# US 11,309,787 B2 · 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 11,309,787 B2 - Document ID: US11309787B2 - Status: Granted - Kind: B2 - Application number: 16/635,297 - Filed: 2018-06-05 - Published: 2021-03-25 - Granted: 2022-04-19 - Earliest claimed: 2017-09-26 - Assignees: MitsubishiI Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Yoshiyuki Kono; Shuhei Fujiwara; Ryosuke Uda; Shigeo Hayashi - Web page: https://patentgrep.com/patent/US11309787B2 ## CPC - H02M 1/32: Means for protecting converters other than automatic disconnection - H02M 5/4585: {having a rectifier with controlled elements} - H02M 7/483: Converters with outputs that each can have more than two voltages levels - 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 3/36: 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 1/325: {with means for allowing continuous operation despite a fault, i.e. fault tolerant converters} - Y02E 60/60: Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD] - 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 - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A power conversion device includes a conversion circuit constituted of a plurality of arm circuits and a bypass circuit. The bypass circuit includes a full-wave rectification circuit, a positive-side connection arm, and a negative-side connection arm. The full-wave rectification circuit is connected between a plurality of AC connections, a positive-side intermediate node, and a negative-side intermediate node, and configured to convert AC voltages generated at the plurality of AC connections into a DC voltage across the positive-side intermediate node and the negative-side intermediate node and output the DC voltage. The positive-side connection arm blocks a current in a direction from a positive-side DC terminal toward the positive-side intermediate node. The negative-side connection arm is connected between the negative-side intermediate node and a negative-side DC terminal and blocks a current in a direction from the negative-side intermediate node toward a negative-side DC terminal. ## Claims ### Claim 1 A power conversion device to convert power between an AC circuit and a DC circuit, the power conversion device comprising: a plurality of positive-side arm circuits connected between a plurality of AC connections connected to the AC circuit and a positive-side DC terminal connected to the DC circuit; a plurality of negative-side arm circuits connected between the plurality of AC connections and a negative-side DC terminal connected to the DC circuit; and a bypass circuit, each of the positive-side arm circuits and each of the negative-side arm circuits each including a plurality of converter cells connected in series, each of the converter cells including: an energy storage; and a bridge circuit to switch connection between the energy storage and outside, the bypass circuit including: a full-wave rectification circuit connected between the plurality of AC connections, a positive-side intermediate node, and a negative-side intermediate node to convert AC voltages generated at the plurality of AC connections into a DC voltage across the positive-side intermediate node and the negative-side intermediate node and output the DC voltage; a positive-side connection arm connected between the positive-side intermediate node and the positive-side DC terminal, the positive-side connection arm blocking a current in a direction from the positive-side DC terminal toward the positive-side intermediate node; and a negative-side connection arm connected between the negative-side intermediate node and the negative-side DC terminal, the negative-side connection arm blocking a current in a direction from the negative-side intermediate node toward the negative-side DC terminal. ### Claim 2 (depends on 1) The power conversion device according to claim 1, wherein each arm constituting the full-wave rectification circuit includes a plurality of diode elements connected in series such that a direction from the negative-side intermediate node toward the positive-side intermediate node is defined as a forward direction, the positive-side connection arm includes a plurality of diode elements connected in series such that a direction from the positive-side intermediate node toward the positive-side DC terminal is defined as the forward direction, and the negative-side connection arm includes a plurality of diode elements connected in series such that a direction from the negative-side DC terminal toward the negative-side intermediate node is defined as the forward direction. ### Claim 3 (depends on 2) The power conversion device according to claim 2, wherein each of the positive-side connection arm and the negative-side connection arm further includes a switching element connected in series to the plurality of diode elements. ### Claim 4 (depends on 3) The power conversion device according to claim 3, wherein the switching element has such a non-linear current and voltage characteristic that when a voltage not lower than a first threshold value is applied, a current flows through the switching element and a voltage across terminals is lowered. ### Claim 5 (depends on 4) The power conversion device according to claim 4, wherein each of the positive-side connection arm and the negative-side connection arm further includes a non-linear element connected in parallel to the switching element, the non-linear element has such a non-linear current and voltage characteristic that when a voltage not lower than a second threshold value is applied, a current flows through the non-linear element and a voltage across terminals is lowered, and the second threshold value is smaller than the first threshold value. ### Claim 6 (depends on 3) The power conversion device according to claim 3, wherein each of the positive-side connection arm and the negative-side connection arm further includes a first resistive element connected in parallel to the switching element. ### Claim 7 (depends on 2) The power conversion device according to claim 2, wherein each diode element included in arms constituting the full-wave rectification circuit, the positive-side connection arm, and the negative-side connection arm is an avalanche diode. ### Claim 8 (depends on 2) The power conversion device according to claim 2, wherein each of arms constituting the full-wave rectification circuit, the positive-side connection arm, and the negative-side connection arm further includes a plurality of second resistive elements connected in parallel to the plurality of diode elements. ### Claim 9 (depends on 3) The power conversion device according to claim 3, wherein the power conversion device has a first operation mode and a second operation mode, in the first operation mode, the switching element is controlled to turn off, in the second operation mode, the switching element is controlled to turn on, and when a short-circuiting failure of the DC circuit is detected, the operation mode of the power conversion device is switched from the first operation mode to the second operation mode. ### Claim 10 (depends on 1) The power conversion device according to claim 1, wherein the bridge circuit included in each of the converter cells is of a half-bridge configuration. ### Claim 11 (depends on 10) The power conversion device according to claim 10, wherein the positive-side connection arm of the bypass circuit is connected to a second positive-side DC terminal provided on a DC line between the positive-side DC terminal and the DC circuit, the negative-side connection arm of the bypass circuit is connected to a second negative-side DC terminal provided on a DC line between the negative-side DC terminal and the DC circuit, and the power conversion device further comprises: a positive-side switch connected between the positive-side DC terminal and the second positive-side DC terminal, the positive-side switch being capable of switching between conduction and non-conduction between the positive-side DC terminal and the second positive-side DC terminal; and a negative-side switch connected between the negative-side DC terminal and the second negative-side DC terminal, the negative-side switch being capable of switching between conduction and non-conduction between the negative-side DC terminal and the second negative-side DC terminal. ### Claim 12 (depends on 11) The power conversion device according to claim 11, wherein the power conversion device has a first operation mode and a second operation mode, in the first operation mode, the positive-side switch and the negative-side switch are controlled to turn on, in the second operation mode, the positive-side switch and the negative-side switch are controlled to turn off, and when a short-circuiting failure of the DC circuit is detected, the operation mode of the power conversion device is switched from the first operation mode to the second operation mode. ### Claim 13 (depends on 1) The power conversion device according to claim 1, wherein each of the positive-side arm circuits and each of the negative-side arm circuits each include at least one first converter cell including a full-bridge or hybrid bridge circuit and at least one second converter cell including a half-bridge bridge circuit. ### Claim 14 (depends on 13) The power conversion device according to claim 13, wherein the energy storage is a capacitor, and the capacitor provided in each first converter cell is higher in capacity than the capacitor provided in each second converter cell. ### Claim 15 (depends on 13) The power conversion device according to claim 13, wherein each first converter cell includes a starting circuit, the starting circuit is a low-voltage circuit started up by a charging voltage of the energy storage, and after the starting circuit is started, the starting circuit controls any one semiconductor switching element constituting the bridge circuit to turn on and controls a remaining semiconductor switching element to turn off. ### Claim 16 (depends on 15) The power conversion device according to claim 15, wherein when the charging voltage of the energy storage reaches a defined voltage, the starting circuit turns on two semiconductor switching elements provided on two arms connected to an identical terminal of the energy storage. ### Claim 17 (depends on 13) The power conversion device according to claim 13, wherein each first converter cell includes a starting circuit, the starting circuit is a low-voltage circuit started up by a charging voltage of the energy storage, and after the starting circuit is started, the starting circuit alternately repeats a first control state and a second control state each for a certain time period, in the first control state, any one semiconductor switching element constituting the bridge circuit is controlled to turn on, and in the second control state, two semiconductor switching elements provided on two arms connected to an identical terminal of the energy storage among four arms constituting the bridge circuit are controlled to turn on. ### Claim 18 (depends on 13) The power conversion device according to claim 13, wherein each first converter cell includes a normally closed switch connected in parallel to any one semiconductor switching element constituting a full bridge or a hybrid bridge. ### Claim 19 A power conversion device to convert power between an AC circuit and a DC circuit, the power conversion device comprising: a plurality of positive-side arm circuits connected between a plurality of AC connections connected to the AC circuit and a positive-side DC terminal connected to the DC circuit; a plurality of negative-side arm circuits connected between the plurality of AC connections and a negative-side DC terminal connected to the DC circuit; and a bypass circuit, each of the positive-side arm circuits and each of the negative-side arm circuits each including a plurality of converter cells connected in series, each of the converter cells including: an energy storage; and a bridge circuit to switch connection between the energy storage and outside, the bypass circuit including; a full-wave rectification circuit connected between the plurality of AC connections, a positive-side intermediate node, and a negative-side intermediate node to convert AC voltages generated at the plurality of AC connections into a DC voltage across the positive-side intermediate node and the negative-side intermediate node and output the DC voltage; a positive-side switch connected between the positive-side intermediate node and the positive-side DC terminal, the positive-side switch being capable of switching between conduction and non-conduction between the positive-side intermediate node and the positive-side DC terminal; and a negative-side switch connected between the negative-side intermediate node and the negative-side DC terminal, the negative-side switch being capable of switching between conduction and non-conduction between the negative-side DC terminal and the negative-side intermediate node. ### Claim 20 (depends on 19) The power conversion device according to claim 19, wherein the power conversion device has a first operation mode and a second operation mode, in the first operation mode, the positive-side switch and the negative-side switch are controlled to turn off, in the second operation mode, the positive-side switch and the negative-side switch are controlled to turn on, and when a short-circuiting failure of the DC circuit is detected, the operation mode of the power conversion device is switched from the first operation mode to the second operation mode.