Research On Wide Speed Method Of PMSM Based On Direct Torque Control For Machine Tool Spindle

Spindle motor control system as one of the most core parts of the machine tool, the outputperformance is very critical for the processing quality and efficiency of machine tool, whichrequires the control system should not only has high machining precision and quick responseability, but also requires to output a larger torque at low speed, in high speed area has a widerange of constant power operation, at the same time should has good earthquake resistance andstability to adapt to different processing conditions.Spindle motor with gear structure of traditional speed regulation system not only hugevolume, but also has low working efficiency, it’s has enormous waste of energy. Along withthe development of permanent magnetic material and control technology, permanent magnetsynchronous motor (PMSM) and direct torque control (DTC) technology with their ownadvantages in the field of the spindle motor and control strategy become the focus of attentionat home and abroad. Therefore, it’s will be very meaningful to researching the highperformance permanent magnet synchronous motor control system for promotion the modernindustrial process and improve energy efficiency.This article researches the machine tool spindle of permanent magnet motor based ondirect torque control method in wide speed. Spindle permanent magnet motor as a controlobject, in-depth research based on DTC control strategy, build a spindle motor control system,and complete the hardware and software design of system, on the basis of the existing controlsystem to adding the star angle conversion of motor, in order to broaden range of speed. Firstlyestablished motor control system based on DTC, which is on the basis of the main shaft modelof permanent magnet motor, and analyze the control system of the working principle of eachcomponents, while in-depth study the weakening the control principle, set up the method ofweak magnetic control based on DTC, according to the correspondence between the statorcurrent and flux of maximum torque/current control, the magnetic chain values was given bythe look-up table method, to judge the weak magnetic switch time, when motor running inweak magnetic regions, with the increase of rotational speed and torque reduction. Then buildthe whole control system modeling in Matlab/Simulink environment, simulation combinedwith the operation of spindle motor, given constant torque and constant power range of simulation waveforms, validate the feasibility and the accuracy of the control strategy. In orderto broaden the motor speed range, used the star angle transform methods, and then analyze theperformance of motor before and after the transformation. Finally, design the hardware,including ST company ARM chip407as the control corer of the control panel circuit design,software design part is composed of main program and interrupt program module, and discussin detail the voltage space vector pulse width modulation (SVPWM) technology and theflux-weakening implementation of the algorithm.Through the Simulink simulation research shows that the spindle permanent magnetmotor control system based on the theory of DTC has advantages of high speed, lowdependence of motor parameter corresponding, verification of permanent magnet motor basedon DTC technology feasibility of weak magnetic control algorithm, to adding star angletransformation can effectively broaden the speed range, maximum speed and rated speed aftertransformation is original with highest weak magnetic speed and extended to2.2times therated speed. Building hardware platform, at the same time, software design for the systemoptimization and improvement of control strategy for the follow-up research work laid thefoundation.