Investigations of clamping circuit in improved resonant DC link converter

摘要

The resonant dc link PWM converter must employ the devices with the higher voltage ratings, because the resonant capacitor voltage becomes above twice as large as the output dc voltage. In order to restrain this voltage, the clamping circuit composed of a capacitor and a switching device can be attached to the converter. The clamping capacitor is usually used with the very large capacity to maintain the specified constant voltage. In this paper, the clamping circuit is investigated quantitatively by simulations and experiments. It is clarified that the smaller clamping capacitor is enough to reduce the distortion of input ac currents and lower the voltage ratings of devices.