Vehicle Motor Emulator Voltage Compensation Research Based On Equivalent Terminal Voltage

Pure electric vehicles have many advantages such as environmental protection and energy saving,which is the future development trend of the automobile industry.Motor Control Unit(MCU)is the core component of electric vehicle,so it is necessary to test its function comprehensively in the process of design and development.Currently,the most advanced method is to use Power-level HIL to test the MCU,which is also called Electric Machine Emulator(EME)for it mainly simulates the real motor and its load.It is a low-cost and effective way to test the MCU with DSP-based EME.This paper studies the principles of EME and the problems of the existing platform,hoping to provide reference and theoretical guidance for the design and implementation of vehicle driving motor emulator.The principle of EME are systematically analyzed in this paper,including the derivation of EME mathematical model,the derivation and analysis of EME current control strategy,and the selection of EME motor model discrete method.Simulation results show the correctness of EME principle analysis under ideal conditions.Two factors affecting the simulation accuracy of EME based on DSP platform were pointed out.This paper analyzes the principle that parasitic capacitance and voltage drop of MCU inverter lead to the change of terminal voltage duty ratio and amplitude,and deduces the process of output voltage distortion and voltage error formula of EME inverter.The effects of MCU terminal voltage acquisition error and EME inverter output voltage distortion on EME simulation accuracy are analyzed by simulation.To solve the problems existing in the platform,an accurate terminal voltage acquisition method of the inverter,and a compensation strategy for the distortion voltage based on this method are proposed.The design and analysis of the terminal voltage acquisition circuit are carried out in detail.Compared with the existing compensation methods,the proposed voltage compensation strategy does not need to judge the current polarity,and the compensation process is simpler and more accurate.The simulation verifies the effectiveness of the proposed compensation strategy.In order to verify the theoretical derivation and methods proposed in this paper,an EME experimental platform based on DSP and its program flow are designed.The acquisition effect of MCU terminal voltage is analyzed,and the EME is realized based on the equivalent terminal voltage.The experimental results show that the distortion voltage of MCU and EME inverters affect the simulation accuracy of EME.The proposed voltage compensation strategy is used to compensate the MCU and EME inverters,and the EME current is almost the same as the real motor,which proves the correctness of the analysis in this paper and the validity of the proposed method.