A Deadbeat-Direct Torque and Flux Control for Speed-Sensorless Induction Motor Drives Using Adaptive Full-Order Observer

Deadbeat-direct torque and flux control (DB-DTFC) has been considered as an effective predictive control scheme for induction motor drives in recent years. It is implemented using a discrete inverse motor model to achieve improved dynamic response within one PWM sampling period. However, in the traditional DB-DTFC, the torque dynamics is degraded due to the inaccurate magnetic field positioning, especially at low-speed range. In this paper, a DB-DTFC without coordinate transform is proposed graphically for induction motor drives. To achieve sensorless control, a speed adaptive full-order observer (AFO) is designed with high robustness and matching degree for DB-DTFC. The comparative experimental results of dynamic evaluation are presented between DB-DTFC and field-oriented control (FOC). Moreover, the synergy effect of AFO and DB-DTFC about robustness is evaluated for sensorless induction motor drives.