Improving dynamic response and stability of three-phase synchronous reluctance machines with a novel higher-order field-oriented sliding mode control

This study introduces a novel higher-order field-oriented sliding mode (HOFOSMC) control strategy for synchronous reluctance motors (SynRMs), addressing the limitations of conventional proportional-integral (PI) and second-order sliding mode controls. The HOFOSMC scheme integrates field-oriented (FOC) control with third-order sliding mode (TOSMC) control (TOFOSMC), enabling precise management of speed and dq-axis stator currents. This integration significantly reduces torque and current fluctuations, enhancing SynRM drive performance. A notable innovation is the replacement of the signal function in control equations with a tanh function, which improves smooth operation and dynamic response. The effectiveness of TOFOSMC was validated through MATLAB/Simulink simulations and comparative analyzes against PI-FOC and SOFOSMC under various conditions. Results showed that TOFOSMC markedly minimized torque and current fluctuations, substantially reducing total harmonic distortion (THD) of the stator current with THD values of 1.27%, compared to 2.11% and 3.82% for SOFOSMC and PI-FOC, respectively. These findings demonstrate the superior performance, robustness, and efficiency of the SynRM drive using the TOSMC strategy, positioning TOFOSMC as a promising control method for SynRMs.