Analysis of circulating current in hybrid AC/DC power supply system

With the continuous growth of electricity demand, higher requirements put forward for the performance, efficiency, and reliability of the power supply system. By combining the advantages of diode and PWM rectifiers, hybrid ac/dc power supply system can provide stable dc source for dc load. This article takes the hybrid ac/dc power supply system as the research object and analyses the circulating current of the system. Firstly, through comprehensive research on the structure and operating characteristic, an average circuit model of the hybrid ac/dc converter is established, and the mechanism of circulating current generation is analysed. Then the circulating current change rate is theoretically derived. Secondly, the circulating current of hybrid ac/dc power supply systems based on buck/boost is elaborated and calculated. The differences in circulating current between the two systems are compared and analysed. Finally, MATLAB is used to simulate and analyse two hybrid ac/dc power supply systems, and compared with theoretical derivation. The simulation results verified the feasibility of the circulating current analysis method.