A double single-ended resonant inverter for low harmonic line frequency applications

Some problems with photovoltaic projects for household applications are the cost, efficiency and complexity of the inverter. Various inverter topologies are used but do not provide a boost and true sinusoidal wave voltage without additional complex circuitry. This paper proposes a double-switch resonant inverter with two different capacitor configurations. The performance of this topology is verified both by simulation and experimentally. The output voltage of the proposed resonant inverter has a true sinusoidal waveform at no-load, pure capacitive and pure inductive load conditions. At resistive load, the waveform is noticeably near sinusoidal but the THD is nonzero. Formulae for the resonant frequency and the voltage gain are derived and verified. The circuit was tested under different operating conditions and parameters for achieving zero-voltage switching (ZVS). The results show that there are no stability issues with the proposed circuit and that a closed-loop control is not required. The proposed topology is applicable to a wide range of loads and DC voltage sources at power-line frequencies.