Speed control of brushless DC motor drive employing hard chopping PWM technique using DSP

Abstract

This paper presents the speed control of brushless dc motor drive employing hard chopping PWM technique using TMS320F240 digital signal processor. BLDC is widely used because of its high mechanical power density, simplicity and cost effectiveness. The complete controller for BLDC is developed using TMS 320F240 digital signal processor, which has the special features for digital motor control. The three hall sensor signals are used to sense the rotor position. A shunt resistor is used to sense the actual current entering into the motor. These three hall signals, phase current sensing signal and the speed command are the input to the DSP. Both the outer velocity control loop and inner current control loop uses PI controller that has been implemented by programming in TMS320F240 DSP processor. According to the input command, feedback command and control algorithm, the PWM pulses for each phase generated by the DSP is given to MOSFET driver. The output of the driver is 6 independent PWM pulses that has to be given to the corresponding gate of the six MOSFET power switches used in the three-phase bridge inverter whose output is given to the stator of the BLDC motor.