# US 2018/0323698 A1 · Capacitor discharge device inside sub module of mmc converter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0323698 A1 - Document ID: US20180323698A1 - Status: Published application - Kind: A1 - Application number: 15/772,999 - Filed: 2016-06-22 - Published: 2018-11-08 - Earliest claimed: 2015-11-03 - Assignees: Hyosung Corporation - Applicants: Hyosung Corporation - Inventors: Jae Hoon OH; Doo Young LEE; Ji Hoon KIM - Web page: https://patentgrep.com/patent/US20180323698A1 ## CPC - 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} - H01H 47/223: {adapted to be supplied by AC} - H01H 50/18: Movable parts of magnetic circuits, e.g. armature - H01H 50/44: Magnetic coils or windings - H01H 50/54: Contact arrangements - H02M 1/32: Means for protecting converters other than automatic disconnection - H02M 7/493: the static converters being arranged for operation in parallel - H02M 1/0048: {Circuits or arrangements for reducing losses (using snubbers H02M1/34)} - H02M 1/322: {Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock} - 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) - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract Provided is a capacitor discharge device that quickly and safely discharges a capacitor charged with energy inside a sub-module of an MMC converter, the device including: a capacitor storing a DC voltage inside a sub-module of an MMC converter; a power supply unit supplying operating power required in the submodule by using the voltage stored in the capacitor; a first resistor connected in parallel to the capacitor; a second resistor having a lower resistance value and a larger heat capacity than the first resistor so as to rapidly discharge the capacitor storing the voltage; a first switching contact connecting and disconnecting the capacitor and the second resistor; a switching unit operating switching of the first switching contact by the operating power; a second switching contact connecting and disconnecting the power supply unit and the switching unit; and a control unit operating switching of the second switching contact. ## Claims ### Claim 1 A capacitor discharge device inside a sub-module of an MMC converter, the device comprising: a capacitor storing a direction current (DC) voltage inside a sub-module of an MMC converter; a power supply unit supplying operating power required in the sub-module by using the voltage stored in the capacitor; a first resistor connected in parallel to the capacitor; a second resistor having a lower resistance value and a larger heat capacity than the first resistor so as to rapidly discharge the capacitor storing the voltage therein; a first switching contact connecting and disconnecting the capacitor and the second resistor; a switching unit operating switching of the first switching contact by the operating power supplied from the power supply unit; a second switching contact connecting and disconnecting the power supply unit and the switching unit; and a control unit operating switching of the second switching contact. ### Claim 2 (depends on 1) The device of claim 1, wherein in an initial state of the sub-module, the first switching contact and the second switching contact remain in an on state, respectively. ### Claim 3 (depends on 2) The device of claim 2, wherein when the voltage stored in the capacitor increases to a preset reference voltage or more, the power supply unit is activated and outputs the operating power, and when the voltage decreases to the reference voltage or less, the power supply unit is deactivated and output of the operating power is blocked. ### Claim 4 (depends on 3) The device of claim 3, wherein when the operating power is supplied to the switching unit, the switching unit operates switching of the first switching contact to turn off the first switching contact. ### Claim 5 (depends on 4) The device of claim 4, wherein when the supplying of the operating power to the switching unit is blocked, the first switching contact returns in the initial state and remains in the on state. ### Claim 6 (depends on 3) The device of claim 3, wherein before the voltage stored in the capacitor falls to the reference voltage, the control unit operates switching of the second switching contact to turn on the second switching contact, such that the operating power from the power supply unit is supplied to the switching unit. ### Claim 7 (depends on 6) The device of claim 6, wherein when the supplying of the operating power to the switching unit is blocked, the first switching contact returns in the initial state and remains in the on state. ### Claim 8 (depends on 1) The device of claim 1, wherein the switching unit includes: a coil wound a preset number of times in a constant radius; and a metal member position inside the wound coil, wherein the metal member is physically connected to the first switching contact, and is linearly moved by a current flowing in the coil, such that switching of the first switching contact is performed. ### Claim 9 (depends on 8) The device of claim 8, wherein the metal member is linearly moved from a preset initial position by a magnetic force generated by the current flowing in the coil, such that the first switching contact is turned off, and when the current is blocked, the metal member returns to the initial position such than the first switching contact is turned on.