A compensation method for electromagnetic hysteresis: Application in linear reluctance actuator

The linear reluctance actuator is a specialized electromagnetic actuator that generates motion based on the reluctance effect. With its high force density and lower power consumption, it presents advantages over Lorentz actuators, which are commonly used in lithography machines. This actuator has the potential to overcome the physical limitations of voice coil motors, which struggle to achieve the high acceleration required for next-generation lithography systems. The complex hysteresis nonlinearity between current and magnetic flux density in linear reluctance actuator, stemming from electromagnetic hysteresis, eddy currents, and motion coupling, induces force deviations that limit their broader application. In this paper, we present a hysteresis model that relates current and flux, developed using flux measurements from sense coils. By integrating this model with the adaptive feedforward parameter tuning method, hysteresis nonlinearity is effectively compensated, enabling precise flux control. Experimental results demonstrate that the model effectively captures the actuator's rate-dependent hysteresis behavior, and the proposed method effectively compensates for hysteresis nonlinearity.