Adaptive nonsingular terminal sliding model control and its application to BPMSM

In order to obtain faster convergence of state variables during the whole process in terminal sliding mode control(TSMC), an adaptive variable-rated exponential reaching law is presented, where the L1 norm of state variables is introduced. Exponential and constant approach speed can adaptively adjust according to the state variables' distance to the equilibrium position, which can shorten the reaching time and weaken system chattering. The method is applied to the bearingless permanent magnet synchronous motor(BPMSM) system. Its speed and the radial displacement controller of adaptive nonsingular terminal sliding mode control(NTSMC) are designed. Simulation results show that, the proposed method can rapidly track the given values, overshoot and static error are small, and higher robustness can be obtained.