3 HIGH EFFICIENCY PHOTOVOLTAIC INVERTER SYSTEM WITH 3-LEVEL BOOST CONVERTER

摘要

The present invention relates to a high efficiency photovoltaic inverter system with a three-level boost converter, capable of enhancing maximum power point tracking (MPPT) efficiency through linearization while maintaining output power produced from a solar cell array at a constant direct current (DC) link voltage. According to the present invention, the system comprises: the solar cell array condensing sunlight inputted from the outside to generate electricity; a DC converter to maintain the output power of the solar cell array at the constant DC link voltage; an inverter to convert DC power outputted from the DC converter into alternating current (AC) power; an inductor-capacitor-inductor (LCL) filter to remove a harmonic wave component from the output power of the inverter; and an MPPT controller to be operated at the maximum power point based on the output power of the solar cell array. The MPPT controller comprises: an MPPT control unit to maintain a voltage of capacitor voltage (Vdcp, Vdcn) of the DC converter based on an MPPT point; a current control unit to control a switching device of the inverter; and a phase locked loop (PLL) control unit to synchronize a system phase with a phase of photovoltaic electricity.