High Performance Cooling of Traction Brushless Machines
Doktorsavhandling, 2021
The work presented in this thesis covers several aspects of traction electric drive system design. Particular attention is given to the traction electrical machine with focus on the cooling solution, thermal modelling and testing.
A 60 kW peak power traction machine is designed to achieve high power density and high efficiency thanks to direct oil cooling. The machine selected has a tooth coil winding, also defined as non-overlapping fractional slot concentrated winding. This winding concept is state of the art for many applications with high volumes and powers below 10 kW. Also, these have been proven successful in high power applications such as wind power generators. In this thesis, it is shown that this technology is promising also for traction machines and, with some suggested design solutions, can present certain unique advantages when it comes to manufacturing and cooling.
The traction machine in this work is designed for a small two-seater electric vehicle but could as well be used in a parallel hybrid. The proposed solution has the advantage of having a simple winding design and of integrating the cooling within the stator slot and core. A prototype of the machine has been built and tested, showing that the machine can operate with current densities of up to 35 A/mm^2 for 30 seconds and 25 A/mm^2 continuously. This results in a net power density of the built prototype of 24 kW/l and a gross power density of 8 kW/l with a peak efficiency above 94%. It is shown that a version of the same design optimized for mass manufacturing has the potential of having a gross power density of 15.5 kW/l which would be comparable with the best in class traction machines found on the automotive industry.
The cooling solution proposed is resulting in significantly lower winding temperature and an efficiency gain between 1.5% and 3.5% points, depending on the drivecycle, compared to an external jacket cooling, which is a common solution for traction motors.
A 60 kW peak power traction machine is designed to achieve high power density and high efficiency thanks to direct oil cooling. The machine selected has a tooth coil winding, also defined as non-overlapping fractional slot concentrated winding. This winding concept is state of the art for many applications with high volumes and powers below 10 kW. Also, these have been proven successful in high power applications such as wind power generators. In this thesis, it is shown that this technology is promising also for traction machines and, with some suggested design solutions, can present certain unique advantages when it comes to manufacturing and cooling.
The traction machine in this work is designed for a small two-seater electric vehicle but could as well be used in a parallel hybrid. The proposed solution has the advantage of having a simple winding design and of integrating the cooling within the stator slot and core. A prototype of the machine has been built and tested, showing that the machine can operate with current densities of up to 35 A/mm^2 for 30 seconds and 25 A/mm^2 continuously. This results in a net power density of the built prototype of 24 kW/l and a gross power density of 8 kW/l with a peak efficiency above 94%. It is shown that a version of the same design optimized for mass manufacturing has the potential of having a gross power density of 15.5 kW/l which would be comparable with the best in class traction machines found on the automotive industry.
The cooling solution proposed is resulting in significantly lower winding temperature and an efficiency gain between 1.5% and 3.5% points, depending on the drivecycle, compared to an external jacket cooling, which is a common solution for traction motors.
drivetrain system analysis.
energy efficiency
Cooling
electrical machine design
permanent magnet synchronous machine (PMSM)
Författare
Alessandro Acquaviva
Chalmers, Elektroteknik, Elkraftteknik
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IEEE Transactions on Transportation Electrification,; Vol. 5(2019)p. 618-629
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Comparison of MTPA and Minimum Loss Control for Tooth Coil Winding PMSM Considering PM and Inverter Losses
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Pole-Slot Selection Considerations for Double Layer Three-phase Tooth-Coil Wound Electrical Machines
2018 XIII International Conference on Electrical Machines (ICEM),; (2018)p. 934-940
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Coupled 3-D Thermal and Electromagnetic Modelling of a Liquid-cooled Transverse Flux Traction Motor
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2018 XIII International Conference on Electrical Machines (ICEM),; (2018)p. 576-582
Paper i proceeding
Energy efficiency of a SiC MOSFET propulsion inverter accounting for the MOSFET's reverse conduction and the blanking time
2017 19th European Conference on Power Electronics and Applications,; (2017)
Paper i proceeding
Styrkeområden
Transport
Ämneskategorier
Elektroteknik och elektronik
Annan elektroteknik och elektronik
ISBN
978-91-7905-433-5
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4900
Utgivare
Chalmers