dSpace Based Implementation of Closed Loop Brushless DC Motor Control

摘要

Brushless Direct Current Motors or BLDC Motors are currently growing in popularity owing to the advent of power electronic switching circuits and further improvements in sensing technologies. As such, now, a lot of fields employ this machine for varied purposes primary among them being motion control, positioning and actuation systems. The industrial engineering industry is shifting to BLDC use due to its high power density, good speed — torque characteristics, high efficiency and wide-speed ranges. Also being brushless, they require lesser maintenance than their brushed counterparts. The paper discusses the Modeling and Simulation of Closed Loop BLDC Motor Control along with implementation of its open loop control for running the motor first using ASIC UC3625 and then using dSpace control unit. Basically, control of BLDC motor consists of supplying the gating pulses for the inverter bridge configuration in order to excite the phases in a particular sequence. Hall sensor input is fed back to the control circuit which then determines which phase to excite next in order to move the motor in a particular direction. This control can then be applied in a closed loop scheme, where a reference input can be used to adjust the output of the control circuit to get the desired gating pulses. This reference input is usually taken as the speed for fixed speed operation or to provide variable speed operation to the user independent of the load. For this, the speed is also taken as an output from the motor normally by using a shaft encoder. It is then fed to the control circuitry after suitable conversion. Speed control results and closed loop performance of the scheme will be reported on the above developed system.