Enhanced Solar-Integrated Quasi-Z-Source DC–DC Converter for Efficient Electric Vehicle Battery Charging

Abstract

The integration of photovoltaic (PV) systems with electric vehicle (EV) charging requires high-gain DC–DC converters that can handle low and variable PV voltages while maintaining efficiency and battery safety. This paper presents the modelling and performance analysis of a solar‑integrated enhanced quasi‑Z‑source DC–DC boost converter (EQZSC) for EV battery charging. The proposed topology incorporates a coupled‑inductor impedance network and an additional voltage‑lift capacitor, thereby achieving a voltage conversion ratio of V0 /Vm = [1+(1+n)D]/[1-(1+n)D]significantly higher than conventional boost and classical quasi‑Z‑source converters. A unified analytical framework is developed, including steady-state analysis, averaged state-space modelling, perturb-and-observe maximum power point tracking (MPPT), and constant-current/constant-voltage (CC–CV) battery charging with hysteresis-based mode transition. Detailed loss and thermal models (semiconductor, magnetic, and junction temperature) are integrated to support a realistic evaluation of efficiency. MATLAB/Simulink simulations are conducted under steady‑state and dynamic irradiance (600–1000 W/m²) conditions, for a PV input range of 60–100 V and a regulated output of 400 V. Key results include a voltage gain of 4.44, peak efficiency of 96.8%, input current ripple below 3%, output voltage ripple below 0.8%, and switch voltage stress limited to 87 V (78% reduction versus conventional boost). Under an irradiance step (600→900 W/m²), the output voltage settles within 25 ms with less than 3% overshoot. The CC–CV charging profile demonstrates state-of-charge (SOC) progression from 10% to 99% in approximately 60 minutes. The proposed converter shows potential as an efficient and thermally stable solution for solar‑powered EV charging infrastructure.