Study Of Efficiency Optimization Control For Drive System With Frequency Control Of Asynchronous Motor

With the changes of the times,asynchronous motors play an increasingly important role in modern industrial production because of their simple structure,low cost,high operational reliability and easy maintenance.The most power-consuming equipment in industrial production such as fan and water pump motors which is in long-term operation in light load conditions with great energy saving potential.This thesis focuses on the low efficiency of asynchronous motor at light load,by reducing the magnetic flux of the asynchronous motor at light load,the loss of the asynchronous motor is reduced,and the efficiency of the fanpump type motor under light load operation is improved.By studying the traditional scalar control and vector control ideas,a vector decoupling method is proposed by combining these two ideas based on excitation component of stator current under constant voltage-to-frequency ratio(V/f)control.Referring to the no-load current value at the rated voltage frequency,the vector decoupling of the stator current under constant V/f control is completed on condition of small value of the torque component.Simulations and experiments verify the accuracy of this decoupling method.Based on the traditional constant V/f control,a speed regulation system is designed based on stator current excitation component based vector decoupling.The stator voltage compensation is added to improve the accuracy of the vector decoupling.The slip compensation is added according to the decoupling result of the stator current to improve the speed regulation.In this thesis,the efficiency optimization strategy of minimizing stator current is applied to the stator current excitation component based vector decoupling speed control system.According to the stator current decoupling result,the voltage-to-frequency ratio is quantitatively changed to minimize the stator current and the purpose of reducing the loss by weakening the magnetic flux is achieved.The slip compensation algorithm ensures that the output power is constant with reduced input power,and the efficiency of the asynchronous motor operation is optimized.In order to verify the effectiveness of the proposed algorithm,the C language program of the proposed efficiency optimization algorithm is written based on TMS320F28035 chip.A hardware-in-the-loop simulation platform based on RT-LAB and an asynchronous motor test experimental platform is built.Simulation and experimental results show that using the efficiency optimization algorithm proposed in this paper,the efficiency of asynchronous motor can be increased by 18% under low speed and light load compared with the traditional constant V/F control,which indicates that the efficiency optimization based on stator current excitation component based vector decoupling proposed in this paper can improve the speed regulation without increasing the speed measuring device,and verifies that the proposed efficiency optimization algorithm is effective in reducing motor loss and optimizing the efficiency of motor operation at the low speed light load condition.