Research On Sensorless Direct Torque Control Of BLDCM

The brushless DC motor is widely used in industry, military and national life fields withits simple structure, high efficiency and well speed regulating performance characteristics.Combined with the structure characteristics of the brushless DC motor, using sensorlessdetection technology without the rotor position sensor avoids a variety of adverse factors, theycaused by the position sensor in the motor control system.In this paper, sensorless brushless DC motor direct torque control technology isresearched in this paper. In Matlab/Simulink software, the simulation model of direct torquecontrol system is built, according to the simulation results verifies the feasibility of the directtorque control system, and the hardware experiment platform of the sensorless brushless DCmotor direct torque control system is designed. This paper mainly researches the followingquestions:First, in view of the principle and mathematical model of the sensorless brushless DCmotor direct torque control, the rotor position detection simulation model is designed inMatlab/Simulink, the simulation model of the direct torque control system has been completeddesign. Through the analysis of the simulation results confirms the feasibility of the DTCsystem.Second, in order to prove the DTC system can effectively reduce the torque ripple, inMatlab/Simulink another rotor control system without DTC is designed, a nd compares withDTC system designed by this paper under the same operation parameters, the current andtorque waveform of two methods make a comparison, the comparison results show the DTCsystem can effectively reduce the torque ripple.Finally, the TMS320F2812is used as the control chip, a set of the hardware experimentalplatform system with the power switch tube driving circuit, three-phase bridge type circuit,back-EMF zero crossing detection circuit, current detection circuit and protection circuit isdesigned. With the theory of terminal voltage detection back-EMF zero crossing and three-stepstating, the rotor starting, commutation processing and the speed PI regulator and otherprogram is compiled. And some experiments are done on the experimental platform, throughthe analysis of the experimental results verifies the feasibility of in this paper the design of the sensorless BLDCM direct torque control system.