Design of a Control Scheme of Fast Braking and Accurate Location for DC Brushless Motor

A new type of control scheme of fast braking and accurate location for DC brushless motor was introduced in the paper. The scheme makes supply terminals of the motor shorting when the motor is in braking and uses braking unit to make current produced by inertia of the motor produce rotating magnetic field whose direction is contrary to rotating direction of inertia, so as to produce bigger damping magnetic field which can make the motor brake fastly. When the motor is in braking of power off, rotation speed of the motor is detected by three angular displacement sensors and starting control point of the motor is calculated and determined according to the rotation speed of the motor. The starting point is transmitted to PLC, then the PLC control the motor to stop at designed position, so as to realize accurate location. The result of experiment showed that the scheme is reliable and accurate.