Influence of Maximum Current Control Strategy on Torque Ripple in BLDC Motor

Brushless dc motors are voltage source inverter (VSI) fed permanent magnet motors which are popularly known for their faster dynamics, high efficiency, and low maintenance. The dynamics of the motor is predominantly influenced by the type of controller employed in the control loop. Faster dynamics and precise control of BLDC motors is usually achieved by employing hysteresis current controllers. The current sensed either from the DC Link or from the phases of the motor is employed for the control. This paper brings out the effects of these current sensing strategies on torque ripple and switching frequency. It also proposes methods to eliminate the nonlinearities in computing Maximum of Phase Currents by employing micro-controllers.