Design Of Dual-PWM Variable Frequency Speed Regulation System Based On Vector Control

Regarding the three-phase Squirrel Cage Asynchronous Motor as the research object, a new design of Dual-PWM variable frequency speed regulation system which has high power factor rectifier and vector control strategy is proposed in this paper. The speed control system can be divided into rectifier part and inverter part. The control system can not only run at unity power factor but also realize bidirectional flow of energy, thus the harmonic pollution on the grid can be effectively reduced.Rectifier of the Dual-PWM variable frequency speed regulation system applies PWM technique. This paper focuses on the operation principle of the three-phase voltage source PWM rectifier and derives a mathematical model based on switch function. In order to solve the coupled relationship between the d, q axis components, feed-forward decoupling module is proposed. Based on that, this paper designs a voltage and current double closed loop control system based on direct current control strategy.In the research on the inverter of the speed regulation system, the vector control strategy based on rotor flux-oriented is introduced. According to the dynamic mathematical model of the asynchronous motor, the mathematical model of the rotor flux observer is established. On the basis of obtaining accurate information of flux,this paper designs the double closed-loop vector control system with the flux and torque as the inner-loop and the speed as the outer-loop.Combining the rectifier and inverter, Dual-PWM variable frequency speed regulation system is established. Based on the theoretical analysis, the main circuit topology, the control strategy and the device parameters of the speed regulation system is designed. By thoroughly comparing the corresponding waveforms associating with different parameter value, the design of the speed regulation system is optimized. Finally, the Dual-PWM variable frequency speed regulation system is simulated with the MATLAB/SIMULINK, and the simulation results shows that the Dual-PWM variable frequency system can improve the power factor to be±1, lower the harmonic distortion of input current, accomplish the four-quadrant operation and bidirectional flow of energy.