Research On Sensorless Control System Of Flux Leakage Controllable Permanent Magnet Motor Based On Sliding Mode Observer

To achieve the goal of‘peak carbon dioxide emissions’and‘carbon neutrality’,adapt to the adjustment of China’s energy structure,and realize the sustainable development of economy and society,it is necessary to accelerate the pace of electric vehicles replacing fuel vehicles and complete the transition and upgrading of the automotive industry.As the core of electromechanical energy conversion,electric machines and its drive systems play an important role in the power supply of electric vehicles.In this thesis,a kind of leakage flux controllable permanent magnet synchronous motor(LFC-PMSM)has been investigated.Based on the novel idea of‘leakage flux controllable’,LFC-PMSM has the advantages of high power density,high torque output capacity,wide speed range and high efficiency.Accurate feedback signal of rotor position and speed information plays a key role in LFC-PMSM drive systems.Normally,mechanical position sensors have been widely used in the motor driving system of electric vehicles to achieve rotor position.However,due to the use of mechanical position sensors the complexity and cost of drive system will be increased.Also,the reliability of the drive system will be reduced.Hence,in this thesis,research on the position sensorless control system of LFC-PMSM has been conducted.Based on the analysis of the influence between the characteristic of LFC-PMSM and obtainment of rotor position,the optimized control scheme for the LFC-PMSM sensorless control system is developed.Firstly,the research background and significance of the position sensorless control system of LFC-PMSM,the state-of-the-art of wide-speed motor and position sensorless control technology are introduced.Also,the topology characteristics and operation principle of LFC-PMSM,and its electromagnetic performance are analyzed.Based on the work mentioned above,the control strategy of LFC-PMSM has been investigated.In addition,the LFC-PMSM sensorless drive system based on i_d=0 and MTPA vector control has been implemented.Based on d SPACE1007,the corresponding drive system has been investigated by experiments.Subsequently,to solve the problems of inductance parameter variations and harmonics in back-EMF under multi-operation conditions for the LFC-PMSM,sensorless control strategy based on adaptive decoupling robust sliding mode observer(ADR-SMO)has been proposed.The influence caused by inductance parameter variations and harmonics in back-EMF have been investigated in detail.Based on the active flux concept and gradient descent method,ADR-SMO has been proposed.The LFC-PMSM sensorless drive system based on the traditional and proposed methods has been compared by experimental verification which validates the effectiveness of the proposed method.Compared with the conventional SMO method,the proposed method decreased the 39%position estimated error and 40.9%position estimated fluctuation.Furthermore,the estimated position error is also impacted by other nonlinear factors.To eliminate the estimated position error caused by the other nonlinear factors,the relationship between the current magnitude and estimated position error in the LFC-PMSM sensorless control system has been analyzed.Then,the sensorless control strategy based on adaptive current vector tracking has been proposed to eliminate the estimated position error.Different suppression strategies for the estimated position error has been designed under i_d=0 and MTPA control,respectively.Finally,the feasibility and effectiveness of the proposed method has been verified by experimental results.