# US 2018/0026557 A1 · Balancing current within a parallel modular converter system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0026557 A1 - Document ID: US20180026557A1 - Status: Published application - Kind: A1 - Application number: 15/219,028 - Filed: 2016-07-25 - Published: 2018-01-25 - Earliest claimed: 2016-07-25 - Assignees: The Boeing Company - Applicants: The Boeing Company - Inventors: Darren Lee PASCHEDAG; Lijun GAO; Shengyi LIU - Web page: https://patentgrep.com/patent/US20180026557A1 ## CPC - H02M 7/493: the static converters being arranged for operation in parallel - H02M 1/088: for the simultaneous control of series or parallel connected semiconductor devices - H02M 1/44: Circuits or arrangements for compensating for electromagnetic interference in converters or inverters - H02M 7/537: using semiconductor devices only, e.g. single switched pulse inverters - H02P 5/505: using equalising lines, e.g. rotor and stator lines of first and second motors - H02P 27/08: with pulse width modulation - H02M 1/0009: {Devices or circuits for detecting current in a converter} - H02M 1/0025: {Arrangements for modifying reference values, feedback values or error values in the control loop of a converter} - 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) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A current balancing system, and associated method and computer-readable medium are disclosed herein. The current balancing system comprises a plurality of power inverters, each power inverter included within a respective current loop and configured to generate a corresponding current amount. The current balancing system further comprises a plurality of inverter controllers, each inverter controller associated with a respective one of the plurality of power inverters and configured to receive a reference frame-transformed amount of the corresponding current amount. Each inverter controller is capable of independently controlling the corresponding current amount provided to a load. ## Claims ### Claim 1 A current balancing system (100, 400) comprising: a plurality of power inverters (1251, 1252, . . . , 125n), each power inverter (125k) included within a respective current loop (422(k)) and configured to generate a corresponding current amount (Iabc(k)); and a plurality of inverter controllers (325(1), 325(2), . . . , 325(n)), each inverter controller (325(k)) associated with a respective one of the plurality of power inverters and configured to receive a reference frame-transformed amount (Id (k), Iq (k)) of the corresponding current amount, whereby each inverter controller is capable of independently controlling the corresponding current amount provided to a load (140). ### Claim 2 (depends on 1) The system of claim 1, wherein at least a first power inverter of the plurality of power inverters has different electrical characteristics than at least a second power inverter of the plurality of power inverters, wherein a same commanded current amount (Iq_command) provided to the first power inverter and to the second power inverter results in an uneven current processing among the plurality of power inverters. ### Claim 3 (depends on 1) The system of claim 1, wherein independently controlling the corresponding current amount provided to a load operates to mitigate one or more of: a current imbalance within the plurality of power inverters; power losses of the plurality of power inverters; a circulation current between at least two of the plurality of power inverters; and electrical noise generated by the plurality of power inverters. ### Claim 4 (depends on 1) The system of claim 1, wherein at least two of the plurality of power inverters provide power to a common load (505). ### Claim 5 (depends on 4) The system of claim 4, wherein the common load comprises a motor (M1, M2, . . . Mj). ### Claim 6 (depends on 1) The system of claim 1, wherein the plurality of inverter controllers are included in a system controller (105), wherein the system controller further comprises a global controller stage (305) configured to: determine (605) a total system current amount (Iq_system) for achieving a commanded motor rotational speed (235); and generate (610) current commands (Iq_command) to distribute the total system current amount evenly (Iq_system n) among the plurality of power inverters. ### Claim 7 (depends on 6) The system of claim 6, wherein the global controller stage further comprises a circulation current module (215) configured to: compare (620), responsive to generating the current commands, the current amounts corresponding to each of the plurality of power inverters; and determine (625), based on the comparison, a circulation current (Icirculation(1), Icirculation(2), . . . , Icirculation(n)) existing between at least two of the plurality of power inverters, wherein the plurality of inverter controllers are further configured to adjust the corresponding current amount provided to the load based on the determined circulation current. ### Claim 8 A method (600) of controlling current production of a plurality of power inverters (1251, 1252, . . . , 125n) controlled by a plurality of inverter controllers (325(1), 325(2), . . . , 325(n)), the method comprising: determining (615) a plurality of current amounts (Iabc(1), Iabc(2), . . . , Iabc(n)), each of the plurality of current amounts produced by a respective one of the plurality of power inverters; transforming (630) a reference frame of each of the plurality of current amounts to produce a plurality of transformed current amounts (Idq(1), Idq(2), . . . , Idq(n)); and generating (635), based on the plurality of transformed current amounts received by the plurality of inverter controllers, gate commands (330(1), 330(2), . . . , 330(n)) for the plurality of power inverters, wherein application of the generated gate commands operates to adjust at least one of the plurality of current amounts to thereby mitigate a current imbalance between at least two of the plurality of power inverters. ### Claim 9 (depends on 8) The method of claim 8, wherein the application of the generated gate commands further operates to mitigate one or more of: power losses of the plurality of power inverters; a circulation current between at least two of the plurality of power inverters; and electrical noise generated by the plurality of power inverters. ### Claim 10 (depends on 8) The method of claim 8, wherein at least a first power inverter of the plurality of power inverters has different electrical characteristics than at least a second power inverter of the plurality of power inverters, wherein a same commanded current amount (Iq_command) provided to the first power inverter and to the second power inverter results in an uneven current processing among the plurality of power inverters. ### Claim 11 (depends on 8) The method of claim 8, further comprising: determining (605) a total system current amount (Iq_system) for achieving a commanded motor rotational speed (235); and generating (610) initial current commands (Iq_command) to distribute the total system current amount evenly (Iq_system/n) among the plurality of power inverters using a plurality of initial gate commands, wherein determining the plurality of current amounts is performed responsive to application of the initial gate commands. ### Claim 12 (depends on 11) The method of claim 11, further comprising: comparing (620), responsive to application of the initial gate commands, the corresponding current amount produced by each of the plurality of power inverters; and determining (625) that the current imbalance exists based on the comparison. ### Claim 13 (depends on 8) The method of claim 8, further comprising: providing (640), using the generated gate commands received by the plurality of power inverters, power from the plurality of power inverters to a common load (505). ### Claim 14 (depends on 13) The method of claim 13, wherein the common load comprises a motor (M1, M2, . . . , Mj). ### Claim 15 A non-transitory computer-readable medium comprising computer program code that, when executed by operation of one or more computer processors, performs an operation (600) of controlling current production of a plurality of power inverters (1251, 1252, . . . , 125n) controlled by a plurality of inverter controllers (325(1), 325(2), . . . , 325(n)), the operation comprising: determining (615) a plurality of current amounts (Iabc(1), Iabc(2), . . . , Iabc(n)), each of the plurality of current amounts produced by a respective one of the plurality of power inverters; transforming (630) a reference frame of each of the plurality of current amounts to produce a plurality of transformed current amounts (Idq(1), Idq(2), . . . , Idq(n)); and generating (635), based on the plurality of transformed current amounts received by the plurality of inverter controllers, gate commands (330(1), 330(2), . . . , 330(n)) for the plurality of power inverters, wherein application of the generated gate commands operates adjust at least one of the plurality of current amounts to thereby mitigate a current imbalance between at least two of the plurality of inverters. ### Claim 16 (depends on 15) The computer-readable medium of claim 15, wherein the application of the generated gate commands further operate to mitigate one or more of: power losses of the plurality of power inverters; a circulation current between at least two of the plurality of power inverters; and electrical noise generated by the plurality of power inverters. ### Claim 17 (depends on 15) The computer-readable medium of claim 15, the operation further comprising: determining (605) a total system current amount (Iq_system) for achieving a commanded motor rotational speed (235); and generating (610) initial current commands (Iq_command) to distribute the total system current amount evenly (Iq_system/n) among the plurality of power inverters using a plurality of initial gate commands, wherein determining the plurality of current amounts is performed responsive to application of the initial gate commands. ### Claim 18 (depends on 17) The computer-readable medium of claim 17, the operation further comprising: comparing (620), responsive to application of the initial gate commands, the corresponding current output produced by each of the plurality of power inverters; and determining (625) that the current imbalance exists based on the comparison. ### Claim 19 (depends on 15) The computer-readable medium of claim 15, the operation further comprising: providing (640), using the generated gate commands received by the plurality of power inverters, power from the plurality of power inverters to a common load (505). ### Claim 20 (depends on 19) The computer-readable medium of claim 19, wherein the common load comprises a motor (M1, M2, . . . , Mj).