Estimated flux compensation for direct torque control in M-T frame synchronized with stator flux-linkage vector

This paper proposes a compensation method of stator flux estimation error for direct torque control in a rotating M-T reference frame which is synchronized with the stator flux-linkage vector. The flux estimation in the M-T frame is based on the integral of the flux error generated by stator flux controller, and no sensor is required to measure the motor terminal voltage. The conventional estimation method does not take into account voltage saturation due to the inverter, and thus, the voltage saturation degrades stator flux estimation accuracy. In the proposed method, the estimated flux is compensated by difference of voltage vectors in the M-T frame. Simulation and experimental results demonstrate the effectiveness of the proposed method.