# US 2021/0344277 A1 · 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 2021/0344277 A1 - Document ID: US20210344277A1 - Status: Published application - Kind: A1 - Application number: 17/283,255 - Filed: 2018-12-13 - Published: 2021-11-04 - Earliest claimed: 2018-12-13 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Hajime TOYODA; Takaaki TAKAHARA - Web page: https://patentgrep.com/patent/US20210344277A1 ## CPC - H02M 1/0009: {Devices or circuits for detecting current in a converter} - 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 1/4208: {Arrangements for improving power factor of AC input} - H02M 3/158: including plural semiconductor devices as final control devices for a single load - H02M 7/217: using semiconductor devices only - H02M 7/4837: {Flying capacitor converters} - H02M 1/0095: {Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck} - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - 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) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract Provided is a power conversion device that can suppress interference between control of input current from an AC power supply and voltage control for a DC capacitor to perform both the controls with high accuracy, and can reduce the capacitance and size of the DC capacitor. A power conversion circuit includes a rectification bridge circuit, a leg circuit having upper and lower legs connected in series, a DC capacitor, a smoothing capacitor, and a reactor. A control circuit performs PWM control of the leg circuit by generating a duty cycle so as to control a voltage of the DC capacitor while controlling an input current from an AC power supply, in a control cycle. When the duty cycle is generated, a sum of duty cycles is made constant in one cycle for each leg. ## Claims ### Claim 1 A power conversion device comprising: a power conversion circuit for converting AC power from an AC power supply, to DC power, and outputting the DC power; and a control circuitry to perform output control for the power conversion circuit, wherein the power conversion circuit includes: a rectification bridge circuit connected to the AC power supply; a leg circuit including an upper leg and a lower leg, connected in series, each of which includes a plurality of semiconductor elements connected in series via connection points, the plurality of semiconductor elements of at least the lower leg being switching elements, the leg circuit connected between DC buses and connected to the AC power supply via the rectification bridge circuit; at least one DC capacitor connected between the connection point in the upper leg and the connection point in the lower leg; a reactor inserted in a current path between the AC power supply and the leg circuit; and a smoothing capacitor connected between the DC buses; and wherein the control circuitry performs PWM control of the leg circuit by generating a duty cycle so as to cause a voltage of the DC capacitor to follow a command value while controlling an input current from the AC power supply, such that a sum of duty cycles corresponding to each leg having the switching elements among the upper and the lower legs, is constant in one cycle. ### Claim 2 (depends on 1) The power conversion device according to claim 1, wherein the at least one DC capacitor includes N DC capacitors which are a first to an N-th DC capacitors, the first to the N-th DC capacitors being disposed sequentially from a center of the leg circuit in an outward direction, and the control circuitry performs PWM control of the leg circuit at a control cycle corresponding to N switching cycles, such that the sum of the duty cycles is constant in one cycle of the control cycle. ### Claim 3 (depends on 2) The power conversion device according to claim 2, wherein the control circuitry includes a first controller to control the input current and causing the power conversion circuit to output DC power, a second controller to cause a voltage of the DC capacitor to follow the command value, a pattern generator to generate a switching pattern including a combination of switching states, of the leg circuit, which vary in one cycle of the control cycle, and an addition/subtraction determination circuitry to determine whether addition or subtraction is to be performed, the first controller generates a first duty cycle according to the switching pattern from the pattern generator, a second duty cycle generated by the second controller is added to or subtracted from the first duty cycle to calculate the duty cycle of the leg circuit, and the addition/subtraction determination circuitry determines, when the second duty cycle is added to or subtracted from the first duty cycle, whether addition or subtraction is to be performed according to the switching pattern. ### Claim 4 (depends on 3) The power conversion device according to claim 3, wherein the control circuitry determines a plurality of operation ranges based on a voltage relationship among a voltage of the DC capacitor, a voltage of the AC power supply, and a voltage of the smoothing capacitor, and the pattern generator generates the switching pattern according to each of the operation ranges. ### Claim 5 (depends on 3) The power conversion device according to claim 3, wherein the sum of the duty cycles corresponding to each leg is equal to a sum of the first duty cycles. ### Claim 6 (depends on 3) The power conversion device according to claim 3, wherein a plurality of sections corresponding to the plurality of switching states of the switching pattern is a combination formed by alternating sections in which excitation of the reactor is performed and sections in which the excitation is reset. ### Claim 7 (depends on 3) The power conversion device according to claim 3, wherein the control circuitry performs control so as to cause a voltage to follow the command value for each DC capacitor, and the number of charging sections and the number of discharging sections are equal to each other for each DC capacitor in the plurality of sections corresponding to the plurality of switching states of the switching pattern. ### Claim 8 (depends on 7) The power conversion device according to claim 7, wherein the control circuitry performs control so as to cause a voltage to follow the command value for each DC capacitor preferentially for a DC capacitor having a greater deviation between a voltage of the DC capacitor and the command value. ### Claim 9 (depends on 3) The power conversion device according to claim 3, wherein the first controller calculates a feedforward term according to the switching pattern and uses the feedforward term. ### Claim 10 (depends on 3) The power conversion device according to claim 3, wherein the second duty cycle generated by the second controller is fixed in one cycle of the control cycle. ### Claim 11 (depends on 2) The power conversion device according to claim 2, wherein the first to the N-th DC capacitors are disposed such that a voltage is increased from the center of the leg circuit in the outward direction. ### Claim 12 (depends on 1) The power conversion device according to claim 1, wherein the rectification bridge circuit is a half-bridge circuit connected between the DC buses, a mid-point of the half-bridge circuit is connected to a first end of the AC power supply, a mid-point of the leg circuit is connected to a second end of the AC power supply, and the plurality of semiconductor elements of the upper leg are switching elements. ### Claim 13 (depends on 1) The power conversion device according to claim 1, wherein the rectification bridge circuit is a full-bridge circuit including two AC terminals connected to a first end and a second end, respectively, of the AC power supply, and a positive electrode of the full-bridge circuit is connected to a mid-point of the leg circuit. ### Claim 14 (depends on 4) The power conversion device according to claim 4, wherein the sum of the duty cycles corresponding to each leg is equal to a sum of the first duty cycles. ### Claim 15 (depends on 4) The power conversion device according to claim 4, wherein a plurality of sections corresponding to the plurality of switching states of the switching pattern is a combination formed by alternating sections in which excitation of the reactor is performed and sections in which the excitation is reset. ### Claim 16 (depends on 5) The power conversion device according to claim 5, wherein a plurality of sections corresponding to the plurality of switching states of the switching pattern is a combination formed by alternating sections in which excitation of the reactor is performed and sections in which the excitation is reset. ### Claim 17 (depends on 4) The power conversion device according to claim 4, wherein the control circuitry performs control so as to cause a voltage to follow the command value for each DC capacitor, and the number of charging sections and the number of discharging sections are equal to each other for each DC capacitor in the plurality of sections corresponding to the plurality of switching states of the switching pattern. ### Claim 18 (depends on 5) The power conversion device according to claim 5, wherein the control circuitry performs control so as to cause a voltage to follow the command value for each DC capacitor, and the number of charging sections and the number of discharging sections are equal to each other for each DC capacitor in the plurality of sections corresponding to the plurality of switching states of the switching pattern. ### Claim 19 (depends on 6) The power conversion device according to claim 6, wherein the control circuitry performs control so as to cause a voltage to follow the command value for each DC capacitor, and the number of charging sections and the number of discharging sections are equal to each other for each DC capacitor in the plurality of sections corresponding to the plurality of switching states of the switching pattern. ### Claim 20 (depends on 4) The power conversion device according to claim 4, wherein the first controller calculates a feedforward term according to the switching pattern and uses the feedforward term.