Applied In Electric Tools Of Sensorless Brushless DC Motor Control Device Research

Sensorless brushless dc motor is compared with sensor brushless dc motor, not only simple and compact structure and small volume, but also good control effect, high conversion efficiency. So the sensorless brushless dc motor is widely used to the life and industrial fields. With the sensorless brushless dc motor is widely used, how to control the sensorless brushless dc motor become more efficient has become a hot research topic. After contrast with brush dc motor, This paper introduces the applied in electric tool sensorless brushless dc motor control system detailed.This paper first introduces the research status of brushless dc motor, technical advantages, specific application and need to explore the research of the three questions: the rotor detection problem, the best phase commutation problem and torque ripple problem. Then from the basic structure of brushless dc motor, introducing the basic working principle of brushless dc motor, mathematical model and speed control model. Analysis the reasons for torque ripple about brushless dc motor, the basic principle of back EMF method is given. After researching the basic structure and working principle of brushless dc motor clearly. Emphasis on brushless dc motor speed control system. This paper introduced the concept of the new BP neural network by compared the traditional vector control with direct torque control. Based on neural network and genetic algorithm, we build a vector controller. The control effect is ideal by simulation. After the completion of the theoretical simulation, making the actual hardware design. We select the chip of TI Company TMS320LF207 as the controller in applied to the control system of electric tools hardware. Introduce the characteristics of the chip is detail. The hardware scheme is designed points each module respectively, eventually completed the construction of the hardware platform. After completing hardware platform is to use software to achieve the ultimate control, Software design is presented the design of the main program and each module flow charts. The motor speed calculating formula is presented at last.Finally, made a comprehensive summary to the full text. Completed the electric tools of colorless brushless dc motor control device research.