Charge Pump Circuit Concept for Single Phase Transformerless Inverter for DC-AC Conversion with Resistive-Load

This project presents a new transformerless inverter which is based on the charge pump circuit conception, which removes a leakage current of the grid-tied photovoltaic system by means of unipolar sinusoidal pulse width modulation (SPWM) technique. Proposed topology consist of only four power switches (S1 to S4), two capacitors (C1, C2) and two diodes (D1, D2) forms the charge pump circuit and an LCL-filter which is used to remove the harmonics of output current. The charge pump circuit in the transformerless inverter has following characteristics for grid-tied applications (1) This circuit has a common line with the negative terminal of the input dc voltage and the neutral point of the grid that causes the leakage current to be eliminate (2) The charge pump circuit has no active device and it has a lower cost for grid tied applications. A description of the operating principle and analysis of the proposed inverter are presented. Experimental results are presented to confirm both the theoretical analysis and the concept of the proposed inverter. The obtained results clearly validate the performance of the proposed inverter.