Sensorless control of BLDC motor drive under DTC scheme with modified integrator

In this paper, sensorless control of Brushless DC (BLDC) motor drive under Direct Torque Control scheme with modified integrator for flux estimation is investigated. The initial transient in flux linkage in first switching is reduced by the modified integrator. The drive is operated in the constant torque region under the DTC scheme. The sensorless control is achieved using PI controller and back EMF observer. Torque estimation is carried out by the observed electrical rotor speed and the back EMF in dq-reference frame. The inverter DC-link voltage and two line currents are measured for control. In DTC, two level hysteresis controllers are used for the torque and the flux control. The effectiveness of the introduced scheme is verified through extensive simulation under MATLAB. Simulation results indicates good speed response is achieved by the BLDC motor.