Modeling and Control of a Hybrid Reluctance Actuator with Tunable Remnant Magnetization

This paper explores the combination of a Hybrid Reluctance Actuator (HRA) with a Hybrid Tunable Magnet Actuator (HTMA) to realize a high bandwidth actuator that can generate low-frequency forces with greater efficiently. The HTMA allows desired forces to be sustained without continuous coil heating by manipulating the remnant magnetisation of an AlNiCo magnet. This enables the actuator to exert force through two modes of operation: by magnetisation of the Tunable AlNiCo Magnet (TM) or by inducing a proportionally force-dependent field. The second mode may furthermore be used to compensate for unwanted variations in forces during magnetisation. Although FEM analyses provide an understanding of the actuator behaviour in steady states, it is inefficient to integrate transient FEM models with accurate hysteresis models. Hence, firstly, an analytical framework is presented to determine the transient behaviour and the comparative energy efficiency of the two actuator modes. Then, a control strategy is presented for the operation of the combined actuator to track a reluctance force step reference. An experimental setup is designed and tested to validate the concept and control method.