Research On Predictive Current Control Of High Performance PMSM Based On Disturbance Observer

In recent years,China has increased the development and utilization of rare earth permanent magnet materials,which has effectively reduced the manufacturing cost of permanent magnet synchronous motors.In addition,it has the characteristics of high power density,wide speed range,and fast dynamic response.Therefore,permanent magnet AC Drive systems are used more and more frequently in various industrial fields.Certain high-performance applications such as precision machining,new energy vehicles and industrial robots put forward higher performance requirements for permanent magnet synchronous motor drive systems.Therefore,the vector control strategy of PMSM with faster dynamic response,higher steady-state accuracy,stronger anti-disturbance and robustness has become a research hotspot in recent years.This paper takes surface-mount permanent magnet synchronous motors as the research object.In order to achieve high-performance motor controller current control performance,the research is carried out from the dead-time effect suppression strategy and the PWM predictive current control strategy.This article first introduces the mathematical model and coordinate transformation of permanent magnet synchronous motors,and then briefly introduces the basic principles and implementation methods of vector control.Through analyzing the characteristics of different vector control methods,the vector control method of_di~e=0to be adopted is finally determined.Aiming at the problem that the dead time and the non-linear characteristics of the inverter have an adverse effect on the current loop of the permanent magnet synchronous motor drive control system,this paper introduces the mechanism of the dead time effect of the permanent magnet synchronous motor in detail,and derives the mathematics of the dead time effect.model.Then this article proposes a method for suppressing the dead-time effect in the full frequency domain based on the disturbance voltage feedforward compensation.By constructing a discrete disturbance voltage observer,the observed disturbance is compensated to a given voltage value,thereby eliminating the motor input voltage and current distortion caused by the dead zone effect.Simulations and experiments have verified that this method has the best waveform improvement effect when the motor is running at low speed and small torque.Aiming at the problem of poor motor parameter robustness in traditional PWM predictive current controllers,this paper first proposes a robust predictive current control method.which reduces the integral coefficient of the inductance error term by introducing a weight coefficient,and then the system’s robustness to the inductance parameters of the controller model is improved.In order to further improve the parameter robustness of the PWM predictive current controller,the discrete Lunberger disturbance observer and discrete sliding mode disturbance observer are designed respectively in this paper.By combining the discrete disturbance observer with the robust predictive current control method,the control performance of the PWM predictive current controller is maximized.In the design of the discrete Lunberger disturbance observer,this paper uses system modeling and transfer function analysis to analyze the performance of the controller.Secondly,the root locus analysis method is used to optimize the controller parameters.The variable exponential approach law is used in the design of the discrete sliding mode disturbance observer,which makes the disturbance observer have higher observation accuracy and faster response speed.Finally,an experimental platform for the PMSM control system is built,and it is verified on the experimental platform that the improved PWM current predictive control method proposed in this paper can significantly improve the dynamic and static performance of the controller’s current loop.There are 60 figures,5 tables and 83 references in this thesis.