Control of DC bus voltage in single-stage AC-to-DC converter

This paper presents a control scheme that provides simultaneous control of the output voltage and DC bus voltage of a fixed frequency, single-stage AC-to-DC converter with high frequency transformer isolation. This bus control scheme facilitates utilization of switches with lower voltage ratings in the bridge converter. The control scheme has been explained with analysis. Based on this analysis design example of a 20 kHz, 500 W, 200 V AC-to-DC single-stage bridge converter is presented with explanations on the design constraints. Theoretical results are also predicted based on the analysis. Detailed results obtained from PSPICE simulation are given to verify the advantages claimed for this controlled bus single-stage converter. As a bonus to the bus voltage control, the bottom right switch undergoes zero-voltage switching at reasonably wide load range because of the overlap of the gating signals of two bottom switches in the bridge.