Demagnetization Fault Diagnosis of PMSM in Electric Vehicles Using H Infinity Filter

Abstract

With the extension of the low-carbon economy in the transportation field, electric vehicles and its related technologies have been rapidly developed. As the power source of electric vehicles, the reliable operation of the motor and its drive system is a key factor to ensure the safe and stable operation of the while vehicle. Permanent magnet synchronous motor (PMSM) have received much attention in this field due to its well- known technical advantages. The control performance, efficiency, and reliability depend to a large extent on the health of the rotor permanent magnet. Therefore, the online and reliable monitoring of permanent magnet flux linkage is particular important. The performance degradation of permanent magnet is called demagnetization fault. It is directly related to the flux linkage of PMSM. In this paper, the whole drive system of an electric vehicle with healthy PMSM and demagnetized PMSM has been built. As the magnet flux linkage is proportional to the strengths of the permanent magnet, it is essential to estimate the flux linkage online to detect the demagnetization fault. Based on that, demagnetization fault diagnosis scheme for PMSM in electric vehicles has been proposed based on the state equation under dq axis reference. The scheme consists of the following serial processes: state judgement, data extraction, H infinity filter, estimation of magnet flux linkage, fault decision. The simulation results show that this method is robust to the inaccurate initial state value and can be used under dynamic progress online.