Abstract

The analysis and design of a high-frequency two-switch forward converter topology with transformer flux balancing and extended duty cycle capability are presented. To improve converter performance, an auxiliary circuit connected in parallel with each power switch is proposed. This auxiliary circuit uses a low-power switch or a nonlinear resistor connected in series with a capacitor. As a result, the DC component of the magnetizing current is minimized, and the converter provides the means of recovering the energy associated with the parasitic inductances of the circuit components. Thus, higher than usual efficiency and higher operating frequencies are obtained. Experimental results are presented for a 4 kW, 40 kHz prototype unit.