Speed Characteristics of Two-Fold Sliding Mode Control of BLDC Motor

BLDC motors are generally implemented in copious industrial processes because of its high proficiency, large torque and minimum volume. The variation in load torque, causes the variation of speed in BLDC motor, which leads the complete system in unstable condition. In this paper a robust first-order SM controller scheme depends on twofold controlling algorithm for angular velocity and also current control in Brushless DC motor to attenuate the chattering problems. Two cascaded sliding mode controllers of first-order are used and first sliding mode controller generates stator currents based on speed error then the second SM controller generates voltage based on current-error in stator which runs the universal bridge by this controlled voltage source. In addition to the method suggested by Slotine, two feed forward loops are added to both speed and current errors to improve the response. The existing sliding-mode control is unresponsive to uncertainties and will cause undesirable chattering problems. To overcome this snag, a manual control law in conjunction with Sliding mode control is utilized that provides smooth and chattering free actual control signal. The overall system stability performance is implemented in MATLAB/SIMULINK and simulation results shows that proposed scheme is robust with respect to uncertainty in the system.