Research On Control Method For Improving Asynchronous Machine Power Factor

Electric energy is the most common energy in modern society,which is applied in all fields of production.Its quality and development are closely related.Power factor and harmonic are two important factors to measure power quality.Therefore,how to reduce waveform distortion and improve power factor in power grid has research significance.Among all kinds of electrical equipment,machine are widely used in industrial production,accounting for about 64%of the total social electricity consumption.In order to establish the magnetic field,the machine needs to absorb a large amount of reactive power from the power system,and often accompanied by power mismatch and other issues,which will lead to the reduction of power factor of the power grid.The development of switching technology and the use of power electronic devices also bring harmonics to the power system,resulting in power loss and affecting the normal use of machine and other equipment.From the perspective of machine,improving power factor and reducing harmonics are also improving the quality of power grid.In this paper,a reactive power and harmonic compensation device for open-winding machine is proposed,which can reduce the influence of machine on the quality of power grid.Based on the topological structure of double-ended inversion of open-winding machine and instantaneous reactive power theory,this paper designs a power factor compensation device for induction machine,deduces the energy exchange relationship between the compensation device and the machine and the power grid,obtains the topological structure and control principle of the compensation device,and proposes a power factor compensation control method for induction machine.Based on the equation of ordinary three-phase asynchronous machine,the compensation control model of open-winding machine is built in MATLAB software,and the simulation is carried out with the parameters of the experimental machine.The results show that the model can compensate reactive power to suppress harmonics and maintain DC voltage stability.The validity of the control method and the feasibility of the compensation device are verified..The hardware circuit is based on TMS320F28335 DSP(Digital Signal Processing).The experimental device platform includes the main circuit,sampling circuit,trigger circuit and other main functional modules.The software part is designed and debugged according to the hardware circuit in CCS(Code Composer Studio).The experimental results show that the power factor of the machine can be significantly increased by the compensation device.Under different load conditions,the power factor can be increased.When approaching the rated load,the maximum power factor can be increased to 0.9618,and the increase range is about 25%.Experiments verify the rationality of the compensation device proposed in this paper.