Study on fault diagnosis of inverters in PMSM drive system

The PMSM drive system contains the continuous state variables and the discrete variables, which is a typical hybrid system. In this paper, the hybrid system theory is introduced into the analysis process, the discrete voltage model of the inverter is embedded into the continuous state equation of the motor, and the hybrid logic dynamic model of the motor drive system is established. On this basis, a diagnosis method in permanent magnet synchronous motor drive system based on current residual is proposed. The method utilizes variables already used by the main controller, avoiding the use of extra sensors. Observation error and time delay is avoided because of the use of the real detection current. The open circuit fault residual is proportional to the time when inverter open circuit fault occur, so fault detection is very easy and reliable. This method can get rid of effects of the load and the main controller to obtain reliable detection. Fault diagnosis and location only need less than 1/4 cycle after the fault occurs. The simulation verifies its feasibility and validity of the proposed diagnostic method. © 2019, Editorial Board of Acta Energiae Solaris Sinica. All right reserved.