Research On Sensorless Control For Brushless DC Motor Base On Saliency Effect

With the development of power electronic technology,the structure of permanent magnet BLDC motors become more simple,more stable and more reliable,So it is widely used in the field of industrial control field and household appliances.But the traditional BLDC motor usually with position sensor,that leads to increase the volume and the cost of motors.To make the BLDC motor is suitable for more occasions,research on the sensor-less BLDC motor control technology has great significance.This paper introduces the operation principle and mathematical model of BLDC motor,and analyzed the principle of back EMF cross zero point.To solve the problem of the back EMF can't be detected when the motor speed is zero or very slow,this article analysis and compare existing boot method of detect the rotor initial position,then proposes a new starting method,rotor position closed-loop start-up method.The start method is divided into three stages: in the process of motor starting zero initial rotor position detection stage,stage of rotor position closed loop speed up,switch to the back emf operation stage.At last,by contrast,experiments and theoretical analysis prove that this method is of sensor-less BLDC motor starting performance improvement.The construction of the experimental platform is based on TI DSP as main control chip,using YANXU TMS320F28335 development board and BLDC motor drive board control sensor-less BLDC motor.The design of principle diagram of motor drive board using Altium Designer16,and motor control program written and debugged in CCS6 development environment.Experiments show that the designed motor driver board and motor control program can complete sensor-less BLDC motor control function excellently,and the control system has simple structure,fast response,high reliability.