Sliding mode direct force control for linear drive system

A linear motor is direct driven and it can achieve far better acceleration, velocity and position accuracy than its rotary rival motor. The simplest linear motor is the single-sided linear induction motor (LIM), which consists of a primary coil assembly and a secondary formed by a reaction plate.This paper proposes a relatively simple and robust control solution to mitigate the uncertainties of a single-sided linear induction motor. A sliding mode based direct force control (DFC) has been used in a linear drive system because of its fast and precise force response. A control method has been designed, implemented and tested on a test bed platform, where the DFC controls the thrust force of the linear motor by directly setting the primary voltages. The experimental results have proven that DFC with a sliding mode can achieve faster response and be more robust than the conventional vector control under the same conditions.