Patent Publication Number: US-10782755-B2

Title: System and method for creating high powered EMC compliant power supply for industrial and military applications

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to computers and electronic equipment, and more particularly relates to industrial and military computers, and even more particularly relates to methods and systems for providing electromagnetic compatible (EMC) power supply units for industrial and military computer systems and electronic equipment. 
     BACKGROUND OF THE INVENTION 
     In recent years, industrial and military computers have become increasingly prevalent in many industries. It is not uncommon today to see rows of high performance computers, or servers, arranged in racks or specialized computers in mining or sensitive deployed military application. These computers, as well as other electronic devices and their peripherals, increasingly need more and more power. With increased power, typically comes an increase in electrical noise, which has an undesirable impact on the operation of equipment within the area. These pieces of equipment are typically sensitive to electromagnetic radiation. The levels being discussed here are well below the conventional concerns typically dealt with by compliance to UL, FCC, TUV, CE and CSA EMC standards. The need for complying with the lower levels are entirely due to the application the computers are being used. While many of these industrial and military power supplies are often designed and manufactured to higher standards than typical power supplies for consumer electronics and computers, they still are occasionally insufficient to meet the even higher military and commercial aviation standards such as MIL-STD-461 and DO-160. MIL-STD-461 is a United States Military Standard that describes, among other things, how to test equipment for electromagnetic compatibility. DO-160, Environmental Conditions and Test Procedures for Airborne Equipment, is a standard for environmental tests of avionics hardware published by RTCA, Incorporated. Both of these documents are used to help power supply designers create EMC compliant products. 
     It is also common for computer power supplies to meet the Advanced Technology eXtended (ATX) specification for motherboards and associated power supplies. 
     However, the increasing power needs and the physical size and volume limitations of the industrial standard form factor has posed a formidable challenge for high power (greater than 300 Watts) 18-36 volt or higher power supplies which meet both the MIL-STD-461 and the DO-160, while still meeting the ATX industry specification, as one example. Solving this problem in a unique way has created a broader application of a method to create compact EMC compliant power sources for these industries. Minimizing the conducted and radiated susceptibility paths from the rear connector of the power source to the filter mechanism, typically a common mode or differential mode choke, can provide the greatest EMC benefit in a power supply front end filter system. 
     Consequently, there exists a need for improved methods and systems for connecting the connector to the primary EMI filter in a system. This problem has prevented the industry from supplying a minimum of 300 watts at a minimum of 18 Volts, power from within an industry standard form factor, such as a 1U ATX, while simultaneously meeting the ATX specification and both the MIL-STD-461 and the DO-160 specifications, all done in a reliable and cost efficient manner. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a system and method for supplying power from a military circular connector to the primary filter of a power supply in such a way as to reliably and easily meet MIL-STD-461 and the DO-160 test criteria in an efficient manner. 
     It is a feature of the present invention to utilize a military pin and socket connector on a case of a military or industrial power supply. 
     It is another feature of the present invention to include a minimum power output capacity of 300 Watts. 
     It is yet another feature of the present invention to have a ferrite bead disposed adjacent the power provisioning outlet conductor. 
     It is still another feature to have a capacitive circuit board disposed immediately adjacent to said ferrite bead and the military pin and socket connector. 
     It is an advantage of the present invention to provide a compact power supply with greater than 300 watts, which meets military and commercial aviation standards. 
     It is still an advantage to create a power supply meeting these criteria in an industry standard ATX form factor. 
     The present invention is an apparatus and method for provisioning a compact power filter connection to a well grounded connector in such a way as to include a capacitive and inductive circuit connection, extremely near the connector and filter, such that EMC compatibility is created in a space roughly 30% of traditional mechanisms, and design approach to satisfy the aforementioned needs, provide the previously stated objects, include the above-listed features, and achieve the already articulated advantages. The present invention is carried out in a “post-internal ferrite bead re-radiation noise-less” manner in a sense that ability to have noise introduced back onto a post-ferrite bead line, has been greatly reduced. 
     Accordingly, the present invention is a system comprising a case, configured with shielding, to reduce EMI emissions therefrom; 
     power supply circuitry disposed in said case and configured to deliver power; 
     an output connector with a low inductance path from said capacitive circuit board to said case; 
     with a shell portion which is grounded to said case; 
     a power provisioning line coupled to said circuitry and providing power to said output connector; 
     a capacitive circuit board coupled directly to said output connector and said power provisioning line; 
     a ferrite bead disposed about a terminal portion of said power provisioning line; and 
     a low inductance path from said capacitive circuit board to said case. 
     A compact and efficient method of minimizing the exposed unfiltered power to the majority of the power supply components by creating a circuit card juxtaposed to the connector, containing capacitive, inductive, and resistive elements in conjunction with one or several juxtaposed ferrite beads which create a pre-filter system in a fraction of the space, which provides superior EMI characteristics compliant with MIL-STD 461 and DO-160. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be more fully understood by reading the following description of the preferred embodiments of the invention, in conjunction with the appended drawings wherein: 
         FIG. 1  is a perspective view of a prior art rack-mounted industrial computer system. 
         FIG. 2  is a simplified perspective view of a 1U system of the present invention. 
         FIG. 3  is a perspective view of a portion of the 1U system of  FIG. 2 . 
         FIG. 4  is a perspective view of a portion of the system of the present invention. 
         FIG. 5  is a perspective view of a portion of the system of the present invention, which is looking in an opposing direction from  FIG. 4 . 
         FIG. 6  is a perspective view of the present invention, which is looking in an opposing direction from  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     Now referring to the drawings wherein like numerals refer to like matter throughout, and more specifically referring to  FIG. 1 , there is shown a system of the prior art, generally designated  100 , including a first rack  102  of industrial power supplies, industrial personal computers and associated hardware and accessories, and a second rack  104  of similar items, with an aisle  106  disposed there between. First rack  102  is representative of second rack  104  and is shown in detail to include a plurality of columns of industrial electronic components  110 . A large industrial computing component  112  is shown disposed in first rack of industrial personal computers  102 . A 1U-sized industrial electronic component  114  is shown disposed at an intermediate height of first rack  102 . A technician may walk in the aisle  106  between first rack  102  and second rack  104  for various reasons, including installation or repair of components, monitoring or data entry into computers in first rack  102 , etc. 
     Now referring to  FIG. 2 , there is shown a system of the present invention, including a 1U industrial ATX power supply generally designated  200 , which is sized and configured for insertion into a 1U receiving bay  120 . The term “1U” is well known in the art to describe a form factor which is approximately 1% inches in height. 
     Throughout this description, the terms “industrial computer” or “industrial computer power supply” are used to represent electronic components of the type which is capable of being stored in racks of multiple rows, where each row has 1U units and where the units are coupled to wiring associated with the rack and other equipment by at least one connector. 
     Referring to  FIG. 2 , there is further shown a top cover  202  and a bottom 1U body  204 , a military pin and socket connector  206  which is mounted on an end of 1U system  200  between ventilation areas  208  and  210 . Connector  206  is coupled to ventilation areas  208  and  210  via screw holes  222  and  220 , respectively. NOTE: Screws are shown disposed in said screw holes. A body end top portion  230  is shown as well. Inside body  204 , there are also shown power connectors  212  and  214 . Connector  206  is grounded to 1U body  204  in 360 degrees of longitudinal orientation (as referenced to the pin orientation in the connector  206 ). 
     Now referring to  FIG. 3 , there is shown a single ferrite bead  300 , which may be a multi-aperture Balun type ferrite core. 
     Now referring to  FIG. 4 , there is shown a close up view of the connector  206  being mounted directly at connection  406  to a circuit board  400  on a connector facing side  402 , which is opposite an internal facing side  404 . An inductance path to chassis ground is made with the circuit board  400  via connection  406 . 
     Now referring to  FIG. 5 , there is shown a view of the connector  206  and circuit board  400  of  FIG. 4  being viewed from an opposing direction. Internal facing side  404  is visible while the opposite side, the connector facing side  402 , is concealed. Five circular solder tail connectors  504  are shown extending through circuit board  400  and inwardly to the 1U body, and a plurality of capacitors  502  are shown disposed on circuit board  400 . It should be noted that only four wires are coupled to these connectors  504 , with the remaining connector being a connection to ground with no wire attached. Portions of the ground connector  504  are not required for operation. 
     Now referring to  FIG. 6 , there is shown more detail of the internal facing side  404  of the circuit board  400 . The single bead  300  comprises a plurality of Balun type ferrite cores  602  and  604 . Apertures  612  and  622 , together with apertures  614  and  624 , are shown in ferrite cores  602  and  604 , respectively. The apertures  612 ,  622 ,  614  and  624  are sized and configured to receive circular solder tail connectors  504  therein so as to minimize the ability of these connectors to act as antennas.  FIG. 6  shows the connectors  504  outside of the apertures. Also shown is an extremely low inductance path  630  to the chassis ground. 
     Throughout this description, reference is made to an industrial PC and to a printed circuit board, because it is believed that the beneficial aspects of the present invention would be most readily apparent when used in connection with industrial PCs and printed circuit boards; however, it should be understood that the present invention is not intended to be limited to industrial PCs and printed circuit boards and should be hereby construed to include other non-industrial PCs and non-printed circuit boards as well. 
     It is thought that the method and apparatus of the present invention will be understood from the foregoing description and that it will be apparent that various changes may be made in the form, construct steps, and arrangement of the parts and steps thereof, without departing from the spirit and scope of the invention or sacrificing all of their material advantages. The form herein described is merely a preferred exemplary embodiment thereof.