Analysis of a Soft Switching PWM Active Clamp Cuk Converter

A soft switching pulse-width modulation (PWM) Cuk converter with boost type of active clamp is proposed. Active clamp circuit can help the switching devices in the Cuk converter to be operated at zero voltage switching (ZVS) turn-on. Therefore this converter is suitable for high frequency operation to reduce the size of reactive components. The clamp capacitor and auxiliary switch are connected in parallel with the primary switch. When main switch is turned off, the positive inductor current will flow through the anti-parallel diode of auxiliary switch. At this instant, the auxiliary switch can turn on at ZVS. On the other hand, the resonance between the resonant inductor and output capacitor of main switch will create a ZVS condition for main switch. The principle of operation, system analysis, and design consideration are presented in this paper. Experimental results for a laboratory prototype rated at 400 W, input voltage of 150 V~300 V, output voltage of 200 V, and operating at 105 kHz are given to demonstrate the effectiveness of the proposed converter.