The Research And Design Of Brushless DC Motor Without Sensor Control System

Brushless DC Motor, is a type of trapezoidal wave or square wave Brushless Motorwhich has the series wound start features and hunt-wound dc Motor speed regulatingcharacteristics. Brushless dc motor has no mechanical contact mechanism ofcommutator and brush, but has features of simple structure, high output and efficiency,and it is using more widely than motors with brush. It has been widely used in theaerospace, automotive electronics, robotics precision machine tools, householdappliances and office automation and other fields.This article develops a solution on the basis of brushless dc motor without positionsensor control theory,which can be used to control the BLDC operating. This is acontrol plan which uses the dsPIC30F4011as main control chip.First of all, the article build brushless dc motor without position sensor controlsystem simulation model in the Matlab/Simulink environment with the idea of modulardesignation. The simulation adopts the double closed loop including current control andspeed control, The terminal voltage test is used to acquire the bemf zero signal and thesignal by the logic commutation module logic operation of inverter control signal, Tostart BLDC, the simulation uses the Matlab Function programming three-step startup.The simulation results show that: the sensorless control of brushless dc motor controlsystem can complete the start of the motor, belt load and speed operating. The motorcan run smoothly, has a fast response speed regulating process, a smooth transition, andhas a better overall system performance. This provides reliable theoretical basis of thefurther research work.Secondly, the paper analyses the back EMF zero test theory, at the same time thedesign make up for the phase shift, which is caused in the rotor position detection circuit.The paper analyses the brushless dc motor speed regulating characteristics of the currentdouble closed loop speed control strategy. By looking up to a large number of circuits and following the actual design principle,the paper developed a hardware controlsystem on the basis of brushless dc motor without position sensor control, andintroduced the operating principle of each part of the circuit, meanwhile, the controlsystem hardware anti-interference measures will also be introduced. Control systemhardware design is mainly the flyback power supply design, IPM power drive circuitand single-chip microcomputer various excuses to circuit design. Again according to thecharacteristics of the dsPIC microcontroller, the paper makes full use of the on-chipresources to design the system software. As is well known, that the motor’selectromotive force is not easy to detect at static and low speed, the design adopts the"three-step" boot method, and carries on the detailed introduction.Finally, on the basis of the building of the control system hardware platform, thepaper completed the system software design, and after debug the program the designruns the sensorless brushless dc motor no-load test, completed the analysis of the testresults, test results show that the design of brushless dc motor without position sensorcontrol mode has a wide speed range and can run smoothly, which verifies thefeasibility of control system scheme.