Decoupling Current Control For AC Induction Machine

In recent years,due to the general trend of environmental protection and resource saving,the market structure of the automotive industry has undergone great changes,the situation of traditional internal combustion car dominated was broken by the strong addition of new energy vehicles.Since 21 st century,the new energy vehicle industry has developed rapidly,and has become a member of the automotive sector that can not be ignored.In China,the main fore of the development of new energy vehicles is pure electric vehicles.There are two common types of motors on pure electric vehicles: Permanent magnet synchronous motor and induction motor,and the object of this paper is induction motor.Vector control of electric drive system is a key technology of EV.This paper mainly studies one of the important links: current control.The current controller plays an important role in the control system of the induction machine.It has a significant influence on the response speed and accuracy of the system.Cross-coupling caused by reference frame transformation which is especially serious in the highspeed area cannot be ignored.Without compensation,it will affect the response performance of the motor control and even affect the stability of the system in severe cases.Conventional current controllers often neglect compensation for coupling conditions which may results in poor control performance.In order to realize the decoupling control of current,this paper introduces the complex vector to analyze the stator voltage equation in synchronous rotating coordinate system.Analysis and compare for decoupling effect and robustness to parameter variation of two common decoupling methods have been done in this paper.In this paper,the electric drive control system of asynchronous motor is built by MATLAB/SIMULINK platform.Firstly,the performance of the traditional PI control and feedforward decoupling control and the internal mode decoupling control on the cross coupling of d and q two axes is simulated respectively,thus,The conclusion that the decoupling control is effective on the inhibition of crosscoupling phenomenon is verified.Then,under the condition that the inductance parameters is changed,the two decoupling methods are simulated and compared,and get the conclusion that the internal model decoupling is better for the robustness when parameter varies is verified.Finally,the torque response effect of two decoupling modes in the change of motor speed ladder is compared,and it is proved that adding decoupling control can better improve the response performance of the motor.