Power capacity enhancement of transformerless photovoltaic inverter

Abstract

A conventional inverter uses a transformer. Some transformers connected in parallel are needed to obtain a high power inverter. They cause the inverter has a big in size, expensive cost and low efficiency. To solve the problem, a transformerless photovoltaic inverter (TPVI) is suitable to be applied. This paper proposes a paralleled full bridge circuit (FBI) to enhance the power capacity of three-level transformerless photovoltaic inverter. It has a pulse driver circuit, five full bridge inverter circuits and a power factor correction (PFC) circuit. To obtain the high power capacity of the TPVI, five FBI circuits are connected in parallel. Each FBI circuit uses MOSFET IRFP460 which has rating current of 20 A, therefore the total FBI circuit has applicable maximum current of 100 A. Its main energy source is a photovoltaic (PV) array that consists of three unit PV modules connected in series, each unit has voltage of 81 V and power of 60 W. Some three unit PV modules are connected in parallel to fulfill the demand of high alternating current (AC) power. In this research, the AC three-level waveform of the TPVI is developed using a PIC microcontroller.