Research On Brushless DC Motor Control Based On DSP

In recent years, with the rapid development of new permanent magnetmaterials, automatic control technology, power electronics technology and electronictechnology, the brushless DC motor (BLDCM) has been extensively used in all fieldsand aspects. It has been applied to military industry,aerospace, medical, information,household appliances, and industrial automation field. The BLDCM has replacedother types of motors in many cases with its own advantages. Therefore, Theapplications and researches of BLDCM have been obtained a very high concern.In-depth study for BLDCM body, control algorithms, and in the process of controlsystem existing problems have very important theoretical and practical significance.1．Firstly this article introduces the BLDCM control technology development atthe world and analyzes the structure, working principle and mathematical model ofthe BLDCM. The BLDCM has multivariable, time-varying, nonlinear, strongcoupling and other features which make the traditional PID control meet the higherrequirements of the control system difficultly. This paper proposed a switch fuzzyneural PID controller which used fuzzy and neural theory to flexibly control thechanges of three parameters of PID.This controller adds adaptive switch to improvethe real-time of system.This algorithm takes into account the advantages of fuzzycontrol and neural network control. It can use existing experience or rules to train thenetwork and trained controller can automatically become more perfect throughonline learning. Secondly this paper designed the fuzzy neural network for onlineidentification of adaptive PID. Simulation results show that this two methods caneffectively achieve the higher requirements of BLDCM control.2．The BLDCM generally relies on the internal position sensor to detect therotor position. This fact increases the cost of the motor and lowers the reliability ofthe system. This limited the widely use of the BLDCM. So the position sensorlessBLDCM becomes a hot research in recent years. This paper analyzes the relationshipbetween back electromotive force (EMF) superposition and the commutation time.It was concluded that the extremum moment of three back-EMF superposition is thecommutation time. This paper proposed rotor position detection strategy based onthree back-EMF superposition and zero crossing point detection. The simulation inconformity with the theoretical calculation.3．The BLDCM digital drive circuit system with the core of TMS320F2812wasdesigned. This system includes current sampling, voltage sampling, PWMoptocoupler isolation circuit, system protection circuit and three back-EMFsuperposition circuit. On the basis of the hardware through software achieved currentsample, rotor position detection and speed adjustment function. The BLDCMcontrol strategy of this paper is proved feasible by experiments.This drive circuitsystem has a good application prospect.