Flux-Weakening Operation of Speed-Sensorless Induction Machine Drives using Deadbeat-Direct Torque and Flux Control

The deadbeat-direct torque and flux control (DB-DTFC) has been studied in recent years for induction machine (IM) drives. The DB-DTFC has the advantages of fast dynamic performance compared to classical field-oriented control (FOC). To achieve stable operation above the base speed, a flux-weakening control with the DB-DTFC is proposed in this paper. The reference flux is reduced by the studied strategy in the flux-weakening region. The DB-DTFC graphically calculate the output voltages with the speed feedback and flux from the full-order observer. The full-order observer can accurately estimate the operating speed, stator and rotor flux linkages. Then, the IM can achieve flux-weakening operation of speed-sensorless with DB-DTFC. The studied DB-DTFC can enhance the voltage utilization compared with the classical FOC. The improvement with flux-weakening strategy is verified by the experimental results from a 3.7kW platform.