Power flow of photovoltaic system using buck-boost PWM power inverter

This paper presents a buck-boost PWM power inverter and its application for residential photovoltaic system. The PWM power inverter is realized by combining two sets of a high frequency buck-boost chopper and by making it operate in the discontinuous conduction mode. Photovoltaic system with the power inverter has the following advantages: (1) the power generated by the photovoltaic array can be transferred to the load and the utility line under any array voltage, (2) isolation between the photovoltaic array and the utility line is performed by a small high frequency reactor operating as energy storage element, (3) unity power factor operation is provided, (4) there is no need of a reactor for interconnection with the utility line, (5) so the system configuration is very simple. The input-output characteristics of the system are analyzed. As a result, the ripple component of the array current and the power flow between the interface and the utility line are derived and verified experimentally.