Current Residual Vector-Based Open-Switch Fault Diagnosis of Inverters in PMSM Drive Systems

This paper presents an open-circuit (OC) fault diagnostic method of inverters in closed-loop controlled permanent magnet synchronous motor drive systems based on current residual vector (CRV). This method can get rid of effects of the load and the main controller to obtain reliable detection. The motor drive system is a hybrid system composed of discrete switching signal events and continuous current state variables, which evolves in certain law driven by discrete events. At the base of analyzing operation modes of the system, a mixed logical dynamic (MLD) model of the motor drive system is built to estimate motor currents. Consequently, the proposed fault diagnostic scheme is constructed by the healthy current estimator based on the MLD model in parallel with the plant. When an OC fault occurs, the CRV between the estimator and the plant will show featured amplitude and phase, and hence the fault can be detected. The method utilizes variables already used by the main controller, avoiding the use of extra sensors. During the implementation, amplitude threshold and phase sector are used in order to avoid effects of measurement errors, model parameter errors and noises, which improves the reliability and robustness. Simulation and experimental results validate the proposed diagnostic method, and the diagnostic duration can be reduced within a quarter of fundamental wave period.