Improved Integral Sliding Mode and Adaptive Super‐Twisting Control for Industrial Servo SPMSM

ABSTRACT Surface‐mounted permanent magnet synchronous motor (SPMSM) acts as the core actuator of industrial servo systems. Sudden load variation and parameter perturbation easily lead to delayed dynamic response and steady‐state chattering. Conventional sliding mode control (SMC) has good robustness but suffers from integral saturation and high‐frequency chattering. Fixed‐gain super‐twisting algorithm (STA) also has troublesome parameter tuning, failing to balance convergence speed, control accuracy, and chattering suppression. This paper proposes an improved piecewise integral terminal sliding mode control with adaptive super‐twisting reaching law (IPISMC‐ADSTA) for SPMSM speed regulation: (1) A piecewise nonlinear sliding surface is developed to suppress large errors and amplify small deviations. Integral clamping is adopted to prevent integral windup under large errors, while increased gain improves sensitivity and accelerates convergence for small deviations. The proposed scheme alleviates integral saturation and improves the overall dynamic and steady‐state control performance. (2). An adaptive‐gain super‐twisting reaching law is constructed herein. The discontinuous sign function is substituted with a continuous hyperbolic tangent function to smooth the control input and reduce high‐frequency chattering. The time‐varying gain and robust adaptive compensation term adjust dynamically against varying disturbances, achieving favorable chattering suppression. Experiments are carried out on TMS320F28379D DSP platform under diverse operating conditions. SMC‐STA, ISMC‐STA, and the algorithm used by Jin et al. are selected for comparison. Results show the no‐load startup time reaches 0.5 s, decreasing by 41.18%. Steady‐state speed ripple is limited within 5 rpm with a reduction of 44.44%. Under 0.1 N·m sudden load, speed drop is 70 rpm and recovery time is 0.3 s. The proposed strategy achieves better dynamic response, steady‐state precision, and anti‐disturbance ability, providing a practical solution for high‐precision speed control of industrial servo systems.