Dual active clamp, zero voltage switching power converter

Abstract

A dual active clamp (DAC) converter comprising two active-clamp, zero-voltage switching (ZVS) converters for converting electrical power from an input source to an output load is described. The two active-clamp ZVS converters are coupled in parallel to one another at their respective inputs and outputs, and are operated in a manner which reduces the overall input and output ripple currents of the DAC converter, which reduces the EMI emissions of the DAC converter. Each of the active-clamp ZVS converters achieves zero-voltage switching on its primary switch means, which also improves EMI emissions. Each active-clamp ZVS converter includes a transformer having a primary winding and a secondary winding, the secondary winding being coupled to the output load and the primary switch means being coupled between the primary winding and a voltage source, and an active clamp circuit comprising a series combination of a storage capacitor and a first switch means. The active clamp is coupled to the transformer to capture energy released from the transformer at specific times, which is then used to reset the transformer's core and to create a zero voltage switching condition across the primary switch means. A second switch means is connected in series with the secondary winding of the transformer and is operated to prevent the loading effects of the secondary from interrupting the creation of the zero-voltage switching condition.