Study On Three-phase High Power Factor Rectifier Based On DSP

With the development and wide application of power electronic devices, power grid harmonic and reactive power pollution become increasingly serious. Therefore, high power factor and low current harmonic distortion of PWM rectifier is becoming a hot spot of power electronic technology application. VIENNA rectifier with low switch voltage stress, less switch signals, high reliability, has a broad prospect in high-pressure, high-power applications. Due to the complex working principle and difficult to control, VIENNA rectifier has yet to mature. Therefore, it has important theoretical significance and engineering value to study three phase voltage synchronous control strategy, topology control implementation and performance improvement research to achieve topology control.Firstly, this dissertation analyzes the working principle of VIENNA rectifier. With state space method, mathematic models of the rectifier are concluded on abc coordinate system, dq coordinate system, equivalent circuit model is established in different coordinate systems.Secondly, With the three-phase DPLL method, current inner loop reference command signal is calculated. The working principle of each PLL component is analyzed in detail. Meanwhile, in order to avoid the second harmonic interference phase lock and shorten the program execution time, an improved DPLL method with notch filter and digital sinusoidal oscillator is discussed.Then, the average current mode control strategy was adopted to realize control of the VIENNA rectifier. The current inner loop transfer function is analyzed, and a suitable controller is used for the loop compensation. Meanwhile, in order to improve power factor, reduce current harmonic distortion, an improved average current mode control strategy with feedforward compensation in the current loop is introduced.Finally, the VIENNA rectifier hardware circuit and software system are designed. The VIENNA main circuit parameter calculation and device type selection, design of control circuit, DSP registers configuration and the PID function are elaborated in detail. A10kw VIENNA rectifier prototype with TMS320F28035as core controller is realized. The traditional average current mode control strategy and the improved average current mode control strategy are tested Respectively. The experimental results show that the improved average current mode control strategy has better control performance than the traditional average current control strategy.