Research On Control Technology Of High Speed Permanent Magnet Synchronous Motor

The high-speed permanent magnet synchronous motor is characterized by its compact size,high power density,and high efficiency.It can be widely applied in various fields such as aerospace,oil and gas,medical devices,and CNC machine tools.A highly efficient and stable control system is crucial for fully utilizing the excellent characteristics of the high-speed permanent magnet synchronous motor.High speed permanent magnet synchronous motor can achieve similar control performance with DC motor by using vector control.However,position sensors for measuring speed and rotor position information are less reliable in high-speed motor control systems.In addition,the d-q axis cross-coupling phenomenon is serious under high fundamental frequency operation conditions,and the current loop control performance is degraded.Restricted by the inverter switching frequency,the high-speed permanent magnet synchronous motor control system has a low carrier ratio,and the digital control delay has a significant impact,and the cross-coupling and problems are more prominent.Therefore,the study of position sensor-free control and decoupling control becomes the key to improve system reliability.This paper addresses the above problems mainly on the key issues related to the theoretical modeling,sensorless control and decoupling control of high-speed permanent magnet synchronous motor control system.Firstly,the spatial vector control system for the high-speed permanent magnet synchronous motor is established based on the mathematical model of high-speed permanent magnet synchronous motors,and then the control strategy and space vector pulse width modulation technology are introduced,based on which the causes of the error of the basic space vector voltage action time in the high-speed system are analyzed.The simulation model of high-speed permanent magnet synchronous motor double closed-loop vector control system based on the direct axis current equals zero control is built to provide the theoretical basis and modeling basis for the subsequent research.Secondly,in order to solve the problem of poor observation performance of the conventional model-referenced adaptive observer using a fixed-gain feedback loop in the high-speed permanent magnet synchronous motor control system,an improved model-referenced adaptive position-sensor-free control is proposed,which uses the tal function to construct a model-referenced adaptive law with variable-gain nonlinear characteristics,and uses the contradiction between the adjustable rapidity and overshoot of the tal function and the continuous The proposed algorithm is used to improve the dynamic and steady-state performance of the observer.The feasibility and effectiveness of the proposed algorithm are verified by simulating the proposed algorithm under the sudden change of speed and load conditions.Thirdly,aiming at the current loop coupling problem of high-speed permanent magnet synchronous motor control system,the limitations of PI current regulator and the control principles of feedforward decoupling,feedback decoupling,deviation decoupling and other control strategies are analyzed,and the closed-loop transfer functions of three decoupling control methods are derived.Based on the zero-pole distribution diagram and Bode diagram,the decoupling performance and system robustness of the three decoupling control strategies are compared and studied when the parameters are not deviated and the parameters are deviated.The analysis shows that the decoupling performance of the deviation decoupling control is better than the other two decoupling control methods.The correctness of the theoretical analysis is verified by simulation.Finally,the problem of digital control delay in high-speed permanent magnet synchronous motor control system is studied in depth.Aiming at the problem that the digital control delay leads to the aggravation of current loop coupling,an improved deviation decoupling control strategy for high-speed permanent magnet synchronous motor is proposed.On the basis of considering the additional coupling term between d-q axes caused by delay effect and the coupling term of the motor itself,according to the principle of traditional deviation decoupling control,the current control equation with coupling term is established,and a new decoupling term is derived,which is used as the system compensation to offset the mutual influence of the coupling term.The simulation and experimental results show that the proposed algorithm can effectively reduce the influence of digital control delay.