Asymmetrical PWM Series-Capacitor High-Conversion-Ratio DC–DC Converter

In this letter, an asymmetrical pulsewidth modulated (PWM) scheme is proposed to solve the inductor current unbalance and nonlinear voltage gain issues of the series-capacitor (SC) high-conversion-ratio (HCR) converter when D > 0.5. With the proposed scheme, the converter can achieve both current balancing and high step-down conversion even for D > 0.5. As a result, combined with the conventional PWM scheme, the duty cycle limitation of the SC-HCR converter is completely eliminated. A 2-kW prototype SC-HCR converter was fabricated and tested to validate the performance of the proposed PWM scheme.