Constant switching frequency LLC-type series resonant converter

An analysis of the LLC-type series resonant converter (SRC) operating in the continuous and discontinuous conduction modes is presented. By using both the time domain and state-plane analyses, the steady state expressions can be derived to facilitate the numerical calculation of the control characteristics. To obtain the maximum range of the output voltage gain, the switching frequency is chosen to be the resonant frequency of the converter operating in the continuous conduction mode. Performance characteristics of the converter operating in this condition are given, and compared with those of the conventional SRC using pulse width modulation (PWM) control.<
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