Impact of size, structure, and active cooling on the design and control of an omni-directional magnetic field generator: experiments and modeling

Omni-directional magnetic field generators (or Omnimagnets) are devices with several potential applications, such as capsule endoscope and magnetic guidance of a cochlear implant. An Omnimagnet heats due to the Joule effect and the resulting excessive temperatures may cause device failure. Thermal analysis of an Omnimagnet can provide operational limits to prevent device failure due to excessive heating; however, as the device is still new, the thermal performance of the Omnimagnet has not yet been completely studied. The thermal behaviour of two Omnimagnets with some structural differences are numerically and experimentally studied in this work. A lumped-capacitance model is validated with experimental results showing the model Normal Root Mean Square Error for both Omnimagnets to be less than 12 % . Results show that increasing the size of the Omnimagnet by about 16 % , slows the rate of temperature increase within the Omnimagnet by 44 % . In addition, a constant frame temperature heat sink at 0 ^∘ C decreases the steady-state temperature of the outer solenoid by approximately 29 % when the outer solenoid is powered at 10 A.