Three-phase Combined-type Buck AC/AC Converter With Controllable Phase

To effectively control the power flow of the line and improve the power transmission capability of the power grid and the stability of the power system,three-phase combined type Buck AC/AC converter with controllable phase based on ACCPA(AC/AC converter with controllable phase and amplitude)is proposed,which can independently adjust the output voltage amplitude and phase.Based on the ACCPA,the output voltage is phase-shifted with respect to the input voltage using a duty cycle with double frequency AC component,and to reduce the switching loss,the ACCPA post stage is discarded.Using only one duty cycle to adjust the phase and amplitude of the output voltage separately.A step-up transformer is inserted at the back end of the three-phase output filter to expand the adjustment range of amplitude and phase.The three-phase symmetry is used to cancel out the third harmonic voltage components.With its topology,the working principle of the circuit is studied.The relationship between the amplitude and phase of the output voltage and each parameter was analyzed.Phase and amplitude close-loop control strategy is given.The three-phase combined type Buck AC/AC converter with controllable phase was simulated by saber software.The simulation results verifies the phase and amplitude regulation function of three-phase combined type Buck AC/AC converter with controllable phase.Using the DSP controller TMS320F2812 as the control core,a prototype of three-phase combined type Buck AC/AC converter with controllable phase was developed.The related software and hardware design of the entire system is introduced in detail,and on this basis,the Open-loop control and closed-loop control experiments and relevant experimental data are given.The experimental results prove the correctness of the previous theoretical analysis and the feasibility of the control strategy.