# US 12,224,668 B2 · Boost converter and method of controlling a boost converter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,668 B2 - Document ID: US12224668B2 - Status: Granted - Kind: B2 - Application number: 18/014,331 - Filed: 2021-06-23 - Published: 2023-09-21 - Granted: 2025-02-11 - Earliest claimed: 2020-08-17 - Assignees: Signify Holding B.V. - Applicants: Signify Holding B.V. - Inventors: Yu Wang; Zhiquan Chen; Jie Fu; Shan Wang; Gang Wang - Web page: https://patentgrep.com/patent/US12224668B2 ## CPC - H02M 3/1588: {comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence)} - H02M 1/36: Means for starting or stopping converters - H05B 45/38: using boost topology - 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) - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A boost converter has a main energy storage inductor and a main GaN boost switch with a node between them. A pre-charging switch is connected at the output side of the main boost switch and the inductor, between the node and an output capacitor. The pre-charging switch comprises a body diode in the forward direction from the output capacitor to the node. The output capacitor is charged by the pre-charging switch in a pre-charge phase and this provides a soft start-up to avoid large inrush currents. A third switch, which is also a GaN switch, is in series with the pre-charging switch to provide synchronous output rectification. The third switch has a body diode in a forward direction from the node to the output capacitor. In the pre-charge phase, both the boost switch and third switch are turned off whereas in a subsequent boost phase, the pre-charging switch is turned constantly on, and alternately the boost switch and the third switch are turned on and off to implement the boost conversion. ## Claims ### Claim 1 A boost converter comprising: a DC input; a boost inductor and a boost switch connected to the DC input, with a node defined between them; an output capacitor; a pre-charging switch connected between the node and the output capacitor, adapted to be conductive to charge the output capacitors from the node in a pre-charge phase, characterized in that: the pre-charging switch comprises a body diode in the forward direction from the output capacitor to the node; the boost converter further comprises a third switch in series with the pre-charging switch, having a source terminal connected to the output capacitor, and having a body diode in a forward direction from the node to the output capacitor, wherein the boost switch and the third switch each comprises a GaN switch and the pre-charging switch comprising a silicon MOSFET; in a pre-charge phase, both the boost switch and third switch are turned off, and the pre-charging switch is operated in a PWM manner to charge the output capacitor, and the body diode of the third switch is adapted to allow a current from the input to the output capacitor when the pre-charging switch is turned on and to block the reverse current from the output capacitor through the body diode of the pre-charging switch when the pre-charging switch is turned off; and in a boost phase after the pre-charge phase, the pre-charging switch is turned constantly on and the boost switch and the third switch are turned on and off oppositely to implement the boost conversion. ### Claim 2 (depends on 1) The boost converter of claim 1, wherein the duty cycle of the PWM of the pre-charging switch is increased from 0% to 100% during the pre-charge phase. ### Claim 3 (depends on 1) The boost converter of claim 1, further comprising an AC mains input and a rectifier, wherein the output of the rectifier comprises said DC input. ### Claim 4 (depends on 3) The boost converter of claim 3, comprising a filtering network across the output of the rectifier, said filtering network comprises a pi-filter including two filtering capacitors and a filtering inductor. ### Claim 5 (depends on 3) The boost converter of claim 3, comprising a non-switched coupling between the AC mains input and the rectifier. ### Claim 6 (depends on 1) The boost converter of claim 1, wherein the output capacitor comprises an electrolytic capacitor. ### Claim 7 (depends on 1) The boost converter of claim 1, wherein in a shut down phase, a shut down signal for the pre-charging switch is adapted to lag behind shut down signals for the third switch and the boost switch. ### Claim 8 (depends on 1) The boost converter of claim 1, wherein the boost mode is a continuous conduction mode. ### Claim 9 (depends on 1) A LED driver comprising: a boost converter according to claim 1, as a PFC stage; a switch mode power converter coupled to an output of the PFC stage; and an output of the switch mode power converter for delivering power to a LED load. ### Claim 10 (depends on 9) The LED driver of claim 9, wherein the switch mode power converter comprises an LLC resonant converter. ### Claim 11 (depends on 9) A lighting unit, comprising: the LED driver of claim 9 and the LED load. ### Claim 12 A method of controlling a boost converter, wherein the boost converter comprises: a DC input; a boost inductor and a GaN boost switch connected to the DC input, with a node defined between them; an output capacitor; a pre-charging switch connected between the node and the output capacitor, the pre-charging switch comprising a body diode in the forward direction from the output capacitor to the node; and a third, GaN, switch in series with the pre-charging switch and having a body diode in a forward direction from the node to the output capacitor, wherein the method comprises: implementing a pre-charge phase by turning off both the boost switch and the third switch, and operating the pre-charging switch in PWM manner to charge the output capacitor and the body diode of the third switch—is adapted to allow a current from the input to the output capacitor when the pre-charging switch is turned on and to block the reverse current from the output capacitor through the body diode of the pre-charging switch when the pre-charging switch is turned off; and implementing a boost phase after the pre-charge phase, by turning the pre-charging switch constantly on and oppositely turning on and off the boost switch and the third switch to implement the boost conversion. ### Claim 13 (depends on 12) The method claim 12, comprising operating the pre-charging switch in a PWM manner and increasing the duty cycle of the pre-charging switch from 0% to 100% during the pre-charge phase. ### Claim 14 (depends on 12) The method of claim 12, comprising, in a shut down phase, generating a shut down signal for the pre-charging switch which lags behind shut down signals for the third switch and the boost switch. ### Claim 15 (depends on 1) The boost converter of claim 1, wherein the frequency of the PWM of the pre-charging switch is in a range of 1 kHz to 10 kHz. ### Claim 16 (depends on 12) The method of claim 12, wherein the frequency of the PWM of the pre-charging switch is in a range of 1 kHz to 10 kHz.