Stand-alone transformerless sinusoidal inverter for PV systems

The authors investigate the design and performance of a nonisolated inverter. The inverter is designed to be powered from a bipolar photovoltaic array series-parallel combination. The array is configured so that its output is compatible with the input of the inverter. The load circuit return is common with the input power return. The inverter control circuit utilizes direct feedback pulse-width-modulated (PWM) control. A signal with a triangular carrier wave is compared to a reference sinusoidal modulating wave to determine the switching instants. This technique is easily implemented using analog circuits. The control and power processor circuits consists of several subcircuits. These subcircuits are described.<>