# US 2025/0085368 A1 · Isolated resonant power supply circuit, magnetic resonance imaging system, and air-core transformer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0085368 A1 - Document ID: US20250085368A1 - Status: Published application - Kind: A1 - Application number: 18/882,443 - Filed: 2024-09-11 - Published: 2025-03-13 - Earliest claimed: 2023-09-13 - Assignees: GE Precision Healthcare LLC - Applicants: GE Precision Healthcare LLC - Inventors: Hong Gu; Haiyuan Sun; Yue Ma; Yalu Wu; Chunlai Xiao - Web page: https://patentgrep.com/patent/US20250085368A1 ## CPC - G01R 33/3614: {RF power amplifiers} - G01R 33/3852: {Gradient amplifiers; means for controlling the application of a gradient magnetic field to the sample, e.g. a gradient signal synthesizer} - H01F 27/2804: {Printed windings} - H02M 1/0032: {Control circuits allowing low power mode operation, e.g. in standby mode} - 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)} - H02M 3/003: {Constructional details, e.g. physical layout, assembly, wiring or busbar connections} - H02M 3/015: {with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuit} - H02M 3/33571: {Half-bridge at primary side of an isolation transformer} - H02M 3/33573: {Full-bridge at primary side of an isolation transformer} - H02M 7/4815: {Resonant converters (H02M7/4811 and H02M7/4826 take precedence)} - 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 - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - 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 isolated resonant power supply circuit, a magnetic resonance imaging system, and an air-cored transformer is provided. The isolated resonant power supply circuit is disposed within a scan room of a magnetic resonance imaging system. The isolated resonant power supply circuit includes: an inverter circuit, a resonant transformer circuit, and a rectifier circuit. The inverter circuit is connected to the resonant transformer circuit and is used for converting inputted direct current power into alternating current power and outputting the same to the resonant transformer circuit. The resonant transformer circuit is used for performing resonant conversion and transformation on the alternating current power, and then output the same to the rectifier circuit. The rectifier circuit is used for rectifying an alternating current output voltage outputted by the resonant transformer circuit into a direct current voltage for output, so as to supply power. The resonant transformer circuit comprises a variable capacitance circuit and an inductor, and by changing an input voltage of the variable capacitance circuit, an equivalent capacitance value of the variable capacitance circuit is caused to change. ## Claims ### Claim 1 An isolated resonant power supply circuit, disposed within a scan room of a magnetic resonance imaging system, the isolated resonant power supply circuit comprising: an inverter circuit, a resonant transformer circuit, and a rectifier circuit, the inverter circuit being connected to the resonant transformer circuit and being used for converting inputted direct current power into alternating current power and outputting the same to the resonant transformer circuit, the resonant transformer circuit being used for performing resonant conversion and transformation on the alternating current power, and then outputting the same to the rectifier circuit, and the rectifier circuit being used for rectifying an alternating current output voltage outputted by the resonant transformer circuit into a direct current voltage for output, so as to supply power, wherein the resonant transformer circuit comprises a variable capacitance circuit and an inductor, and by changing an input voltage of the variable capacitance circuit, an equivalent capacitance value of the variable capacitance circuit is caused to change. ### Claim 2 (depends on 1) The isolated resonant power supply circuit according to claim 1, wherein the variable capacitance circuit comprises a first capacitor, a second capacitor, and a variable resistor, wherein one end of the second capacitor is connected to one end of the variable resistor, the other end of the second capacitor is connected to one end of the first capacitor, and the other end of the first capacitor is connected to the other end of the variable resistor, wherein by changing an input voltage of the variable resistor to change the input voltage of the variable capacitance circuit, the equivalent capacitance value of the variable capacitance circuit is caused to change. ### Claim 3 (depends on 2) The isolated resonant power supply circuit according to claim 2, wherein the variable resistor is a switching transistor operating in a linear region. ### Claim 4 (depends on 3) The isolated resonant power supply circuit according to claim 3, wherein by changing the input voltage of the variable resistor to change a degree of linear conduction of the switching transistor, the equivalent capacitance value of the variable capacitance circuit is caused to change. ### Claim 5 (depends on 3) The isolated resonant power supply circuit according to claim 3, wherein the isolated resonant power supply circuit further comprises: a voltage feedback circuit, used for feeding the direct current voltage outputted by the rectifier circuit back to the variable capacitance circuit; and a feedback voltage of the voltage feedback circuit is used as the input voltage of the variable resistor. ### Claim 6 (depends on 5) The isolated resonant power supply circuit according to claim 5, wherein the voltage feedback circuit is connected to a gate of the switching transistor. ### Claim 7 (depends on 5) The isolated resonant power supply circuit according to claim 5, wherein by changing the feedback voltage, the equivalent capacitance value of the variable capacitance circuit is caused to change between a first value and a second value, wherein the first value is a capacitance value of the first capacitor, and the second value is the sum of capacitance values of the first capacitor and the second capacitor. ### Claim 8 (depends on 5) The isolated resonant power supply circuit according to claim 5, wherein the equivalent capacitance value of the variable capacitance circuit is a second value when the feedback voltage controls the switching transistor to fully turn on, and the equivalent capacitance value of the variable capacitance circuit is a first value when the feedback voltage controls the switching transistor to fully turn off, wherein the first value is a capacitance value of the first capacitor, and the second value is the sum of capacitance values of the first capacitor and the second capacitor. ### Claim 9 (depends on 3) The isolated resonant power supply circuit according to claim 3, wherein the resonant transformer circuit further comprises a third capacitor, one end of the third capacitor is connected to the other end of the first capacitor, and the other end of the third capacitor is connected to a gate of the switching transistor. ### Claim 10 (depends on 1) The isolated resonant power supply circuit according to claim 1, wherein the resonant transformer circuit further comprises an air-cored transformer, the air-cored transformer comprises a bobbin and a first number of windings wound around the bobbin, each winding is formed by winding a wire bundle around the bobbin multiple times, and each wire bundle comprises a second number of winding wires which are twisted together; wherein a third number of winding wires in each winding serve as a primary winding, two ends of the third number of winding wires are connected to a primary circuit of the air-cored transformer, a fourth number of winding wires in each winding serve as a secondary winding, and two ends of the fourth number of winding wires are connected to a secondary circuit of the air-cored transformer, the first number being an integer greater than or equal to 1, and the second number, the third number, and the fourth number all being integers greater than 1. ### Claim 11 (depends on 10) The isolated resonant power supply circuit according to claim 10, wherein the third number is equal to the fourth number. ### Claim 12 (depends on 10) The isolated resonant power supply circuit according to claim 10, wherein the diameter of each winding wire is less than or equal to a first threshold. ### Claim 13 (depends on 10) The isolated resonant power supply circuit according to claim 10, wherein when the first number is greater than 1, a plurality of primary windings in the first number of windings are connected in series, and a plurality of secondary windings in the first number of windings are connected in parallel. ### Claim 14 (depends on 13) The isolated resonant power supply circuit according to claim 13, wherein all of the secondary windings in the first number of windings pass through rectifiers and are then connected in parallel. ### Claim 15 (depends on 10) The isolated resonant power supply circuit according to claim 10, wherein the first number of windings are all wound in a slot of the bobbin, or the first number of windings are respectively wound in a first number of slots of the bobbin. ### Claim 16 (depends on 1) A magnetic resonance imaging system, comprising: a main magnet for generating a main magnetic field; a gradient coil assembly; a gradient amplifier, used for exciting the gradient coil assembly to generate a gradient magnetic field on a selected gradient axis so as to apply the gradient magnetic field to the main magnetic field; a radio-frequency coil assembly; a radio-frequency amplifier for exciting the radio-frequency coil assembly to generate a radio-frequency signal; the isolated resonant power supply circuit according to claim 1, the isolated resonant power supply circuit being disposed within a scan room of the magnetic resonance imaging system, and supplying power to a device in the scan room. ### Claim 17 An air-cored transformer, wherein the air-cored transformer comprises a bobbin and a first number of windings wound around the bobbin, each winding is formed by winding a wire bundle around the bobbin multiple times, and each wire bundle comprises a second number of winding wires which are twisted together, wherein a third number of winding wires in each winding serve as a primary winding, two ends of the third number of winding wires are connected to a primary circuit of the air-cored transformer, a fourth number of winding wires in each winding serve as a secondary winding, and two ends of the fourth number of winding wires are connected to a secondary circuit of the air-cored transformer, the first number being an integer greater than or equal to 1, and the second number, the third number, and the fourth number all being integers greater than 1. ### Claim 18 (depends on 17) The air-cored transformer according to claim 17, wherein when the first number is greater than 1, a plurality of primary windings in the first number of windings are connected in series, and a plurality of secondary windings in the first number of windings are connected in parallel. ### Claim 19 (depends on 18) The air-cored transformer according to claim 18, wherein all of the secondary windings in the first number of windings pass through rectifiers and are then connected in parallel. ### Claim 20 (depends on 17) The air-cored transformer according to claim 17, wherein the first number of windings are all wound in a slot of the bobbin, or the first number of windings are respectively wound in the first number of slots of the bobbin.