A Novel Medium Voltage Inverter With the Control Strategy Based on a Hybrid of ACC and VSC

To improve power transmission efficiency and power density, a novel medium voltage inverter topology is proposed. It consists of a current source actively commutated converter (ACC) and a three-phase voltage source converter (VSC). It is operated in a fundamental frequency switching mode for ACC. The switching frequency of the internal power semiconductor device is consistent with the grid frequency which reduces switching losses of devices, significantly. The proposed three-phase VSC is capable of suppressing the current harmonics and compensating reactive components generated by ACC while undertaking partial power transmission, ensuring high power quality on the grid side. It integrates a small amount of energy storage capacitors internally for the proposed medium voltage inverter which effectively reduces system weight and volume. Moreover, the matched control strategy is also proposed. Simulations on a 1MVA 10kV ac/ 15kV dc medium voltage inverter by Matlab/Simulink verify the effectiveness of the proposed topology and control strategy.