Intelligent Brushless DC Motors Direct Torque Control

Brushless DC motor (BLDCM) motor is a electromechanical energy conversion devices consist of manufacturing technology, power electronics conversion technology and control technology, which has good mechanical and electrical properties. And BLDCM is extensive applications, in particular, it has its unique advantages in certain applications. In recent years, with the continuous development of motor technology, BLDCM has been greatly improved no matter in manufacturing technology or control--technology, which is also conducive to the brushless motor play their strengths part in more applications. Due to its structural features and square wave drive to commutation principle, BLDCM is easy to generate the torque ripple, which pulsating commutation torque ripple. BLDCM work commutation which requires to obtain the rotor position signal, and the commonly used method is the Hall position sensor detection method, however, the sensor installation limits the application of BLDCM in a broader field. And if the sensor is not properly installed, it will easily lead to a signal detection error, then cause a failure of BLDCM commutation.As for the adverse factors of Practical application for BLDCM torque ripple. This paper put forward direct torque control method which achieve the purpose of the closed-loop torque control. And suppress the torque ripple effectively. Then eliminate the use of position sensors, and calculate the rotor position signal by measuring electric parameters. And improve the conventional speed PID controller by using intelligent neural network, it adjust the PID parameters online and improve the system adaptive performance.According to the structural characteristics of BLDCM, simplify the structure of the traditional direct torque control by leaving out flux observed link, and improved the electromagnetic torque calculation model. At the same time, realize high-performance of BLDCM which controlled under the method of rotor direct torque control and without rotor position sensors. But it is found that BLDCM could not drived in stationary or low speed operation by the EMF to detect the rotor position signal.so this paper did a deeper study for the start problem of BLDCM under the sensorless control technology based on EMF. And put forward the three-stage start method with a comprehensive variety of starting advantage. The three-stage start method is mainly divided into pre-positioning, the VVVF quick start and the synchronous operation based on rotor position detected by EMF. Also did a improvement for the regulate aspects of the overall poor performance of conventional PID speed control system. It make full use of neural network intelligent algorithm on conventional PID controller. Turn adjustment the three parameters PID controller online, make the speed adjustment changed for the better performance, And also improve the overall system adaptive ability to make a stronger anti-disturbance ability.Finally, build a simulation model for the entire control system. And have a focus analysis of the critical control module. By doing the intelligent direct torque control system simulation experiment of BLDCM, It come to the validity of the control method that suppress the torque ripple and improve system dynamic performance.