The Design Of BLDC Motor Control System

Traditional servo control system usually use the DC motor as servo motor, but the mechanical commutation and wire brush bring many uncertain factors to the whole system. As a new type motor, permanent brushless DC motor conquer the limitation of DC motor which bring by the mechanical brush and commutators, besides it has a simpler structure, low power dissipation and EMI. So in the nowadays, the AC servo system is replacing the market quotient of DC servo system.This paper analyses the mathematical model and control method of BLDC, establishes the mathematical model with the motor phase variable, and researches some key problem like the motor's control method, included the process of commute, modulation of PWM and the detection of position , and so on..From the view-point of engineering applications, it studies the system structure of high performance BLDC servo system, the design theory of software and hardware, and so on. Then according to the result of analyses and the request of practically, it designs the structure of servo system. The system use the LM3S8962 which base on the Cortex-M3 as the controller, and use the C language for the control algorithm, the program is structural, succinct and clear. In the process of designing, the EMC and thermal control of system is analyzed, and then designs the circuit for protection and isolation, also obligate the interface of communications and extension for the system. So that ,the system can be realizable and high performance.By the experiment of BLDC motor, it proved that this system is approaching the servo performance of DC motor, can be the replacement of DC servo system in the future days.