# US 10,771,002 B2 · Device for stabilizing direct current (DC) distribution system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,771,002 B2 - Document ID: US10771002B2 - Status: Granted - Kind: B2 - Application number: 16/124,327 - Filed: 2018-09-07 - Published: 2019-03-14 - Granted: 2020-09-08 - Earliest claimed: 2017-09-08 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Seongju Kim; Mun Seok Seo; Joonsik An - Web page: https://patentgrep.com/patent/US10771002B2 ## CPC - H02P 27/08: with pulse width modulation - F04B 35/04: the means being electric - H02M 1/083: {for the ignition at the zero crossing of the voltage or the current} - H02M 1/088: for the simultaneous control of series or parallel connected semiconductor devices - H02M 1/143: {using compensating arrangements (for reducing noise from the supply in transmission systems H04B15/005)} - H02M 7/53871: {with automatic control of output voltage or current} - H02M 1/0058: {by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826)} - 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 - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) - 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 A device for stabilizing a direct current (DC) distribution system includes a capacitor unit charged by a DC voltage supplied by a power supply stage of the distribution system. The device further includes an inverter that has three pair of switching elements. The device also includes a voltage stabilization circuit constructed using one pair out of the three pairs of switching elements in the inverter. The device also includes a controller that controls the voltage stabilization circuit to alleviate instability of a DC voltage generated in a transient period. ## Claims ### Claim 1 A device for stabilizing a direct current (DC) distribution system, wherein the system includes a power supply stage, the device comprising: a capacitor unit charged by a DC voltage supplied from the power supply stage; an inverter unit including two pairs of driving switching elements and a pair of common switching elements, wherein the inverter unit is configured to use the two pairs of driving switching elements to convert the voltage charged in the capacitor unit into an AC power and to provide the AC power to a motor connected to the device; a voltage stabilization unit including the pair of common switching elements and at least one passive element, wherein the voltage stabilization unit is configured, based on a charging or discharging signal, to charge the capacitor unit with the DC voltage supplied from the power supply stage or to discharge the voltage charged in the capacitor unit to the power supply stage; and a control unit configured to compare the DC voltage supplied from the power supply stage with a reference range, and to provide the charging or discharging signal to the voltage stabilization unit based on the comparison result. ### Claim 2 (depends on 1) The device of claim 1, wherein the power supply stage is connected to a DC power supply for outputting the DC voltage or to a converter for converting an AC power supply to the DC voltage. ### Claim 3 (depends on 1) The device of claim 1, wherein the motor drives a reciprocating compressor. ### Claim 4 (depends on 1) The device of claim 1, wherein the control unit is configured to provide a driving signal to the inverter unit, wherein the driving signal is configured for controlling turn-on or turn-off of the two pairs of driving switching elements. ### Claim 5 (depends on 1) The device of claim 1 further comprising a voltage sensor provided in the power supply stage, wherein the voltage sensor measures the DC voltage supplied from the power supply stage. ### Claim 6 (depends on 5) The device of claim 5, wherein the control unit is configured to receive a measured value of the DC voltage from the voltage sensor and to compare the received measured value with the reference range. ### Claim 7 (depends on 1) The device of claim 1, wherein when the DC voltage exceeds the reference range, the control unit is configured to provide a charging signal to the voltage stabilization unit, wherein when the DC voltage is smaller than the reference range, the control unit is configured to provide a discharging signal to the voltage stabilization unit. ### Claim 8 (depends on 1) The device of claim 1, wherein the common switching elements are turned on or off based on the charging or discharging signal. ### Claim 9 (depends on 1) The device of claim 1, wherein the passive element includes a first inductor having one end connected to a node between the pair of common switching element, and further includes a second inductor or a capacitor connected to the other end of the first inductor. ### Claim 10 (depends on 1) The device of claim 1, wherein the pair of common switching elements includes a first common switching element and a second common switching element, wherein the voltage stabilization unit includes: a first inductor having one end connected to a node between the first common switching element and the second common switching element, and the other end connected to a positive terminal of the power supply stage; and a first capacitor having one end connected to the positive terminal of the power supply stage and the other end connected to a negative terminal of the power supply stage. ### Claim 11 (depends on 10) The device of claim 10, wherein the voltage stabilization unit is configured to charge the capacitor unit with a current stored in the first inductor or to discharge the voltage charged in the capacitor unit to the power supply stage through the first inductor. ### Claim 12 (depends on 10) The device of claim 10, wherein the voltage stabilization unit is configured to, in response to a charging signal, turn on the second common switching element and turn off the first common switching element for a predetermined time, so that a current output from the power supply stage is stored in the first inductor. ### Claim 13 (depends on 12) The device of claim 12, wherein, after the predetermined time has elapsed, the voltage stabilization unit is configured to turn off the common switching elements, so that the capacitor unit is charged with the current stored in the first inductor. ### Claim 14 (depends on 10) The device of claim 10, wherein the voltage stabilization unit is configured to, in response to a discharge signal, turn on the first common element and turn off the second common switching element for a predetermined time, so that the voltage charged in the capacitor unit is discharged to the power supply stage via the first inductor. ### Claim 15 (depends on 1) The device of claim 1, wherein the capacitor unit includes a first capacitor and a second capacitor, wherein the pair of common switching elements includes a first common switching element and a second common switching element, wherein the first and second capacitors are coupled in series to each other, wherein the capacitor unit is coupled in parallel with the power supply stage, and wherein the voltage stabilization unit includes: a second inductor having one end connected to a node between the pair of common switching elements and the other end connected to a node between the first capacitor and second capacitor; and a third inductor having one end connected to the second inductor and the other end connected to the first capacitor. ### Claim 16 (depends on 15) The device of claim 15, wherein the voltage stabilization unit is configured to charge the first capacitor with a current stored in the second inductor or to discharge the voltage charged in the first capacitor to the power supply stage through the second inductor. ### Claim 17 (depends on 15) The device of claim 15, wherein the voltage stabilization unit is configured to, in response to a charging signal, turn on the second common switching element and turn off the first common switching element for a predetermined time, so that a current output from the power supply stage is stored in the second inductor. ### Claim 18 (depends on 17) The device of claim 17, wherein, after the predetermined time has elapsed, the voltage stabilization unit is configured to turn off the common switching elements, so that the first capacitor is charged by the current stored in the second inductor. ### Claim 19 (depends on 15) The device of claim 15, wherein the voltage stabilization unit is configured to, in response to a discharge signal, turn on the first common element and turn off the second common switching element for a preset time, so that the voltage charged in the first capacitor is discharged to the power supply stage through the second inductor. ### Claim 20 (depends on 1) The device of claim 1, wherein said one pair of common switching elements are configured to perform zero voltage switching (ZVS) based on the charging or discharging signal.