Open Circuit Fault-tolerant Operation of a Modified Hybrid String Inverter/Rectifier Leg

Failures in bidirectional power converters can be critical and challenging especially in the energy storage applications due to their nature and high replacement costs. This paper presents a modified topology based on the 6-switch hybrid string converter. In the modified structure, the diodes have been replaced by the active switches to add switching redundancy and to provide open circuit fault-tolerant control while improving the efficiency by means of synchronous rectification. As a result, post fault operation at full power can be performed preventing the power to be interrupted in case of any OCF incidents. The processor-in-the-loop (PIL) test results have been provided on a 1 kW 400VDC/700VDC converter to demonstrate the performance of the proposed converter along with the fault-tolerant control. A 1kW 400VDC/700VDC prototype has been designed to verify the feasibility of the proposed concept.