# US 11,909,371 B2 · EMI structure for electronic circuit box > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,371 B2 - Document ID: US11909371B2 - Status: Granted - Kind: B2 - Application number: 17/890,445 - Filed: 2022-08-18 - Published: 2023-03-16 - Granted: 2024-02-20 - Earliest claimed: 2021-09-14 - Assignees: Hamilton Sundstrand Corporation - Applicants: Goodrich Corporation - Inventors: Grzegorz Popek; Stephen Minshull - Web page: https://patentgrep.com/patent/US11909371B2 ## CPC - H03H 7/0138: {Electrical filters or coupling circuits} - H05K 9/0066: {Constructional details of transient suppressor} - B64D 47/00: Equipment not otherwise provided for - H02M 1/44: Circuits or arrangements for compensating for electromagnetic interference in converters or inverters - H03H 7/0115: {comprising only inductors and capacitors (H03H7/075, H03H7/09, H03H7/12, H03H7/13 take precedence)} - H03H 1/0007: {of radio frequency interference filters} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract An EMI filter arrangement includes a noise source, an input filter connected to the input of the noise source, and an output filter connected to the output of the noise source, the noise source, input filter and output filter provided in an electrically conductive electronics box, and an input filter capacitor electrically connecting the input filter to the electrically conductive electronics box and an output filter capacitor electrically connecting the output filter to the electrically conductive electronics box; the arrangement characterised by further comprising an intermediate reference plane provided in the electrically conductive electronics box, and an intermediate capacitor provided in the electrically conductive electronics box electrically connected between the intermediate reference plane and the electrically conductive electronics box, the input filter capacitor and the output filter capacitor being electrically connected to the box via the intermediate reference plane and the intermediate capacitor. ## Claims ### Claim 1 An EMI filter arrangement comprising: a noise source; an input filter connected to the input of the noise source; an output filter connected to the output of the noise source; an electrically conductive electronics box, wherein the noise source, input filter and output filter are in the electrically conductive electronics box; and an input filter capacitor electrically connecting the input filter to the electrically conductive electronics box; an output filter capacitor electrically connecting the output filter to the electrically conductive electronics box; an intermediate reference plane provided in the electrically conductive electronics box; and an intermediate capacitor provided in the electrically conductive electronics box electrically connected between the intermediate reference plane and the electrically conductive electronics box; wherein the input filter capacitor and the output filter capacitor are electrically connected to the electrically conductive electronics box via the intermediate reference plane and the intermediate capacitor such that each of the input and output filter capacitors are connected in series with the intermediate capacitor between their respective one of the input filter and output filter and the electrically conductive electronics box; wherein the electrically conductive electronics box has an input interface and an output interface, wherein an input capacitance seen from the input interface is the total capacitance resulting from the series connected input capacitor and intermediate capacitor and an output capacitance is the total capacitance resulting from the series connected output capacitor and intermediate capacitor. ### Claim 2 (depends on 1) The EMI filter arrangement of claim 1, arranged to be provided in or on an aircraft in conductive connection with an aircraft chassis. ### Claim 3 (depends on 1) The EMI filter arrangement of claim 1, wherein the input interface and/or the output interface are AC or DC interfaces. ### Claim 4 (depends on 1) The EMI filter arrangement of claim 1, wherein the noise source comprises a power converter. ### Claim 5 (depends on 4) The EMI filter arrangement of claim 4, wherein the noise source further includes a power converter input filter and a power converter output filter. ### Claim 6 (depends on 5) The EMI filter arrangement of claim 5, wherein the power converter input filter and the power converter output filter are inductive. ### Claim 7 (depends on 1) The EMI filter arrangement of claim 1, wherein the input filter and the output filter consist of a common mode choke. ### Claim 8 (depends on 1) The EMI filter arrangement of claim 1, further comprising: an intermediate resistor provided in the electrically conductive electronics box electrically connected between the intermediate reference plane and the electrically conductive electronics box in parallel with the intermediate capacitor. ### Claim 9 (depends on 1) The EMI filter arrangement of claim 1, wherein the electrically conductive electronics box is connected to a chassis via an electrical bond.