Loss analysis and calculation of IPMSM with SiC inverter based on field circuit coupling method

Abstract

In the early design stage of electric drive system, electric machine performance and controller performance usually cannot be considered at the same time. The torque and speed range of traction machine is large, and the harmonic loss caused by current harmonic generated by PWM power supply will not be ignored. The working point of electric vehicle traction machine changes frequently. The current harmonics vary with the working point because the electric machine magnetic field saturation degree is different. In order to solve this problem, a simulation model for fast prediction of harmonic current at each working point is established in this paper. Firstly, the analytical models of SiC device and machine loss are analyzed. Then, based on the experimental prototype parameters, the finite element model of the machine is established, and the dq axes current of different working points are extracted. Based on the field circuit coupling method, a system level simulation analysis model is built, which can realize the current harmonic extraction and loss calculation at different working points. Finally, the effectiveness of the model is verified by selecting the corresponding work points. The results show that the optimized switching frequency can further reduce the system loss. Compared with the traditional Si devices, the high switching frequency of SiC is beneficial to further reduce the harmonic loss.