The auxiliary resonant snubber inverter (RSI) has demonstrated superiority in reduction of switching losses and dv/dt. It was found that the overall inverter system efficiency might not be improved if the resonant current was not controlled in accordance with the load current. This paper proposes an improved control scheme to minimize the operation of auxiliary circuit for efficiency improvement. The principle of this control scheme is to vary the resonant current with variable timing control based on the load current magnitude and to disable the auxiliary circuit operation when diode freewheeling occurs after switching. To illustrate the operation of this control scheme, this paper compares the switching characteristics and inverter power loss of hard-switching inverter, RSI with fixed-timing and variable-timing control and RSI with the proposed control scheme. Experimental results fully agree with the analyses and prove that the proposed control scheme is suitable for RSI to achieve better operating conditions.
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