Research On Direct Torque Control Of Permanent Magnet Synchronous Motor Based On Active Disturbance Rejection Sliding Mode Control

Permanent magnet synchronous motor(PMSM)has been widely used in all aspects of life due to its small size,high efficiency and low noise.Direct Torque Control(DTC),as a new AC control technology,not only has a relatively simple motor structure,but also has a good control accuracy.Direct torque strategy introduces the concept of torque angle to directly control the electromagnetic torque.Through the rapid change of the torque angle controlled by the inverters,the corresponding change of the motor torque can be made,so that the motor can be directly controlled.While this method has many advantages,it also has some problems,such as poor torque stability,serious ripple and poor operation effect when motor speed is too low.Based on the traditional direct torque strategy,this paper studies the eommon problems,and then takes improvement measures according to the problems.The main work of this paper is as follows:Firstly,through reading the literature to understand the development history of motor and the research status of motor at home and abroad,the general classification methods of permanent magnet synchronous motor are briefly introduced,several commonly used motor control methods are analyzed,their advantages and disadvantages and the future development direction of motor are simply pointed out,and the origin of sliding mode variable structure control and its application are also discussed.The basic principles are introduced and analyzed.Secondly,the mathematical model of permanent magnet synchronous motor is established.Several coordinates and coordinate transformation methods commonly used in motor analysis are introduced.Different mathematical models of motor are analyzed and deduced,and the mathematical expression of motor under direct torque strategy is obtained.Then,aiming at the unstable switching of inverters in traditional schemes,the strategy of replacing switch tables in original schemes with SVPWM is proposed.According to the problem of excessive torque ripple caused by hysteresis controller in traditional schemes,a second-order sliding mode control scheme is introduced,and a new type of torque and flux controller is designed based on the nonlinear smoothing function.Finally,aiming at the problems of PI controller in traditional speed control system,this paper proposes a sliding mode control scheme based on ADRC.ESO,the core component of ADRC,is introduced into sliding mode control.Integral term is added and non-linear smooth function g function is used instead of traditional symbolic function.The control scheme designed in this paper is verified by simulation experiment.In summary,the high-order sliding mode controller is designed to solve the problem of large torque flux ripple,and the active disturbance rejection sliding mode controller is designed to replace the PI controller,so that the system has strong disturbance rejection performance and good dynamic and static performance.The validity of the design method is verified by simulation on MATLAB platform.This method has high theoretical and practical significance in the field of non-linear control.