| Electricity,the major driving force of social development is being widely used in all fields of society.Therefore,the higher quality of electric energy is necessary.The power factor and harmonics of power system are two important parameters to determine the power quality.It is of great importance to improve the power factor and reduce the harmonics.Induction motors are widely used in industrial production.Their power consumption accounts for about 64%of the total electricity consumption in the society,but their power factor is too low.Therefore,the operation of asynchronous motors needs to absorb a large amount of reactive power from the power system,causing the power system run in a low power factor.At the same time,with the use of a large number of power electronic devices,serious harmonic pollution is brought to the power system,which not only causes a lot of power losses,but also affects the normal use of electric equipment such as asynchronous motors.For this reason,improving the power factor of induction motors and reducing harmonics are of great significance to improve the quality of electric energy.In this paper,came up with a comprehensive reactive power and harmonic compensation device to improve the power factor of induction motors and reduce the harmonics in the power system.Based on the structure of open-winding induction motor,this paper draws lessons from the two-ended inverter control motor topological structure.Using the instantaneous reactive power theory,deduced the relationship between harmonic and asynchronous motor torque and the mathematical model of the integrated compensation device,then designed the topology and control method.The simulation model of the integrated compensation device based on open-winding motor is established based on the actual parameters of the experimental motor by MATLAB simulation software.The simulation results show that the power factor can reach 1 when the device works,and the harmonics also decrease,which verifies the feasibility of this theory and compensation device.TMS320F28335 DSP(Digital Signal Processing)is the core of the control system.The experimental platform of the asynchronous motor compensation device including the main circuit,trigger circuit,sampling circuit and power supply circuit.The programming of the circuit is designed according to the hardware circuit.In this paper,the experimental platform of 0.75kW induction motor is built to learn about and test the experiment.The experimental results show that under different loading conditions,the reactive power after compensation is significantly less than the reactive power before compensation.The power factor is greatly improved then before.Power factor can be increased to 0.9407 at rated power,the improvement can reach up to 31%,when the load factor is 69%,the maximum power factor increase is 44.22%.The experimental results show that the compensation method can improve the power factor of induction motor.And the compensation method is feasible in practice. |
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