# US 12,224,662 B2 · LLC resonant converter with variable turns ratio > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,662 B2 - Document ID: US12224662B2 - Status: Granted - Kind: B2 - Application number: 17/966,833 - Filed: 2022-10-15 - Published: 2024-03-07 - Granted: 2025-02-11 - Earliest claimed: 2022-09-05 - Assignees: Phihong Technology Co., Ltd. - Applicants: Phihong Technology Co., Ltd. - Inventors: Chun-Chen Chen; Jian-Hsieng Lee; Yao-Chun Tung - Web page: https://patentgrep.com/patent/US12224662B2 ## CPC - H02M 3/015: {with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuit} - H02M 1/12: Arrangements for reducing harmonics from AC input or output - 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 3/003: {Constructional details, e.g. physical layout, assembly, wiring or busbar connections} - H02M 3/33573: {Full-bridge at primary side of an isolation transformer} - H02M 3/33576: {having at least one active switching element 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 An LLC resonant converter with variable turns ratio includes a switching circuit coupled to a DC input voltage for converting the DC voltage into switching signal, a resonant tank coupled to the switching circuit and configured to receive the switching signal to provide a primary current, a transformer circuit coupled to the resonant tank. The transformer circuit includes a plurality of separated transformers, each has a primary side winding and a side secondary side winding, where individual transformer has different turns of primary side winding, which can be dynamically selected to couple with the primary side winding of other transformers in series or in parallel to form a dynamically changing equivalent primary side winding, so that the turns ratio in the transformer circuit can be dynamically changed accordingly. ## Claims ### Claim 1 An LLC converter with variable turns ratio, said LLC converter comprising: a switching circuit coupled to an input DC voltage for converting said input DC voltage into a switching signal; a resonant tank electrically coupled to said switching circuit, said resonant tank including a resonant inductor, a magnetizing inductor and a resonant capacitor connected in series to receive said switching signal for providing a primary current; a transformer circuit electrically coupled to said resonant tank, said transformer circuit having a plurality of discrete transformers, each of said discrete transformers containing a primary winding and a secondary winding, wherein said primary winding of each of said discrete transformers have different turns and are dynamically selected to be electrically coupled or isolated from said resonant tank, and are dynamically selected to be connected in series or in parallel with said primary side windings of other transformers to form a dynamically changed equivalent primary winding of said transformer circuit; wherein turns of said secondary winding of each of said discrete transformers are fixed and the same, so that turns ratio of said transformer circuit can be dynamically changed accordingly; and a rectifying and filtering circuit electrically coupled to said transformer circuit to rectify and filter a secondary current outputted by said secondary winding for providing an output voltage; wherein one end of said resonant inductor is electrically coupled to said switching circuit and another end of said resonant inductor is connected in series to said equivalent primary winding; wherein said magnetizing inductor is connected in series to said resonant inductor, said resonant capacitor with one end is connected in series to said magnetizing inductor and said equivalent primary winding, and with another end is coupled to said switching circuit; wherein said magnetizing inductor is connected in parallel to said equivalent primary winding. ### Claim 2 (depends on 1) The LLC converter with variable turns ratio of claim 1, wherein said equivalent primary winding is formed by arranging a plurality of switches to dynamically adjust coupling between said primary windings. ### Claim 3 (depends on 2) The LLC converter with variable turns ratio of claim 2, wherein said plurality of switches are transistor switching devices or relays. ### Claim 4 (depends on 3) The LLC converter with variable turns ratio of claim 3, wherein inductance of said resonant inductor, inductance of said magnetizing inductor and said turns ratio are dynamically adjusted by said plurality of switches. ### Claim 5 (depends on 1) The LLC converter with variable turns ratio of claim 1, wherein said primary windings and said secondary windings are fabricated on a multi-layered printed circuit board (PCB) to reduce stray characteristics caused by wiring. ### Claim 6 (depends on 5) The LLC converter with variable turns ratio of claim 5, further including an adjustable capacitor disposed on said multi-layered PCB and been integrated into said primary windings and said secondary windings of said transformer circuit to form an additional resonant capacitor. ### Claim 7 (depends on 6) The LLC converter with variable turns ratio of claim 6, wherein said adjustable capacitor is formed by fabricating a plurality of metal plates with fixed area and size at same location on each layer of said multi-layered PCB, and said plurality of metal plates together with a plurality of dielectric layers therein between are combined to form said adjustable capacitor. ### Claim 8 (depends on 7) The LLC converter with variable turns ratio of claim 7, wherein said adjustable capacitor changes resonant capacitance of said resonant tank by adjusting distance between said metal plates and by changing configuration of positive and negative terminals of said metal plates. ### Claim 9 (depends on 6) The LLC converter with variable resonant tank of claim 6, wherein capacitance of said additional resonant capacitor is configured to coupled with said resonant capacitor in parallel, in series or completely isolated by arranging a plurality of switches between said additional resonant capacitor and said windings of said transformer circuit. ### Claim 10 (depends on 4) The LLC converter with variable turns ratio of claim 4, wherein said plurality of switches are configured to dynamically adjust turns ratio of said transformer circuit by sending turns ratio adjustment signals to said transformer circuit through an external controller coupled to said LLC resonant converter, according to received feedback of output voltage and feedback of output current respectively to achieve increasing of range of output voltage and current of said LLC resonant converter. ### Claim 11 (depends on 9) The LLC converter with variable turns ratio of claim 9, wherein said plurality of switches are configured to dynamically adjust capacitance of said resonant capacitor by sending resonant capacitor adjustment signals to said resonant tank through an external controller coupled to said LLC resonant converter, according to received feedback of output voltage and feedback of output current respectively to achieve increasing of range of output voltage and current of said LLC resonant converter. ### Claim 12 (depends on 10) The LLC converter with variable turns ratio of claim 10, wherein said external controller is a microprocessor, microcontroller or a digital processor. ### Claim 13 (depends on 1) The LLC converter with variable turns ratio of claim 1, wherein said plurality of discrete transformers form an array-typed transformer. ### Claim 14 (depends on 11) The LLC converter with variable turns ratio of claim 11, wherein said external controller is a microprocessor, microcontroller or a digital processor. ### Claim 15 An LLC converter with variable turns ratio, said LLC converter comprising: a switching circuit coupled to an input DC voltage for converting said input DC voltage into a switching signal; a resonant tank electrically coupled to said switching circuit, said resonant tank including a resonant inductor, a magnetizing inductor and a resonant capacitor connected in series to receive said switching signal for providing a primary current; a transformer circuit electrically coupled to said resonant tank, said transformer circuit having a plurality of discrete transformers, each of said discrete transformers containing a primary winding and a secondary winding, wherein said primary winding of each of said discrete transformers have fixed turns and are dynamically selected to be electrically coupled or isolated from said resonant tank, and are dynamically selected to be connected in series or in parallel with said primary side windings of other transformers to form a dynamically changed equivalent primary winding of said transformer circuit; wherein turns of said secondary winding of each of said discrete transformers are varied, so that turns ratio of said transformer circuit can be dynamically changed accordingly; and a rectifying and filtering circuit electrically coupled to said transformer circuit to rectify and filter a secondary current outputted by said secondary winding for providing an output voltage; wherein one end of said resonant inductor is electrically coupled to said switching circuit and another end of said resonant inductor is connected in series to said equivalent primary winding; wherein said magnetizing inductor is connected in series to said resonant inductor, said resonant capacitor with one end is connected in series to said magnetizing inductor and said equivalent primary winding, and with another end is coupled to said switching circuit; wherein said magnetizing inductor is connected in parallel to said equivalent primary winding. ### Claim 16 (depends on 15) The LLC converter with variable turns ratio of claim 15, wherein said equivalent primary winding is formed by arranging a plurality of switches to dynamically adjust coupling between said primary windings. ### Claim 17 (depends on 16) The LLC converter with variable turns ratio of claim 16, wherein said plurality of switches are transistor switching devices or relays. ### Claim 18 (depends on 17) The LLC converter with variable turns ratio of claim 17, wherein inductance of said resonant inductor, inductance of said magnetizing inductor and said turns ratio are dynamically adjusted by said plurality of switches. ### Claim 19 (depends on 15) The LLC converter with variable turns ratio of claim 15, wherein said primary windings and said secondary windings are fabricated on a multi-layered printed circuit board (PCB) to reduce stray characteristics caused by wiring. ### Claim 20 (depends on 19) The LLC converter with variable turns ratio of claim 19, further including an adjustable capacitor disposed on said multi-layered PCB and integrated into said primary windings and said secondary windings of said transformer circuit to form an additional resonant capacitor, wherein said adjustable capacitor is formed by fabricating a plurality of metal plates with fixed area and size at same location on each layer of said multi-layered PCB, and wherein said plurality of metal plates together with a plurality of dielectric layers therein between are combined to form said adjustable capacitor.