Research On Servo System Of Electronic Winding Brushless DC Motor Based On DSP

With the rapid development of science and technology,power electronics devices,integrated circuits and microprocessor all have progressed each passing day. The implementation of high degree of accuracy of position and velocity servo-control is posted by increasing industrial occasions such as robust and electronic winding technology.In addition,the thesis that utilizing energy at the moment when motor is braking also becomes a focus in the project of country's saving energy.Brushless DC motor(BLDCM),which has many good performances,such as simple structure,high running efficiency and convenient maintainability,is a kind of mechatronics products.The position sensor increase the complexity and costs of structure,made the lower reliability of running,so controlling without position sensor become a hot topic for researching.On the other hand,the 16-bits DSP, TMS320LF2407,which is manufactured by TI for motor's digital controlling,can give reliable and efficient signal process as well as hardware support by its high processing speed and improved surrounding circuits.Therefore,this paper is mainly engaged in researches on velocity and position servo-system of BLDCM without position sensor based on TMS320LF2407 to meet the requirements of high accuracy control and energy saving.The controlling, hardware and software design of the servo system are included in this paper.The general survey of winding and BLDCM as well as servo-control system included its' control strategies are simply introduced at the beginning of this paper. The basic structure and working principles are presented with math models established secondly.The fundamentals of position detecting and phase-switching are detailedly demonstrated finally.The BEMF zero crossing point detection formulas are deduced with phase difference compensations as well.Three-phase full-bridge MOSFET inverter is chosen as the main control circuit, and a control scheme with 120°switching mode is adopted in the argument of controlling.Current is detected by current-hall sensor,three-phase voltage are fetched via BEMF zero crossing point detection method which can not only supply the phase switching signal after software calculation and time delay but also obtain the velocity by the relation of time span.The speed and current dual closed-loop control strategy is adopted in this control system in order to construct a high performance permanent magnetic brushless DC motor full digital control system.Further more,double goals involved position and speed control strategy is adopted to achieve winding accuracy. Then,the design of energy feedback system is deeply studied with the background analysis followed by a feasible solution presented.The energy feedback system which consists of super capacitors,bi-directional DC-DC converter and inverter circuit is designed,and the principles of buck/boost working principles are explicated with related parameters' setting for the model established.In the hardware design of servo-system,the overall system is firstly designed, then the main circuit,power module,communication module and other interface circuits are designed,the focus is elements' selection and parameters' calculations. In the software design of servo-system,the development process of DSP and the requirements are firstly discussed,the flow of main program and function sub-program are designed and programmed in C and assembly language.In the software design of servo-system,the development process of DSP and the requirements are firstly discussed,the flow of main program and function sub-program are designed and programmed in C and assembly language.On the basic of theory research,the algorithm of BEMF zero crossing point detection,the adjusting of the closed loops named current,velocity and position as well as energy feedback technology model are all validated by simulation using MATLAB7.1.Then,experiments are implemented on the equipments and debugging software to obtain results.Finally,analysis and summary are made based on the results to prove that the performance of the whole system is perfect and can meet all the objectives in this paper.