Research On Flux-Weakening Control Method Of IPMSM Vector Control System

With the breakthrough of material barriers and the innovation of control technology,PMSM has gained an increasing popularity in the field of AC speed regulation.Because of attractive benefits such as simple structure,reliable performance,light weight,small size and high efficiency,PMSM has received unprecedented attention.As an important method to increase the constant power speed ratio of the motor system,the flux-weakening strategy has far-reaching significance in the field of high-performance AC speed regulation.In this paper,in order to broaden the speed range and optimize the dynamic performance under overmodulation for PMSM,the IPMSM is taken as the main research object.The flux-weakening control technology and dynamic overmodulation technology of PMSM are studied.The structure model,dynamic mathematical model,steady-state operation characteristics and basic control theory of permanent magnet synchronous motor are introduced,which lays a foundation for the introduction of the flux-weakening control and the overmodulation strategy.The flux weakening control strategy of permanent magnet synchronous motor is systematically analyzed.Based on the comprehensive comparison and analysis of the existing flux-weakening speed regulation control strategy,a new flux-weakening control method based on the effective voltage vector action time is proposed.A new type of flux-weakening loop is constructed by introducing the effective voltage vector action time,which can effectively improve the utilization ratio of DC bus voltage.Finally,the effectiveness and feasibility of the proposed strategy are verified by simulation comparison.The dynamic overmodulation strategy of IPMSM is studied and analyzed.Firstly,the traditional static overmodulation strategy is briefly introduced and the disadvantages of the traditional overmodulation strategy in the optimization of motor dynamic performance are analyzed by graphic method.Then,two commonly used dynamic overmodulation strategies are introduced.Moreover,the basic ideas and implementation methods of the strategies are described in detail.In order to overcome the shortcomings of the existing overmodulation technology,a novel dynamic overmodulation strategy based on the voltage self-locking and the current dynamic restriction is proposed.The better dynamic performance of the motor in the over-modulation region can be guaranteed by the strategy of voltage self-locking strategy and current dynamic restriction strategy.Through the simulation comparison of several overmodulation strategies,the advantages of the proposed dynamic overmodulation strategy in performance optimization are verified.Finally,the experiment platform of PMSM is built.The hardware design and software design of the platform are briefly introduced and the related experiments are carried out to verify the feasibility of the various control strategies proposed in this paper.