Abstract
This paper introduces a novel sensorless model-predictive torque-flux control (MPTFC) for two-level inverter-fed induction motor (IM) drives to overcome the high torque ripples issue, which is evidently presented in model-predictive torque control (MPTC). The suggested control approach will be based on a novel modification for the adaptive full-order-observer (AFOO). Moreover, the motor is modeled considering core losses and a compensation term of core loss applied to the suggested observer. In order to mitigate the machine losses, particularly at low speed and light load operations, the loss minimization criterion (LMC) is suggested. A comprehensive comparative analysis between the performance of IM drive under conventional MPTC, and those of the proposed MPTFC approaches (without and with consideration of the LMC) has been carried out to confirm the efficiency of the proposed MPTFC drive. Based on MATLAB® and Simulink® from MathWorks® (2018a, Natick, MA 01760-2098 USA) simulation results, the suggested sensorless system can operate at very low speeds and has the better dynamic and steady-state performance. Moreover, a comparison in detail of MPTC and the proposed MPTFC techniques regarding torque, current, and fluxes ripples is performed. The stability of the modified adaptive closed-loop observer for speed, flux and parameters estimation methodology is proven for a wide range of speeds via Lyapunov’s theorem.
Highlights
Several schemes for speed-sensorless vector-controlled induction motor (IM) drives have been suggested for nearly a decade
The majority of estimators proposed in sensorless IM drives for combined flux and speed estimation could be divided into three categories: (a) Modelreference-adaptive system (MRAS) [1,2]
The proposed adaptive full-order-observer (AFOO) can be used to determine the electromagnetic torque to reduce the error between the reference and desired motor output torque based on estimated stator current and flux
Summary
Several schemes for speed-sensorless vector-controlled induction motor (IM) drives have been suggested for nearly a decade. Rather than the traditional rotor flux plus stator current IM model, the rotor and stator flux models are utilized in the rotor speed reference frame This makes it probable to apply the suggested observer in both stator and rotor-flux vector-controlled IM drives and in DTC-IM drives. The current study introduces an efficient MPTFC technique for the IM drive in which some of the MPTC shortcomings can be mitigated, in specific by reducing the ripples of torque, stator flux and current. A loss minimization criterion (LMC) is suggested to improve the drive efficiency, under light loads and low-speed operations, extending the IM’s lifetime. Developing a novel AFOO, which contributes to reducing the fluctuations and thereby enhancing the method torque-flux and prediction, with the compensation of core-loss, for; rotor speed estimation, stator flux estimation, rotor flux estimation, stator and rotor resistance estimation, stator current estimation, electromagnetic torque estimation has been introduced. The complete system design and performance test results are introduced and discussed
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