Coupled inductor arrays and associated methods
A coupled inductor array includes a monolithic magnetic core formed of magnetic materials having a distributed gap, first and second windings, and a low-permeability magnetic structure. The first and second windings form respective first and second winding turns around a common winding axis extending in the height direction. The low-permeability magnetic structure is embedded in the monolithic magnetic core and forms a loop around the common winding axis. The low-permeability magnetic structure separates the first and second winding turns in the height direction, and the low-permeability magnetic structure is formed of a magnetic material having a lower magnetic permeability than the one or more magnetic materials forming the monolithic magnetic core. One possible application of the coupled inductor array is in a multi-phase switching power converter.
1. A coupled inductor array having length, width, and height, comprising:
a monolithic magnetic core formed of one or more magnetic materials having a distributed gap, the monolithic magnetic core having opposing first and second sides separated from each other in a widthwise direction;
a first winding embedded in the monolithic magnetic core and having two opposing ends terminating at the first and second sides of the monolithic magnetic core, respectively, the first winding forming N first winding turns around respective winding axes extending in a height direction, each winding axis offset from each other winding axis in the widthwise direction, N being an integer greater than one; and
a second winding embedded in the monolithic magnetic core and having two opposing ends terminating at the first and second sides of the monolithic magnetic core, respectively, the second winding forming N second winding turns,
each of the N first winding turns and each of the N second winding turns being fully embedded in the monolithic magnetic core,
each of the N second winding turns overlapping with a respective one of the N first winding turns in the height direction, and
the N first winding turns and the N second winding turns being configured such that current of increasing magnitude flowing into the first winding at the first side of the monolithic magnetic core induces current of increasing magnitude flowing into the second winding at the first side of the monolithic magnetic core.
2. The coupled inductor array of claim 1 , each of the N second winding turns being formed around a respective one of the winding axes such that each of the N second winding turns is coaxial with a respective one of the N first winding-turns.
3. The coupled inductor array of claim 2 , the first winding comprising a plurality of first electrical conductors electrically coupled in parallel with each other, and the second winding comprising a plurality of second electrical conductors electrically coupled in parallel with each other, the plurality of first electrical conductors stacked on each other in the height direction, the plurality of second electrical conductors stacked on each other in the height direction, and the plurality of second electrical conductors stacked on the plurality of first electrical conductors in the height direction.
4. The coupled inductor array of claim 2 , the first winding comprising a plurality of first electrical conductors electrically coupled in parallel with each other, and the second winding comprising a plurality of second electrical conductors electrically coupled in parallel with each other, the plurality of second electrical conductors interleaved in the height direction with the plurality of first electrical conductors.
5. The coupled inductor array of claim 1 , each of the N first winding turns wound in a first direction, and each of the N second winding turns wound in a second direction opposite of the first direction, as seen when the coupled inductor array is viewed cross-sectionally in the height direction.
6. The coupled inductor array of claim 1 , the monolithic magnetic core being formed of at least two different magnetic materials.
7. The coupled inductor array of claim 6 , portions of the monolithic magnetic core within the N first and second winding turns being formed of a magnetic material having a greater magnetic permeability than at least some portion of the monolithic magnetic core outside of the N first and second winding turns, as seen when the coupled inductor array is viewed cross-sectionally in the height direction.
8. The coupled inductor array of claim 1 , each of the first and second windings being electrically isolated from each other within the monolithic magnetic core.
9. The coupled inductor array of claim 1 , the one or more magnetic materials forming the monolithic magnetic core comprising powdered magnetic material within a binder.
10. The coupled inductor array of claim 9 , the monolithic magnetic core being a block magnetic core.
11. The coupled inductor array of claim 9 , the monolithic magnetic core comprising a plurality of layers of magnetic film stacked in the height direction.
12. The coupled inductor array of claim 1 , wherein N is greater than two, and the monolithic magnetic core is configured to magnetically couple each of the N first winding turns with each of the N second winding turns.