Design And Realization Of A Sensorless BLDC Driver

Replaced the mechanical commutation by electronic in DC Motor, the Brushless DC Motor not only retains the DC Motor’s advantage of small package, high torque, but also has simple structure, reliable operation, easy maintenance, leading to using wildly, but the high cost and hard to process restrict its more use. Without the sensor detecting rotor position any more, the brand-new Sensorless Brushless DC Motor driver becomes a hot research topic.This article describes the present situation to realize the Sensorless Brushless DC Motor Driver, analyzes and compares the several current design of Sensorless Brushless DC Motor Driver and then designs a Sensorless Brushless DC Motor Driver based on the detection of back electromotive force and realizes by device. This article includes:Through the introduce of the present situation of Sensorless Brushless DC Motor Driver, the Sensorless Brushless DC Motor Driver based on Back Electromotive Force, Diode, Inductance and Status Observation are proposed and analyzed in theory and character, then relatively the advantage of the method used in this article is presented based on detected by Back Electromotive Force. The method of detecting by Back Electromotive Force is proposed through analyzing the structure of the Sensorless Brushless DC Motor in theory. This article analyzes the character and solution of both the start phase and steady phase, then makes a proposal practically. There is also some principle of the three phase inverter brought forward including Pulse Width Modulation and Rectification.With the common device, by divided and realized in several pieces respectively, the circuit is devised according to the target. This article also describes the problem when designing the PCB especially in the connection of ground and power filter.Emphatically, this article proposes the main algorithm and the flow chart used in the program of the single chip, and programs by C language based on the MPLAB IDE designed by MICROCHIP.According to the test result, the performance of this circuit is analyzed. At the end of this article, the weakness of the solution used by this circuit is proposed, and some ideas are provided to improve.