Patent Application
20140327505
The invention relates to an inductor and an associated production method.
Inductors or storage inductors are preferably used for the integration of clocked voltage signals, for example in DC choppers. In particular with high medium currents with significant current ripple, considerable problems are encountered in respect of losses and cooling of the winding.
Conventional windings of storage inductors are formed, for example, from layered lamination constructions, flat-wire edge windings and copper strip windings. Materials formed from ferrite, amorphous metallic glass, nanocrystalline strips or metal powders are used as core materials.
All of the above-mentioned solutions have the common problem of efficient cooling of the inductor. For example, defined cooling by means of a plate through which a cooling medium flows is typically necessary in a closed housing.
In the case of inductive components however, the heat is generally produced in a volume, such that complex cooling concepts are generally necessary.
The object of the invention is to provide an inductor and an associated production method which enable efficient cooling of the inductor with the lowest possible outlay.
The invention achieves this object by an inductor as claimed in claim 1 and a production method as claimed in claim 13. Preferred embodiments are disclosed in the dependent claims, the wording of which is hereby incorporated in the content of the description.
The inductor, in particular in the form of what is known as a storage inductor or high-current inductor, has a magnetic or magnetizable core, which defines a winding axis or has a winding axis, and at least one winding, which is formed by a conductor which at least partly surrounds, in particular at the shortest possible distance, the at least one winding axis of the core or a limb of the core, through which the at least one winding axis runs. The at least one winding is formed in one layer, that is to say windings formed by the conductor run only adjacently and are not layered. A cross section of the conductor in the winding direction is rectangular, in particular square. Due to the cross section and the resultant outer contour, the winding can be coupled very easily and with low thermal resistance to a cooling surface for example. The cross section of the winding, which is solid in particular, or of the solid conductor is intentionally overdimensioned here, such that an efficient heat flow is possible within the winding.
In accordance with the invention the inductor has a magnetic or magnetizable core, at which the heat dissipation occurs significantly via the winding coupled thermally to the core. Due to the selection of a large solid conductor cross section or winding cross section, a sufficient heat flow and therefore heat dissipation is made possible, for example via a plate cooled by water on one side.
In an embodiment the conductor solid, that is to say the entire cross section of the conductor is filled with conductor material, or the conductor is filled completely with conductor material within its outer dimension. The conductor in particular is not constructed by interwoven stranded wires, by a plurality of combined individual conductors, or in the form of a hollow conductor or the like.
In an embodiment the at least one winding is formed from a profiled tube, in particular a rectangular profiled tube, which is structured to form the conductor, in particular is structured by material removing machining, in particular is structured by drilling, sawing, milling and/or electric discharge machining. Alternatively the at least one winding is formed from a diecast shaped article.
In an embodiment the inductor has a nominal current-carrying capacity, wherein the cross section of the conductor is dimensioned in such a way that a current-carrying capacity of the conductor is greater than the nominal current-carrying capacity, that is to say the cross section of the conductor is overdimensioned in relation to the nominal current-carrying capacity. In addition or alternatively, the winding and the core can be dimensioned in such a way that, if the inductor is loaded by its nominal current-carrying capacity, the winding losses are greater than the core losses, such that efficient cooling can be ensured on the whole due to the optimized ability to cool the winding.
In an embodiment the conductor consists of copper or titanium, particularly preferably of aluminum.
In an embodiment a planar cooling element is provided, which is thermally coupled to the winding, in particular to the side or surface of the winding facing away from the winding axis of the core. A heat-conductive electric insulator is preferably provided and is arranged between the cooling element and the winding. The electric insulator is preferably an electrically insulating heat-conductive foil.
In an embodiment the winding forms a heat sink.
In an embodiment a distance between the winding and the core is selected in such a way that losses caused by leakage fields are minimized.
In the method for producing the above-mentioned inductor, the winding is formed from a profiled tube, in particular from a rectangular profiled tube, which is structured to form the conductor, in particular as a result of material removing machining in the form of drilling, sawing, milling and/or electric discharge machining of the profiled tube.
The invention will be described hereinafter with reference to the drawings, which illustrate preferred embodiments of the invention and in which, schematically:
The inductor 1 has a nominal current-carrying capacity of nominally 200 A of medium current, wherein the cross section of the conductor 5 is dimensioned in such a way that it can conduct more than the nominal current. The winding 4 and the core 2 are dimensioned in such a way that, if the inductor 1 is loaded by the nominal current, winding losses are greater than core losses, such that the heat produced during operation can be easily removed by cooling the winding 4, which can be implemented much more easily than a cooling of the core 2.
For efficient cooling, a planar cooling element 7 is further provided, which is to be thermally coupled to the side or surface of the winding 4 facing away from the winding axis 3 of the core 2, wherein a heat-conductive electric insulator in the form of an electrically insulating heat-conductive foil 8 is provided between the cooling element 7 and the winding 4. Corresponding cooling elements can be provided on the upper face and/or the lower face of the winding 4.
A distance between the limb of the core 2 and the surface of the winding 4 facing the limb is fixed by means of a spacer 9 to be low, in such a way that leakages are minimized.
The cross section of the conductor 5 is dimensioned in such a way that, at an intended working frequency of the inductor 1, the effective replacement area due to the skin effect is much smaller than the cross section of the solid conductor 5. The dominating alternating current loss thus flows in the outer region of the conductor 5 or winding 4 in the direction of the core region of the winding 4 and lastly along the winding 4 to the heat sink in the form of the cooling element 7.
Bores 10 serve as connection elements for further parts (not shown) of a circuit that uses the inductor 1.
A rectangular profiled tube 6, which is illustrated in the form in which it has already been structured or machined, is structured to form the winding 4 or the conductor 5.
The structuring occurs by helical milling to form the winding 4 or the conductor 5, wherein individual winding segments are produced by sawing in the transverse direction of the profiled tube 6 and each form a respective coil together with an associated core and the further illustrated components. The connection points 10 are produced by drilling.
When produced in very high numbers, the winding may alternatively be formed from a diecast shaped article.
In accordance with the invention a solid winding 4 is provided, which has square or rectangular outer dimensions. The winding 4 can therefore be coupled very easily and with low thermal resistance to a cooling surface 7. The cross section of the solid winding 4 is intentionally overdimensioned here, such that an efficient heat flow is possible within the winding 4, that is to say the winding 4 is simultaneously the inner heat sink of the component 1.
The electrical insulation of the winding 4 with respect to the cooling plate or the heat sink 7 is achieved by a thin heat-conductive foil 8 or ceramic material.
The material of the winding 4 is aluminum, copper or titanium.
The highly efficient ability to cool the coil or the component 1 via the solid winding 4, which can be effectively thermally coupled, is advantageous. Furthermore, aluminum can be used as a conductor material due to the large cross section, whereby weight and costs are saved.
The inductor 1 according to the invention has a solid winding, of which the cross section is dimensioned in such a way that transport of the produced heat loss to a planar heat sink 7 is possible, and therefore complex cooling measures can be omitted.
Instead of the illustrated E-I-shaped core 2, a differently shaped core can, of course, be used, for example a U-shaped core having two externally arranged windings.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102011082045.0 | Sep 2011 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/066205 | 8/20/2012 | WO | 00 | 5/15/2014 |
