Research On High Dynamic Flux Weakening For Surface Mount Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor has the advantages of high power density and simple structure that are widely used in electric vehicles,aerospace,deep-sea submersible,CNC machine tools and other fields.However,the traditional flux weakening control only considering the steady-state performance and dynamic performance is rarely studied.Therefore,the research on high dynamic fluxweakening control of surface mounted permanent magnet synchronous motor for some occasions with high dynamic performance,has important practical significance.Firstly,the theoretical analysis was established for the process of SPMSM flux control.On this basis of the traditional flux weakening control in constant power region,the flux-weakening control in constant torque region was established.Then,a novel flux-weakening control method and switching condition are propo sedA novel flux weakening control method based on single current regulator is proposed in the constant torque region.Through comparing the steady state performance of traditional double current regulator flux-weakening control method and the single current regulator,the results show that the double current method regulator speed ratio is 1.13,while the single the current regulator method can reach 1.30,with the better steady state performance.At the same time,this paper focuses on the dynamic performance of single current regulator flux-weakening control.Respectively,operating the motor in four different conditions,including starting with load,load,dump load and constant speed loading,which simulating the normal operating process.Analysis the dynamic response in these four different conditions of two kinds of flux weakening control methods,the results show that the single current regulator flux-weakening control are better than the double current regulator in anti-interference ability and dynamic response,with better dynamic performance.In order to the further speed expansion of the motor,this paper studies the over modulation of the voltage vector,which can improve the utilization of the bus voltage,and then achieve further expansion of the motor.In this paper,an over modulation strategy is proposed to distinguish the modulation region,which can control th e voltage vector on the hexagon,and the voltage utilization rate is increased by 1.05.On this basis,combined with the single current regulator flux-weakening control method is proposed,and analyzed the steady state performance of the strategy,the results show that under the over modulation strategy with the current flux weakening control the expansion ratio can reach 1.37.In addition,focuses on the analysis of dynamic performance,the results show that the dynamic performance is slightly inferior to linear modulation because of the current harmonics,but the motor running smoothly without fluctuation,so it has feasibility.Finally,the drive system of permanent magnet synchronous motor is designed,and the feasibility and effectiveness of the proposed control strategy are verified.