Improvement of Harmonic Mitigation Capability of 12-Pulse Diode Bridge Rectifier using Interphase Transformer and High Frequency Solid State Transformer for EV Fast Charging Applications

Abstract

a new hybrid approach for improving harmonic mitigation capability of a 12-pulse diode bridge rectifier (DBR) for EV battery fast charging application is proposed in this research. In this approach, diode rectifier with clamp circuit having only two active switches has been employed for conversion of power frequency ac voltage into high frequency voltage. The proposed approach uses reduced number of active switches resulting easier control strategy for regulation of dc output voltage. This approach uses weak dc link film capacitor which eliminates the use of bulky electrolytic dc link capacitor. This system employs zigzag configured high frequency solid state transformer, which can block zero sequence component, providing high power density, high frequency galvanic isolation, reduced size, cost, and complexity of system, with improved grid side current quality. As, the 12 pulse DBR circuit is not sufficient to meet the harmonic distortion as per IEEE- 519 standard, hence a passive harmonic mitigation circuit with optimally tapped interphase transformer (TIPT) is implemented to suppress harmonics of grid current. The proposed technique is scrutinized and simulated with the help of MATLAB SIMULINK. It is observed that the system is capable of providing high quality input current with THD of 3.08% with additional benefits for the system being smaller, cheaper and less complex structure for EV fast charging application.