An improved energy recovery soft-switching turn-on/turn-off passive boost snubber with peak voltage clamp

This paper present an improved energy recovery soft-switching turn-on and turn-off snubber with switch peak voltage clamp for high frequency boost converters. Comparing the proposed circuit to existing passive snubber circuits, it is simpler than the conventional energy recovery passive snubber, which has the drawbacks of too many parts, difficult circuit layout, and high stray inductance. As a result, the unwanted high frequency current and voltage ringing at switching transitions of the boost switch are reduced, which significantly reduces the voltage stress on boost devices and mitigates EMI noise problem. Moreover, the proposed circuit overcomes the shortcomings of the traditional resonant nondissipative snubber, which usually does not have turn-on current snubbing for the boost diode and has a very narrow soft switching operating range with extremely high peak voltage stress on boost devices. The proposed circuit not only serves as an energy recovery turn-on snubber, which greatly reduces the reverse-recovery peak current of the power boost diode and the turn-on loss of the boost switch, but also provides a zero-voltage or reduced voltage turn-off condition for the boost switch with extended operating range. Since it uses fewer circuit components, the circuit layout is simpler. It has less current ringing problem, which helps to reduce the EMI generated. The presented circuit is especially suited for high power boost converter applications. In this paper, the circuit operation, the analysis, and comparisons with other snubber circuits are provided. The simulation results based on a 3 kW telecom rectifier are shown. The experimental results showing energy recovery soft-switching turn-off and turn-on features with clamped peak switch voltages are also included.