Tunable magnets: dynamic flux-feedback compensation methods for improved magnetization state tuning performance and minor-loop magnetization state tuning for the validation and reduction of the break-even tuning interval

Tunable magnets: dynamic flux-feedback compensation methods for improved magnetization state tuning performance and minor-loop magnetization state tuning for the validation and reduction of the break-even tuning interval

Meijer, Romano (TU Delft Mechanical, Maritime and Materials Engineering; TU Delft Mechatronic Systems Design)

Hossein Nia Kani, S.H. (mentor)
Hunt, A. (graduation committee)
Spronck, J.W. (graduation committee)

Delft University of Technology

Mechanical Engineering | Mechatronic System Design (MSD)

2021-08-20

In precision engineering, thermal stability is of great importance in order to keep up with the ever-increasing demand for faster and more precise positioning actuators. Most notably, actuator magnetizing coils dissipate heat to surrounding machine components as a result of Joule heating. With changing temperatures, system components expand and contract - causing unwanted structural deformations that can lead to a decline in positioning accuracy and repeatability. This phenomenon is especially pronounced in quasi-static processes that operate in vacuum environment – examples of which can be found in lithography mirror alignment systems, deformable space mirrors and magnetic gravity compensators. Prior TU Delft research introduced a method to accurately tune a low-coercivity AlNiCo 5 magnet to a set of user-predefined magnetization states – the novel Tunable Magnet (TM) actuator. This way, by precisely 'tuning' the magnet with a single current pulse, the magnetization state is sustained even after tuning, making this method especially efficient for quasi-static operation. In order to advance the development of functional TM actuators, this research provides four contributions. First, limitations within the original setup prohibit to the dynamic stage movement that makes a reluctance actuator functional. By introducing a modular compliant stage attachment to the existing setup, this discrepancy is overcome – making dynamic-gap experimentation possible. Second, magnetization state tuning robustness, accuracy and repeatability are significantly improved by introducing a series of four dynamic compensation methods. Third, a novel minor-loop tuning approach is proposed as a replacement of the original major loop tuning algorithm in order to improve energy efficiency, dynamic behavior and tuning times. Lastly, the Break-even Tuning Interval (BTI) metric as conceived by previous research has been experimentally validated – allowing for comparison between TM and conventional electromagnetic (EM) actuators.

Tunable
Magnet
Actuators

http://resolver.tudelft.nl/uuid:2b525c3e-3d5c-40d7-a894-5b709df2e49f

Student theses

master thesis

© 2021 Romano Meijer