This digest presents a novel single-stage inverter based on a multi-resonant LLC converter and the optimal design method. In comparison to conventional LLC converters, an added L-C series resonant branch is paralleled to the original resonant tank to generate a zero-gain point in the gain curve and introduce high-order harmonics in resonant current. The proposed inverter can achieve a wider output range with a narrower fs range, more straightforward control, and less circulating energy. A 1.2 kW prototype that converts 380 Vdc to 600 Vac is built and achieves 97.3% efficiency and 2.17% THD at full load condition.
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