Study On Large-Airgap High-Speed Permanent Magnet Synchronous Motor For Electrically Assisted Turbocharger

Electrically assisted turbocharger(EAT)can enhance output power and dynamic response speed of the engine,the performance of the high-speed motor directly affects the supercharging effect of EAT.For the front-mounted EAT,the motor is installed at the front of the compressor inlet,which will affect the air intake of the compressor,thereby affecting the aerodynamic performance of the compressor.Therefore,this thesis investigates the high-speed motor for EAT.In this thesis,high-speed permanent magnet synchronous motor(PMSM)with high power density and high efficiency is selected as the assisted motor.In order to balance the electromagnetic performance of the motor and the aerodynamic performance of the compressor,this thesis combines the three intake structures of large-airgap,stator long-tooth and external duct to obtain two composite intake structures,namely duct and large-airgap structure and long-tooth and largeairgap structure.For the long-tooth and large-airgap structure,there are two ways of windings arrangement,namely attached to the tooth and attached to the yoke.According to the design requirements,multi-physics optimal design is carried out,including electromagnetic design,demagnetization analysis,stress check,rotor dynamic analysis,temperature check and fluid field simulation analysis.In the electromagnetic design,the influence of airgap length and slot opening width on the electromagnetic performance of the motor is explored.It is found that for the largeairgap motor,appropriately increasing the airgap length and slot opening width is beneficial to reduce the electromagnetic loss and torque ripple.After the multi-physics optimal design,various schemes of three structures satisfying the complex constraints are obtained.The effects of the airgap length and ventilation area on electromagnetic loss and air friction loss are analyzed.Finally,the schemes with low air friction loss are combined with the compressor to simulate the aerodynamic performance.The effects of each scheme on the aerodynamic performance of the compressor are analyzed.Considering the electromagnetic performance of the motor and the aerodynamic performance of the compressor comprehensively,it is determined that the large-airgap and long-tooth structure with the windings attached to the tooth(the largest ventilation area)is the optimal solution under complex constraints.