Research On Dual-pwm Converter And It's Control Strategy

The AC Variable Frequency (VF) speed regulation has brought huge economic and social benefits in various fields. At present, the AC/DC/AC VF speed regulation system is the most widely used form. However, due to the limitation of the circuit structure, the traditional AC/DC/AC converter causes harmonic pollutions to the power grid. A novel dual-PWM converter is introduced in this paper. The converter composed of a PWM rectifier and a PWM inverter without any additional circuits can realize bidirectional flux of energy and improve the dynamic performance of the system.Firstly, the structure and the working principle of this dual-PWM converter are analyzed. Secondly, the working principle and mathematical model are analyzed in details. Compared to the traditional voltage oriented vector control, the virtual flux oriented vector control, which is one type of the direct current control based on space vector pulse width modulation (SVPWM), can obtain higher power factor, lower harmonic distortion, reduce system cost and volume, and provide stable direct current voltage for the inverter. While the traditional direct torque control has some shortcomings, including unsatisfied low-speed performance, torque rippling and unfixed switching frequency, the SVPWM-based direct torque control with no speed sensor is proposed. This method effectively reduces the cost of the system and enhances the stability and reliability of the system.Ultimately, the rectifier and the inverter systems are simulated in MATLAB7.0/Simulink. And the system was realized on TMS320LF2407A digital signal processor. The experimental results confirmed the theoretical analysis.