Abstract
This paper proposes a design methodology for linear actuators, considering thermal and electromagnetic coupling with geometrical and temperature constraints, that maximizes force density and minimizes force ripple. The method allows defining an actuator for given specifications in a step-by-step way so that requirements are met and the temperature within the device is maintained under or equal to its maximum allowed for continuous operation. According to the proposed method, the electromagnetic and thermal models are built with quasi-static parametric finite element models. The methodology was successfully applied to the design of a linear cylindrical actuator with a dual quasi-Halbach array of permanent magnets and a moving-coil. The actuator can produce an axial force of 120 N and a stroke of 80 mm. The paper also presents a comparative analysis between results obtained considering only an electromagnetic model and the thermal-electromagnetic coupled model. This comparison shows that the final designs for both cases differ significantly, especially regarding its active volume and its electrical and magnetic loading. Although in this paper the methodology was employed to design a specific actuator, its structure can be used to design a wide range of linear devices if the parametric models are adjusted for each particular actuator.
Highlights
The advantages of linear actuators over rotation-to-translation conversion systems when linear motion is needed are well documented in the literature [1]
Linear actuators that have interesting characteristics are the cylindrical actuators equipped with quasi-Halbach arrays of permanent magnets (PMs) [4,5]
N, which close to specifications, i.e., 120 N. These results show that the end effect has little significance,iswhich is the specifications, i.e., 120 N. These results show that the end effect has little significance, which is consistent with the assumption that PMs with radial magnetization at the end poles should present an axial length of τ r /2, as expected
Summary
The advantages of linear actuators over rotation-to-translation conversion systems when linear motion is needed are well documented in the literature [1]. Applications of linear actuators are mainly in industry and transportation due to its force density, efficiency, levels of acceleration, and precision. An application that has drawn particular interest to linear actuators is mechanical vibration control [2,3]. For such an application, linear actuators that have interesting characteristics are the cylindrical actuators equipped with quasi-Halbach arrays of permanent magnets (PMs) [4,5]. The advantages of quasi-Halbach arrays are well known, and include applicability for a wide range of electromechanical devices [6]. There are still recent developments and designs for specific applications under research, such as, for example, for limited angle torque actuators [7] and for assemblies in which the flux density can be altered by a mechanical operation [8]
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