Fault Current Control of Three-Phase Dual Active Bridge DC–DC Converter Employing Modified Asymmetrical Duty Cycle Control Modulation

Abstract

DC distribution systems are drawing huge attention from researchers and industries because of their many advantages over AC systems. Due to its various benefits, including isolation and good fault current performance which is a big challenge for DC grids. the three-phase dual active bridge (DAB) converter is one of the most widely used converters for high power applications. However, the existing modulation techniques of the three-phase DAB have some drawbacks including high peak current, very low voltage ratio limitation as well as low output current. This paper proposes a new modified asymmetrical duty cycle control (MADCC) method to enable fault ride through operation of the three-phase DAB. By having three independent control parameters, the modulation strategy presented here efficiently controls the peak current and allows for high output current, all the while ensuring the converter switches operate with soft switching. Both simulation and experimental verification have been performed to test the proposed schemes. A comparison has been made between the performance of the proposed scheme and other existing control methods, and their key features are outlined and emphasized. During reference DC voltage tracking, low ripple voltage, small overshoot, and nearly no steady-state error was attained. Experimental and simulation results also confirmed the high DC current injection capability of the proposed technique during short circuit faults. This improvement in fault ride-through capability (FRT) enhances the performance of the three-phase DAB converter.

Keywords

• Three-phase DAB
• phase shift
• current limiter
• DC fault ride-through capability
• modified asymmetrical duty cycle control