N.H. Vrijsen

Comparison of linear voice coil and reluctance actuators for high-precision applications

This paper concerns the comparison of three linear reluctance actuators and four voice coil actuators for high-precision applications. The short-stroke actuators with reasonably low variation of the force are optimized on actuator mass and power dissipation. For actuators with a significantly high force variation, the configuration is modified with the objective to improve the actuator properties for high-precision applications. Finally, the comparison is made on performance regarding, force, mass, losses and stiffness.

Prediction of Magnetic Hysteresis in the Force of a Prebiased E-Core Reluctance Actuator

Magnetic hysteresis in the force of a prebiased E-core reluctance actuator is researched using three analysis methods. Simulations are performed with a 2-D/3-D finite-element method (FEM); and two semianalytic methods are evaluated, namely, a generalization of the classical Preisach model, which is combined with a dynamic magnetic equivalent circuit (MEC) method, and a complex impedance model, which is combined with a static MEC model. Ultimately, the FEM simulations and analytic models are examined by a comparison with force measurements performed with a piezoelectric load cell.

Finite element analysis and Preisach hysteresis model of a toroid compared to measurements

Two methods predicting magnetic hysteresis effects are compared to measurements on a closed and open toroid. The soft-magnetic laminated toroids are simulated with a 3-dimensional finite element method (3D-FEM) and the classical Preisach model (CPM). On the closed toroid a direct comparison between both models has been made and the CPM shows better agreement with the measurements, especially at low excitation field strengths. In the open toroid with a 1.0 millimeter airgap, it is shown that the prediction and measurement of the magnetic flux density in the airgap are strongly influenced by leakage and fringing fluxes. Nevertheless, both predictive methods show reasonable agreement with the preformed measurements.

Measurement method for determining the magnetic hysteresis effects of reluctance actuators by evaluation of the force and flux variation

A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator.

Requirements for 3-D Magnetostriction Measurement Instruments

This paper concerns the requirement analysis and implementation of a measurement instrument, which can identify the 3-D magnetostriction strain. To measure magnetostriction, a high-accuracy magnetic flux density and strain measurement are required, while the mechanical stress in the sample is minimized. The full block tester is proposed as a measurement instrument. In this instrument, homogeneity of flux density within the measured sample and the strain measurement resolution are sufficient, but stress caused by magnetic forces is higher than required.

Force prediction including hysteresis effects in a short-stroke reluctance actuator using a 3d-FEM and the preisach model

Magnetic hysteresis effects, present in the force of an E-core reluctance actuator, are examined by simulations and measurements. Simulations have been performed with a 3d finite element method (3d-FEM) and a Preisach model, which is extended with a dynamic magnetic equivalent circuit (MEC) model. Both simulation methods are first examined on the prediction of the magnetic flux density in a closed-and open toroid for dc-and ac excitations. Finally, both methods are used to predict the force of the E-core reluctance actuator, which is compared to ac force measurementsperformed with a piezoelectric load cell.

Optimization of the Force Density for Medium-Stroke Reluctance Actuators

This paper concerns the force density optimization for medium-stroke reluctance actuators applied in anti-vibration applications. The force density in a conventional E-core reluctance actuator is limited for medium strokes by the non-linear force-displacement characteristic. In this paper, different tooth topologies are analyzed to maximize the force density along the stroke using the finite element analysis. Teeth parameters are tuned in each topology to analyze the influences on the force density over a stroke of

Prediction of magnetic hysteresis in the force of a pre-biased E-core reluctance actuator

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Optimization of the force density for medium-stroke reluctance actuators

12.5 mm. An analytic thermal model is used to estimate the surface temperature and is verified with finite element simulations. The optimal topology is validated by experiments on a prototype.

Hybridizing network reluctance and boundary integral methods: comparisons on an E-core actuator

Magnetic hysteresis in the force of a pre-biased E-core reluctance actuator is researched. The simulations are performed with a 2d/3d finite element method (FEM) and two semianalytic methods are evaluated namely, the classical Preisach model (CPM), which is combined with a dynamic magnetic equivalent circuit (MEC) method, and a complex impedance model, which is combined with a static MEC model. Ultimately, the FEM simulations and analytical models are compared to force measurements performed on a piezoelectric load cell.