# US 2018/0025828 A1 · Insulation type step-down converter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0025828 A1 - Document ID: US20180025828A1 - Status: Published application - Kind: A1 - Application number: 15/541,400 - Filed: 2016-02-19 - Published: 2018-01-25 - Earliest claimed: 2015-03-27 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Koji NAKAJIMA; Takashi KUMAGAI; Yuji SHIRAKATA; Yujiro KIDO; Kenji NISHIZAKA - Web page: https://patentgrep.com/patent/US20180025828A1 ## CPC - H01F 27/2804: {Printed windings} - H01F 27/2876: {Cooling (cooling transformers and inductances in general H01F27/08)} - H01F 27/40: Structural association with built-in electric component, e.g. fuse - H02M 3/335: using semiconductor devices only - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H05K 1/0298: {Multilayer circuits} - H05K 1/115: {Via connections; Lands around holes or via connections (H05K1/112 takes precedence)} - H01F 27/2809: {on stacked layers} - H01F 27/2819: {Planar transformers with printed windings, e.g. surrounded by two cores and to be mounted on printed circuit} - H01F 27/408: {Association with diode or rectifier} - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - 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) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract An insulation type step-down converter includes first and second step-down transformers each of which includes an input-side coil and an output-side coil. An intermediate portion of the output-side coil of the first step-down transformer and an intermediate portion of the output-side coil of the second step-down transformer are connected to each other. First, second, third, and fourth rectifier elements are connected in series with first, second, third, and fourth output-side coils, respectively. Smoothing coils are connected to the first to fourth output-side coils. The first, second, third, and fourth rectifier elements are connected such that electric currents flow simultaneously in the first output-side coil and the third output-side coil, and electric currents flow simultaneously in the second output-side coil and the fourth output-side coil in a manner alternating with the electric currents in the first output-side coil and the third output-side coil. ## Claims ### Claim 1 An insulation type step-down converter comprising first and second step-down transformers aligned with each other, the first step-down transformer including a first core including a first middle leg, a first one outer leg spaced from the first middle leg and arranged to extend in a direction identical to the first middle leg, and a first other outer leg spaced from the first middle leg opposite to the first one outer leg, a first input-side coil wound around the first middle leg of the first core, and first and second output-side coils wound around the first middle leg of the first core, overlapping at least part of the first input-side coil and spaced from each other, the second step-down transformer including a second core including a second middle leg, a second one outer leg spaced from the second middle leg and arranged to extend in a direction identical to the second middle leg, and a second other outer leg spaced from the second middle leg opposite to the second one outer leg, a second input-side coil wound around the second middle leg of the second core, and third and fourth output-side coils wound around the second middle leg of the second core, overlapping at least part of the second input-side coil and spaced from each other, the insulation type step-down converter further comprising: a first rectifier element connected in series with the first output-side coil; a second rectifier element connected in series with the second output-side coil; a third rectifier element connected in series with the third output-side coil; a fourth rectifier element connected in series with the fourth output-side coil; and first and second smoothing coils each connected to two of the serial connections between the first to fourth output-side coils and the first to fourth rectifier elements, the first output-side coil includes a first end connected to a reference potential and a second end located opposite to the first end and connected to the first rectifier element, the second output-side coil includes a first end connected to the reference potential and a second end located opposite to the first end and connected to the second rectifier element, the third output-side coil includes a first end connected to the reference potential and a second end located opposite to the first end and connected to the third rectifier element, the fourth output-side coil includes a first end connected to the reference potential and a second end located opposite to the first end and connected to the fourth rectifier element, and each of the first, second, third and fourth output-side coils has an intermediate portion at a part of a path from the first end toward the second end, the intermediate portion of the first output-side coil and the intermediate portion of the third output-side coil being connected to each other, the intermediate portion of the second output-side coil and the intermediate portion of the fourth output-side coil being connected to each other, the first, second, third, and fourth rectifier elements being connected such that electric currents flow simultaneously in the first output-side coil and the third output-side coil, and electric currents flow simultaneously in the second output-side coil and the fourth output-side coil in a manner alternating with the electric currents in the first output-side coil and the third output-side coil, so as to cancel out magnetic fluxes passing through the middle legs each time when electric current flowing in the first and second input-side coils is changed in direction. ### Claim 2 (depends on 1) The insulation type step-down converter according to claim 1, wherein the first output-side coil and the third output-side coil are integrated and partly shared with each other, and the second output-side coil and the fourth output-side coil are integrated and partly shared with each other. ### Claim 3 (depends on 1) The insulation type step-down converter according to claim 1, wherein the first output-side coil, the third output-side coil, and a connection portion connecting the intermediate portion of the first output-side coil and the intermediate portion of the third output-side coil are arranged on an identical layer, and the second output-side coil, the fourth output-side coil, and a connection portion connecting the intermediate portion of the second output-side coil and the intermediate portion of the fourth output-side coil are arranged on an identical layer. ### Claim 4 (depends on 1) The insulation type step-down converter according to claim 1, further comprising a multilayer printed board having a plurality of patterns stacked therein, wherein the first, second, third and fourth output-side coils are arranged as the plurality of stacked patterns included in the multilayer printed board, the first output-side coil and the third output-side coil are arranged on layers different from each other, and the intermediate portion of the first output-side coil and the intermediate portion of the third output-side coil are connected to each other by a via interposed between the different layers, and the second output-side coil and the fourth output-side coil are arranged on layers different from each other, and the intermediate portion of the second output-side coil and the intermediate portion of the fourth output-side coil are connected to each other by a via interposed between the different layers. ### Claim 5 (depends on 1) The insulation type step-down converter according to claim 1, further comprising an input-side drive circuit configured to apply voltages to the first and second input-side coils alternately in directions opposite to each other at regular time intervals. ### Claim 6 (depends on 1) The insulation type step-down converter according to claim 1, further comprising: a radiator arranged to come into contact with the first and second step-down transformers; and an insulating component arranged between the radiator and at least one of the first and second input-side coils and at least one of the first, second, third, and fourth output-side coils, wherein heat generated by at least one of the first and second input-side coils and at least one of the first, second, third, and fourth output-side coils is transferred to the radiator through the insulating component. ### Claim 7 (depends on 6) The insulation type step-down converter according to claim 6, wherein at least one of the first, second, third, and fourth output-side coils is arranged between the radiator and at least one of the first and second input-side coils, and the radiator is arranged as the reference potential of an output-side circuit including the first, second, third, and fourth output-side coils of the first and second step-down transformers. ### Claim 8 (depends on 6) The insulation type step-down converter according to claim 6, wherein the radiator comes into contact with an intermediate portion between the first output-side coil and the third output-side coil or an intermediate portion between the second output-side coil and the fourth output-side coil, through the insulating component. ### Claim 9 (depends on 1) The insulation type step-down converter according to claim 1, wherein each of the first, second, third, and fourth output-side coils is formed as a flat plate component made of copper.