A Three-Phase Constant Common-Mode Voltage Inverter With Triple Voltage Boost for Transformerless Photovoltaic System

Abstract

This paper introduces a new three-phase two-level inverter based on the switched-capacitor voltage multiplier. By adding a voltage multiplier network at the DC side of the traditional three-phase inverter topology, the DC-link voltage of the introduced inverter is stepped up to triple of the input voltage. Compared to the existing solutions, the common-mode voltage of the introduced topology is kept constant. Moreover, the voltage stress across additional semiconductor components is the same as one-third of DC-link voltage. Operating principles, mathematical analysis, circuit analysis, and pulse-width modulation (PWM) method based on the Boolean logic function for introduced inverter are presented. A comparison of the introduced inverter with other inverter topologies is also reported. The simulation results are shown to verify the introduced three-phase triple voltage boost inverter. Besides that, a laboratory-built prototype is developed based on a DSP F280049C microcontroller and the corresponding experimental tests are provided to prove the introduced inverter.

Keywords

• Three-phase inverter
• transformerless PV system
• common-mode voltage
• leakage current
• switched-capacitor network