Fault-tolerant tracking control design for a permanent magnet spherical motor under single stator coil open-circuit fault condition

An adaptive non-singular fast terminal sliding mode control(ANFTSMC) based on a disturbance observer (DO) was designed for tracking control of a permanent magnet spherical motor (PMSpM) under single stator coil open-circuit fault conditions. By optimizing the energization strategy, fault-tolerant control (FTC) of a PMSpM was achieved. Firstly, a method for detecting disturbance signals was proposed, and the stability of its convergence was demonstrated using the Lyapunov method. Then, the estimated value of external disturbance signals was introduced into the controller, and ANFTSMC based on DO was designed using an adaptive law. Meanwhile, the redundant input current characteristic of the PMSpM’s stator coil was analyzed, and an energization strategy was devised for the scenario of a single stator coil open-circuit fault. Finally, both simulations and experimental results demonstrate that the strategy is effective in ensuring the tracking performance of the PMSpM’s FTC system under single stator coil open-circuit fault conditions.