Open-circuit fault diagnosis and voltage sensor fault tolerant control of a single phase pulsed width modulated rectifier

Recently, single phase pulsed width modulated (PWM) rectifiers become very attractive in different industrial applications that need connection to single phase grid. Like any other PWM converter, the single phase PWM rectifier may be subject to different failures like power switch failures or sensor faults. Hence, fault diagnosis and monitoring are essential to optimize the maintenance costs and increase the reliability levels of the system. This paper discusses the fault detection and isolation (FDI) of both failures. A new open circuit fault detection and isolation approach is proposed. The fault detection method is based on residual generation between measured and observed current form factors (CFFs) with an adaptive threshold in order to avoid the false alarm and increase the reliability of the diagnosis algorithm. Also, the grid voltage sensor FDI is considered in this contribution thanks to the use of parity space equations approach. Moreover, after sensor fault detection and isolation, a grid virtual flux estimator is used to achieve the grid voltage sensor fault tolerance (FTC). Each failure may be detected in few hundred of microseconds. Theoretical analysis, simulations and experimental results are presented to validate the effectiveness of the proposed method.