High-efficient, ultra compact integrated
electric drives for tomorrow’s
alternative drivetrains
Mojgan Nikouei-Harnefors,
Funding period: 2013-08-01 – 2015-03-31
Dept. Electrical Energy Conversion, KTH Royal Institute of Technology
Swedish Hybrid Vehicle Centre (SHC)
Granted funding: 1.58 MSEK
Mojgan Nikouei Harnefors| SHC
1
Motivation
Producibility
Cost
Size/Weight
Integration
EMI
Cabling
Fault tolerance
Mojgan Nikouei Harnefors| SHC
Loss
2
Integrated drives (examples)
Volvo ReCharge
Mojgan Nikouei Harnefors| SHC
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Project overview
Low-voltage MOSFETs
Torque/ speed
Gear box limitations
Specifications
Short circuit protection during
short circuit
Battery technology
Level of fault
tolerance of the
electric machine and
power electronics
Interleaved switching to
minimize battery losses?
Performance
Power converter
Total drive cycle
losses
Converter control first evaluated
on the real time simulator
DC-voltage sharing
between modules
Torque dynamics
and voltage stability
during transient
Should battery be splitted into
several, parallel modules?
Non-electrolytic capacitors
Control
Integrated
electric drive
Where to place the modules?
(close to end windings or in axial
middle)
Control in fault modes
Water or oil or only
air?
Forced air cooling on
heat sinks integrated in
chassies
1,2 or 3 coolant loops
Parallel or series
connection of coolant
loops
Mojgan Nikouei Harnefors| SHC
Concentrated windings where
each 3-phase set makes up a
module
Cooling
Electric machine
Thermal teeth?
Rotor ferrites+SynRel
Coolant loop design
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Project overview
Project team
Ph.D student
Funding
Supervisor
Swedish hybrid
vehicle center (SHC)
Oskar Wallmark
Mojgan Nikouei
Harnefors
Mats Leksell
Hui Zhang
Lebing Jin
Mojgan Nikouei Harnefors| SHC
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Stacked polyphase bridges (SPB)
Power converter
Electric machine
Battery
1.
PCB Cell
SPI
CS1
CS2
CSN
Multiplestar
PMSM
Central DSP
Mojgan Nikouei Harnefors| SHC
2.
PCB Cell
N.
PCB Cell
RS 232
PC
USB
PC
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Machine considerations
Fractional-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
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Control considerations
Converter sub module
- Current control
- Field weakening
Master control
- DC-link voltage control and communication (ongoing work)
- Fault handling (ongoing work)
Mojgan Nikouei Harnefors| SHC
8
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, nonelectrolytic capacitors
• Potential fault tolerance (limp home) is “in built”
9/31
Mojgan Nikouei Harnefors| SHC
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Future/ongoing work
•
•
•
•
•
•
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
10/31
Mojgan Nikouei Harnefors| SHC
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High-efficient, ultra compact integrated
electric drives for tomorrow’s
alternative drivetrains
Mojgan Nikouei-Harnefors,
Funding period: 2013-08-01 – 2015-03-31
Dept. Electrical Energy Conversion, KTH Royal Institute of Technology
Swedish Hybrid Vehicle Centre (SHC)
Granted funding: 1.58 MSEK
Mojgan Nikouei Harnefors| SHC
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