The Research Of Single-Phase PWM Rectifier And Control Strategy

With the development of society, the requirement of high quality and reliability powersupply is increasing all the time. As one of the efficient device to improve power supplyquality, Electronic Power Transformer (EPT) attracts an increasing attention of researchers.Compared with traditional transformer, EPT has a lot of advantages. The output voltage ofthe EPT is constant. The currents of the primary side and the voltage of the secondary sideof the EPT are sinusoidal waves with very low total harmonic distortion (THD). The powerfactor of the primary side and the voltage of the secondary side could be flexibly controlled.It has the ability to keep system auto-balancing. This paper focuses on the control strategiesof the single phase PWM rectifier of the EPT.In this paper, the working principle of the single phase PWM rectifier is analyzed anda mathematical model is founded. The third harmonic in the supply current is also analyzedand a method is presented to improve the supply current. Traditional methods for phaselock loop is also introduced in this paper.To keep the DC voltage constant and the single phase rectifier working at unit powerfactor, two control strategies are introduced in this paper, one of the strategies is repetitivecontrol strategy and the other is feedback linearization control strategy. A second harmonicnotch filter is presented to reduce the impact of the second harmonic voltage of the DCvoltage on the control of the current.The hardware system and software system of the experiment system are designed toverify the effectiveness of the control strategies. The paper introduces the design of electricscheme, control system, and gives the flow chart of the main program. Finally theexperimental results prove that it is accorded the proposed methods and it is satisfied withthe waveform.