Research On Position Sensorless Control For BLDCM Based On Sliding Mode Observer

Brushless DC Motors(BLDCM)with Concentrated Winding are widely used in home appliances,automotive,aerospace and industrial automation drive field in the advantage of good speed control performance,high torque to inertia ratio,high power density,high efficiency,simple structure and low manufacturing cost.Back electromotive force(EMF)waveform of the traditional BLDCM with concentrated Winding is trapezoidal wave.With the need of high performance sine-wave drive,a variety of means is used to optimize BLDCM with concentrated Winding ontology,which makes the back EMF waveform of BLDCM with concentrated Winding is more close to the sine waveform and suitable for high performance space vector control.But the double closed-loop space vector control need accurate position and speed signals,and using mechanical position sensors will bring a lot of problems.So the research on sensorless vector control for BLDCM with sinusoidal back EMF has important research significance and broad application prospects.In the numerous sensorless methods,sliding mode observer has strong adaptability,and it's not sensitive to motor parameter variations and load disturbance.What's more,the algorithm is simple and easy engineering implementation,it has small amount of calculation and the advantages of good dynamic and static performance,so it's widely used in the actual control.This paper introduces the structure and mathematical model of BLDCM,and briefly expounds the space vector control theory firstly.Then building the double BLDCM ontology model and double closed-loop speed control system of space vector based on the motor mathematical model.After giving a detailed introduction of the principle of sliding mode observer,this paper establish and analyzed the principle of traditional sliding mode observer based on motor mathematical model in the two-phase static coordinate system.In view of the traditional sliding mode observer has inherent chattering,the phase delay and compensation problems of low pass filter,an improved sliding mode observer is proposed.The improved sliding mode observer method construct the current observer using the sign function with variable sliding mode gain,and extract the estimation value by EMF observer,and the rotorspeed and position are gained by phase-locked loop(PLL).In order to verify the validity of the improved method,sensorless control system simulation model of BLDCM is built based on Matlab/Simulink.The traditional sliding mode observer and improved sliding mode observer are compared under the same conditions.The simulation results and analysis show that control system with improved sliding mode observer has better effect of rotation speed and position estimation compared with the traditional sliding mode observer,it can achieve good sensorless vector control of BLDCM with sinusoidal back EMF.Finally,this paper design a drive control system based on STM32F103RCT6 and set up the motor experimental platform,the algorithm that this paper has proposed is verified on this experiment platform.