Research of symmetrical voltages and phase of three-phase inverter with dual-loop control

Abstract

In terms of the conventional inverter doesn't match all unbalanced loads, a topology and strategy of nature- decoupling in circuit and magnetic circuit is proposed for aeronautic and military equipment field. Each phase voltage is controlled independently by PI controller and double-loop controller with voltage and current instantaneous feedback, and phase angle by closed-loop control with PLL , which make the output voltage and phase angle track the references sine wave. Pulse width and phase angle of reference sine wave are modulated by voltage-loop and phase-loop, which ensures phase and voltage of the inverter to symmetry. At first, output unsymmetrical mechanism of a traditional inverter is analyzed in this paper; Second, its main circuit topology, construction of voltage current feedback circuits, its control principle and implementation method are discussed; then, its mathematic models are set up and analyzed; At last, simulation and experiment results of 30 kW three-phase inverter is obtained that proves this circuit design to be feasible.