Research And Implementation Of Vector Control Strategy For Permanent Magnet Synchronous Motor

As the permanent magnet synchronous motor(PMSM)has the advantages of light weight,low torque ripple and spread speed range,it is widely used in various fields of modern industrial control and has the optimistic prospect as well as the development trend.The control algorithm motor adopted has a great influence on the actual motor performance,therefore,studying on the PMSM control system is of much practical significance.The PMSM ontology and vector control algorithm are studied in this paper.Firstly,the structure and working principle of PMSM are introduced in the paper.After the deeply understanding on the basic structure and operation mode,the mathematical model is given later.Based on “double-reaction theory”,the three-phase “ABC” stationary coordinate system with the difference of 120 degrees among stator windings is transformed through coordinate transformation to two-phase orthogonal rotating coordinate system called “d-q”.The torque equation is simplified by means of the coordinate transformation where the electromagnetic torque is proportional to the product of permanent magnet flux and current component of q axis as the surface PMSM is used in this research.The basic axiom and several concrete realization methods of vector control are discussed.As the permanent magnet flux is known before,the control of the motor torque can be converted to motor current control,which can be attributed to regulate the current components of d and q axis further more.Consequently,“id = 0” method is specified for vector control,that is,the stator current is fixed on the q axis direction so as to be perpendicular to permanent magnet flux.This method is simple to calculate and has excellent control performance,forming a solution chain of speed,torque and current.The space vector pulse width modulation technology plays a vital role in the process of vector control,the importance of which is obvious to exist and is described in detail.It transforms the study of circular trajectory on the magnetic field into the research of the motion trajectory on the voltage vector and is the key step to achieve variable-frequency control by outputting the three-phase sinusoidal voltages.Followed by familiarizing with the vector control flow and the realization process of each step,the simulation models are established in MATLAB/Simulink environment to verify the feasibility of algorithm itself and system design.The motor vector control system is simulated according to the SimPowerSystems expansion module library provided by MATLAB.Then,referred to the actual PMSM of DBL140 P and DSP(Digital Signal Processor)chip TMS320F28035 used in the experiment,automatic model code generation is achieved by the interact development between MATLAB and CCS(Code Composer Studio)to complete the speed control.The focus of this research is to verify the effectiveness of vector control algorithm via two simulation models,including the pure software simulation on MATLAB and the real motor experiment.The former is observed by a series of parameter figures,while the latter can be visualized by running effect of motor.Both of them prove the feasibility and practicability of the vector control strategy for PMSM system.The results show that the starting and braking performance is fine and the speed fluctuation cycle is short,what's more,the current can respond to the change of torque quickly and the motor rotates smoothly during the operation process,which interprets the advantages of the algorithm totally.It can be convinced that the algorithm is capable of controlling PMSM effectively.