Analysis and design of buck/boost zero-voltage-switching resonant DC/DC convertor

A steady-state analysis is presented for a buck/boost zero-voltage-switching resonant DC/DC power convertor. The current and voltage waveforms are derived using differential equations. Conditions for lossless operation are determined. Design equations are given for the DC transfer function, on-switch duty cycle, DC input resistance, maximum switching frequency, peak currents and voltages, power-conversion capability and component values. Whereas this analysis is directed toward the design of a high-efficiency high-power-density buck/boost convertor, it also provides insight into the behaviour and performance of modern resonant DC/DC convertors.