Research On Current Segmented Control Strategy For Flux-intensifying Interior Permanent Magnet Motor

With the increasing energy crisis and environmental pollution,the development of green,energy saving,environmental protection and high efficiency has become the main direction of the development of the world today.As one of the main development directions of new energy vehicles,pure electric vehicles have been strongly supported and are focused by governments and automobile enterprises.The interior permanent magnet(IPM)motor due to its advantages of high power density,high torque density,high efficiency and good dynamic performance,has been widely used in electric vehicles.With the increasing complexity of road driving,higher requirements are put forward for electric vehicle motors to exhibit the high output torque and wide speed range.In addition,because the permanent magnet material with high coercivity is used in the IPM motor,the permanent magnet excitation magnetic field is not easy to be adjusted,and the constant power operation area at high speed of the motor is limited.Therefore,it can not meet the requirements of low speed,large torque and wide speed range of electric vehicles.Recently,because of the characteristics of "straight axis magnetic field enhancement ",the direct axis inductance is larger than the cross-axis inductance,which is counter-convex pole.This kind of motor not only has the advantage of IPM motor,but also has wider constant power speed range and unsuitable demagnetization at high speed.Aiming at the complex current control and poor dynamic performance caused by the back-convex characteristics of this kind of FI-IPM motor,a new current piecewise control strategy is proposed in this paper.The main work is as follows:1)The domestic and foreign research situation of FI-IPM motor and its control strategy are introduced in detail.The topology and working principle of the new FI-IPM motor are analyzed and the electromagnetic properties are analyzed by simulation and experiment.The mathematical modeling of this kind of motor,and the Matlab/Simulink simulation model are built.The vector control research is carried on to verify the correctness of the mathematical model.2)The driving control system based on FI-IPM motor and the traditional current piecewise control strategy are introduced,the principle of maximum torque per amplitude(MTPA)control and flux-weakening control is expounded.The methods of MTPA and flux-weakening control are analyzed and compared.The principle that traditional current segment control strategy can not be directly applied to FI-IPM motor is explained.3)In this paper,a current piecewise control strategy based on a new FI-IPM motor is put forward,which divides the whole operation area into flux-intensifying I area,flux-intensifying II area,flux-weakening I area,flux-weakening II area.In addition,a adjustable reference voltage is set in the flux-intensifying II area,this can not only be adjusted according to different operating conditions,but also solve the current oscillation problem of transition links in different operating areas,the inverse saliency characteristics of FI-IPM motor are well utilized.4)The traditional MTPA and flux-weakening control and the proposed control strategy are compared in this paper,the effectiveness of the proposed algorithm is verified.Based on this,the experimental platform is built based on the d SPACE DS1007,and the experimental research is carried out.The theoretical analysis verifies the simulation results.