The technical field of this disclosure is inductor devices, particularly, integrated passive components including foil wound low profile power processors having inductor and capacitor characteristics.
There has been an aggressive pursuit after lower profile packages for power electronic circuits and components over recent years. This has lead to unconventional designs both in high and low power applications of switching power electronic circuitry. Although low profile is essential in some applications where flatness of the power supply complements the main product features, it has also found a niche in many other applications as a secondary design objective to improve cost and performance. Other related developments, such as integrated power circuits, modularization, standardization in power electronics, power electronic building blocks and distributed power systems, are fueling the evolution of low profile packaging technologies.
Often misunderstood, however, is that striving for low profile with the current materials and manufacturing technologies involves certain fundamental trade-offs. From a purely electromagnetic perspective, fiat power processing components do not utilize materials as well as box-type structures do in general. This means that a flattened structure will require a larger volume and an even more substantial footprint area to perform the same function.
Present pure planar power devices use rectangular foil alternating with rectangular insulating material, arranged in a stack. The insulating material typically has the undesired characteristic of low thermal conductivity accompanying the desired characteristic of low electrical conductivity. The insulating material lies in the primary heat flow path along the direction of the stack and impedes heat transfer. The rectangular shape precludes efficient conductive heat flow along the foil, because the center of the rectangle is too far from any heat sink. These factors can lead to high temperatures in the center of the device.
Low eddy current losses and design flexibility are achievable by using litz-wire, but litz-wire windings suffer from several disadvantages. Besides being expensive and difficult to work with, litz wire also inhibits higher winding packing densities due to the amount of insulation involved. As a result, litz-wound components often run the risk of developing hot-spot temperatures inside the windings.
The size and weight of power conversion devices are governed by the size and weight of the passive components, i.e., capacitors, transformers, and inductors. A greater number of passive components not only increases the size and weight, but also increases the cost and manufacturing complexity.
It would be desirable to have a foil wound low profile L-C power processor that would overcome the above disadvantages.
One aspect of the present invention provides a foil wound low profile power L-C processor with low profile packaging.
Another aspect of the present invention provides a foil wound low profile power L-C processor operating at a high power density.
Another aspect of the present invention provides a foil wound low profile power L-C processor with superior heat transfer to avoid hot spots.
Another aspect of the present invention provides a foil wound low profile power L-C processor integrating the inductive and capacitive characteristics to reduce the number of passive components.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention, rather than limiting the scope of the invention being defined by the appended claims and equivalents thereof.
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