Research On Sensorless A Ctive Disturbance Rejection Control Of A Flux-Decoupling Magnetic-Geared Permanent-Magnet Brushless Machine

The magnetic-geared permanent-magnet brushless machine(MG-PMBM)has advantages of high transmission efficiency,high torque density and compact structure.It has great application potential in the field of low speed and high torque direct drive.However,the coupling of magnetic fields of magnetic gears and internal machine leads to the decrease of overall operating efficiency in conventional MG-PMBM.The inner PMBM field and the outer MG field effectively decoupled in the Flux-decoupled magnetic-geared permanent-magnet brushless machine.this not only improved the overall efficiency of the machine,but also had good sinusoidal of back EMF and current,which created favorable conditions for sensorless control.In this paper,the sensorless operation of flux-decoupled magnetic-geared permanent magnet brushless machine is studied.The main achievements are as follows:Firstly,by tracing the origin of active disturbance rejection control(ADRC),the deviation control principle implied in the traditional extended state observer(ESO)is analyzed.The theoretical basis and construction method of the improved extended state observer are proposed,and the stability of the error system of the improved second-order and third-order extended state observers is proved.The steady-state error of the improved extended state observer is derived in the presence of disturbances,and compared with the traditional second-order and third-order extended state observers.Theoretical analysis and computer simulation show that the improved extended state observer is superior to the traditional extended state observer.The ESO is an important part of ADRC system,and its performance is directly related to the performance of ADRC system.The introduction of an improved extended state observer will promote the further development of ADRC theory and broaden its application fields.Secondly,aiming at the starting and low-speed operation of flux-decoupled MG-PMBM without rotor position sensor,a new sensorless control method combining high frequency voltage signal injection method with extended state observer is proposed.This method constructs ESO using rotor position angle as main variable and enriches the theory and method of high frequency injection sensorless control of permanent magnet synchronous motor.The rotor position estimation error is proposed by high frequency voltage injection method,and the rotor position signal estimation value is obtained by using the extended observer.The effectiveness of the method is verified by computer simulation and practical experiments.Before starting the motor,after determining the position of the rotor,the rotor permanent magnet polarity identification is carried out.High-frequency pulsating voltage is injected into the estimated direct axis direction of the rotor,and the rotor permanent magnet polarity is determined by detecting and processing the high-frequency pulsating currents.Thirdly,the sliding mode observer method,which estimates the rotor position by the motor back EMF,is suitable for the middle and high speed operation of the motor.Based on the analysis of the extended back EMF mathematical model of permanent magnet synchronous motor,a high order non-singular sliding mode observer and a model reference adaptive speed estimation system are established to estimate the rotor position and speed of permanent magnet synchronous motor.A method of estimating rotational speed based on the period of estimated back EMF in high speed section is proposed.The method is simple and effective in high speed section of motor operation.The position sensorless control system using high-order non-singular sliding mode observer and traditional sliding mode observer is simulated and compared.The simulation results verify the superiority of using high-order non-singular sliding mode observer.Fourthly,in order to improve the operation reliability of the flux-decoupled MG-PMBM,a dual-torsion spring structure model of the internal motor-magnetic gear of the MG-PMBM is proposed based on the analysis of the mathematical models of the magnetic gear and the internal motor.The method of improving the overall operational reliability of the system by adjusting the equivalent torsion spring stiffness of the internal motor according to the running state is given.The low stiffness and the difficulty of direct control of magnetic gears result in transient oscillation,even the risk of slippage and out of step when the MG-PMBM is running under abrupt load.This method provides a theoretical basis and practical method for improving the dynamic performance and its operational reliability of the flux decoupled MG-PMBM.Finally,on the basis of the above research,the sensorless control experiment of a 100 N·m/100 rpm flux decoupled permanent magnet brushless motor prototype is carried out.The experimental results show that the motor can realize zero-speed starting,low-speed,medium-speed and high-speed sensorless operation,and the system runs smoothly when switching from high-frequency injection control in low-speed to extended back-EMF sliding mode control in medium and high-speed.