Sensorless Control Of Exterior Rotor Permanent Magnet Brushless DC Motor

Permanent Magnet Brushless DC Motor(PMBLDCM) has found widely used in many fields, in which electronic commutation is used instead of traditional mechanical commutation, so it not only has a brush dc motor speed control performance, and small volume, high efficiency. Moreover, the sensorless control technology, not only can overcome the ills generated by the sensor, but also can further broaden the application range of the Permanent Magnet Brushless DC Motor. At present, the sensorless control is an important development direction of control technique for Permanent Magnet Brushless DC Motor.Permanent Magnet Brushless DC Motor structure and working principles are introduced. Then the paper establishes the mathematical model and analyzes the working characteristics of the different ways of connection of motor winding between star and triangle connection. At last, the speed and current double closed-loop controller is designed.The paper chooses the method of detecting the rotor position based on the back-emf detection of terminal voltage. Low-pass filtering, armature reaction and commutation freewheeling is studied. The characteristics of the phase current are analyzed between the accurate commutation and lead or lag commutation, on the basis of this, a self-tuning control method is put forward to eliminate the phase error. The validityof the method is verified by simulating and experimentswThe new I/F current frequency ratio starting method is used through the error compensation of conducting phase current, which ensures better starting performance.In order to speed up the product development speed and reduce the research cost, the basic parameters of the machine are checked and optimized through Ansoft which is the Finite Element simulation software. Combined with the motor parameters, motor model and control system simulation model are set up using MATLAB/Simulink based on back emf zero crossing detection, the simulation results are analyzed, which provides certain reference for the system implementation.The design of sensorless controller based on Exterior Rotor Permanent Magnet Brushless DC Motor, includes hardware design, which takes TMS320F2812 as the core device, and software design, which is based on PID correction and I/F current frequency ratio starting. The controller to collect and process the motor terminal voltage and current signals, produces the PWM control signal used to drive motor, and complete the double closed loop control. The motor load control system alignment platform is used to verify the startup ability, tracking performance and load testing controller performance. Experiments prove drive controller can accurate estimate rotor position and the system working properly and operating stability. The control system has good static and dynamic performances.