Bipolar Modular AC–AC Converter for Low-Frequency Transmission

AC–AC converter plays a pivotal role in low-frequency alternating current transmission. This article proposes a bipolar modular ac–ac converter (BMAC) for low-frequency transmission, which consists of six arms and a triple-winding transformer referred to as bipolar transformer. Considering the unbalance of the grid voltage, the mathematical model for proposed BMAC is analyzed, and the control strategies for BMAC are proposed. Compared with other converters, the proposed BMAC has less SMs, lower cost and lower power losses. Simulation studies and experiment studies are conducted, and their results confirm the effectiveness of the proposed BMAC and control strategy.