High-Gain Symmetrical Z-Source Hybrid Converter with Low Leakage Currents

In order to achieve low leakage currents, a symmetrical Z-source hybrid converter is proposed to simultaneously obtain a wide range of DC and AC output voltages. The proposed converter is derived from a traditional Z-source converter by replacing the control switch to a highly efficient and reliable inverter concept (HERIC) inverter. To be applied in PV applications, the impedance network is symmetrical, which can clamp the common-mode voltage of the proposed converter to be a constant (i.e., obtaining low leakage currents). A dedicated modulation scheme is introduced so that the symmetrical Z-source hybrid converter can achieve low leakage currents, a wide range of output voltages, high efficiency and reactive power injection. Simulations are performed on a 2-kW symmetrical Z-source hybrid converter to verify the effectiveness.