An alternative bus clamp for resonant DC-link converters

This paper presents an alternative circuit configuration for clamping the link voltage in a resonant DC-link converter. The alternative circuit is a lossless clamp which allows for totally autonomous control of the clamp voltage and resonant link under all operating conditions. The clamp is comprised of two capacitors, three controllable switches and three diodes. The clamp does not require the use of external bias supplies for startup or no-load operation. Control of the input and/or output waveforms for a converter employing this circuit remains virtually identical to that for the resonant DC-link inverter (RDCLI). An analysis of clamp operation is performed detailing its modes of operation. From this analysis, insight is gained into the appropriate selection of clamp capacitors. Simulations and experimental results are presented to corroborate the analysis. The control of the clamp is discussed in detail