# US 12,113,435 B2 · Active-clamp forward converter with regenerative snubber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,113,435 B2 - Document ID: US12113435B2 - Status: Granted - Kind: B2 - Application number: 17/806,261 - Filed: 2022-06-09 - Published: 2022-12-15 - Granted: 2024-10-08 - Earliest claimed: 2021-06-09 - Assignees: Delta Electronics (Thailand) Public Co., Ltd. - Applicants: Delta Electronics (Thailand) Public Co., Ltd. - Inventors: Philipp Rehlaender; Bastian Korthauer; Frank Schafmeister; Joachim Böcker - Web page: https://patentgrep.com/patent/US12113435B2 ## CPC - H02M 1/342: {Active non-dissipative snubbers} - H02M 3/01: {Resonant DC/DC converters} - H02M 3/33538: {of the forward type (H02M3/3353, H02M3/33569 take precedence)} - H02M 3/33571: {Half-bridge at primary side of an isolation transformer} - H02M 3/33592: {having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer} - 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 power converter-circuit (100) having a transformer (T), comprising a snubber-circuit (Csn, DSn,S3, S3, DSn,S4) for suppressing voltage peaks on a secondary side of the transformer (T) that comprises a snubber capacitor (Csn); and an auxiliary DC-DC converter (101) having a first input connected with the snubber capacitor (Csn) and a first output connected with a first output (VOut) of the power converter-circuit (100). This circuit increases efficiency of electrical conversion and reduces thermal losses. ## Claims ### Claim 1 A power converter-circuit having a transformer, comprising: a snubber-circuit for suppressing voltage peaks on a secondary side of the transformer that comprises a snubber capacitor; and an auxiliary DC-DC converter having a first input connected with the snubber capacitor and a first output connected with a first output of the power converter-circuit; wherein the auxiliary DC-DC converter is a multiphase buck converter in which a number of n buck converter circuits are placed in parallel between an input and an output of the auxiliary DC-DC converter, and wherein a phase of each of the n buck converters is turned on at equally spaced intervals over a switching period. ### Claim 2 (depends on 1) The power converter-circuit according to claim 1, wherein the power converter-circuit is a DC-DC converter or a PWM-based DC-DC converter. ### Claim 3 (depends on 2) The power converter-circuit according to claim 2, wherein the power converter circuit is an Active Clamped Forward Converter. ### Claim 4 (depends on 1) The power converter-circuit according to claim 1, wherein the buck-converter comprises a transistor and a diode for controlling the current in an inductor. ### Claim 5 (depends on 4) The power converter-circuit according to claim 4, wherein the buck-converter is a synchronous buck converter comprising a synchronous rectifier. ### Claim 6 (depends on 1) The power converter-circuit according to claim 1, wherein a second input of the auxiliary DC-DC converter is connected with a ground potential. ### Claim 7 (depends on 1) The power converter-circuit according to claim 1, wherein a second output of the auxiliary DC-DC converter is connected with a ground potential. ### Claim 8 (depends on 1) The power converter-circuit according to claim 1, wherein at least one synchronous rectifier for rectifying an output voltage of the power converter-circuit is arranged on the secondary side. ### Claim 9 A converting method for a power converter-circuit having a transformer, comprising the steps of: suppressing voltage peaks on a secondary side of the transformer with a snubber circuit that comprises a snubber capacitor; returning energy from the snubber capacitor to a first output of the power converter-circuit by means of an auxiliary DC-DC converter having a first input connected with the snubber capacitor and a first output connected with the first output of the power converter-circuit; wherein the auxiliary DC-DC converter is a multiphase buck converter in which a number of n buck converter circuits are placed in parallel between an input and an output of the auxiliary DC-DC converter; and turning on a phase of each of the n buck converters at equally spaced intervals over a switching period. ### Claim 10 (depends on 9) The method according to claim 9, wherein the converter circuit is an Active Clamped Forward Converter. ### Claim 11 (depends on 9) The method according to claim 9, wherein the voltage of the snubber capacitor is controlled by the auxiliary DC-DC converter. ### Claim 12 (depends on 10) The method according to claim 10, wherein the voltage of the snubber capacitor is controlled by the auxiliary DC-DC converter. ### Claim 13 (depends on 9) The method according to claim 9, wherein the current in an inductor of the auxiliary DC-DC converter is controlled by a transistor and a rectifier. ### Claim 14 (depends on 10) The method according to claim 10, wherein the current in an inductor of the auxiliary DC-DC converter is controlled by a transistor and a rectifier. ### Claim 15 (depends on 11) The method according to claim 11, wherein the current in an inductor of the auxiliary DC-DC converter is controlled by a transistor and a rectifier. ### Claim 16 (depends on 9) The method according to claim 9, wherein rectifying an output voltage of the power converter-circuit is performed by at least one synchronous rectifier arranged on the secondary side.