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Efficiency Optimization Control Of Asynchronous Motor

Posted on:2021-03-08Degree:MasterType:Thesis
Country:ChinaCandidate:J B YangFull Text:PDF
GTID:2392330611453484Subject:Control engineering
Abstract/Summary:PDF Full Text Request
Asynchronous motor,also known as induction motor,is a device that converts three-phase AC to mechanical drive.Because of its simple structure,high reliability,convenient use and low cost,it is widely used in industrial and agricultural production and people's daily life,such as production equipment such as machine tools,pumps,fans,elevators,locomotives,new energy automobiles and other living facilities.Asynchronous motor may run in no-load or light-load state for a long time due to the actual needs of production and life,which results in low power efficiency of the motor system,and the internal parameters of the motor are susceptible to temperature changes,which will also cause the control performance of the motor to decrease.In order to optimize the efficiency of three-phase asynchronous motor and its drive system,starting from the loss analysis of three-phase asynchronous motor,this paper studies the mathematical model,efficiency optimization method and control method of asynchronous motor,improves the traditional efficiency optimization method and improves the related control performance.The work in this paper is as follows:First,the research background and significance of this topic are explained,and the progress of efficiency optimization research at home and abroad is introduced.The loss composition of asynchronous motor is analyzed,and the influencing factors of motor loss are clarified.Secondly,the dynamic mathematical model of three-phase asynchronous motor considering iron loss has complex structure and higher order,which is not easy to be studied in the future.The dynamic simplified model of asynchronous motor is deduced based on reasonable assumptions,combining coordinate transformation and rotor magnetic field orientation strategy.On this basis,its steady-state mathematical model is obtained.Thirdly,the coordinate transformation theory of three-phase asynchronous motor is introduced,the calculation of the rotor magnetic chain considering iron loss is deduced,and the vector control system of three-phase asynchronous motor considering iron loss is simulated based on MATLAB/Simulink.The efficiency optimization principle based on loss model and golden section is analyzed.The expression of loss minimization is derived from the asynchronous motor steady-state mathematical model,and two classical efficiency optimization methods are implemented.Fourthly,the hardware platform of 3kW three-phase asynchronous motor drive is improved,and the software of drive system is designed to realize the frequency conversion and speed regulation control of three-phase asynchronous motor.The innovations in this paper are as follows:(1)In the efficiency optimization control of the motor,the current control at the bottom is very important,because the parameters of the motor will change over a long period of time and the load is uncertain,so the performance of the traditional PI control method will decrease and the loss of the motor will increase.Therefore,this paper presents a current control method based on ADRC,which improves the bottom current control performance of traditional efficiency optimization algorithm.The simulation results show that the proposed method is robust to the parameter changes and load uncertainties of the motor,also reduces the loss of the motor.(2)In the optimization algorithm of motor efficiency,it is necessary to control the speed and the magnetic chain of the motor separately.There is strong coupling between the speed and the magnetic chain,and the time-varying parameters and the uncertainty of the load during the operation of the motor make the design of the controller difficult.The traditional PI control method currently used sets different parameters according to different working conditions,but it still cannot get a good control effect.Based on the simplified dynamic model of asynchronous motor with iron loss,this paper uses the back-step adaptive method to design the estimation rules of motor speed,magnetic chain tracking controller and unknown parameters,in which the current is used as virtual control and the current instruction value is tracked quickly by sliding mode control.Compared with PI control method,this method is more robust in the face of time-varying motor parameters and load uncertainties.The most important thing is that the estimated unknown parameters are conducive to the calculation of optimal magnetic chains.The simulation results show that the method proposed in this paper is correct and has good performance.
Keywords/Search Tags:Asynchronous motor, Efficiency optimization, Golden section, Auto disturbance rejection control, Back-step adaptive sliding mode
PDF Full Text Request
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