# US 11,077,514 B2 · Systems and methods to reduce magnetic flux in a transformer in a switched mode power supply > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,077,514 B2 - Document ID: US11077514B2 - Status: Granted - Kind: B2 - Application number: 15/786,013 - Filed: 2017-10-17 - Published: 2019-04-18 - Granted: 2021-08-03 - Earliest claimed: 2017-10-17 - Assignees: Illinois Tool Works Inc. - Applicants: Illinois Tool Works Inc. - Inventors: Adam E. Anders; Brian Schwartz; Andrew D. Nelson; Bernard J. Vogel - Web page: https://patentgrep.com/patent/US11077514B2 ## CPC - B23K 9/1006: {Power supply} - B23K 9/1056: {by using digital means (B23K9/1068 takes precedence)} - B23K 11/25: Monitoring devices - H02M 1/10: Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from AC or DC - H02M 1/40: Means for preventing magnetic saturation - H02M 3/285: {Single converters with a plurality of output stages connected in parallel (parallel operation of a plurality of converters in DC distribution networks H02J1/10)} - H02M 3/33571: {Half-bridge at primary side of an isolation transformer} - H02M 3/33573: {Full-bridge at primary side of an isolation transformer} - H02M 1/007: {Plural converter units in cascade (push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826)} - H02M 1/0074: {Plural converter units whose inputs are connected in series} - H02M 1/0077: {Plural converter units whose outputs are connected in series} - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - 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 Systems and methods to reduce magnetic flux in a switched mode power supply are disclosed. An example welding-type power supply includes a switched mode power supply, including a transformer configured to transform an input voltage to a welding-type voltage; switches configured to control a voltage applied to the primary winding of the transformer; a current detector configured to measure a current through the primary winding; a flux accumulator configured to determine a net flux in the transformer based on a number of volt-seconds applied to the primary winding of the transformer; and a controller configured to: control duty cycles of the switches based on the net flux; and set a value of the net flux in response to the current through the primary winding satisfying a current threshold. ## Claims ### Claim 1 A welding-type power supply, comprising: a switched mode power supply, including a transformer configured to transform an input voltage to a welding-type voltage; switches configured to control a voltage applied to the primary winding of the transformer; a current detector configured to measure a current through the primary winding; a flux accumulator configured to determine a net flux in the transformer based on a number of volt-seconds applied to the primary winding of the transformer; and a controller configured to: control duty cycles of the switches based on the net flux; receive a signal representative of the current through the primary winding measured by the current detector; and set a value of the net flux to a predetermined net flux value in response to the current through the primary winding satisfying a current threshold, wherein the current threshold is at least one of a positive threshold current or a negative threshold current. ### Claim 2 (depends on 1) The welding-type power supply as defined in claim 1, wherein the current threshold is the positive threshold current. ### Claim 3 (depends on 2) The welding-type power supply as defined in claim 2, wherein the controller is configured to set the value of the net flux to a positive flux saturation value of the transformer in response to the current through the primary winding satisfying the positive threshold current. ### Claim 4 (depends on 1) The welding-type power supply as defined in claim 1, wherein the current threshold is a negative threshold current. ### Claim 5 (depends on 1) The welding-type power supply as defined in claim 1, wherein the current detector comprises at least one of a current transformer, a Hall effect sensor, a sense resistor, or a magnetoresistive current sensor. ### Claim 6 (depends on 1) The welding-type power supply as defined in claim 1, wherein the controller is configured to control duty cycles of the switches to reduce the value of the net flux from a saturation value while continuing to generate an output from the welding-type power supply. ### Claim 7 (depends on 1) The welding-type power supply as defined in claim 1, wherein the controller is configured to count a number of occurrences of the current through the primary winding satisfying the current threshold and, in response to the number of occurrences satisfying a threshold number, control the switched mode power supply or the switches to stop a current output. ### Claim 8 (depends on 1) The welding-type power supply as defined in claim 1, wherein the controller is configured to count a number of occurrences of the current through the primary winding satisfying the current threshold and, in response to the number of occurrences satisfying a threshold number, control the switches to change a welding parameter. ### Claim 9 (depends on 1) The welding-type power supply as defined in claim 1, wherein the controller is configured to count a number of occurrences of the current through the primary winding satisfying the current threshold and, in response to the number of occurrences satisfying a threshold number, change at least one component of a control loop. ### Claim 10 A welding-type power supply, comprising: a switched mode power supply, including a transformer configured to transform an input voltage to a welding-type voltage; switches configured to control a voltage applied to the primary winding of the transformer; a current detector configured to measure a current through the primary winding; a flux accumulator configured to determine a net flux in the transformer based on a number of volt-seconds applied to the primary winding of the transformer; and a controller configured to: control duty cycles of the switches based on the net flux; receive a signal representative of the current through the primary winding measured by the current detector; determine whether the current through the primary winding satisfies a current threshold, the current threshold comprising at least one of a positive threshold current or a negative threshold current; and set a value of the net flux in response to the current through the primary winding satisfying the current threshold, wherein the controller is configured to at least one of set the value of the net flux to a positive flux saturation value of the transformer in response to the current through the primary winding satisfying the positive threshold current or set the value of the net flux to a negative flux saturation value of the transformer in response to the current through the primary winding satisfying the negative threshold current. ### Claim 11 A method to control a welding-type power supply, comprising: transforming an input voltage to a welding-type voltage via a transformer having a primary winding and a secondary winding; controlling switches to control a voltage applied to the primary winding of the transformer; determining a net flux in a primary winding of a transformer of a switched mode power supply based on a number of volt-seconds applied to the primary winding of the transformer; measuring a current through the primary winding using a current detector; and in response to the current through the primary winding measured by the current detector satisfying a current threshold, setting a value of the net flux to indicate magnetic saturation of the transformer, wherein the current threshold is at least one of a positive threshold current or a negative threshold current. ### Claim 12 (depends on 11) The method as defined in claim 11, further comprising comparing the current to the positive threshold current corresponding to a positive saturation flux in the transformer. ### Claim 13 (depends on 12) The method as defined in claim 12, wherein the setting of the value of the net flux comprises setting the value of the net flux to a positive flux saturation value of the transformer in response to the current satisfying the positive threshold current. ### Claim 14 (depends on 11) The method as defined in claim 11, further comprising comparing the current to the negative threshold current corresponding to a negative saturation flux in the transformer. ### Claim 15 (depends on 14) The method as defined in claim 14, wherein the setting of the value of the net flux comprises setting the value of the net flux to a negative flux saturation value of the transformer in response to the current satisfying the negative threshold current. ### Claim 16 (depends on 11) The method as defined in claim 11, further comprising controlling duty cycles of a plurality of switches of the switched mode power supply based on the net flux, the duty cycles of the switches controlling a voltage applied to the primary winding of the transformer. ### Claim 17 (depends on 11) The method as defined in claim 11, further comprising controlling duty cycles of the plurality of switches of the switched mode power supply to reduce the value of the net flux from a saturation value while continuing to generate an output from the welding-type power supply. ### Claim 18 (depends on 11) The method as defined in claim 11, further comprising: counting a number of occurrences of the current through the primary winding satisfying the current threshold; and in response to the number of occurrences satisfying a threshold number, controlling the switched mode power supply to stop a current output. ### Claim 19 (depends on 11) The method as defined in claim 11, further comprising: counting a number of occurrences of the current through the primary winding satisfying the current threshold; and controlling the switched mode power supply to change a welding parameter in response to the number of occurrences satisfying a threshold number. ### Claim 20 (depends on 11) The method as defined in claim 11, further comprising: counting a number of occurrences of the current through the primary winding satisfying the current threshold; and changing at least one component of a control loop in response to the number of occurrences satisfying a threshold number.