The research of a novel single-phase three-level inverter circuit with its modulation strategy

Abstract

This paper proposes a new single-phase three-level inverter topology and describes the control method for the proposed inverter. The inverter contains a H-bridge inverter circuit and an auxiliary circuit. The auxiliary circuit enables H-bridge circuit to be operated in the mode of five kinds of voltage level with unipolar pulse width modulation (PWM) strategy. The operation principle of proposed inverter topology is analyzed in detail. The proposed inverter eliminates the problems of DC capacitors voltage unbalance without additional control. The control of inverter is simple and easy to implement. And it is suitable for small or medium power applications. In this paper, the proportional-resonant (PR) controller is used in the proposed inverter, the feasibility and the analysis of principle of the proposed inverter is verified by simulation. The results show that the proposed inverter can output currents of low total harmonic distortion and has higher efficiency than the H-bridge inverter.