Combined Speed and Direct Thrust Force Control of Linear Permanent-Magnet Synchronous Motors With Sensorless Speed Estimation Using a Sliding Mode Control With Integral Action

A sliding-mode-based control scheme with integral action for combined speed and direct thrust force control of a linear permanent-magnet synchronous motor is proposed. A nonlinear state-space model for the combined dynamics of speed and thrust force as system states is utilized for the synthesis of the sliding-mode control law. Direct integral action is also included in the control law to eliminate the steady-state error in the speed tracking. The sensorless speed estimation is performed by using an adaptive flux observer with a modified dual boundary layer sliding-mode component. Lyapunov stability analysis to prove the global asymptotic stabilities of both the controller and observer is provided. The effectiveness of the proposed method is validated experimentally and demonstrates excellent transient and steady-state speed control performance.