Multiscalar Control-Based Flux Optimization for Efficiency Improvement of Induction Motor

Constant flux control is typically used for induction motor (IM) drives to offer the same torque capabilities across all operating ranges. Unfortunately, the motor efficiency is low because, this control system produces high stator current at light loads. The model-based techniques are superior to the traditional efficiency optimization algorithms in accuracy and fast response. Additionally, an IM sensitivity to parameter variations still presents a challenge in the high-speed range to operate at maximum torque across the whole flux-weakening area. The energy efficiency of IM drives depends strongly on the choice of flux. This work proposes a novel online model-based maximum reactive power per flux controlling variable (MRPPFCV) control method to determine an optimum rotor flux level for efficiency optimization based on reactive power, resulting in improved system stability at low speeds and light loads. The new online model-based strategy, utilizing the multiscalar control principle of IM drives, is introduced to optimize rotor flux, ensuring maximum torque operation while maintaining robustness to parameter variations in the flux-weakening region. This method calculates the reference flux controlling variable online and does not use a lookup table. The primary contribution is designing a straightforward and simple yet effective online flux optimization method to enhance performance, allowing the flux to be modified based on motor requirements for energy efficiency. Consequently, the proposed approach is resilient to parameter variations. The real-time implementation of the proposed MRPPFCV technique is tested on a 5.5 kW IM drive in the lab. The simulations and experimental results demonstrate the effectiveness and validity of the proposed technique.