Bobbin design for conduction-cooled, gapped, high-permeability magnetic components
A coil former, also referred to herein as a bobbin, is provided for use in conduction-cooled magnetic components that contain an air gap. The diameter of the disclosed bobbin is increased and ribs/splines or tabs are created to keep the winding centered about the core center post while allowing thermally conductive silicone-based or equivalent encapsulant to fill the voids between the coil former and the core, the coil former and the windings and/or both depending on the placement of the locating tabs. The disclosed bobbin may be fabricated from traditional injection molding resins or from high-thermal conductivity resins. As a result of the disclosed bobbin designs, the achievable power density is increased while maintaining acceptable temperatures.
1. A conduction-cooled magnetic component comprising:
core portions that are complementary to each other, configured so that a predefined gap is formed between at least first opposing core legs and so that at least second opposing core legs abut each other;
first encapsulant material in the predefined gap;
a bobbin that encloses the first opposing core legs, wherein the first encapsulant material contacts the bobbin;
a winding on the bobbin, the bobbin having first spacers on an inward surface of a wall of the bobbin configured to direct flow of the first encapsulant material between the inward surface of the wall of the bobbin and the first opposing core legs, and second spacers on an outward surface of the wall of the bobbin configured to direct flow of second encapsulant material between the outward surface of the wall of the bobbin and the winding; and
a seal for the first encapsulant material located between one of the first opposing core legs and the bobbin.
2. The conduction-cooled magnetic component of claim 1 , wherein the second spacers are arced and staggered on the outward surface.
3. The conduction-cooled magnetic component of claim 1 , wherein the bobbin comprises inner and outer concentric cylinder walls connected by at least one member.
4. The conduction-cooled magnetic component of claim 3 , wherein the inner and outer concentric cylinder walls are connected by essentially linear members.
5. The conduction-cooled magnetic component of claim 3 , wherein the member undulates between the inner and outer concentric cylinder walls.
6. The conduction-cooled magnetic component of claim 1 , wherein the first encapsulant material substantially fills the predefined gap.
7. The conduction-cooled magnetic component of claim 1 , further comprising another gap between the inward surface and the first opposing core legs, wherein the first encapsulant material substantially fills the another gap.
8. A conduction-cooled magnetic component comprising:
a two-piece magnetic core, each piece of the two-piece magnetic core having a center leg, a right leg, and a left leg, the two-piece magnetic core assembled to form opposing center legs separated by a predefined gap, abutting right legs, and abutting left legs;
a bobbin surrounding the opposing center legs and including:
an inward surface adjacent the opposing center legs;
an outward surface adjacent the abutting right legs and the abutting left legs;
first spacers formed on the inward surface; and
second spacers formed on the outward surface;
a winding on the bobbin in contact with the second spacers; and
encapsulant material in the predefined gap and between the inward surface and the center legs.
9. The conduction-cooled magnetic component of claim 8 , wherein the first spacers are configured to direct flow of the encapsulant material between the inward surface of the bobbin and the opposing center legs.
10. The conduction-cooled magnetic component of claim 9 , wherein the second spacers are configured to direct flow of the encapsulant material between the outward surface of the bobbin and the winding.
11. The conduction-cooled magnetic component of claim 10 , further comprising a seal for the encapsulant material.
12. The conduction-cooled magnetic component of claim 11 , wherein the seal for the encapsulant material is located between one of the opposing center legs and the bobbin.
13. The conduction-cooled magnetic component of claim 8 , wherein the second spacers are arced and staggered on the outward surface of the bobbin.
14. The conduction-cooled magnetic component of claim 8 , wherein the bobbin comprises inner and outer concentric cylinder walls connected by at least one member.
15. The conduction-cooled magnetic component of claim 14 , wherein the inner and outer concentric cylinder walls are connected by essentially linear members.
16. The conduction-cooled magnetic component of claim 14 , wherein the at least one member undulates between the cylinder walls.