# US 10,122,281 B2 · Power conversion device for cancelling leakage current > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,281 B2 - Document ID: US10122281B2 - Status: Granted - Kind: B2 - Application number: 15/262,789 - Filed: 2016-09-12 - Published: 2016-12-29 - Granted: 2018-11-06 - Earliest claimed: 2014-08-25 - Assignees: Fuji Electric Co., Ltd. - Applicants: Fuji Electric Co., Ltd. - Inventors: Qichen Wang; Satoru Fujita - Web page: https://patentgrep.com/patent/US10122281B2 ## CPC - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H02M 1/44: Circuits or arrangements for compensating for electromagnetic interference in converters or inverters - H02M 7/217: using semiconductor devices only - H02M 7/487: Neutral point clamped inverters - H02M 1/123: {Suppression of common mode voltage or current} - 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) ## Abstract A power conversion device includes a potential variation suppression portion having first and second ground capacitors and a reactor, for suppressing a potential variations at an A point at which switching elements and are connected together and at a B point in a bidirectional switch. The potential variation suppression portion suppresses potential variation at the A point by cancelling a first leakage current, which flows due to the potential variation at the A point at the positive and negative polarities of an alternating current voltage, with a first compensating current flowing via the reactor and ground capacitor, and suppresses the potential variation at the B point by cancelling a second leakage current, which flows due to the potential variation at the B point at the negative polarity of the alternating current voltage, with a second compensating current flowing via the reactor, a switch, and the second ground capacitor. ## Claims ### Claim 1 A power conversion device, comprising: first and second semiconductor switching elements connected together at a first connection point; third and fourth semiconductor switching elements connected together at a second connection point, the first, second, third, and fourth semiconductor switching elements configured to convert power from a power source and to supply the power to a load; a voltage potential variation suppression device configured to suppress voltage potential variations at the first connection point and the second connection point, the voltage potential variation suppression device comprising a reactor, a first ground capacitor and a second ground capacitor, the reactor including a main winding connected to the first connection point, and an auxiliary winding connected to the first and second ground capacitors, the main winding and the auxiliary winding being configured such that a voltage in the main winding generates an induced voltage in the auxiliary winding having a polarity opposite from the voltage in the main winding, the reactor and the first ground capacitor being connected between the first connection point and ground, the reactor and the second ground capacitor being connected between the second connection point and ground, wherein the voltage potential variation suppression device is configured to suppress the voltage potential variations at the first connection point by cancelling a first leakage current, which flows to a ground point from the first connection point via a parasitic capacitance due to the voltage potential variation at the first connection point at first and second opposing polarities of an alternating current voltage, with a first compensating current flowing via the reactor and the first ground capacitor connected to the first connection point, and the voltage potential variation suppression device is configured to suppress the voltage potential variations at the second connection point by cancelling a second leakage current, which flows to the ground point from the second connection point via a parasitic capacitance due to the voltage potential variation at the second connection point at the second polarity of the alternating current voltage, with a second compensating current flowing via the reactor and the second ground capacitor. ### Claim 2 (depends on 1) The power conversion device according to claim 1, wherein the third and fourth semiconductor switching elements are connected in anti-series to form a bidirectional switch, the second connection point located between the third and fourth semiconductor switching elements, and the first connection point connected to one of the third and fourth semiconductor switching elements. ### Claim 3 (depends on 2) The power conversion device according to claim 2, wherein the voltage potential variation suppression device includes a switch, through which the auxiliary winding is connected to the second ground capacitor, and the switch is configured to open based on a voltage of the first polarity of the alternating current voltage applied to the first connection point and to close based on a voltage of the second polarity of the alternating current voltage applied to the first connection point. ### Claim 4 (depends on 2) The power conversion device according to claim 2, wherein the first to fourth semiconductor switching elements perform a switching operation to convert an alternating current voltage to a direct current voltage. ### Claim 5 (depends on 2) The power conversion device according to claim 2, wherein the first to fourth semiconductor switching elements perform a switching operation to convert a direct current voltage to an alternating current voltage. ### Claim 6 (depends on 2) The power conversion device according to claim 2, wherein the first to fourth semiconductor switching elements perform a switching operation to convert an alternating current voltage to an alternating current voltage of a different magnitude. ### Claim 7 (depends on 1) The power conversion device according to claim 1, wherein the voltage potential variation suppression device further includes a switch, through which the auxiliary winding is connected to the second ground capacitor, and the switch is configured to open based on a voltage of the first polarity of the alternating current voltage applied to the first connection point and to close based on a voltage of the second polarity of the alternating current voltage applied to the first connection point. ### Claim 8 (depends on 7) The power conversion device according to claim 7, wherein the switch is a fifth semiconductor switching element configured to open and close in accordance with the polarity of the induced voltage in the auxiliary winding. ### Claim 9 (depends on 1) The power conversion device according to claim 1, wherein the first to fourth semiconductor switching elements perform a switching operation to convert an alternating current voltage to a direct current voltage. ### Claim 10 (depends on 1) The power conversion device according to claim 1, wherein the first to fourth semiconductor switching elements perform a switching operation to convert a direct current voltage to an alternating current voltage. ### Claim 11 (depends on 1) The power conversion device according to claim 1, wherein the first to fourth semiconductor switching elements perform a switching operation to convert an alternating current voltage to an alternating current voltage of a different magnitude. ### Claim 12 (depends on 3) The power conversion device according to claim 3, wherein each of the main winding and the auxiliary winding has a first end and a second end, the first end of the main winding is connected to the first connection point, the second end of the main winding is connected to the first end of the auxiliary winding, and the second end of the auxiliary winding is connected to the first ground capacitor, and to the second ground capacitor via the switch. ### Claim 13 (depends on 7) The power conversion device according to claim 7, wherein each of the main winding and the auxiliary winding has a first end and a second end, the first end of the main winding is connected to the first connection point, the second end of the main winding is connected to the first end of the auxiliary winding, and the second end of the auxiliary winding is connected to the first ground capacitor, and to the second ground capacitor via the switch.