Coreless power conversion technology for high magnetic field applications

Powerbox has announced the release of a coreless technology platform to power medical and industrial equipment operating in very high magnetic field environments such as magnetic resonance imaging (MRI) or particle accelerators (PA).

Using the latest technology in high-frequency switching topologies and digital control with proprietary firmware to optimise efficiency and voltage regulation, Powerbox’s GB350 buck-converter module is the first building block in its category that is able to operate safely when exposed to high radiation magnetic fields of 2 to 4 Tesla. GB350 delivers an output power of 350W and when higher power levels are required it can be paralleled using an interleaving mode thus reducing EMI.

Modern MRI systems usually generate 1.5 to 4 Tesla, making conventional power supplies using ferrite material useless due to inductance saturation as a result of the MRI magnet disturbing the energy transfer. To prevent parasitic saturation, power supplies are traditionally positioned outside the shielded operation room.Installing the power supplies remotely requires long cables with subsequent power losses, and it is also a big challenge to power the latest generation of measuring equipment that require stable and tightly regulated voltages under fast transient load conditions.

To reduce energy consumption and to guarantee the level of quality required by integrated equipment, systems manufacturers are now integrating local power supplies near to the load.However, placing equipment directly in the radiated magnetic field requires an innovative power solution known as ‘coreless power units’ and a state of the art switching power stage.

Designed to respond to this demand and to guarantee the highest efficiency and tightly regulated output voltage at any load-condition, Powerbox’s GB350 coreless power unit is fully controlled by a digital processor that manages the complete power unit from switching parameters to output voltage characterisation. To guarantee a high level of flexibility and the possibility to re-profile the power unit characteristics when equipment manufacturers upgrade new hardware or implement a software revision, the GB350 micro-controller can be programed with optimised configuration files downloaded through the digital interface.

The standard GB350 platform delivers a nominal current of 50A, preset output voltages of 6.8, 3.3 or 1.6V and a switching frequency of 600kHz. Equipment installed within the magnetic field often require higher power levels than 350W and low EMI. With a switching frequency of 600kHz and its 4 phase interleave mode, the GB350 has a resultant output frequency of 2.4MHz. This is said to allow easier filtering and fast regulation response times.