Abstract:

FM controlled ZVS LLC resonant converter operates with low switching losses at high switching frequencies for a wide input voltage range. To obtain a constant output voltage against varying input voltage and load, the DC voltage gain of the converter, hence its operating intervals, needs to be changed. In different operating intervals, many operating parameters change besides the DC voltage gain of the converter. In this study, ZVS operating intervals of the converter are compared in terms of efficiency, switch stresses, and soft switching for constant output voltage against varying input voltage and load. The prototype circuit of the converter with the input voltage range of 80-120 V, nominal input voltage of 100 V, and output voltage of 8 V is established. The measurement results obtained from the prototype circuit for much different input voltage and load values are presented comparatively. The effect of different ZVS operating intervals on the operating parameters of the converter is revealed in many ways. Moreover, it is observed that the operating performance of the converter around series resonance frequency is better than the operating frequencies far from this frequency value.

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