An Improved Current Sensor Fault Diagnosis and Fault-tolerant Control for Multisector Permanent Magnet Synchronous Motor

Multisector in-wheel motors have been widely used in the fields of electric vehicles and electric aircraft due to their high torque density, high power, and strong reliability. As the core component of the current controller and various observers, the current sensor plays a vital role in the stable control of the motor, thus the fault diagnosis and fault-tolerant control of current sensors is essential. However, the characteristics of both single-phase open-circuit faults and current sensor break faults are similar, making it difficult to distinguish between the two faults. In addition, for current sensor faults, the winding is usually directly cut off and controlled as a phase fault condition, which limits the output capability of the system. How to fully utilize the healthy windings after the current sensor fault is critical. Aiming at the above problems, this paper firstly analyzes the differences in the mechanism of current sensor fault and phase break fault and proposes a fault diagnosis algorithm based on a neutral point voltage observer. Secondly, to improve the robustness of the proposed method under the inaccurate motor parameters, an improved diagnostic algorithm by compensating the neutral voltage observation of the health sector is proposed. Finally, for fault-tolerant operation after current sensor failure, an extended Kalman observer which integrates the information of healthy and faulty sectors is proposed to realize the observation of faulty-phase current and fault-tolerant operation. The experiments with a four-sector in-wheel motor drive finally prove the evidence of the proposed algorithm.

1. Introduction

The multisector in-wheel motor is a novel special type of multi-phase motor. Due to its modularity, large capacity, and high reliability, it has a wide range of applications in electric vehicles, electric aircraft, and other fields^[1]. However, the above-mentioned fields have strict requirements on the safety and reliability of the motor drive control system, how to quickly diagnose the faults in the multisector in-wheel motor and achieve fault-tolerant operation after a fault occurs is a significant topic in current research^[2].