Resonant converter controlled by variable capacitance devices

A new device called the variable capacitance device is proposed, and its application to the output voltage regulation of resonant converters is discussed. The new device has an independent input terminal for controlling its capacitance. The converters used are the well-known Schwarz circuit and the buck-type current-resonant converter with a resonant switch. By applying the devices to the capacitors in LC resonant tanks, the resonant converters can be regulated with the switching frequency fixed.<>