Fault diagnosis and PD-PWM reconfiguration of a 5-level double-boost PFC with fault-tolerant capability

A 5-level PFC topology with fault-diagnostic and fault-tolerant capability is proposed and compared to known structures. It is derived from a 3-level non differential double-boost PFC including fly-cap cells. The series-connection of the two low-voltage switching-cells is decoupled by a single flying capacitor that provides a direct fault-tolerant capability and a post-failure operation increasing the availability of converter. The monitoring of the voltages across flying capacitors allows a rapid detection and localization either for open circuit failure or short-circuit failure. A phase-disposition PWM reconfiguration is also used and presented in order to optimize both normal operation and post-fault continuation. The design and the most important features are highlighted thanks to a digital control frame and a mock-up rated to AC115V-DC400V-4kW-2×31kHz.