03-31

Dept. Electrical Energy Conversion, KTH Royal Institute of TechnologySwedish Hybrid Vehicle Centre (SHC)

Granted funding: 1.58 MSEK

High-efficient, ultra compact integrated electric drives for tomorrow’s

alternative drivetrains

Mojgan Nikouei Harnefors| SHC 2

Motivation

Producibility Size/WeightCost

EMI Cabling

Fault tolerance Loss

Integration

Mojgan Nikouei Harnefors| SHC 3

Integrated drives (examples)

Volvo ReCharge

Mojgan Nikouei Harnefors| SHC 4

Project overviewGear box limitations

Torque/ speed

Battery technology

Specifications

Torque dynamics and voltage stability

during transient

DC-voltage sharing between modules

Control in fault modes

Control

Forced air cooling on heat sinks integrated in

chassies

Water or oil or only air?

1,2 or 3 coolant loops

Cooling

Parallel or series connection of coolant

loops

Short circuit protection during short circuit

Low-voltage MOSFETs

Power converter

Interleaved switching to minimize battery losses?

Non-electrolytic capacitors

Where to place the modules?(close to end windings or in axial

middle)

Should battery be splitted into several, parallel modules?

Converter control first evaluated on the real time simulator

Thermal teeth?

Concentrated windings where each 3-phase set makes up a

module

Electric machine

Rotor ferrites+SynRel

Coolant loop design

Integrated electric drive

Performance

Level of fault tolerance of the

electric machine and power electronics

Total drive cycle losses

Mojgan Nikouei Harnefors| SHC 5

Project overview

Funding Ph.D studentSupervisor

Project team

Mojgan Nikouei Harnefors

Hui Zhang

Lebing J in

Oskar Wallmark

Mats Leksell

Swedish hybrid vehicle center (SHC)

Mojgan Nikouei Harnefors| SHC 6

1.

2.

N.

Multiple-star

PMSM

PCB Cell

PCB Cell

PCB Cell

CS1

CS2

CSNSPI

Central DSP

PC

PC

RS 232

USB

Battery

Power converter Electric machine

Stacked polyphase bridges (SPB)

Mojgan Nikouei Harnefors| SHC 7

Machine considerationsFractional-slot concentrated-winding (FSCW)- Short end-turns- Low cogging torque- High slot filling factor (segmented stator)

Challenges- Suitable slot/pole combinations to obtain:

- High fundamental winding factor- Low rotor losses- Ease of integration (identical converter sub modules)

- Fault tolerance to handle a converter sub module fault

Mojgan Nikouei Harnefors| SHC 8

Control considerationsConverter sub module- Current control- Field weakening

Master control- DC-link voltage control and communication (ongoing work)- Fault handling (ongoing work)

Mojgan Nikouei Harnefors| SHC 9

Technical summary

• New method of machine and converter integration• New converter topology (SPB converter)

• Low voltage Si MOSFETs provide very high efficiencies and allows reasonably high junction temperatures• Future GaN may enable even lower losses• Low voltage, high switch frequency → very small, non-

electrolytic capacitors• Potential fault tolerance (limp home) is “in built”

9/31

Mojgan Nikouei Harnefors| SHC 10

• Refine the design of the electric machine• Develop a robust control technique• Evaluate tolerance to faults• Investigate power electronic manufacturing techniques• Full-scale prototype evaluation• Identify suitable applications for the converter topology

Future/ongoing work

10/31

Mojgan Nikouei Harnefors| SHC 11

Mojgan Nikouei-Harnefors, Funding period: 2013-08-01 – 2015-03-31

Dept. Electrical Energy Conversion, KTH Royal Institute of TechnologySwedish Hybrid Vehicle Centre (SHC)

Granted funding: 1.58 MSEK

High-efficient, ultra compact integrated electric drives for tomorrow’s

alternative drivetrains