A DC to DC PWM series resonant converter operated at resonant frequency

Resonant DC-DC converters that are usually operated using frequency modulation to achieve regulation have the disadvantage of wideband frequency modulation. An alternate regulation scheme that uses fixed-frequency pulse width modulation (PWM) is proposed. This control scheme is applied to a series-loaded, series-resonant converter. When operated in a full-bridge configuration and with a variation of PWM that can be described as a phase shift modulation between the two sets of switches, the converter presents low switching stresses. Analytical results presented include VA rating and stresses on critical active and passive components as a function of input voltage variation. A 200 kHz, 700 W, 48 V output offline converter was realized using this concept, and some experimental results are presented to corroborate the analysis