# US 11,909,258 B2 · Method to detect back-feed and mis-wiring events by a UPS system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,258 B2 - Document ID: US11909258B2 - Status: Granted - Kind: B2 - Application number: 17/655,474 - Filed: 2022-03-18 - Published: 2022-09-22 - Granted: 2024-02-20 - Earliest claimed: 2021-03-22 - Assignees: Schneider Electric It Corporation - Applicants: Schneider Electric It Corporation - Inventors: Kenneth A. Colby, Jr.; Wei-Hsiang Lin; Venkatraman Chennakesavan; Eyob Demissie; Luka Petrovic; Himamshu V Prasad; Yu Zhang - Web page: https://patentgrep.com/patent/US11909258B2 ## CPC - H02J 9/062: {for AC powered loads} - H01H 47/002: {Monitoring or fail-safe circuits} - H02M 5/42: by static converters - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) - 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 Power supplies and methods of use thereof are provided, where a power supply includes an input configured to receive input AC power an output configured to provide output AC power to a load, at least one power converter coupled to the input and configured to convert the input AC power into the output AC power, a controller coupled the at least one power converter. The controller is configured to adjust at least one parameter of the output AC power provided by the at least one power converter, detect, in response to adjusting the at least one parameter of the output AC power, at least one of an adjusted input AC power or an adjusted output AC power, and determine that a fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power. ## Claims ### Claim 1 A power supply comprising: an input configured to receive input AC power; an output configured to provide output AC power to a load; at least one power converter coupled to the input and configured to convert the input AC power into the output AC power; and a controller coupled the at least one power converter, the controller being configured to: adjust at least one parameter of the output AC power provided by the at least one power converter, detect, in response to adjusting the at least one parameter of the output AC power, at least one of an adjusted input AC power or an adjusted output AC power, and determine that a fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power, wherein the fault provides an indication that contacts of at least one relay included in the power supply are welded or shorted together. ### Claim 2 (depends on 1) The power supply of claim 1, wherein adjusting the at least one parameter of the output AC power comprises adding a high frequency component to the output AC power. ### Claim 3 (depends on 2) The power supply of claim 2, wherein determining that the fault has occurred based on the adjusted output AC power comprises determining that the fault has occurred in response to a detection of the high frequency component in the adjusted input AC power. ### Claim 4 (depends on 1) The power supply of claim 1, wherein determining that the fault has occurred includes determining that the fault has occurred based on the adjusted input AC power. ### Claim 5 (depends on 1) The power supply of claim 1, wherein determining that the fault has occurred includes determining that the fault has occurred based on the adjusted output AC power. ### Claim 6 (depends on 1) The power supply of claim 1, wherein adjusting the at least one parameter of the output AC power comprises adjusting a frequency of the output AC power. ### Claim 7 (depends on 6) The power supply of claim 6, wherein adjusting the frequency of the output AC power comprises adjusting the frequency of the output AC power such that the frequency of the adjusted output AC power is different than a frequency of the input AC power. ### Claim 8 (depends on 6) The power supply of claim 6, wherein determining that the fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power comprises determining that the fault has occurred in response to a difference between a frequency of the adjusted input AC power and the frequency of the adjusted output AC power being less than a threshold difference. ### Claim 9 (depends on 8) The power supply of claim 8, wherein determining that the fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power comprises determining that the fault has occurred in response to the difference between the frequency of the adjusted input AC power and the frequency of the adjusted output AC power being less than the threshold difference and a difference between a voltage of the adjusted input AC power and a voltage of the adjusted output AC power being less than a voltage difference threshold. ### Claim 10 (depends on 1) The power supply of claim 1, wherein detecting the at least one of the adjusted input AC power or the adjusted output AC power comprises monitoring a current of the output AC power at the output relative to a nominal current threshold. ### Claim 11 (depends on 10) The power supply of claim 10, wherein determining that the fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power comprises determining that the fault has occurred in response to the current of the adjusted output AC power rising above the nominal current threshold. ### Claim 12 (depends on 10) The power supply of claim 10, wherein determining that the fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power comprises determining that the fault has occurred in response to the current of the adjusted output AC power falling below the nominal current threshold. ### Claim 13 (depends on 1) The power supply of claim 1, wherein detecting the at least one of the adjusted input AC power or the adjusted output AC power comprises monitoring the input AC power at the input. ### Claim 14 (depends on 1) The power supply of claim 1, wherein detecting the at least one of the adjusted input AC power or the adjusted output AC power comprises monitoring the output AC power at the output. ### Claim 15 (depends on 1) The power supply of claim 1, wherein the at least one relay is coupled to the input at a first connection and to the output at a second connection. ### Claim 16 (depends on 1) The power supply of claim 1, wherein adjusting the at least one parameter of the output AC power comprises adjusting a voltage of the output AC power. ### Claim 17 (depends on 16) The power supply of claim 16, wherein adjusting the voltage of the output AC power comprises chopping a portion of the voltage of the output AC power. ### Claim 18 (depends on 1) The power supply of claim 1, wherein adjusting the at least one parameter of the output AC power comprises adjusting a phase of the output AC power. ### Claim 19 A method of operating a power supply including an input configured to receive input AC power, an output configured to provide output AC power to a load, at least one power converter coupled to the input and configured to convert the input AC power into the output AC power, and a controller coupled to the at least one power converter, the method comprising: receiving input AC power at the input; providing, at the output, output AC power to the load; converting, by the at least one power converter, the input AC power into the output AC power coupled to the input; adjusting at least one parameter of the output AC power provided by the at least one power converter; detecting, in response to adjusting the at least one parameter of the output AC power, at least one of an adjusted input AC power or an adjusted output AC power; and determining that a fault has occurred based on the at least one of the adjusted input AC power or the adjusted output AC power, wherein the fault provides an indication that contacts of at least one relay included in the power supply are welded or shorted together. ### Claim 20 (depends on 19) The method of claim 19, wherein adjusting the at least one parameter of the output AC power comprises adding a high frequency component to the output AC power. ### Claim 21 (depends on 19) The method of claim 19, wherein detecting the adjusted input AC power comprises monitoring the input AC power at the input. ### Claim 22 (depends on 19) The method of claim 19, wherein detecting the adjusted output AC power comprises monitoring the output AC power at the output. ### Claim 23 (depends on 19) The method of claim 19, wherein adjusting the at least one parameter of the output AC power comprises adjusting a frequency of the output AC power. ### Claim 24 (depends on 19) The method of claim 19, wherein adjusting the at least one parameter of the output AC power comprises adjusting a phase of the output AC power. ### Claim 25 A non-transitory computer-readable medium storing thereon sequences of computer-executable instructions for operating a power supply, the sequences of computer-executable instructions including instructions that instruct at least one processor to control the power supply to: receive input AC power at an input; provide output AC power to an output; operate at least one power converter to convert the input AC power into the output AC power; adjust at least one parameter of the output AC power provided by the at least one power converter; detect, in response to adjusting the at least one parameter of the output AC power, at least one of an adjusted input AC power or an adjusted output AC power; and determine that a fault has occurred based on at least one of the adjusted input AC power or the adjusted output AC power, wherein the fault provides an indication that contacts of at least one relay included in the power supply are welded or shorted together. ### Claim 26 A power supply comprising: an input configured to receive input AC power; an output configured to provide output AC power to a load; at least one power converter coupled to the input and configured to convert the input AC power into the output AC power; and a controller coupled the at least one power converter, the controller being configured to: detect a change of at least one parameter of the input AC power; detect a change in the output AC power in response to detecting the change of the at least one parameter of the input AC power; and determine that a fault has occurred based on the detection of the change in the output AC power, wherein the fault provides an indication that contacts of at least one relay included in the power supply are welded or shorted together. ### Claim 27 (depends on 26) The power supply of claim 26, wherein detecting the change of the at least one parameter of the input AC power comprises detecting a change in a voltage of the input AC power. ### Claim 28 (depends on 26) The power supply of claim 26, wherein detecting the change in the output AC power comprises detecting a change in a voltage of the output AC power at the output. ### Claim 29 (depends on 26) The power supply of claim 26, wherein detecting the change in the output AC power comprises detecting a change in a current of the output AC power at the output. ### Claim 30 (depends on 26) The power supply of claim 26, wherein detecting the change in the output AC power comprises detecting a change in a frequency of the output AC power.