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 power systems. The PWM power inverter is realized by combining two sets of high frequency buck-boost choppers and by making them operate in the discontinuous conduction mode. A PV power 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; and (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