# US 12,224,671 B2 · Power supply circuit with two power conversion circuits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,224,671 B2 - Document ID: US12224671B2 - Status: Granted - Kind: B2 - Application number: 18/069,527 - Filed: 2022-12-21 - Published: 2023-04-20 - Granted: 2025-02-11 - Earliest claimed: 2020-07-03 - Assignees: Murata Manufacturing Co., Ltd. - Applicants: Murata Manufacturing Co., Ltd. - Inventors: Kazuaki Mino - Web page: https://patentgrep.com/patent/US12224671B2 ## CPC - H02M 3/33569: {having several active switching elements (H02M3/3353 takes precedence)} - H02M 1/007: {Plural converter units in cascade (push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826)} - H02M 1/008: {Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators} - H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters - H02M 1/32: Means for protecting converters other than automatic disconnection - H02M 1/4225: {using a non-isolated boost converter} - H02M 1/4283: {by adding a controlled rectifier in parallel to a first rectifier feeding a smoothing capacitor} - H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - 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} - H02M 7/217: using semiconductor devices only - H02M 7/537: using semiconductor devices only, e.g. single switched pulse inverters - H02M 1/0009: {Devices or circuits for detecting current in a converter} - 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 supply circuit includes a transformer having a primary winding and secondary windings, a first power conversion circuit configured to convert a DC voltage into an AC voltage and output the AC voltage to the primary winding, a rectifying and smoothing circuit that is connected to the secondary winding and is configured to rectify and smooth an alternating current output from the secondary winding, and a second power conversion circuit configured to boost a direct current output from the rectifying and smoothing circuit and supply to a load a DC voltage lower than a rated voltage of the load set in advance. ## Claims ### Claim 1 A power supply circuit comprising: a transformer comprising a primary winding and a secondary winding; a first power conversion circuit configured to convert a DC voltage into an AC voltage and output the AC voltage to the primary winding; a rectifying and smoothing circuit configured to rectify and smooth an AC voltage output from the secondary winding; a second power conversion circuit configured to boost a DC voltage output from the rectifying and smoothing circuit and supply to, a first load, a DC voltage lower than a rated voltage of the first load set in advance; and a controller configured to: determine whether an input voltage of the second power conversion circuit falls within a first reference voltage range set in advance, and control the first power conversion circuit, wherein, when the controller is configured to determine that the input voltage of the second power conversion circuit is greater than or equal to an upper limit of the first reference voltage range, the controller is configured to control the first power conversion circuit so as to reduce an output voltage of the second power conversion circuit, and when the controller is configured to determine that the input voltage of the second power conversion circuit is greater than or equal to the upper limit of the first reference voltage range after the control of the first power conversion circuit, the controller is configured to stop the first power conversion circuit. ### Claim 2 (depends on 1) The power supply circuit according to claim 1, wherein the secondary winding comprises two secondary windings. ### Claim 3 (depends on 2) The power supply circuit according to claim 2, wherein at least one of the two secondary windings is provided on a side of the first load. ### Claim 4 (depends on 2) The power supply circuit according to claim 2, wherein at least one of the two secondary windings includes a pair of sub-windings. ### Claim 5 (depends on 1) The power supply circuit according to claim 1, wherein the controller is further configured to control the second power conversion circuit, and wherein, when the controller is configured to determine that the input voltage of the second power conversion circuit is greater than or equal to the upper limit of the first reference voltage range, the controller is configured to stop the second power conversion circuit. ### Claim 6 (depends on 1) The power supply circuit according to claim 1, wherein the controller is further configured to: determine whether an output voltage of the second power conversion circuit falls within a second reference voltage range set in advance, and control the second power conversion circuit, wherein the second power conversion circuit comprises a second inductor, a first end of which is connected to a high-potential-side output terminal of the rectifying and smoothing circuit, and a second switching element connected between a second end of the second inductor and a low-potential-side output terminal of the rectifying and smoothing circuit, and wherein, when the controller is configured to determine that the input voltage of the second power conversion circuit falls within the first reference voltage range set in advance and the controller is configured to determine that the output voltage of the second power conversion circuit is greater than or equal to an upper limit of the second reference voltage range, the controller is further configured to control an ON/OFF operation of the second switching element to reduce the output voltage of the second power conversion circuit. ### Claim 7 (depends on 6) The power supply circuit according to claim 6, wherein the controller is further configured to determine whether a current flowing through the second switching element is greater than or equal to a current threshold value set in advance, and wherein, when the controller is configured to determine that a current value of the current flowing through the second switching element is greater than or equal to the current threshold value, the controller is configured to maintain the second switching element in an OFF state. ### Claim 8 (depends on 7) The power supply circuit according to claim 7, wherein, when the controller is configured to determine that the current value of the current flowing through the second switching element in an ON state is less than the current threshold value after an elapse of a reference time period set in advance from a time at which the second switching element has been brought into the OFF state, the controller is configured to restart the ON/OFF operation of the second switching element. ### Claim 9 (depends on 6) The power supply circuit according to claim 6, wherein the controller is further configured to determine whether a current flowing through the second switching element is greater than or equal to a current threshold value set in advance, and wherein, when the controller is configured to determine that a current value of the current flowing through the second switching element is greater than or equal to the current threshold value, the controller is further configured to reduce a duty ratio of the second switching element. ### Claim 10 (depends on 1) The power supply circuit according to claim 1, further comprising a third power conversion circuit configured to convert an alternating current into a direct current and output the direct current from the secondary winding to a second load, the second load being different from the first load. ### Claim 11 (depends on 10) The power supply circuit according to claim 10, wherein the third power conversion circuit comprises a plurality of switching elements. ### Claim 12 (depends on 11) The power supply circuit according to claim 11, wherein at least one of the plurality of switching elements comprises a drain that is connected to a first end of the secondary winding. ### Claim 13 (depends on 1) The power supply circuit according to claim 1, further comprising a power factor correction circuit configured to improve a power factor of an alternating current that is supplied from a system. ### Claim 14 (depends on 13) The power supply circuit according to claim 13, wherein the power factor correction circuit comprises a plurality of inductors, a plurality of switching elements, and a plurality of diodes. ### Claim 15 (depends on 14) The power supply circuit according to claim 14, further comprising one or more smoothing capacitors. ### Claim 16 (depends on 15) The power supply circuit according to claim 15, wherein at least one of the one or more smoothing capacitors is connected between a first switching element and a second switching element. ### Claim 17 (depends on 1) The power supply circuit according to claim 1, further comprising a diode bridge configured to rectify an alternating current supplied from a system. ### Claim 18 (depends on 17) The power supply circuit according to claim 17, wherein the diode bridge comprises a high-potential-side output terminal and a low-potential-side output terminal. ### Claim 19 (depends on 18) The power supply circuit according to claim 18, further comprising a first smoothing capacitor, wherein a first end of the first smoothing capacitor is connected to the low-potential-side output terminal of the diode bridge. ### Claim 20 (depends on 1) The power supply circuit according to claim 1, wherein the rectifying and smoothing circuit comprises one or more diodes, and a smoothing capacitor, wherein a first end of the smoothing capacitor is connected to one of the one or more diodes, and a second end of the smoothing capacitor is connected to the secondary winding.