Three-phase Power Factor Correction System Research And Implementation Of Control Algorithm

People’s production and life have got a great convenience for the rapid development of the power electronic technology, however,the public power grid have been polluted by the harmonic produced by power electronic equipments, and power quality have been influenced. In order to ensure the safety in production and improve the utilization ratio of energy, measures must be taken to suppress harmonic and improve the power factor.In view of the situation that high power rectifier equipment in the grid is the main harmonic sources, the purpose of this thesis is to study a tri-phase high power factor rectifier control strategy,which will not only steady the output DC voltage but also make sure that the input current have low harmonic and high power factor.Firstly, the low frequency and high frequency mathematical model of tri-phase PWM rectifier is established and analyzed on the basis of coordinate transformation. Secondly, the mutiple-loop and direct-current control method in dq coordinate is choosed on the comparison with the several current existing ones. According to the different requirements of outer voltage loop and inner current loop of the system, a system control structure has been designed, and the calculation formula of PI parameters in each loop have been derived. Space vector pulse width modulation (SVPWM) is adopted as the rectifier’s modulation method. The modulation method of SVPWM and how to realize it in actual programming are presented in details. In order to validate the proposed control algorithm,the proposed control structure and algorithm are simulated in matlab/simulink environment. The result shows that the proposed control scheme is feasible in theory.According to the above analysis, TMS320F2812is choosed as the main control chip of the actual physical test platform build on the consideration of the actual need of the control system. The software of the control system, which is automatically scheduled by DSP/BIOS of2812own for the reliability of software,have realized the signal acquisition, PI adjustment, and produce SVPWM wave.The test results of test system show that the control method of tri-phase PWM converter expounded in this thesis can not only steady the dc bus voltage but also inhibit the public power grid pollution by current harmonic from input current AC-side,and improve the power quality compared with traditional control methods. The method this paper expounded has improved the power factor of the system, which means that the energy efficiency has been improved,and the series problems caused by low power factor in traditional methods have been solved.