Cooling magnetic cores with ferrofluid and magnetic cores so cooled
Core-coil devices operate by electromagnetic induction and include inductors, transformers, and electromagnets. Cooled core-coil devices include a magnetic core having a channel through it, and a coil wound around the core. Cooled core-coil devices additionally include a coolant loop that carries ferrofluid coolant through the channel and forms a loop with the channel that extends outside the core. Ferrofluid coolant circulates in the loop without a pump due to a thermo-magnetic response to the device's thermal and magnetic field gradients and thereby cools the core while simultaneously adding to the device's inductance.
1. A core-coil device comprising:
a core having at least one channel passing through it;
an electromagnetic coil wound around at least a portion of the core;
at least one coolant loop passing through the at least one channel, such that the at least one channel forms a portion of the at least one coolant loop; and
a ferrofluid at least partially filling the coolant loop,
wherein the coolant loop is substantially aligned with magnetic flux generated by the core-coil device.
2. The core-coil device as recited in claim 1 , wherein the core comprises a solid magnetic core.
3. The core-coil device as recited in claim 2 , wherein the solid magnetic core comprises a material selected from the group consisting of: iron; and an iron-containing alloy.
4. The core-coil device as recited in claim 2 , wherein the solid magnetic core comprises a “U” core.
5. The core-coil device as recited in claim 1 , further comprising a heat sink positioned to receive heat directly from ferrofluid in the coolant loop.
6. The core-coil device as recited in claim 4 , wherein a portion of the at least one coolant loop exclusive of the coolant channel passes through the heat sink.
7. The core-coil device as recited in claim 1 , further comprising:
a sensor configured to determine a flow rate of ferrofluid coolant at one or more positions in the coolant loop; and
a controller in signal communication with the sensor, and configured to activate a secondary cooling device when the sensor measures a flow rate beyond a threshold.
8. A wireless charging system for an electrified motor vehicle, the system comprising:
a secondary battery configured to provide power to the vehicle powertrain;
a rectifier in electrical communication with the battery; and
an electromagnetic induction receiver in electrical communication with the rectifier and configured to generate an alternating current in response to an oscillating magnetic field, the electromagnetic induction receiver comprising:
a core having at least one channel passing through it;
an electromagnetic coil wound around at least a portion of the core;
at least one coolant loop passing through the at least one channel in the, such that the at least one channel forms a portion of the at least one coolant loop; and
a ferrofluid at least partially filling the coolant loop.
9. The system as recited in claim 8 , wherein the core comprises a solid magnetic core.
10. The system as recited in claim 9 , wherein the solid magnetic core comprises a material selected from the group consisting of: iron; and an iron-containing alloy.
11. The system as recited in claim 9 , wherein the solid magnetic core comprises a “U” core.
12. The system as recited in claim 8 , further comprising a heat sink positioned to receive heat directly from ferrofluid in the coolant loop.
13. The system as recited in claim 12 , wherein a portion of the at least one coolant loop exclusive of the coolant channel passes through the heat sink.
14. A method for cooling a core-coil electromagnetic device, the method comprising:
inducing magnetic flux and temperature field around a core of the core-coil device, thereby inducing flow of a coolant liquid comprising ferrofluid through the core and transferring heat generated by the core-coil electromagnetic device to the coolant fluid;
circulating the coolant liquid, via a response of the ferrofluid to thermal and magnetic field gradients generated by the device, through a coolant loop, thereby removing heat from the coolant fluid;
directing the coolant fluid back to the core of the core-coil electromagnetic device, thereby forming a continuous moving coolant loop,
wherein the ferrofluid is impelled through the coolant loop by a magnetic field generated by the core-coil device, the magnetic field being immobile relative to the coolant loop.
15. The method as recited in claim 14 , comprising:
positioning at least a portion of the coolant loop adjacent to a heat sink.
16. The method as recited in claim 15 , comprising:
transferring heat from the coolant liquid to the heat sink during circulation.
17. The method as recited in claim 16 , wherein the heat sink substantially surrounds an exterior portion of the coolant loop.
18. The method as recited in claim 14 , wherein the core comprises a solid magnetic core.
19. The method as recited in claim 17 wherein the solid magnetic core comprises a material selected from the group consisting of: iron; and an iron-containing alloy.
20. The method as recited in claim 18 , wherein the solid magnetic core comprises a “U” core.