# US 11,909,308 B2 · Power conversion circuit, method for controlling power conversion circuit, and transformer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,909,308 B2 - Document ID: US11909308B2 - Status: Granted - Kind: B2 - Application number: 17/544,690 - Filed: 2021-12-07 - Published: 2022-06-09 - Granted: 2024-02-20 - Earliest claimed: 2020-12-08 - Assignees: Huawei Digital Power Technologies Co., Ltd. - Applicants: Huawei Digital Power Technologies Co., Ltd. - Inventors: Zhuyong Huang; Xiaofei Zhang; Peng Shuai; Peiguo Liu - Web page: https://patentgrep.com/patent/US11909308B2 ## CPC - H02M 1/36: Means for starting or stopping converters - H02M 7/49: Combination of the output voltage waveforms of a plurality of converters - H02M 5/10: using transformers - 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 1/0085: {Partially controlled bridges} - H02M 7/4807: {having a high frequency intermediate AC stage} - 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 Embodiments of this application provide a power conversion circuit. The power conversion circuit includes at least one first power conversion unit connected in series to a first phase line, at least one second power conversion unit connected in series to a second phase line, at least one third power conversion unit connected in series to a third phase line, a plurality of first start circuits connected in series to the first phase line, and a plurality of second start circuits connected in series to the second phase line. Each first start circuit includes a first relay and a first resistor that are connected in parallel, and first relays in all the first start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. Each second start circuit includes a second relay and a second resistor that are connected in parallel. ## Claims ### Claim 1 A power conversion circuit, comprising: at least one first power conversion unit connected in series to a first phase line, at least one second power conversion unit connected in series to a second phase line; a plurality of first start circuits connected in series to the first phase line, wherein_each of the plurality of first start circuits comprises a first relay and a first resistor, the first relay and the first resistor are connected in parallel, and first relays in all the first start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit; and a plurality of second start circuits connected in series to the second phase line, wherein_each of the plurality of second start circuits comprises a second relay and a second resistor, the second relay and the second resistor are connected in parallel, and second relays in all the second start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. ### Claim 2 (depends on 1) The circuit of claim 1, wherein after the power conversion circuit is powered on, in the first relays in the plurality of first start circuits, a resistance of the first resistor correspondingly connected in parallel to the first relay closed at a moment T1 is greater than or equal to the resistance of the first resistor correspondingly connected in parallel to the first relay closed at a moment T2, and the moment T1 is earlier than the moment T2; and in the second relays in the plurality of second start circuits, a resistance of the second resistor correspondingly connected in parallel to the second relay closed at a moment T3 is greater than or equal to the resistance of the second resistor correspondingly connected in parallel to the second relay closed at a moment T4, and the moment T3 is earlier than the moment T4. ### Claim 3 (depends on 1) The circuit of claim 1, wherein a rated voltage of the first relay closed at a moment T1 is greater than or equal to the rated voltage of the first relay closed at a moment T2, and a rated voltage of the second relay closed at a moment T3 is greater than or equal to the rated voltage of the second relay closed at a moment T4. ### Claim 4 (depends on 1) The circuit of claim 1, wherein the first relays in all the first start circuits are sequentially opened to shut down the power conversion circuit, and the second relays in all the second start circuits are sequentially opened to shut down the power conversion circuit. ### Claim 5 (depends on 4) The circuit of claim 4, wherein before the power conversion circuit is powered off, in the first relays in the plurality of first start circuits, a resistance of the first resistor correspondingly connected in parallel to the first relay opened at a moment T5 is less than or equal to the resistance of the first resistor correspondingly connected in parallel to the first relay opened at a moment T6, and the moment T5 is earlier than the moment T6; and in the second relays in the plurality of second start circuits, a resistance of the second resistor correspondingly connected in parallel to the second relay opened at a moment T7 is less than or equal to the resistance of the second resistor correspondingly connected in parallel to the second relay opened at a moment T8, and the moment T7 is earlier than the moment T8. ### Claim 6 (depends on 1) The circuit of claim 1, further comprising: a plurality of third start circuits connected in series to a third phase line, wherein each of the plurality of third start circuits comprises a third relay and a third resistor, the third relay and the third resistor are connected in parallel, and third relays in all the third start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. ### Claim 7 (depends on 6) The circuit of claim 6, wherein after the power conversion circuit is powered on, the third relays in all the third start circuits are sequentially opened to shut down the power conversion circuit. ### Claim 8 (depends on 1) The circuit of claim 1, wherein a capacitance of a bus capacitor in at least one of the at least one first power conversion unit, the at least one second power conversion unit, and the at least one third power conversion unit is not zero before the power conversion circuit is powered on. ### Claim 9 A method, comprising: controlling first relays in a plurality of first start circuits of a power conversion circuit to be sequentially closed after the power conversion circuit is powered on, wherein the power conversion circuit comprises the plurality of first start circuits and at least one first power conversion unit that are connected in series to a first phase line, a plurality of second start circuits and at least one second power conversion unit that are connected in series to a second phase line, wherein each of the plurality of first start circuits comprises a first relay and a first resistor, the first relay and the first resistor are connected in parallel, each of the plurality of second start circuits comprises a second relay and a second resistor, and the second relay and the second resistor are connected in parallel; and controlling second relays in all the second start circuits to be sequentially closed after the power conversion circuit is powered on. ### Claim 10 (depends on 9) The method of claim 9, wherein a resistance of the first resistor correspondingly connected in parallel to the first relay closed at a moment T1 is greater than or equal to the resistance of the first resistor correspondingly connected in parallel to the first relay closed at a moment T2, and the moment T1 is earlier than the moment T2; and a resistance of the second resistor correspondingly connected in parallel to the second relay closed at a moment T3 is greater than or equal to the resistance of the second resistor correspondingly connected in parallel to the second relay closed at a moment T4, and the moment T3 is earlier than the moment T4. ### Claim 11 A transformer, comprising a controller and a power conversion circuit, wherein the controller is configured to control a relay in the power conversion circuit to be opened or closed; wherein the power conversion circuit comprises: at least one first power conversion unit connected in series to a first phase line, at least one second power conversion unit connected in series to a second phase line; a plurality of first start circuits connected in series to the first phase line, wherein-each of the plurality of first start circuits comprises a first relay and a first resistor, the first relay and the first resistor are connected in parallel, and first relays in all the first start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit; and a plurality of second start circuits connected in series to the second phase line, wherein_each of the plurality of second start circuits comprises a second relay and a second resistor, the second relay and the second resistor are connected in parallel, and second relays in all the second start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. ### Claim 12 (depends on 11) The transformer of claim 11, wherein after the power conversion circuit is powered on, in the first relays in the plurality of first start circuits, a resistance of the first resistor correspondingly connected in parallel to the first relay closed at a moment T1 is greater than or equal to the resistance of the first resistor correspondingly connected in parallel to the first relay closed at a moment T2, and the moment T1 is earlier than the moment T2; and in the second relays in the plurality of second start circuits, a resistance of the second resistor correspondingly connected in parallel to the second relay closed at a moment T3 is greater than or equal to the resistance of the second resistor correspondingly connected in parallel to the second relay closed at a moment T4, and the moment T3 is earlier than the moment T4. ### Claim 13 (depends on 11) The transformer of claim 11, wherein a rated voltage of the first relay closed at a moment T1 is greater than or equal to the rated voltage of the first relay closed at a moment T2, and a rated voltage of the second relay closed at a moment T3 is greater than or equal to the rated voltage of the second relay closed at a moment T4. ### Claim 14 (depends on 11) The transformer of claim 11, wherein the first relays in all the first start circuits are sequentially opened to shut down the power conversion circuit, and the second relays in all the second start circuits are sequentially opened to shut down the power conversion circuit. ### Claim 15 (depends on 14) The transformer of claim 14, wherein before the power conversion circuit is powered off, in the first relays in the plurality of first start circuits, a resistance of the first resistor correspondingly connected in parallel to the first relay opened at a moment T5 is less than or equal to the resistance of the first resistor correspondingly connected in parallel to the first relay opened at a moment T6, and the moment T5 is earlier than the moment T6; and in the second relays in the plurality of second start circuits, a resistance of the second resistor correspondingly connected in parallel to the second relay opened at a moment T7 is less than or equal to the resistance of the second resistor correspondingly connected in parallel to the second relay opened at a moment T8, and the moment T7 is earlier than the moment T8. ### Claim 16 (depends on 11) The transformer of claim 11, further comprising: a plurality of third start circuits connected in series to a third phase line, wherein each of the plurality of third start circuits comprises a third relay and a third resistor, the third relay and the third resistor are connected in parallel, and third relays in all the third start circuits are sequentially closed after the power conversion circuit is powered on, to start the power conversion circuit. ### Claim 17 (depends on 16) The transformer of claim 16, wherein after the power conversion circuit is powered on, the third relays in all the third start circuits are sequentially opened to shut down the power conversion circuit. ### Claim 18 (depends on 11) The transformer of claim 11, further comprising at least one third power conversion unit connected in series to a third phase line, wherein a capacitance of a bus capacitor in at least one of the at least one first power conversion unit, the at least one second power conversion unit, and the at least one third power conversion unit is not zero before the power conversion circuit is powered on. ### Claim 19 (depends on 1) The circuit of claim 1, further comprising at least one third power conversion unit connected in series to a third phase line. ### Claim 20 (depends on 9) The method of claim 9, further comprising, and at least one third power conversion unit connected in series to a third phase line.