Switched-coupled-inductor inverter

A new family of switched-coupled-inductor inverters has been proposed in this paper, with voltage buck-boost function. In voltage-fed switched-coupled-inductor inverter, a boost function can be implemented by introducing an extra shoot-through state on the inverter bridge. It utilizes the same principle as the Z-source inverter, but has higher boost ratio and lower active device voltage stress at the same voltage gain. It also has wider voltage buck/boost range than conventional boost-converter inverter. In current-fed switched coupled inductor inverter, a buck function can be implemented by introducing an extra open zero state on the inverter bridge. The current-fed topologies are capacitor-less solution among the buck-boost inverters, which reduces the system size significantly. In addition, compared to traditional boost-converter-inverter, it has less switch count, and less active device current stress. Compared to current-fed Z-source inverter, it has higher boost ratio and lower active device current stress. The inverter can sustain minimum voltage and current stress at a certain operation point, through adjusting the trans-ratio and the shoot through/open circuit duty cycle. The simulation results are given to verify the theory analysis and demonstrate the great merits of the switched-coupled-inductor inverter. It is beneficial to be applied in dc-ac applications that demand a high voltage gain from a very low voltage dc source, such as the micro-inverter in photovoltaic, or G/M in HEV.