Modified Quasi-Z-Source Resonant Converter–Based Concurrent CC-CV Charging in a Dual-Port Charger for EV Applications

Conventional multiport resonant converters are the most sought-after solution to reduce the installation costs of electric vehicle battery charging applications. Despite its attractive features, inductor-inductor-capacitor (LLC) resonant converters face a limited extension of the duty cycle, operate in multistage power conversion, and mainly rely on pulse frequency modulation (PFM). To resolve these problems, a single-stage power conversion topology, known as a quasi-z-source resonant converter, has been recently introduced at fixed-frequency operation to concurrently charge two batteries. However, the work has not addressed the constant current and constant voltage (CC-CV) mode operation concurrently. Moreover, the use of traditional PWM has reduced the overall efficiency of charging. To address these issues, this article proposes a modified dual tank resonant circuit integrating a quasi-z-source inverter (MQZSRC) to charge the two batteries in CC-CV modes concurrently. The improved MQZSRC employs phase shift PWM achieved by carrier shifting techniques with the aid of the WAVECT WCU 300 controller at a fixed frequency with and without shoot-through duty cycles. The test results related to enhancing efficiency and voltages are documented and compiled. The MQZSRC achieved validation in a laboratory prototype, where each circuit is powered with 200 W, and achieved overall 90% efficiency.