Sliding-Mode Control Strategies for PMSM speed control: A Comprehensive Review, Taxonomy and Research Gaps

Permanent Magnet Synchronous Motors (PMSMs) are widely employed in high-performance drive systems due to their high efficiency, power density, and precise dynamic behavior. However, nonlinearities, load disturbances, and parameter uncertainties present persistent challenges to control. Sliding-Mode Control (SMC) remains one of the most reliable strategies for high-performance PMSM drives. Yet, the rapid proliferation of adaptive, fractional-order, and intelligent variants has fragmented recent literature. This paper presents a comprehensive review and taxonomy of SMC-based PMSM speed-control methods published between 2020 and 2025. More than 200 studies are systematically analyzed and classified according to control order, surface design, disturbance-observer integration, optimization approach, and intelligent augmentation. Trends in publication activity, dominant hybrid structures, and application domains are quantitatively summarized. The review reveals a clear evolution from conventional discontinuous SMC toward adaptive, higher-order, and data-driven frameworks that mitigate chattering while preserving robustness. Persistent research gaps are identified in hardware validation, energy-efficiency assessment, and real-time tuning strategies. The taxonomy and critical synthesis provided herein establish a coherent reference for researchers and form the conceptual foundation for the companion paper (Part II), which delivers a unified benchmark and comparative simulation study of representative SMC designs.