Fixed-Time High-Order Dynamic Observation Strategy for PMSM Sensorless Control

This article presents a fixed-time high-order dynamic observation strategy which possesses the fixed time convergence feature. It mainly includes two aspects: 1) introducing dynamic surface into high-order sliding mode and 2) semiglobal fixed time uniformly ultimately bounded stability in backstepping dynamic surface design. Besides, this strategy is adopted to design a novel cascade fixed-time sliding mode observer-extended state observer for permanent magnet synchronous motor states observation. Specifically, the observer is capable of achieving fixed-time convergence. This implies that the upper bound of the convergence time depends solely on the designed parameters, enabling the system to reach convergence in a limited time with fixed upper bound under any initial conditions. Furthermore, the upper bound of convergence time is calculated and the exact stability is mathematically proved. A tuning guideline for all parameters is also elaborated. Fixed time convergence feature is the major concern in experimental and numerical works arranging. Through the experiment and numerical results, the validate and fixed time convergence feature of the proposed observer are verified.