A soft-switching hybrid boost-buck PFC converter for high power quality EV battery charging applications

The growing penetration of electric vehicles (EVs) necessitates the design of high-reliability, high power quality and efficient charging systems that can control regulated DC power extracted from an AC utility source. Conventional power factor correction (PFC) converters usually have serious limitations in terms of voltage regulation, harmonic distortion and switching losses. This paper presents a high-efficiency hybrid boost-buck power factor correction converter for electric vehicle (EV) charger applications to tackle these problems. The proposed topology consists of the cascaded boost and buck conversion stages with resonant soft-switching elements and a high-frequency transformer to achieve both step-up/step-down voltage regulation that can be used in applications where high efficiency and improved power quality need to be maintained. An accurate control over the DC-link voltage regulation and the input current shaping is achieved by implementing a dual-loop control strategy with an outer voltage regulation loop and an inner current control loop utilizing proportional-integral (PI) controllers. The converter switches at 15 kHz with an input supply of 190 V AC and generates a regulated output voltage of 270 V DC for EV battery charging. MATLAB/Simulink simulations to validate the maximum performance of the proposed converter were performed and finally, which were validated by a laboratory prototype. The experimental results show a power factor of 0.998, a total harmonic distortion (THD) of about 2.1% for the input current, and peak efficiency close to 97%. The results validate the capability of the enhanced hybrid boost-buck PFC converter in achieving high efficiency, reduced harmonic distortion and maintaining tight voltage regulation compared to previously reported PFC topologies, which makes it attractive for modern EV charging systems.