# US 8,542,467 B2 · Switching device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,467 B2 - Document ID: US8542467B2 - Status: Granted - Kind: B2 - Application number: 13/014,004 - Filed: 2011-01-26 - Published: 2011-07-28 - Granted: 2013-09-24 - Earliest claimed: 2010-01-26 - Assignees: Denso Corporation - Applicants: Nobuhisa Yamaguchi - Inventors: Nobuhisa Yamaguchi - Web page: https://patentgrep.com/patent/US8542467B2 ## CPC - H02M 7/5387: in a bridge configuration - H02M 7/003: {Constructional details, e.g. physical layout, assembly, wiring or busbar connections} - 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 switching device includes a plurality of semiconductor switching elements coupled in series, a smoothing capacitor, and snubber circuit. Each of the semiconductor switching elements includes a free wheel diode. The smoothing capacitor is coupled in parallel with a direct current power source and the semiconductor switching elements. The smoothing capacitor smoothes an output of the direct current power source and supplies the smoothed output to the semiconductor switching elements. The snubber circuit is coupled between a first connecting point and a second connecting point in parallel with the semiconductor switching elements. An inductance of a first channel provided from the first connecting point to the second connecting point through the smoothing capacitor is equal to or more than 10 times as large as an inductance of a second channel including the semiconductor switching elements and the snubber circuit. ## Claims ### Claim 1 A switching device comprising: a plurality of semiconductor switching elements coupled in series, each of the plurality of semiconductor switching elements including a free wheel diode; a smoothing capacitor coupled in parallel with a direct current power source and the plurality of semiconductor switching elements, the smoothing capacitor smoothing an output of the direct current power source and supplying the smoothed output to the plurality of semiconductor switching elements; and a snubber circuit coupled between a first connecting point and a second connecting point in parallel with the plurality of semiconductor switching elements, wherein an inductance of a first channel provided from the first connecting point to the second connecting point through the smoothing capacitor is equal to or more than 10 times as large as an inductance of a second channel including the plurality of semiconductor switching elements and the snubber circuit so as to reduce a power dissipation associated with a recovery current of the free wheel diode. ### Claim 2 (depends on 1) The switching device according to claim 1, wherein the inductance of the first channel includes stray inductances of the smoothing capacitor and wirings in the first channel, and the inductance of the second channel includes stray inductances of the plurality of semiconductor switching elements, the snubber circuit, and wirings in the second channel. ### Claim 3 (depends on 1) The switching device according to claim 1, further comprising a coil dispose in the first channel, wherein the inductance of the first channel includes stray inductances of the smoothing capacitor and wirings in the first channel and an inductance of the coil, and the inductance of the second channel includes stray inductances of the plurality of semiconductor switching elements, the snubber circuit, and wirings in the second channel. ### Claim 4 (depends on 1) The switching device according to claim 1, wherein the snubber circuit includes a capacitor or a capacitor and a resistor coupled in series. ### Claim 5 (depends on 1) The switching device according to claim 1, wherein the snubber circuit includes a rectifying element and a capacitor coupled in series, and a resistor coupled in parallel with the rectifying element. ### Claim 6 (depends on 1) The switching device according to claim 1, wherein the snubber circuit includes a first resistor, a rectifying element, and a capacitor coupled in series, and a second resistor coupled in parallel with the rectifying element. ### Claim 7 (depends on 1) The switching device according to claim 1, wherein the snubber circuit includes a first resistor, a rectifying element, and a capacitor coupled in series, and a second resistor coupled in parallel with the first resistor and the rectifying element coupled in series. ### Claim 8 (depends on 7) The switching device according to claim 7, wherein the first resistor is an internal resistor of the rectifying element. ### Claim 9 (depends on 5) The switching device according to claim 5, wherein the rectifying element includes a diode. ### Claim 10 (depends on 9) The switching device according to claim 9, wherein the rectifying element includes a silicon carbide schottky barrier diode. ### Claim 11 (depends on 9) The switching device according to claim 9, wherein the rectifying element includes a silicon carbide junction barrier schottky diode. ### Claim 12 (depends on 1) The switching device according to claim 1, wherein the inductance of the second channel is equal to or less than 10 nH. ### Claim 13 (depends on 1) A power converter comprising the switching device according to claim 1, wherein the switching device is configured to convert a power from the direct current power source.