Practical Compensation Strategy for Accurate Torque Control in Mass-Produced High-speed Traction IPM E-Drives

Abstract

Accurate torque control of interior permanent magnet (IPM) synchronous machines across the full speed range is the main control goal for EV/HEV traction applications. In this paper, the leading causes for torque inaccuracy in mass-produced IPM drive systems are thoroughly analyzed. Both parameter inconsistency and sensor errors in mass-produced IPMs can lead to errors in Field-Oriented Control (FOC). These FOC-related errors eventually result in the deterioration of high-speed performance. The general relation of torque and output voltage to current angle is deduced mathematically. Then it is used to develop a compensation strategy to achieve the required torque accuracy while maintaining the motor's efficiency in the high-speed region, even under imperfect motor and inverter parameters in the actual commercial products. The method's effectiveness is validated on a 200 kW/15000 rpm industry-grade traction IPM e-drive product.