An inrush current mitigation approach of The output transformer for inverter

When a short circuit fault occurs on the load side of inverter, the control system based on hardware and software current limiting strategy can confine output currents to a certain value. In order to shorten outage time, output voltages should be restored to rated value as soon as possible after the fault is cleared by the circuit breaker of the faulty branch. However, the voltage recovery may cause significant inrush current phenomenon because of magnetic saturation of the output transformer. The high inrush current could lead to voltage distortion and even trigger the protection mechanism. To effectively eliminate the inrush current, this paper proposes an inrush current mitigation approach for three-phase inverter. The phase angle of recovery voltage is controlled so that it is equal to that of fault occurring, which is detected and saved utilizing the double synchronous rotating d-q transformation algorithm. Both simulation and experimental results are provided to demonstrate the feasibility of this method.