Open-Circuit Switch Fault Diagnosis in Single-Phase CHMC with Switching Duty Ratio-Based Estimated Grid Current

Brief Introduction

This paper introduces a method for diagnosing open-circuit switch (OCS) faults in single-phase cascaded H-bridge multilevel converters (CHMC) using an estimated grid current based on the switching duty ratio. The proposed technique estimates the grid current through the switching duty ratio of each switch during the control period. The faulty switch pair is then identified by analyzing the sign and magnitude of the residual between the estimated and sampled grid currents. Finally, the location of the faulty switch is determined by comparing the magnitude of the residual with the reversely calculated residual. DSIM simulation results confirm the effectiveness of this approach.

Verify the effectiveness of the OCS fault diagnosis techniques using DSIM

In the topology where DSIM is used to verify the effectiveness of OCS fault diagnosis techniques, the gate voltage is 100 V, the gate frequency is 60 Hz, the module DC-link voltage is 60 VDC, the switching frequency of CHMC is 1.67 kHz, the control period of CHMC is 200 μs, the DAB output voltage is 40 VDC, the switching frequency of DAB is 10 kHz, and the Filter inductance is 1.9 mH. According to the DSIM simulation results, the faulty switch can be identified.