In this paper, speed control of Brushless DC (BLDC) motor drive under Direct Torque Control scheme with modified integrator for flux estimation is investigated using optimal controller. The modified integrator reduces the initial transient in flux linkage in first switching. Here the drive is operated in the constant torque region under the DTC scheme. The performance comparison between PI controller and optimal controller for speed control operation is evaluated. The electrical rotor speed and the back EMF in dq-reference frame is used for the torque estimation. The inverter DC-link voltage, speed and two line currents are measured for control the drive. The effectiveness of the proposed scheme is verified through extensive simulation under MA TLAB. Simulation results indicate better speed regulation of BLDC motor achieved using optimal controller.

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