Study On Single/Three-phase Conversion Circuit Based On The Three-phase Bridge Inverter

With the rapid development of the economy and the improvement of people living standards, the total electricity consumption in China has been growing in a fast speed. While the electrical environment becomes more complicated, the problem of single-phase sources powering three-phase sources is being more and more apparent. The technical issue of single-phase sources being transferred to three-phase sources exists not only widely in the electrified railway systems, but also in some industrial power systems and civil power systems, which has not been solved well for a long time.The main contents of this article include:(1) It analyzes ways of single-phase being transferred to three-phase proposed in the domestic and overseas, and compares their advantages and disadvantages. A new topology circuit based on three-phase bridge inverter is proposed in this paper, and the theoretical analysis of the topology transferring principle is given.(2) In order to realized the control strategy, this paper introduces the three-phase digital phase-locked loop and by measuring the load side voltage and current to calculate the load impedance. According to its transfer function and Bode plot, this paper has analyzed the system performance. The new single-three phase conversion circuit adopts the PWM control method principle of the current hysteresis. The simulation model of the main circuit and control method is established in the PSCAD/EMTDC simulation software platform(3) The output reactors of the main circuit, capacitors of the DC side, and filtering device parameters have been analyzed and calculated.(4) The proposed three-phase converter topologies and control methods were validated in the PSCAD/EMTDC simulation software platform for both of the fixed load and load changes cases, Simulation results show that:the control circuit topology and associated methods described herein proposed respond to load changes quickly, and at the same time the single-phase power can transfer to the desired three-phase symmetrical power.