Position Sensorless Brushless Dc Motor Control System Design And Research

Sensorless control technology has been a hot research in BLDCM control domain. This paper introduces the design of the sensorless control system for brushless DC motor based on DSP TMS320LF2407A, discusses in detail the current commutation and motor speed withdraw problem without the position sensor, and designs the corresponding hardware and software circuit.In this paper, considering the control system having no position sensor, the Back-EMF method is applied to scan the rotor position signals of the motor, by inspecting the BEMF-crossing-zero signals, then after delays for thirty degree, the current is commuted correctly. In order to improve speed control performance of motor in a wide range, this paper adopts the double-closed-loop (speed-loop and current-loop) control strategy and gives the corresponding implement methods. Considering the BEMF very little in the process of motor starting, the Back-EMF method is expired, combined with the rotor pre-setting method and the variable -frequency increase-voltage method, this paper realizes the open-loop start of motor using DSP.The whole control system makes good use of resources on chip and high data-processing ability of DSP, instead of the former complicated hardware circuit, which simplifies the hardware structure of the system.