# US 9,520,798 B2 · Multi-level DC-DC converter with galvanic isolation and adaptive conversion ratio > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,520,798 B2 - Document ID: US9520798B2 - Status: Granted - Kind: B2 - Application number: 14/469,002 - Filed: 2014-08-26 - Published: 2016-03-03 - Granted: 2016-12-13 - Earliest claimed: 2014-08-26 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Ravisekhar Nadimpalli Raju; Rajib Datta; Xu She - Web page: https://patentgrep.com/patent/US9520798B2 ## CPC - H02M 3/285: {Single converters with a plurality of output stages connected in parallel (parallel operation of a plurality of converters in DC distribution networks H02J1/10)} - H02M 3/33571: {Half-bridge at primary side of an isolation transformer} - H02M 3/33573: {Full-bridge at primary side of an isolation transformer} - H02M 1/0074: {Plural converter units whose inputs are connected in series} - 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) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A multi-level DC-DC converter includes an input side to receive a DC power having an input voltage and current, an output side to provide power to a load at a desired output voltage and current, and a plurality of tranformer-isolated DC-DC converters connected between the input and output sides, with the tranformer-isolated DC-DC converters being connected in series on one side and connected in parallel on another side. Each of the tranformer isolated DC-DC converters further includes a power transformer having a primary winding and a secondary winding, and a plurality of switching devices each selectively operable in one of an On state and an Off state. Operating the switching devices in a complementary On state and Off state alternately at a controlled switching frequency provides for engaging the tranformer isolated DC-DC converter and operating the switching devices in a simultaneously On state bypasses the transformer isolated DC-DC converter. ## Claims ### Claim 1 A multi-level DC-DC converter comprising: an input side to receive a DC power having an input voltage and current; an output side to provide power to a load at a desired output voltage and current; and a plurality of tranformer-isolated DC-DC converters connected between the input side and the output side, with the plurality of tranformer-isolated DC-DC converters being connected in series on one side and connected in parallel on another side; wherein each of the plurality of tranformer isolated DC-DC converters comprises: a power transformer comprising a primary winding arranged in an input side converter stage on the input side and a secondary winding arranged in an output side converter stage on the output side; and a plurality of switching devices each selectively operable in one of an On state and an Off state, wherein operating the plurality of switching devices in a complementary On state and Off state alternately at a controlled switching frequency provides for engaging the tranformer isolated DC-DC converter and operating the plurality of switching devices in a simultaneously On state bypasses the transformer isolated DC-DC converter. ### Claim 2 (depends on 1) The multi-level DC-DC converter of claim 1 further comprising a rectifier circuit configured to rectify AC power from an AC power source to a DC power, with the DC power being provided to the plurality of tranformer isolated DC-DC converters. ### Claim 3 (depends on 1) The multi-level DC-DC converter of claim 1 wherein the plurality of switching devices in each tranformer isolated DC-DC converter comprises a half-bridge circuit. ### Claim 4 (depends on 1) The multi-level DC-DC converter of claim 1 wherein the plurality of switching devices in each tranformer isolated DC-DC converter comprises a full-bridge circuit. ### Claim 5 (depends on 1) The multi-level DC-DC converter of claim 1 wherein each of the plurality of tranformer isolated DC-DC converters further comprises one or more capacitors configured to store and release DC power received on the input side. ### Claim 6 (depends on 5) The multi-level DC-DC converter of claim 5 further comprising a controller in operable communication with the arrangement of switching devices to selectively operate each of the plurality of switching devices in one of the On state and the Off state. ### Claim 7 (depends on 6) The multi-level DC-DC converter of claim 6 wherein, for each of the plurality of transformer isolated DC-DC converters, the controller is programmed to operate a plurality of switching devices in the On state so as to bypass the respective input capacitors, such that a respective transformer isolated DC-DC converter can be disengaged. ### Claim 8 (depends on 7) The multi-level DC-DC converter of claim 7 wherein the controller is programmed to selectively cause one or more of the transformer isolated DC-DC converters to be bypassed, so as to control a conversion ratio of the multi-level DC-DC converter. ### Claim 9 (depends on 1) The multi-level DC-DC converter of claim 1 wherein, for each of the plurality of transformer isolated DC-DC converters, the controller is programmed to selectively operate each of the plurality of switching devices in the On state and the Off state such that the respective transformer isolated DC-DC converter is engaged at a peak of an AC cycle. ### Claim 10 (depends on 1) The multi-level DC-DC converter of claim 1 wherein one or more of the plurality of tranformer isolated DC-DC converters comprises a chopper stage to feed the input side converter stage of the respective tranformer isolated DC-DC converter, the chopper stage performing modulation to provide for regulation of the voltage and/or current output from the respective tranformer isolated DC-DC converter. ### Claim 11 (depends on 1) The multi-level DC-DC converter of claim 1 wherein the output side converter stage of each of the plurality of tranformer isolated DC-DC converters comprises one of a diode rectifier or an arrangement of active switching devices. ### Claim 12 (depends on 1) The multi-level DC-DC converter of claim 1 wherein the plurality of switching devices are operated at a substantially fixed frequency and duty ratio. ### Claim 13 A multi-level DC-DC converter comprising: an input side to receive a DC power having an input voltage and current; an output side to provide power to a load at a desired output voltage and current; a plurality of tranformer isolated DC-DC converters connected between the input side and the output side such that the plurality of tranformer isolated DC-DC converters are connected in series on one side and connected in parallel on the other side, each of the plurality of tranformer isolated DC-DC converters including a bridge circuit therein; and a controller in operable communication with each of the plurality of tranformer isolated DC-DC converters to selectively operate each respective bridge circuit, the controller being programmed to: determine a desired value of a voltage conversion ratio between the input voltage and the output voltage; and control operation of the bridge circuit in each respective tranformer isolated DC-DC converter based on the desired value of the voltage conversion ratio; wherein one or more of the tranformer isolated DC-DC converters may be shorted based on the controlled operation of the respective bridge circuits, so as to bypass one or more of the tranformer isolated DC-DC converters and set the voltage conversion ratio to the desired value. ### Claim 14 (depends on 13) The multi-level DC-DC converter of claim 13 wherein each of the plurality of tranformer isolated DC-DC converters further comprises: an input capacitor arranged in parallel with the bridge circuit; and a power transformer comprising a primary winding arranged on the input side and a secondary winding arranged on the output side. ### Claim 15 (depends on 14) The multi-level DC-DC converter of claim 14 wherein, for each of the plurality of transformer isolated DC-DC converters, the controller is programmed to operate the bridge circuit so as to bypass the input capacitor, such that a respective transformer isolated DC-DC converter is bypassed. ### Claim 16 (depends on 13) The multi-level DC-DC converter of claim 13 wherein one or more of the plurality of tranformer isolated DC-DC converters comprises a chopper stage to feed the input side converter stage of the respective tranformer isolated DC-DC converter, the chopper stage performing modulation to provide for regulation of the voltage and/or current output from the respective tranformer isolated DC-DC converter. ### Claim 17 (depends on 13) The multi-level DC-DC converter of claim 13 wherein the bridge circuit in each of the plurality of tranformer isolated DC-DC converters comprises one of a half-bridge circuit and a full bridge circuit. ### Claim 18 A method of manufacturing a multi-level DC-DC converter, the method comprising: providing a plurality of tranformer isolated DC-DC converters, each of the plurality of tranformer isolated DC-DC converters comprising: a power transformer comprising a primary winding arranged in an input side converter stage and a secondary winding arranged in an output side converter stage; and a plurality of switching devices arranged in the input side converter stage, with each of the plurality of switching devices being selectively operable in one of an On state and an Off state to control voltage and current flow to the primary winding; connecting the plurality of tranformer isolated DC-DC converters in series on one side of the multi-level DC-DC converter and in parallel on another side of the multi-level DC-DC converter; and providing a controller that is in operable communication with each of the plurality of tranformer isolated DC-DC converters and the plurality of switching devices therein, with the controller being programmed to operate the plurality of switching devices in each respective tranformer isolated DC-DC converter in one of the On state and the Off state so as to selectively engage and disengage the respective tranformer isolated DC-DC converter. ### Claim 19 (depends on 18) The method of claim 18 wherein each of the plurality of tranformer isolated DC-DC converters further comprises one or more input capacitors that are selectively shorted based on the operation of the plurality of switching devices in one of the On state and the Off state, so as to so as to selectively engage and disengage the respective tranformer isolated DC-DC converter. ### Claim 20 (depends on 18) The method of claim 18 wherein one or more of the plurality of tranformer isolated DC-DC converters further comprises a chopper stage that performs a modulation to provide for regulation of an input voltage or current provided to a respective tranformer isolated DC-DC converter.