Advanced rotor temperature estimation of permanent magnet synchronous machines for electric vehicles

Changhong Du,Anjian Zhou,Zhiyuan Peng,Tao Deng,Yong Ren,Jian Chen,Yongquan Ma

doi:10.1177/1687814020918742

Abstract

The actual power capacity of permanent magnet synchronous machine for electric vehicles is usually limited by rotor temperature, and rotor overheating is one of the major reasons for permanent magnet synchronous machine failure. Therefore, an approach of rotor temperature estimation is proposed to improve motor peak power utilization and protect permanent magnet synchronous machine from serious demagnetization due to thermal damage. A real-time iterative algorithm is provided based on the equivalent thermal model for rotor temperature. First, the heat generating principle of each part as well as the power flow transferring of the motor system is analyzed. Second, rotor temperature model is built based on the conservation of energy loss from the stator and real-time superposition of temperature variation rate for the rotor. Finally, the motor performance test bench is built to validate the proposed algorithm and numerical models are also constructed to simplify estimation parameters for rotor temperature model. The algorithm accuracy is improved and verified by optimizing control parameters with given environment temperature and power load. The experimental result shows that the maximum error between actual test value and estimation value is within ±10°C, and it meets the requirement of algorithm accuracy and also benefits on system performance and manufacture cost efficiently.

Highlights

Permanent magnet synchronous motor (PMSM) plays an important role in electric vehicle industry due to its advantages including high power density, high operation efficiency, as well as excellent start torque, and the present researches focus on how to improve motor thermal safety and excellent torque capability with smaller size
PMSM torque usage expectation is lower than its fact capability without high accurate rotor temperature estimation (RTE) to avoid its overheating and thermal damage.[4,5,6]
To protect PMSM from overheating, breakdown, and improve continuous behavior of motor torque, an applicable real-time algorithm of RTE is proposed in this article

Summary

Introduction

Permanent magnet synchronous motor (PMSM) plays an important role in electric vehicle industry due to its advantages including high power density, high operation efficiency, as well as excellent start torque, and the present researches focus on how to improve motor thermal safety and excellent torque capability with smaller size. The performance test bench for PMSM is built and a series of experiments are carried out on the hardware and software of PMSM controller to verify whether the RTM estimation accuracy meets the requirement with different environment temperature and variation power load.

Results

Conclusion