# US 12,009,671 B2 · System and method for ground fault monitoring in an aircraft > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,671 B2 - Document ID: US12009671B2 - Status: Granted - Kind: B2 - Application number: 17/674,669 - Filed: 2022-02-17 - Published: 2023-08-17 - Granted: 2024-06-11 - Earliest claimed: 2022-02-17 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Frederic Lacaux; Shengyi Liu; Eugene V. Solodovnik; Vyacheslav Khozikov; Kamiar J. Karimi - Web page: https://patentgrep.com/patent/US12009671B2 ## CPC - H02J 4/00: Circuit arrangements for mains or distribution networks not specified as AC or DC; Circuit arrangements for mains or distribution networks combining AC and DC sections or sub-networks (arrangements using intermediate DC-AC-DC conversion H02J1/002; arrangements using high-voltage DC [HVDC] links H02J3/36) - B60L 3/0061: {relating to electrical machines} - B60L 3/0069: {relating to the isolation, e.g. ground fault or leak current} - B60L 15/007: {Physical arrangements or structures of drive train converters specially adapted for the propulsion motors of electric vehicles} - B60L 50/51: characterised by AC-motors - H02H 3/165: {for three-phase systems} - H02H 3/32: involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors - H02H 7/0838: {with H-bridge circuit} - H02H 7/1257: {responsive to short circuit or wrong polarity in output circuit} - B60L 2200/10: Air crafts - B60L 2210/30: AC to DC converters - B60L 2210/40: DC to AC converters - B60L 2210/42: Voltage source inverters - B60L 2240/429: Current - B60L 2240/529: Current - B64D 2045/0085: {Devices for aircraft health monitoring, e.g. monitoring flutter or vibration} - B64D 2221/00: Electric power distribution systems onboard aircraft - H02J 2105/32: {for aircrafts} - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT ## Abstract An electrical system for an aircraft includes an AC electric power source electrically connected to a rotary electric motor via a plurality of AC contactors. An AC/DC inverter is electrically connected to the rotary electric motor, a DC power bus is electrically connected to the AC/DC inverter, and a plurality of sensors are arranged to monitor electric currents between the AC electric power source and the rotary electric motor. A first controller is arranged to control the AC/DC inverter; and a second controller is arranged to monitor the sensors and are operatively connected to the AC contactors. The second controller is operable to monitor, via the sensors, the electric currents between the AC electric power source and the rotary electric motor, and detect a fault based upon the electric currents, and deactivate the AC contactors in response to the fault. ## Claims ### Claim 1 An electrical system for an aircraft, comprising: a polyphase AC electric power source electrically connected to a polyphase rotary electric motor via a plurality of AC contactors; an AC/DC inverter electrically connected to the polyphase rotary electric motor; a DC power bus electrically connected to the AC/DC inverter; a plurality of sensors arranged to monitor a plurality of electric currents between the polyphase AC electric power source and the polyphase rotary electric motor; a first controller arranged to control the AC/DC inverter; and a second controller arranged to monitor the plurality of sensors and operatively connected to the plurality of AC contactors; wherein the second controller is operable to: monitor, via the plurality of sensors, the plurality of electric currents between the polyphase AC electric power source and the polyphase rotary electric motor; detect a fault based upon the plurality of electric currents; and deactivate the plurality of AC contactors in response to the fault. ### Claim 2 (depends on 1) The electrical system of claim 1, wherein the AC/DC inverter includes a plurality of upper switches that are arranged in series with a plurality of lower switches between a positive side of the DC power bus and a negative side of the DC power bus; wherein the second controller is configured to communicate the fault to the first controller; wherein the first controller is configured to open the plurality of upper switches and close the plurality of lower switches in response to the fault; and wherein the second controller is configured to deactivate the plurality of AC contactors when the first controller opens the plurality of upper switches and closes the plurality of lower switches. ### Claim 3 (depends on 1) The electrical system of claim 1, wherein the second controller being operable to detect the fault based upon the plurality of electric currents comprises the second controller being operable to detect an asymmetry between the plurality of electric currents. ### Claim 4 (depends on 1) The electrical system of claim 1, wherein the second controller being operable to detect the fault based upon the plurality of electric currents comprises the second controller being operable to detect a ground fault in the DC power bus based upon the plurality of electric currents. ### Claim 5 (depends on 1) The electrical system of claim 1: wherein the AC/DC inverter is electrically connected to a plurality of 3-phase windings arranged on a stator of the polyphase rotary electric motor; wherein each of the plurality of 3-phase windings is electrically connected to a respective neutral lead; and wherein the respective neutral lead is connected to one of the phases of the polyphase AC electric power source via one of the plurality of AC contactors. ### Claim 6 (depends on 1) The electrical system of claim 1, wherein each of the plurality of AC contactors comprises a switch. ### Claim 7 (depends on 1) The electrical system of claim 1, wherein the DC power bus is electrically connected to a DC power device, and wherein the first controller is operable to deactivate the AC/DC inverter to deactivate the DC power device in response to the fault. ### Claim 8 (depends on 7) The electrical system of claim 7, wherein the DC power device comprises a DC-powered actuator. ### Claim 9 (depends on 7) The electrical system of claim 7, wherein the DC power device comprises a rechargeable electrical energy storage device. ### Claim 10 (depends on 1) The electrical system of claim 1, wherein the second controller is operable to open the plurality of AC contactors to deactivate the polyphase rotary electric motor in response to the fault. ### Claim 11 A ground fault monitoring system for an aircraft, comprising: a polyphase AC electric power source electrically connected to a polyphase rotary electric motor via a plurality of AC contactors; an AC/DC inverter electrically connected to the polyphase rotary electric motor; a DC power bus electrically connected to the AC/DC inverter; a plurality of sensors arranged to monitor a plurality of electric currents between the polyphase AC electric power source and the polyphase rotary electric motor; a first controller arranged to control the AC/DC inverter; and a second controller arranged to monitor the plurality of sensors and operatively connected to the plurality of AC contactors; wherein the second controller is operable to: monitor, via the plurality of sensors, the plurality of electric currents between the polyphase AC electric power source and the polyphase rotary electric motor, detect a ground fault based upon the plurality of electric currents, and deactivate the plurality of AC contactors in response to the ground fault. ### Claim 12 (depends on 11) The ground fault monitoring system of claim 11, wherein the AC/DC inverter includes a plurality of upper switches that are arranged in series with a plurality of lower switches between a positive side of the DC power bus and a negative side of the DC power bus; wherein the second controller is configured to communicate the ground fault to the first controller; wherein the first controller is configured to open the plurality of upper switches and close the plurality of lower switches in response to the ground fault; and wherein the second controller is configured to deactivate the plurality of AC contactors when the first controller opens the plurality of upper switches and closes the plurality of lower switches. ### Claim 13 (depends on 11) The ground fault monitoring system of claim 11, wherein the second controller being operable to detect the ground fault based upon the plurality of electric currents comprises the second controller being operable to detect an imbalance between the plurality of electric currents. ### Claim 14 (depends on 11) The ground fault monitoring system of claim 11: wherein the AC/DC inverter is electrically connected to a plurality of 3-phase windings arranged on a stator of the polyphase rotary electric motor; wherein each of the plurality of 3-phase windings is electrically connected to a respective neutral lead; and wherein the respective neutral lead is connected to one of the phases of the polyphase AC electric power source via one of the plurality of AC contactors. ### Claim 15 (depends on 11) The ground fault monitoring system of claim 11, wherein each of the plurality of AC contactors comprises a switch. ### Claim 16 (depends on 11) The ground fault monitoring system of claim 11, wherein the DC power bus is electrically connected to a DC power device, and wherein the first controller is operable to deactivate the AC/DC inverter to deactivate the DC power device in response to the ground fault. ### Claim 17 (depends on 16) The ground fault monitoring system of claim 16, wherein the DC power device comprises one of a DC-powered actuator or a rechargeable electrical energy storage device. ### Claim 18 (depends on 11) The ground fault monitoring system of claim 11, wherein the second controller is operable to open the plurality of AC contactors to deactivate the polyphase rotary electric motor in response to the ground fault. ### Claim 19 A method for controlling an electrical system for an aircraft that includes a polyphase AC electric power source electrically connected to a polyphase rotary electric motor via a plurality of AC contactors, an AC/DC inverter electrically connected to the polyphase rotary electric motor, a first controller operably connected to the AC/DC inverter, and a DC power bus electrically connected to the AC/DC inverter, the method comprising: monitoring, via a plurality of sensors, a plurality of electric currents between the polyphase AC electric power source and the polyphase rotary electric motor; detecting, via a second controller in communication with the plurality of sensors, a fault based upon the plurality of electric currents; and deactivating, via the second controller, the plurality of AC contactors in response to the fault. ### Claim 20 (depends on 19) The method of claim 19, wherein the AC/DC inverter includes a plurality of upper switches that are arranged in series with a plurality of lower switches between a positive side of the DC power bus and a negative side of the DC power bus; the method further comprising: communicating, via the second controller, the fault to the first controller; controlling, via the first controller, the plurality of upper switches to an open state and controlling the plurality of lower switches to a closed state in response to the fault; and deactivating, via the second controller, the plurality of AC contactors.