Technical Review of PWM Techniques for Dual Active Bridge for EV Charging

The need for bidirectional power flow between Electric Vehicle (EV) chargers and the grid via Vehicle-to-Grid (V2G) technology demands efficient power electronic converters. In modern technology Dual Active Bridge (DAB) has played a pivotal role in the electronic interface (DC–DC) conversion due to its galvanic isolation (High Frequency Transformer (HFT)) structure, bidirectional flow capability, power density, and wide voltage regulation capability. At the core of the efficient operation of the DAB are the Pulse Width Modulation (PWM) techniques. The PWM strategies also extend the zero-voltage switching (ZVS) range and reduce circulating inductive current. This paper reviews and compares the technical aspects of PWM techniques applied in DAB-based EV charging systems, inter alia, Phase Shift Modulation (PSM), Combined PWM (CPWM), Dual Phase Shift (DPS), Triangular and Trapezium Modulation (TTM), PWM plus Phase Shift (PWM–PS), and Asymmetric Duty Cycle Control (ADC). The mathematical analysis of the strategies was done using the power transfer equations and loss mechanisms. Performance evaluation was done based on soft-switching range, circulating inductive current, efficiency, and aptness to Electric Vehicle charging needs. The paper concludes that Dual Phase Shift and PWM plus Phase Shift have superior wide voltage variations, which is standard for fast DC charging, but Phase Shift Modulation is simplified for medium-power onboard chargers.