Abstracto

Sliding Mode Observer Based Sensorless Control of BLDC Motor under DTC Scheme

Girija P K, Prince A

Direct Torque Control (DTC) is a method to control the torque in variable frequency drives. This paper describes sensorless DTC of brushless dc (BLDC) motor drive operating in constant torque region under two phase conduction mode to get instantaneous torque control. Sliding Mode Observer (SMO) which is robust to parameter uncertainties is proposed to estimate the phase-to-phase trapezoidal back-EMF for the sensorless operation. This estimated back-EMF is used to deduce the rotor position and the angular velocity of the rotor. And instantaneous electromagnetic torque can be calculated by the product of back-EMF and current.In this paper the effectiveness of sliding mode observer with signum and saturation functions for DTC scheme is investigated.