Research On VIENNA Rectifier And Neutral-point Voltage Balance Control Technology

With the increase of the application of power electronic devices to all aspects of daily life, the harmonic pollution in power grid becomes more and more serious. In order to solve the problem of "harmonic pollution", there are two aspects being studied: filtering the harmonics of the power grid and improving the power factor of the power electronic devices. Therefore, the research on the quality and efficiency of power electronic devices is important. It is very significant to study the high power factor PWM rectifier,for it plays an important role in the power electronic devices. And the VIENNA rectifier circuit has been widely used. LC filter structure is introduced in the front of the VIENNA rectifier. Therefore, there exists a LCL structure being consist of the LC filter and the traditional Boost inductance. Compared with the VIENNA rectifier circuit topology with only Boost inductance, the introduction of LC L structure can reduce the filter volume and the system cost. Therefore, it is significant to study the VIENNA rectifier circuit with a LC L structure in its front end.In this paper, the mathematical model of VIENNA rectifier topology is established, and the stability of the VIENNA rectifier system based on a LC L structure is analyzed. However, the existence of the LC L structure may lead to a resonance peak, which may cause system instability. In order to suppress the resonance problem of the system, a control strategy based on capacitor current feedback is introduced. The theoretical analysis and simulation verification are carried out. In addition, a new control strategy based on capacitor voltage feedback is proposed. The theoretical analysis and simulation verification are carried out to verify the effectiveness of suppressing the resonance of the system.In this paper, a control strategy based on SPWM modulation is used to control the neutral point balance with the imbalance of the midpoint in the VIENNA rectifier circuit. Through theoretical analysis and mathematical deduction, a relatively simpler, easier control strategy to adjust the balance of neutral point voltage is analyzed.Finally, the main circuit and the control circuit are designed. TMS320F2812 is chosen as its main controller chip of the digital control system. The software programming of the system is programmed by using C language. The experimental verification is carried out on the above research.