Design Of Non-singular Terminal Sliding Mode Controller For Permanent Magnet Synchronous Motor With Disturbance Compensation

The persistent blossom of power electronics makes the property of permanent magnet synchronous motor control system got promoted,but the capability of the system is still by the motor parameters change and load change and other factors,the characteristics of the sliding mode control is strong robustness,when motor parameters perturbation,the motor model error and extrinsic applying interference,sliding mode control can still keep excellent control performance,this thesis is aim at the conventional sliding mode which makes improvements,and in order to overcome the shortcoming of conventional non-singular terminal sliding mode control in the convergence stage has sluggishly speed,the non-singular fast terminal sliding mode is designed.To increase the immunity of the system,estimating the torque which applied externally by devising a disturbance observer,and the estimated results were feedforward compensated to the speed controller.First,the mathematical model and motion equation of permanent magnet synchronous motor are deduced,and combining the theory of conventional sliding mode control design speed loop controller,according to conventional sliding mode control theory can only make the system error of gradual convergence of the defect,taking advantage of nonlinear functions to construct terminal sliding mode surface,the system error convergence in limited time.Secondly,although the terminal sliding mode control can allow the system error converge in finite time,if the parameters are not properly selected,the "singularity" phenomenon will appear.It is necessary to use non-singular terminal sliding mode control to prevent this phenomenon.The convergence speed of non-singular terminal sliding mode control is slow when the system error converges to the equilibrium point along the sliding mode,in order to make the system error can achieve rapid global convergence,and nonlinear function using linear function common building nonsingular terminal sliding mode surface quickly,make the system error realize fast convergence in different stages.Rapid nonsingular terminal sliding mode control often use the larger switch gain to suppress external load to the system,it will inevitably cause rotation speed fluctuation,aiming at this problem,also using the principle of rapid non-singular terminal sliding mode to design disturbance observer,the external torque is estimated by using a disturbance observer,large switching gain is avoided.Thus,the robustness of the system is improved.Finally,permanent magnet synchronous motor is adjustable load experiment platform,by adjusting the output torque of the magnetic powder brake,impose various load on the motor.The results of experiment explain that the control measurement strategy combining disturbance observer and non-singular fast terminal sliding mode can make the motor speed rise to the specified speed period without overshoot when the motor starts at no load.The disturbance observer weakens chattering when the motor is working at a designated speed.When the external load is exerted on the motor,the speed of motor falls less and the time which returns to the reference speed is shorter.The results of experiment prove the practicability of the speed controller designed in this thesis.