# US 12,191,844 B2 · Overcurrent detection circuit, drive control device, and power conversion device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,191,844 B2 - Document ID: US12191844B2 - Status: Granted - Kind: B2 - Application number: 18/187,670 - Filed: 2023-03-22 - Published: 2023-07-20 - Granted: 2025-01-07 - Earliest claimed: 2021-04-23 - Assignees: Fuji Electric Co., Ltd. - Applicants: Fuji Electric Co., Ltd. - Inventors: Kenshi Terashima - Web page: https://patentgrep.com/patent/US12191844B2 ## CPC - H03K 17/08122: {in field-effect transistor switches} - H02M 1/0025: {Arrangements for modifying reference values, feedback values or error values in the control loop of a converter} - H02M 1/32: Means for protecting converters other than automatic disconnection - H03K 17/08: Modifications for protecting switching circuit against overcurrent or overvoltage - H03K 17/082: by feedback from the output to the control circuit - H03K 17/0828: {in composite switches} - H03K 17/687: the devices being field-effect transistors - H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters - H02M 7/48: using discharge tubes with control electrode or semiconductor devices with control electrode - H02M 7/5387: in a bridge configuration - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - 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 overcurrent detection circuit including a detection unit for detecting whether a current flowing between main terminals of a main switching device used by a power conversion device is an overcurrent, and a switching unit for switching among thresholds used for determining the overcurrent in the detection unit according to in which phase of the power conversion device the main switching device is used, in which the detection unit includes a plurality of comparison units for comparing a parameter according to the current flowing between main terminals, and thresholds different from each other, and the switching unit is for switching a comparison unit to use for detection of the overcurrent among the plurality of comparison units. ## Claims ### Claim 1 An overcurrent detection circuit comprising: a detection unit configured to detect whether a current flowing between main terminals of a main switching device used by a power conversion device is an overcurrent; and a switching unit configured to switch among thresholds used for determining the overcurrent in the detection unit according to in which phase of the power conversion device the main switching device is used, wherein the switching unit is configured to select any of the thresholds set for each phase based on a signal supplied according to the phase in which the main switching device is used, the detection unit includes a plurality of comparison units configured to compare a parameter according to the current flowing between the main terminals, and thresholds different from each other, and the switching unit is configured to switch, among the plurality of comparison units, a comparison unit for use in detection of the overcurrent. ### Claim 2 (depends on 1) The overcurrent detection circuit according to claim 1, wherein each of the plurality of comparison units is configured to compare a voltage detected according to the current flowing between the main terminals, and reference voltages different from each other. ### Claim 3 (depends on 1) The overcurrent detection circuit according to claim 1, wherein the detection unit includes a comparison unit configured to compare a voltage detected according to the current flowing between the main terminals, and a reference voltage, and the switching unit is configured to switch the reference voltage supplied to the comparison unit. ### Claim 4 (depends on 1) A drive control device comprising: a gate driving circuit configured to drive a gate of a main switching device; and the overcurrent detection circuit according to claim 1 configured to detect whether a current flowing between the main terminals of the main switching device is an overcurrent, wherein the gate driving circuit is configured to put the main switching device in OFF state in response to detection of the overcurrent by the overcurrent detection circuit. ### Claim 5 (depends on 4) A power conversion device comprising: multiple pairs of main switching devices connected in series between a positive-side power supply line and a negative-side power supply line; and the drive control device according to claim 4 provided for each phase of main switching devices, among the multiple pairs of main switching devices, on a side of the negative side power supply line, wherein the overcurrent detection circuit in each drive control device is set with the thresholds that are mutually different, according to in which phase the main switching device in correspondence is used.