Single-phase Quasi-Z-source Inverter with Enhanced-boost Ability

A single-phase quasi-Z-source inverter (qZSI) with enhanced-boost ability is proposed. The key technologies of the inverter such as circuit topology, control strategy, high-frequency switching process, voltage transfer ratio, and design criteria of key parameters are analyzed, and important conclusions are obtained. The inverter consists of an impedance network with enhanced-boost ability, a single-phase inverter bridge, and an output LC filter, adopting the unipolar SPWM control strategy with instantaneous feedback of output voltage and energy storage capacitor voltage. The impedance network is cascaded by an energy storage inductor and n identical diode-inductor-capacitor-capacitor (DLCC) cells in sequence, including n diodes, n+1 energy storage inductors, and 2n energy storage capacitors. The experimental results of a 1 KVA prototype verify that the proposed inverter features simple control, high voltage gain, high power density, low output waveform distortion, and high reliability. It has an important prospect in single-phase inversion with low input voltage or wide input voltage range.