A Novel Transformer-less Buck-Boost Inverter with Coupled Inductor for Photovoltaic Systems

Among several proposed inverter topologies, the improved inverter based on the Aalborg inverter which can track the maximum energy from two independent photovoltaic arrays was proposed as a high efficiency, high power density, and dual-mode time-sharing inverter based on MOSFET switches. In order to further reduce the cost, improve the power density, and extend the lifetime, a novel dual-mode time-sharing inverter with features of high efficiency, a low number of semiconductor devices, leakage current suppression, the wide variation of input DC voltage, and various operating modes are proposed in this article. Besides, the principle of operation is demonstrated through the equivalent circuits. Then, the theoretical analysis shows that the proposed inverter will be converted from Buck and Boost mode to Buck-boost mode when the electrolytic capacitor ages. The lifetime of the inverter is extended and the cost is reduced. Finally, theoretical analysis and the correctness of the topology are confirmed through PSIM-Software simulations.