# US 12,009,759 B2 · Power conversion system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,009,759 B2 - Document ID: US12009759B2 - Status: Granted - Kind: B2 - Application number: 17/919,703 - Filed: 2020-06-17 - Published: 2023-05-11 - Granted: 2024-06-11 - Earliest claimed: 2020-06-17 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Yoshiyuki Kono; Shuhei Fujiwara; Ryosuke Uda; Takuya Kajiyama; Toshiyuki Fujii - Web page: https://patentgrep.com/patent/US12009759B2 ## CPC - H02M 7/12: using discharge tubes with control electrode or semiconductor devices with control electrode - H02M 7/4835: {comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage} - H02J 3/001: Arrangements for handling faults or abnormalities, e.g. emergencies or contingencies - H02J 3/34: Arrangements for transfer of electric power between networks of substantially different frequency - H02J 3/36: Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links - H02M 1/0067: {Converter structures employing plural converter units, other than for parallel operation of the units on a single load} - H02M 1/32: Means for protecting converters other than automatic disconnection - H02M 1/325: {with means for allowing continuous operation despite a fault, i.e. fault tolerant converters} - H02M 1/4208: {Arrangements for improving power factor of AC input} - H02M 7/539: with automatic control of output wave form or frequency (H02M7/5375 - H02M7/5387 take precedence) - 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) - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY ## Abstract A power conversion system includes: a first power converter to perform power conversion between a first AC system and a DC circuit; and a second power converter to perform power conversion between a second AC system and the DC circuit. Each of the first power converter and the second power converter includes a plurality of submodules connected in series. Each of the plurality of submodules includes a plurality of switching elements and a capacitor. A first fundamental frequency of the first AC system is greater than a second fundamental frequency of the second AC system. A first average voltage value of a capacitor in a first submodule included in the first power converter is larger than a second average voltage value of a capacitor in a second submodule included in the second power converter. ## Claims ### Claim 1 A power conversion system comprising: a first power converter to perform power conversion between a first AC system and a DC circuit; and a second power converter to perform power conversion between a second AC system and the DC circuit, wherein each of the first power converter and the second power converter includes a plurality of submodules connected in series, each of the plurality of submodules includes a plurality of switching elements and a capacitor, a first fundamental frequency of the first AC system is greater than a second fundamental frequency of the second AC system, and a first average voltage value of a capacitor in a first submodule included in the first power converter is larger than a second average voltage value of a capacitor in a second submodule included in the second power converter, wherein the first average voltage value is a value obtained by adding, to the second average voltage value, a difference value between a ripple voltage of the capacitor in the second submodule and a ripple voltage of the capacitor in the first submodule. ### Claim 2 (depends on 1) The power conversion system according to claim 1, further comprising a first controller to control each of a plurality of the first submodules in the first power converter, wherein when one or more of the first submodules included in an arm of the first power converter fail, the first controller increases the first average voltage value in each of the first submodules included in the arm, based on the number of the one or more first submodules that have failed. ### Claim 3 (depends on 2) The power conversion system according to claim 2, wherein the first controller increases, by a factor of m/(m−k), the first average voltage value in each of the first submodules included in the arm, where m (m is an integer equal to or greater than 2) represents the number of the first submodules included in the arm, and k (k is an integer equal to or greater than 1 and k