Four-fold growth move for Planar Magnetics

Planar Magnetics Ltd is to quadruple production, having relocated into a brand new purpose-built factory near Gloucester, UK. The growth curve has already started, following the winning of a £1m plus order from a global telecoms company.

 
Planar transformers are relatively new but Planar Magnetics is already taking a world lead in the technology. Founded in 1996 as part of the Gloucester based Cardinal Technology Group, initially to supply transformers for digital variable speed motor drives, Planar has broadened its market to include transformers and inductors for mainframe computer power supplies, telecommunications rectifiers, battery chargers and a wide range of industrial applications.
 
Planar’s transformers were used in the induction-linked battery chargers for the athletes'electric buggies at the Sydney Olympics. A 4kW unit is at the heart of an innovative variable frequency portable welding unit manufactured by Green 3K. A more unusual application is for the power supplies for the refrigerator units being incorporated into the glove compartments of some larger American cars!
 
Compact power conversion is critical to the growth and continued miniaturisation in telecommunications, computing and a host of other applications. Transformers are required for the two fundamental functions of converting power and providing galvanic isolation. However, compactness in transformers is directly related to operating frequency and previously, switching frequencies much above 20kHz were precluded by the non-availability of suitable semiconductor switching devices. Today, with the development of power MOSFETS, power handling in kilowatts at switching frequencies well above 200kHz is commonplace and many barriers to producing small efficient transformers have been breached by planar technology, displacing wire or foil wound round a laminated iron core.

By employing planar technology, bulky, wire wound transformers have been superseded in many applications by coils encapsulated within multi-layer pcbs and sandwiched between state-of-the-art low-profile ferrite cores to make small, flat components ideally suited to pcb mounting. The major benefits of such transformers and inductors, is a size and weight reduction of up to 60%. This technique is now employed to produce low profile, highly efficient, transformers as large as 20kW.
 
Managing Director Colin Day said ‘The future of planar technology is assured and this is reflected in our aggressive expansion plans. Telecoms particularly, but also the advent of electric vehicle technology, driven by environmental considerations, will spectacularly fuel demand for planar devices and we intend to be in the vanguard of suppliers. Although we do a number of semi-standard designs, most of our customers need devices tailored to their physical and circuit specifications, so design and development is a big part of our operation. Fortunately, since the applications are usually for volume produced products, production is serial rather than single-batch based and this expansion will enable us to produce a large number of variants in volume.’
 
This quantum leap in transformer design brings major benefits alongside the size and weight reduction. By virtue of the much-improved magnetic coupling and thermal management, efficiency is better than in wire wound transformers. In converter design, a 0.5 percent improvement in efficiency is a significant benefit. The upper frequency limit is higher, up to several MHz and multiple windings are simplified by the use of multiple layers within the circuit board ‘sandwich’.
 
Pin positions are more easily optimised to fit in with the main circuit board design, electro-magnetic compatibility is superior so EMC compliance is easily achieved and temperature operating range is typically from – 40oC to +155oC.  With all those benefits, it is no surprise that planar devices have become today’s magnetics of choice for designers of high frequency, high-density power conversion equipment.