Patent Application
20170208705
This application relates to immersion cooling of power electronic circuits.
Modern systems are becoming more and more complex and, as a result, complex electrical controls are provided for many such systems. One example system would be aerospace equipment, such as an aircraft.
Control modules for such system often include a motherboard and a plurality of line removable modules (“LRMs”) or other circuit boards. One particular type of LRM carries a number of power transistors forming solid state power controllers (“SSPC”). Power transistors have unique cooling challenges.
One known type of power transistors is a metal oxide field effect transistor (“MOSFET”). Although MOSFETs are mentioned, other types of solid state power controllers also raise similar challenges.
Modern control modules may include a very high number of such transistors and electronic controls. The heat generated by these transistors raises challenges with cooling.
Solid state power controllers are subject to transient heat loss due to a number of reasons, including load in-rush currents, fly back when inductive load currents are braked, lightning strikes, overcurrent faults that must be carried for a short period of time prior to turning the SSPC off, etc.
In general, fluid immersion cooling for control circuits have surrounded the entire control module. This raises challenges, as a designer of modern control modules would like to be able to tailor a particular combination of motherboard and circuit boards. Further, when the entire control module is surrounded by cooling fluid, it is difficult to replace any one LRM. Fluid cooling circuits typically include a hermetic seal and, thus, are not prone to easy repair.
A cooling arrangement has a circuit board and a plurality of electronic components in operable communication with the circuit board. An enclosure is attached to the circuit board being configured to retain a fluid around at least one of the plurality of electronic components. The circuit board with the enclosure is attached thereto being removably connectable to a motherboard.
These and other features may be best understood from the following drawings and specification.
As mentioned above, it would be desirable to be able to freely replace the circuit boards 24 on the motherboard 22 to achieve tailored control features for a particular system. Also, some replacement may be required for maintenance purposes. In addition, it is desirable to provide cooling for elements on the circuit boards 24. This becomes particularly valuable if the circuit boards are power distribution circuits carrying power transistors.
As mentioned above, much of the heat generated by the transistor 32 may be transient. As the fluid absorbs this heat, the fluid expands such that the pressure within the chamber 34 rises. Pressure relief valve 36 may allow fluid to then flow outward of the enclosure. A holding container 38 is shown schematically along with a return inlet 40. Once the fluid within chamber 34 cools, the fluid may return from holding chamber 38 into inlet 40. In this manner, the enclosure 30 facilitates handling an expanding fluid. In some embodiments the fluid may boil as result of absorbing the heat, increasing the pressure and assisting heat transfer.
As an alternative, the pressure relief valve may simply vent the fluid to the environment.
Another embodiment 230 is shown in
Notably, the
As shown in each of
With these embodiments, individual line removable modules 24 may be removed from a control module 20 without the complexity of removing the cooling liquid from the enclosure. Also, with these embodiments, individual transistors or groups of transistors, and the associated enclosures, may be removed from the circuit board 24 for replacement or repair.
The enclosed circuit board 300 is illustrated in
In sum, a control module 20, 310 has a motherboard 22 and a plurality of removable circuit boards 24/124/300. At least one of the circuit boards is provided with immersion cooling of an electronic component surrounded by an enclosure that does not enclose others of the plurality of circuit boards.
In embodiments, a circuit board 24/300 has a plurality of electronic components, with an immersion cooling fluid within an enclosure 30/302, such that the circuit board and enclosure can be removed or inserted as a unit into a motherboard without releasing the fluid from the enclosure.
Providing the enclosed cooling facilitates the specific tailoring of the circuit boards 24 or 300. Further, this arrangement facilitates the replacement or repair of individual line removable modules or circuits.
The assembly can facilitate the tailoring of a combination of boards. Typically, a system would have a number of different module/board types such as a power supply, microprocessor, discrete I/O communications, and SSPC modules. As different customers have different numbers and types of loads to be controlled, a mix of modules can be tailored to particular needs. For example, one customer may need several low current DC SSPCs while another might need a mix of AC and DC of various load currents.
It is desirable to be able to have high loss boards (high current especially AC) be specially cooled while the rest of the system be traditional boards. This disclosure achieves such a goal.
Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
