Study On Control Mode Of Doubly Salient Permanent Magnet Motor

In order to overcome the centrifugal force in high-speed rotation,the permanent magnet on the rotor must be specially reinforced,which make rotor structure complex and cost high,moreover,because permanent magnets are installed on the rotor,it is difficult to dissipate heat,which will lead to the demagnetization of permanent magnets.In order to overcome these problems,a doubly salient permanent magnet motor with permanent magnet mounted on the stator was born.This paper takes a 12/8 class doubly salient permanent magnet motor as the research object,mainly devotes to the research of the control mode of this motor,including the following contents.:Firstly,the mathematical model of doubly salient permanent magnet motor is constructed.The dynamic mathematical model on the natural coordinate system of doubly salient permanent magnet motor are deduced.The working principle of generator and motor are analyzed respectively.The physical model of doubly salient permanent magnet synchronous motor is established on FLUX finite element software,and its magnetic field distribution is analyzed minutely.The influence of different magnetic saturation degree on inductance,flux linkage and torque is analyzed.The better magnetic potential of permanent magnet is determined.Based on this,the self-inductance curve,mutual inductance curve,self-inductance change rate curve,mutual inductance change rate curve,permanent magnet flux change rate curve and rated torque are calculated,which provides data basis for establishing mathematical model.The reason of torque ripple is analyzed.Then,neglecting the influence of reluctance torque,in order to overcome the problem of large torque ripple in conventional control mode,the torque of doubly salient permanent magnet motor is regarded as the quantity product of two three-dimensional space vectors,thus the concepts of permanent magnet flux change rate vector and current vector are introduced,and a new current hysteresis control system is constructed.In order to better suppress the torque ripple,a direct torque control system is proposed.Two kinds of torque observers are constructed.The correctness of the new hysteresis current control and direct torque control are verified by simulation.Finally,a prototype is made according to the parameters calculated by finite element analysis,and the control software and hardware are designed with Infineon XE164 FN as the main control chip.The prototype is debugged on site,and the correctness of the new current hysteresis control and direct torque control proposed in this paper is verified by experiments.