A Voltage Equalizing Model Predictive Control Strategy for 3-level T-type Grid-tied Fault-tolerant Inverter

In this paper a 3-Level T-type fault-tolerant Inverter topology is proposed for grid-tied application. Thanks to a thyristor and a TRIAC device, the faulty leg is isolated in a short time and the corresponding load is directly connected to the middle point of the DC link capacitors, to providing the inverter with fault-tolerant capability. Then the fault-tolerant operation of fault phase current is reconstructed based on the relationship between DC current and grid side current. An optimal model prediction control strategy applies to this fault-tolerant structure. The available voltage vectors of 3-Level T-type grid-tied converter are analyzed. By increasing the balance factor and the current injection method, the midpoint voltage balance effect can be improved. The experimental results show that the control strategy is effective and the output current is stable and the reliability of the system is improved.