# US 12,015,356 B2 · Method and apparatus for absorption of high energy load feedback in degaussing applications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,015,356 B2 - Document ID: US12015356B2 - Status: Granted - Kind: B2 - Application number: 17/466,598 - Filed: 2021-09-03 - Published: 2023-03-09 - Granted: 2024-06-18 - Earliest claimed: 2021-09-03 - Assignees: L3Harris Technologies, Inc. - Applicants: L3Harris Technologies, Inc. - Inventors: Constantin Stancu; Joaquin Gabriels - Web page: https://patentgrep.com/patent/US12015356B2 ## CPC - H02M 7/5387: in a bridge configuration - H02M 1/088: for the simultaneous control of series or parallel connected semiconductor devices - H02M 1/32: Means for protecting converters other than automatic disconnection - H02M 1/36: Means for starting or stopping converters - H02M 3/1555: {for the generation of a regulated current to a load whose impedance is substantially inductive} - H02M 7/53871: {with automatic control of output voltage or current} - 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 apparatus includes a power converter having switches coupled to input voltage rails and to opposing terminals of a coil to be energized. The switches are configured to be turned ON or OFF to conduct or block current, respectively, responsive to switch control signals. The apparatus also includes a controller to generate the switch control signals to compel the power converter to selectively operate (i) in a normal mode in which the switches are periodically turned ON and OFF to supply current from the input voltage rails to the coil to energize the coil, and (ii) in a protection mode in which first switches are continuously turned ON, and second switches are continuously turned OFF, to interrupt the current, and to circulate an initial current, flowing in the coil when the protection mode is entered, through the power converter and the coil so that the initial current decays toward zero. ## Claims ### Claim 1 An apparatus comprising: a power converter having multiple switches coupled to input voltage rails and to opposing terminals of a coil to be energized, the multiple switches configured to be turned ON or OFF to conduct or block a current, respectively, responsive to switch control signals, wherein the coil includes a degaussing coil to generate a degaussing field responsive to the current; and a controller to receive a fault command that indicates a failure condition or a power-down condition upon occurrence of the failure condition or the power-down condition, and to generate the switch control signals responsive in part to the fault command to compel the power converter to selectively operate: when the fault command is not received, in a normal mode in which the multiple switches are periodically turned ON and OFF to supply the current from the input voltage rails to the coil to energize the coil; and when the fault command is received, in a protection mode in which first switches of the multiple switches are continuously turned ON, and second switches of the multiple switches are continuously turned OFF, to interrupt the current from the input voltage rails, and to circulate an initial current, flowing in the coil when the protection mode is entered responsive to the fault command, through the power converter and the coil to cause the initial current to decay toward zero. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the power converter includes an H-bridge converter, and wherein: in the normal mode, first diagonal switches and second diagonal switches of the multiple switches are periodically turned ON and OFF in a complementary fashion to supply the current from the input voltage rails to alternating ones of the opposing terminals of the coil; and in the protection mode, one of an upper set of switches and a lower set of switches of the multiple switches are continuously turned ON, and an alternate one of the upper set of switches and the lower set of switches are continuously turned OFF, to interrupt the current, and to circulate the initial current through the H-bridge converter and the coil. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein, in the protection mode, the one of the upper set of switches and the lower set of switches that are continuously turned ON short-circuit the opposing terminals of the coil to a first voltage rail of the input voltage rails. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein, in the protection mode, the alternate one of the upper set of switches and the lower set of switches that are continuously turned OFF disconnect the opposing terminals of the coil from a second voltage rail of the input voltage rails. ### Claim 5 (depends on 2) The apparatus of claim 2, wherein: the upper set of switches have respective inputs coupled to a first voltage rail of the input voltage rails and respective outputs coupled to the opposing terminals of the coil; and the lower set of switches have respective inputs coupled to the opposing terminals of the coil and respective outputs coupled to a second voltage rail of the input voltage rails. ### Claim 6 (depends on 2) The apparatus of claim 2, wherein, in the protection mode, the upper set of switches are continuously turned ON and the lower set of switches are continuously turned OFF. ### Claim 7 (depends on 2) The apparatus of claim 2, wherein, in the protection mode, the upper set of switches are continuously turned OFF and the lower set of switches are continuously turned ON. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the multiple switches include switch transistors respectively having control terminals to receive the switch control signals and current paths configured to be turned ON or OFF responsive to the switch control signals. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein the switch transistors include field effect transistors (FETs) or bipolar transistors. ### Claim 10 (depends on 8) The apparatus of claim 8, wherein the switch transistors are configured with corresponding internal diodes connected in parallel with corresponding ones of the current paths such that the initial current flows through the corresponding internal diodes or the current paths when the initial current circulates in a first direction or a second direction that is opposite to the first direction, respectively. ### Claim 11 (depends on 1) The apparatus of claim 1, further comprising one or more snubber circuits that are connected to the input voltage rails and a snubber circuit that is connected to the coil. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the current decays toward zero without employing additional circuit components external to the power converter. ### Claim 13 A method comprising: providing a power converter having multiple switches coupled to input voltage rails and to opposing terminals of a coil to be energized, the multiple switches configured to be turned ON or OFF to conduct or block a current, respectively, responsive to switch control signals, wherein the coil includes a degaussing coil to generate a degaussing field responsive to the current; and by a controller, receiving a fault command that indicates a failure condition or a power-down condition upon occurrence of the failure condition or the power-down condition, and generating the switch control signals responsive in part to the fault command to compel the power converter to perform: when the fault command is not received, operating in a normal mode in which the multiple switches are periodically turned ON and OFF to supply the current from the input voltage rails to the coil to energize the coil; and when the fault command is received, operating in a protection mode in which first switches of the multiple switches are continuously turned ON, and second switches of the multiple switches are continuously turned OFF, to interrupt the current from the input voltage rails, and to circulate an initial current, flowing in the coil when the protection mode is entered responsive to the fault command, through the power converter and the coil to cause the initial current to decay toward zero. ### Claim 14 (depends on 13) The method of claim 13, wherein the power converter includes an H-bridge converter, and wherein: in the normal mode, first diagonal switches and second diagonal switches of the multiple switches are periodically turned ON and OFF in a complementary fashion to supply the current from the input voltage rails to alternating ones of the opposing terminals of the coil; and in the protection mode, one of an upper set of switches and a lower set of switches of the multiple switches are continuously turned ON, and an alternate one of the upper set of switches and the lower set of switches are continuously turned OFF, to interrupt the current from the input voltage rails to the coil, and to circulate the initial current through the H-bridge converter and the coil. ### Claim 15 (depends on 14) The method of claim 14, wherein, when operating in the protection mode, the one of the upper set of switches and the lower set of switches that are continuously turned ON short-circuit the opposing terminals of the coil to a first voltage rail of the input voltage rails. ### Claim 16 (depends on 15) The method of claim 15, wherein, when operating in the protection mode, the alternate one of the upper set of switches and the lower set of switches that are continuously turned OFF disconnect the opposing terminals of the coil from a second voltage rail of the input voltage rails. ### Claim 17 (depends on 14) The method of claim 14, wherein: the upper set of switches have respective inputs coupled to a first voltage rail of the input voltage rails and respective outputs coupled to the opposing terminals of the coil; and the lower set of switches have respective inputs coupled to the opposing terminals of the coil and respective outputs coupled to a second voltage rail of the input voltage rails. ### Claim 18 (depends on 14) The method of claim 14, wherein, when operating in the protection mode, the upper set of switches are continuously turned ON and the lower set of switches are continuously turned OFF. ### Claim 19 (depends on 14) The method of claim 14, wherein, when operating in the protection mode, the upper set of switches are continuously turned OFF and the lower set of switches are continuously turned ON. ### Claim 20 (depends on 14) The method of claim 14, further comprising operating in the normal mode and in the protection mode during first and second successive time periods, respectively.