Real-Time Parameter Identification and Integration on Deadbeat-Direct Torque and Flux Control (DB-DTFC) Without Inducing Additional Torque Ripple

This paper is dedicated to exploring real-time parameter identification approaches and their integration with deadbeat-direct torque and flux control (DB-DTFC) without additional torque ripple. Using the voltage model at medium- and high-speed ranges, DB-DTFC is insensitive to parameters. Performance degrades at low speeds with the rotor time constant errors, because the current model is utilized for flux linkage estimation. Two different real-time parameter estimation approaches are developed, including a flux observer-based model reference adaptive system (MRAS) and a pulsating flux injection-based method. Both are experimentally evaluated for how well they mitigate DB-DTFC performance degradation at low speed. For the MRAS-based method, the fundamental components are used for parameter convergence, which does not induce additional torque ripple. For the injection-based method, traditional d-axis pulsating voltage vector injection used in indirect field-oriented control (IFOC) yields significant torque ripple, particularly at high speed. The proposed pulsating flux injection scheme used in DB-DTFC excites the same magnitude of current harmonics and induces no additional torque ripple over a wide speed range.