# A topology optimized switchable permanent magnet system

## TL;DR

This paper presents a topology optimization method for a switchable magnetic system using a Halbach cylinder and iron inserts, achieving significantly improved flux density variation between high and low states.

## Contribution

It introduces a topology optimization approach to design switchable magnetic systems with enhanced flux density modulation capabilities.

## Key findings

- Optimized structures are parabolic shaped iron inserts.
- Flux density difference is 1.29 times higher than regular pole pieces.
- Maximum flux density increase is 2.08 times compared to regular pole pieces.

## Abstract

The design of a magnetic field source that can switch from a high field to a low field configuration by rotation by $90^\circ$ of a set of iron pieces is investigated using topology optimization. A Halbach cylinder is considered as the magnetic field source and iron inserts are placed in the air gap of the Halbach cylinder. The ideal shape of these iron inserts is determined as function of the field generated by the Halbach cylinder and as function of the size of the iron segments. The topology optimized structures are parabolic shaped pieces and have a difference in flux density between the high and low positions that is on average 1.29 times higher than optimized regular pole pieces. The maximum increase is a factor of 2.08 times higher than the regular pole pieces.