New switching technique for quasi-Z-source resonant converter

The Quasi-Z-Source (QZS) inverters are the promising topology for the renewable integration with the grid. QZSI achieves the MPPT during the shoot through state, without additional DC-DC converter, and simultaneously delivering the AC power to the grid or motor load. The quasi components (L and C) sizes are reduced by increasing the switching frequency of the converters. But the switching losses of the converter will dominate at the higher frequencies. To minimize the switching losses of the converter, this paper proposes reduced switching loss single stage inverter for high power applications. Using only six devices rated at supply voltage, the QZS resonant converter can operate properly by adding resonant inductor and capacitor to the ac side of each phase. The proposed converter can control the output with true pulse width modulation (PWM) at high frequency and the Zero Voltage Switching (ZVS) and Zero Current Switching is achieved at every switching cycle. The detailed analysis, modulation and simulation are presented to verify the operating principle of the QZS resonant converter.