Secondary-side phase-shift-controlled high step-up hybrid resonant converter with voltage multiplier for high efficiency PV applications

A family of isolated resonant converter with voltage multiplier is proposed for high step-up applications. The output voltage is improved significantly by integrating switched-capacitor cells into the secondary-side rectifier of the converter, which benefits to reduce the turns ratio of the transformer. Low voltage-rated switches and diodes with high switching and conduction performances can also be applied to improve the efficiency. Secondary-side phase-shift modulation strategy is adopted to implement output voltage/power control. With the phase-shift control strategy, zero voltage switching performance is achieved for both the primary- and secondary-side power devices, and zero-current-switching is achieved for all the diodes within the whole voltage and load range to reduce the switching losses. The operational principles and characteristics of the proposed converter are presented in detail. The analysis and performance have been validated experimentally on a 400V/400W-output hardware prototype.