# US 10,122,256 B1 · Method and apparatus for zero-current switching control in switched-capacitor converters > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,122,256 B1 - Document ID: US10122256B1 - Status: Granted - Kind: B1 - Application number: 15/648,764 - Filed: 2017-07-13 - Granted: 2018-11-06 - Earliest claimed: 2017-07-13 - Assignees: Infineon Technologies Austria AG - Applicants: Infineon Technologies Austria AG - Inventors: Amir Babazadeh; Rakesh Renganathan; Danny Clavette; Christian Rainer - Web page: https://patentgrep.com/patent/US10122256B1 ## CPC - H02M 3/073: {Charge pumps of the Schenkel-type} - H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters - H02M 1/083: {for the ignition at the zero crossing of the voltage or the current} - H02M 3/01: {Resonant DC/DC converters} - H02M 3/18: using capacitors or batteries which are alternately charged and discharged, e.g. charged in parallel and discharged in series - H02M 3/33571: {Half-bridge at primary side of an isolation transformer} - H02M 7/219: in a bridge configuration - H02M 1/0009: {Devices or circuits for detecting current in a converter} - 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 - 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 switched-capacitor converter includes a plurality of legs coupled between the input and a rectifier at the output. Each leg includes a capacitor. A first group of legs is coupled to a first branch of the rectifier, and a second group is coupled to a second branch of the rectifier. A switch device is connected to each leg. The controller alternates switching of the switch devices connected to the first and second groups of legs to transfer energy from input to output. The switching is modified based on zero-crossing information which indicates when current through each switch device crosses or nearly crosses zero, so that each switch device connected to the same group of legs is turned off when current through that switch device crosses or nearly crosses zero and remains off until all switch devices connected to that group have been turned off for a predetermined amount of time. ## Claims ### Claim 1 A switched-capacitor converter, comprising: an input; an output; a rectifier at the output; a plurality of legs coupled between the input and the rectifier, each leg comprising a capacitor, a first group of the legs being coupled to a first branch of the rectifier and a second group of the legs being coupled to a second branch of the rectifier; a switch device connected to each leg; and a controller operable to alternate switching of the switch devices connected to the first and the second groups of legs to transfer energy from the input to the output, wherein the switching is modified based on zero-crossing information which indicates, for each leg of the first group of legs, when current through the switch device connected to said each leg crosses or nearly crosses zero, so that each switch device connected to a leg within the first group of legs is turned off when the current through that switch device crosses or nearly crosses zero and remains off until all switch devices connected to legs within the first group of legs have been turned off for a predetermined amount of time, and wherein at least two switch devices connected to legs within the first group of legs are turned on for partially overlapping time intervals within a switching cycle, the partially overlapping time intervals having different time durations. ### Claim 2 (depends on 1) The switched-capacitor converter of claim 1, wherein the zero-crossing information comprises sensed current through each switch device. ### Claim 3 (depends on 1) The switched-capacitor converter of claim 1, wherein the zero-crossing information comprises a derivative of a sensed capacitor voltage across each capacitor of the legs. ### Claim 4 (depends on 1) The switched-capacitor converter of claim 1, wherein the controller is operable to produce an individual PWM (pulse width modulation) signal for switching each switch device, and wherein the controller is operable to adjust the duty cycle of each PWM signal based on the zero-crossing information for the corresponding switch device so that the duty cycle for each switch device corresponds to the zero-crossing current of that switch device. ### Claim 5 (depends on 1) The switched-capacitor converter of claim 1, wherein each switch device connected to the first group of legs is implemented as an integrated power stage configured to sense output current of the power stage, wherein the controller is operable to produce a single PWM (pulse width modulation) signal for switching each switch device connected to the first group of legs, and wherein each integrated power stage is operable to adjust the duty cycle of the PWM signal based on the output current of the power stage so that the duty cycle for the switch device included in the power stage corresponds to the zero-crossing current of that switch device. ### Claim 6 (depends on 1) The switched-capacitor converter of claim 1, wherein each leg in the first group includes an inductor connected to the capacitor of that leg, wherein the inductor is formed by a first winding of a current transformer, and wherein the zero-crossing information for each leg in the first group is obtained by a sense circuit connected to a second winding of the current transformer of that leg, the sense circuit being configured to sense the zero-crossing current of the switch device connected to the corresponding leg. ### Claim 7 (depends on 1) The switched-capacitor converter of claim 1, wherein each leg in the first group includes an inductor connected to the capacitor of that leg, and wherein the zero-crossing information for each leg in the first group is obtained by a DCR sense circuit connected to the inductor of that leg, the DCR sense circuit being configured to sense the zero-crossing current of the switch device connected to the corresponding leg. ### Claim 8 (depends on 1) The switched-capacitor converter of claim 1, wherein each leg in the first group includes an inductor connected to the capacitor of that leg, and wherein the zero-crossing information for each leg in the first group is obtained by a sense circuit configured to sense a voltage across the inductor of that leg, referenced to ground, and wherein the controller is operable to account for mismatch in sensing the zero-crossing of a voltage across each inductor. ### Claim 9 (depends on 1) The switched-capacitor converter of claim 1, wherein each switch device connected to the first group of legs is implemented as an integrated power stage configured to sense output current of the power stage, and wherein the zero-crossing information for each leg in the first group is derived from the output current sensed by the integrated power stage of that leg. ### Claim 10 (depends on 1) The switched-capacitor converter of claim 1, wherein the zero-crossing information for each leg is derived from an on-state resistance measurement for the switch device connected to that leg. ### Claim 11 (depends on 1) The switched-capacitor converter of claim 1, wherein each branch of the rectifier comprises an integrated power stage configured to sense current through that branch, and wherein the zero-crossing information for each leg is derived from the current sensed by the integrated power stage of the branch coupled to that leg. ### Claim 12 (depends on 1) The switched-capacitor converter of claim 1, wherein the controller is operable to switch the first group of legs on during a first part of each switching cycle and off during a second part of each switching cycle, wherein the controller is operable to switch the second group of legs off during the first part of each switching cycle and on during the second part of each switching cycle, and wherein the controller is operable to use the same zero-crossing information determined for the present switching cycle to modify the point at which each switch device connected to the first group of legs is switched off during the first part of the present switching cycle and modify the point at which each switch device connected to the second group of legs is switched off during the second part of the present switching cycle. ### Claim 13 (depends on 1) The switched-capacitor converter of claim 1, wherein the controller is operable to switch the first group of legs on during a first part of each switching cycle and off during a second part of each switching cycle, wherein the controller is operable to switch the second group of legs off during the first part of each switching cycle and on during the second part of each switching cycle, wherein the controller is operable to use first zero-crossing information determined for the first part of the present switching cycle to modify the point at which each switch device connected to the first group of legs is switched off during the first part of the present switching cycle, and wherein the controller is operable to use second zero-crossing information determined for the second part of the present switching cycle to modify the point at which each switch device connected to the second group of legs is switched off during the second part of the present switching cycle. ### Claim 14 A method of operating a switched-capacitor converter that includes an input, an output, a rectifier at the output, and a plurality of legs coupled between the input and the rectifier, each leg comprising a capacitor, a first group of the legs being coupled to a first branch of the rectifier and a second group of the legs being coupled to a second branch of the rectifier, and a switch device connected to each leg, the method comprising: alternately switching the switch devices connected to the first and the second groups of legs to transfer energy from the input to the output; and modifying the switching based on zero-crossing information which indicates, for each leg of the first group of legs, when current through the switch device connected to said each leg crosses or nearly crosses zero, so that each switch device connected to a leg within the first group of legs is turned off when the current through said each switch device crosses or nearly crosses zero and remains off until all switch devices connected to legs within the first group of legs have been turned off for a predetermined amount of time, wherein the modified switching turns on at least two switch devices connected to legs within the first group of legs for partially overlapping time intervals within a switching cycle, the partially overlapping time intervals having different time durations. ### Claim 15 (depends on 14) The method of claim 14, further comprising: determining the zero-crossing information based on sensed current through each switch device. ### Claim 16 (depends on 14) The method of claim 14, further comprising: determining the zero-crossing information based on a derivative of a sensed capacitor voltage across each capacitor of the legs. ### Claim 17 (depends on 14) The method of claim 14, further comprising: producing an individual PWM (pulse width modulation) signal for switching each switch device; and adjusting the duty cycle of each PWM signal based on the zero-crossing information for the corresponding switch device, so that the duty cycle for each switch device corresponds to the zero-crossing current of that switch device. ### Claim 18 (depends on 14) The method of claim 14, wherein each switch device connected to the first group of legs is implemented as an integrated power stage configured to sense output current of the power stage, the method further comprising: producing a single PWM (pulse width modulation) signal for switching each switch device connected to the first group of legs; and adjusting the duty cycle of the PWM signal at each integrated power stage based on the output current of that power stage, so that the duty cycle for the switch device included in the power stage corresponds to the zero-crossing current of that switch device. ### Claim 19 (depends on 14) The method of claim 14, wherein each switch device connected to the first group of legs is implemented as an integrated power stage configured to sense output current of the power stage, the method further comprising: deriving the zero-crossing information for each leg in the first group from the output current sensed by the integrated power stage of that leg. ### Claim 20 (depends on 14) The method of claim 14, wherein each branch of the rectifier comprises an integrated power stage configured to sense current through that branch, the method further comprising: deriving the zero-crossing information for each leg from the current sensed by the integrated power stage of the branch coupled to that leg. ### Claim 21 (depends on 14) The method of claim 14, further comprising: switching the first group of legs on during a first part of each switching cycle and off during a second part of each switching cycle; switching the second group of legs off during the first part of each switching cycle and on during the second part of each switching cycle; and modifying the point at which each switch device connected to the first group of legs is switched off during the first part of the present switching cycle and the point at which each switch device connected to the second group of legs is switched off during the second part of the present switching cycle, based on the same zero-crossing information determined for the present switching cycle. ### Claim 22 (depends on 14) The method of claim 14, further comprising: switching the first group of legs on during a first part of each switching cycle and off during a second part of each switching cycle; switching the second group of legs off during the first part of each switching cycle and on during the second part of each switching cycle; modifying the point at which each switch device connected to the first group of legs is switched off during the first part of the present switching cycle, based on first zero-crossing information determined for the first part of the present switching cycle; and modifying the point at which each switch device connected to the second group of legs is switched off during the second part of the present switching cycle, based on second zero-crossing information determined for the second part of the present switching cycle.