Fast detection of open-switch fault using moving filter for a PWM VSI-fed PMSM drive system

To improve the reliability of a pulsewidth modulation (PWM) voltage source inverter (VSI) fed permanent magnet synchronous motor (PMSM) drive system, this paper presents a fast openswitch fault detection scheme in multiple switches. An openswitch fault in a PWM VSI often introduces over-current stress to other electric components and can be easily propagated. Thus, it may lead to a severe secondary damage in the entire drive system. Furthermore, the open-switch fault produces increased current harmonics and distortion as well as large torque pulsation. In contrast to the conventional schemes, the proposed fault detection scheme uses the moving filter to process the current information, which facilitates a fast detection of fault without increasing the computational burden severely. The proposed scheme is not only immune to false alarms due to inexact detection, but also independent of operating conditions because it uses normalization quantity. The proposed scheme detects a fault by online basis without any additional hardware while keeping control at the same time. To verify the proposed fault detection scheme, the entire system is constructed using digital signal processor (DSP) TMS320F28335. The comparative simulations and experimental results validate the practical usefulness of the proposed scheme.