# US 12,191,792 B2 · Circuit for an inverter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,191,792 B2 - Document ID: US12191792B2 - Status: Granted - Kind: B2 - Application number: 17/905,983 - Filed: 2021-03-10 - Published: 2023-03-30 - Granted: 2025-01-07 - Earliest claimed: 2020-03-11 - Assignees: Protean Electric Limited - Applicants: Protean Electric Limited - Inventors: Chao Ji - Web page: https://patentgrep.com/patent/US12191792B2 ## CPC - H02P 29/0241: {the fault being an overvoltage} - H02P 27/08: with pulse width modulation - H02P 29/028: the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault - H02M 7/5387: in a bridge configuration - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - 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 A circuit for a multi phase bridge inverter having a plurality of high and low side switches arranged to be coupled, respectively, to first and second power source busbars. The multi phase inverter is arranged to control current flow in coil windings of an electric motor, and a DC link capacitor is coupled between the first and second power source busbars. The circuit comprises first and second impedances coupled in series between the first and second power source busbars and in parallel to the DC link capacitor, and means coupled between the first and second impedances for providing a voltage from the coupling between the first and second impedances to the low side switches upon the occurrence of a first predetermined condition to place the low side switches in a close circuit configuration to allow coil windings of an electric motor to be placed in a short circuit configuration. ## Claims ### Claim 1 A circuit for a multi phase bridge inverter having a plurality of high side switches arranged to be coupled to a first power source busbar and a plurality of low side switches arranged to be coupled to a second power source busbar, wherein the multi phase inverter is arranged to control current flow in coil windings of an electric motor, and wherein a DC link capacitor is coupled between the first power source busbar and the second power source busbar, the circuit comprising: a first impedance and a second impedance coupled in series between the first power source busbar and the second power source busbar and in parallel to the DC link capacitor and configured for providing a voltage from the coupling between the first impedance and the second impedance to the plurality of low side switches upon the occurrence of a first predetermined condition to place the plurality of low side switches in a close circuit configuration to allow coil windings of the electric motor to be placed in a short circuit configuration or to the plurality of high side switches upon the occurrence of a first predetermined condition to place the plurality of high side switches in a close circuit configuration to allow coil windings of the electric motor to be placed in a short circuit configuration; and a controller and a first switch, wherein the switch is coupled between the first power source busbar and the first impedance and the controller is arranged to close the switch upon a second predetermined condition; wherein the second predetermined condition is a voltage difference between the first power source busbar and second power source busbar increases above a predetermined value. ### Claim 2 (depends on 1) The circuit according to claim 1, wherein the first impedance is created by a first capacitor and the second impedance is created by a second capacitor. ### Claim 3 (depends on 2) The circuit according to claim 2, wherein the first capacitor is a high voltage capacitor and the second capacitor is a low voltage capacitor. ### Claim 4 (depends on 1) The circuit according to claim 1, wherein the first predetermined condition is the closing of the first switch. ### Claim 5 (depends on 1) The circuit according to claim 1, wherein the first predetermined condition is the voltage difference between the first power source busbar and second power source busbar dropping of a voltage from a low voltage power rail falling below a predetermined value. ### Claim 6 (depends on 1) The circuit according to claim 1, further comprising a high voltage clamp coupled in parallel with a first capacitor for clamping the voltage across the first capacitor to a predetermined value and a low voltage clamp coupled in parallel to a second capacitor for clamping the voltage across the second capacitor to a predetermined value. ### Claim 7 (depends on 1) The circuit according to claim 1, wherein the first switch is a depletion mode semiconductor switch. ### Claim 8 (depends on 1) The circuit according to claim 1, further comprising a logic device to determine if one of the low side inverter switches remains open, wherein upon determining if one of the low side inverter switches remains open, the plurality of high side switches are placed in a close circuit configuration to allow coil windings of an electric motor to be placed in a short circuit configuration. ### Claim 9 (depends on 1) The circuit according to claim 1, further comprising a logic device to determine if one of the high side inverter switches remains open, wherein upon determining if one of the high side inverter switches remains open, the plurality of low side switches are placed in a close circuit configuration to allow coil windings of an electric motor to be placed in a short circuit configuration. ### Claim 10 (depends on 1) The circuit according to claim 1, further comprising a high voltage clamp coupled in parallel with a first capacitor for clamping the voltage across the first capacitor to a predetermined value and a low voltage clamp coupled in parallel to a second capacitor for clamping the voltage across the second capacitor to a predetermined value. ### Claim 11 A circuit for a multi phase bridge inverter having a plurality of high side switches arranged to be coupled to a first power source busbar and a plurality of low side switches arranged to be coupled to a second power source busbar, wherein the multi phase inverter is arranged to control current flow in coil windings of an electric motor, and wherein a DC link capacitor is coupled between the first power source busbar and the second power source busbar, the circuit comprising: a first impedance and a second impedance coupled in series between the first power source busbar and the second power source busbar and in parallel to the DC link capacitor and configured for providing a voltage from the coupling between the first impedance and the second impedance to the plurality of low side switches upon the occurrence of a first predetermined condition to place the plurality of low side switches in a close circuit configuration to allow coil windings of the electric motor to be placed in a short circuit configuration or to the plurality of high side switches upon the occurrence of a first predetermined condition to place the plurality of high side switches in a close circuit configuration to allow coil windings of the electric motor to be placed in a short circuit configuration; and a controller and a first switch, wherein the switch is coupled between the first power source busbar and the first impedance and the controller is arranged to close the switch upon a second predetermined condition; wherein the second predetermined condition is the dropping of a voltage from a low voltage power rail falling below a predetermined value. ### Claim 12 (depends on 11) The circuit according to claim 11, wherein the first impedance is created by a first capacitor and the second impedance is created by a second capacitor. ### Claim 13 (depends on 12) The circuit according to claim 12, wherein the first capacitor is a high voltage capacitor and the second capacitor is a low voltage capacitor. ### Claim 14 (depends on 11) The circuit according to claim 11, wherein the first predetermined condition is the closing of the first switch. ### Claim 15 (depends on 11) The circuit according to claim 11, wherein the second predetermined condition is a voltage difference between the first power source busbar and second power source busbar increases above a predetermined value. ### Claim 16 (depends on 11) The circuit according to claim 11, wherein the first predetermined condition is a voltage difference between the first power source busbar and second power source busbar increasing above a predetermined value or the dropping of a voltage from a low voltage power rail falling below a predetermined value. ### Claim 17 (depends on 11) The circuit according to claim 11, wherein the first switch is a depletion mode semiconductor switch. ### Claim 18 (depends on 11) The circuit according to claim 11, further comprising a logic device configured to determine if one of the low side inverter switches remains open, wherein upon determining if one of the low side inverter switches remains open, the plurality of high side switches are placed in a close circuit configuration to allow coil windings of an electric motor to be placed in a short circuit configuration. ### Claim 19 (depends on 11) The circuit according to claim 11, further comprising a logic device configured to determine if one of the high side inverter switches remains open, wherein upon determining if one of the high side inverter switches remains open, the plurality of low side switches are placed in a close circuit configuration to allow coil windings of an electric motor to be placed in a short circuit configuration.