METHOD FOR CONTROLLING A POWER CONVERTER USING AN AUXILIARY RESONANT COMMUTATION CIRCUIT

摘要

The present invention relates to a method for controlling a power converter by appropriately controlling the associated auxiliary resonant circuit which ensures soft-switching of all switching devices included in the power converter. The power converter includes an inverter having two or more main switching devices per phase. Each main switching device is coupled with a diode coupled anti-parallel to the switching device and a relatively large snubber capacitor coupled across the switching device. The auxiliary resonant circuit includes two antiparallel-coupled auxiliary switching devices, which are coupled in series with a resonant circuit having an inductor and a snubber capacitor. The gating and induction times of the main and auxiliary switching devices are controlled to apply boosting energy to the resonant operation, thus ensuring that the inverter output voltage reaches at least the positive and negative inverter rail voltages during each resonant rectification cycle. As a result, the control method can achieve rectification of the converter poles without actually switching losses.