Wireless power transmission system and transmitter and receiver thereof

Abstract

A transmitter for transmitting power to a receiver of a wireless power transfer system. The transmitter includes a transmitter element and an inverter including a switched mode zero voltage switching (ZVS) amplifier. The amplifier includes a pair of circuits. The circuit includes at least one transistor and at least one capacitor arranged in parallel. The circuit also includes at least one inductor arranged in series with the transistor and the capacitor. The amplifier also includes a ZVS inductor electrically connected to the pair of circuits. The ZVS inductor operates as a transmitter element of a transmitter to transfer power to a receiver of a wireless power transfer system via magnetic field coupling. The transmitter may alternatively include a transmitter element, as well as a combined direct current / direct current (DC / DC) converter and inverter. The combined DC / DC converter and inverter includes an amplifier including a pair of circuits. The circuit includes at least one transistor and at least one capacitor arranged in parallel, and at least one inductor arranged in series with the transistor and the capacitor. The combined DC / DC converter and inverter includes a half-bridge and an inductor of the pair of circuits. The inductor is electrically connected to the half-bridge. The inductor is adapted to store and release energy for DC / DC conversion, and the inductor is adapted to operate as a choke of the inverter. Other aspects are also provided.

Description

Technical Field

[0001] This disclosure relates generally to wireless power transmission, and more particularly to wireless power transmission systems and transmitters and receivers for such wireless power transmission systems. Background Technology

[0002] Wireless power transfer systems, such as wireless charging, are becoming increasingly important technologies for enabling next-generation devices. As more manufacturers and companies invest in this technology, its potential benefits and advantages are becoming clear.

[0003] Various wireless power transmission systems are known. A typical wireless power transmission system consists of a power source electrically connected to the wireless power transmitter and a wireless power receiver electrically connected to the load.

[0004] In a magnetic induction system, the transmitter has a transmitter coil with a certain inductance that transfers electrical energy from a power source to a receiver, which has a receiver coil with a certain inductance. Power transfer occurs due to the coupling of the magnetic fields between the coils or inductors of the transmitter and receiver. This induction system can be non-resonant or resonant. In resonant magnetic induction, the inductor uses a capacitor for resonance. The power transfer range in a resonant magnetic system can be increased compared to that in a magnetic induction system, and alignment problems can be corrected.

[0005] In an inductive system, the transmitter and receiver have capacitive electrodes. Power transfer occurs due to the coupling of the electric field between the capacitive electrodes of the transmitter and receiver. Similar to a resonant magnetic system, there exists a resonant electrical system in which an inductor (e.g., a coil) is used to make the capacitive electrodes of the transmitter and receiver resonate. Compared to an inductive system, a resonant electrical system can have an increased power transfer range and can correct alignment problems.

[0006] While some wireless power transmission systems are known, improvements are needed. Therefore, one objective is to provide a cooling device for a wireless power transmission system, a wireless power transmission system, and / or a method for cooling a receiver.

[0007] The background information provided is merely to set the scene and allow those skilled in the art to better understand the following description. Therefore, the foregoing discussion should not be construed as an admission that it is part of the prior art or common knowledge. One or more aspects / embodiments of the present invention may or may not solve one or more of the background problems. Summary of the Invention

[0008] According to one aspect, a transmitter is provided for transmitting power to a receiver in a wireless power transmission system. The transmitter includes transmitter elements and an inverter, the inverter including a switch-mode zero-voltage switching (ZVS) amplifier, the switch-mode ZVS amplifier comprising:

[0009] A pair of circuits, including:

[0010] At least one transistor and at least one capacitor arranged in parallel; and

[0011] At least one inductor arranged in series with a transistor and a capacitor;

[0012] The ZVS inductor is electrically connected to the pair of circuits. The ZVS inductor operates as a transmitter element of the transmitter to transfer power to the receiver of the wireless power transmission system via magnetic field coupling.

[0013] Since the ZVS operates as both an inductor and a transmitter element in the inverter, the need for an additional coil operating as a transmitter element is eliminated, thus reducing losses from the typically lossy coil / inductor. Therefore, the power transfer efficiency of the transmitter can be improved compared to conventional transmitters.

[0014] ZVS inductors may include multiple windings. These multiple windings can form a coil. The coil may have an air core.

[0015] A transmitter may include a combined DC / DC converter and inverter. The combined DC / DC converter and inverter can provide the functionality of both a DC / DC converter and an inverter, while using fewer components than two separate circuits suitable for performing both tasks. The combined DC / DC converter and inverter may include one or more inductors. The inductor may be a choke inductor. A choke inductor can be used to provide dual DC conversion and inversion. The choke inductor operates as an energy storage component adapted to convert the input DC voltage applied to the inverter to a lower value (to provide DC / DC conversion) and to regulate and control the generated AC output current (to provide inverter functionality). By having a single combined DC converter and inverter that provides both DC / DC conversion and DC signal to AC inversion, the size and weight of the transmitter can be reduced. Furthermore, since multiple inductors are not required in either the DC / DC converter or the inverter, the number of inductors needed is reduced, improving power transfer efficiency, as inductors are typically lossy electrical components.

[0016] An inverter may include a combination of a DC / DC converter and an inverter for converting the input DC signal of the inverter to a desired level and inverting the DC signal to AC, with the DC / DC converter electrically connected to the inverter.

[0017] A combined DC / DC converter and inverter can receive power signals from a power source. The power source can be a DC power supply. The combined DC / DC converter and inverter can convert a power signal with one voltage level into another signal with a different voltage level for input to the transmitter.

[0018] The combined DC / DC converter and inverter may include a half-bridge and an inductor in the circuit, with the inductor electrically connected to the half-bridge.

[0019] Therefore, the inductor serves as both a DC / DC converter and an inverter. In other words, the inductor has a dual function. This avoids additional components in the DC / DC converter that could affect efficiency, size, and weight. In particular, it eliminates the need for additional inductors and chokes. Since these components are large and contribute to power losses, the transmitter has reduced weight and size and improved power transfer efficiency compared to conventional transmitters in power delivery systems.

[0020] In this arrangement, the combined DC / DC converter and inverter are not separate blocks / circuits because the described inductor provides functionality for both DC / DC conversion and DC / AC inversion. Conventional DC / DC converters and inverters are typically separate blocks / circuits, resulting in larger and heavier transmitters.

[0021] Additionally, power transfer efficiency may be reduced when compared to the described non-separable DC / DC converters and inverters.

[0022] A half-bridge or H-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0023] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0024] The half-bridge can have a first switching frequency, and the transistors in the pair of circuits can have a second switching frequency.

[0025] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0026] Inductors can be adapted to store and release energy for DC / DC conversion, and inductors can be adapted to operate as chokes in inverters.

[0027] Inductors can be adapted to provide a constant DC current.

[0028] The combined DC / DC converter and inverter can be a Class E inverter.

[0029] The combined DC / DC converter and inverter can be load-independent.

[0030] According to another aspect, a transmitter is provided for transmitting power to a receiver in a wireless power transmission system, the transmitter including transmitter elements and a combined DC / DC converter and inverter.

[0031] The combined DC / DC converter and inverter include:

[0032] A pair of circuits, including:

[0033] At least one transistor and at least one capacitor arranged in parallel; and

[0034] At least one inductor arranged in series with the transistor and the capacitor, and

[0035] The half-bridge and the inductor in this circuit, with the inductor electrically connected to the half-bridge.

[0036] Inductors are suitable for storing and releasing energy for DC / DC conversion, and are also suitable for operation as choke coils in inverters.

[0037] Inductors serve as both DC / DC converters and inverters. In other words, inductors have a dual function. This eliminates the need for additional components in DC / DC converters that could affect efficiency, size, and weight. In particular, it eliminates the need for additional inductors and chokes. Since these components are large and contribute to power losses, transmitters in this configuration have reduced weight and size and improved power transfer efficiency compared to conventional transmitters in power delivery systems.

[0038] In other words, the combined inverter and DC / DC converter form an inseparable circuit; that is, the circuit components of the DC / DC converter cannot be separated from the inverter, and similarly, the circuit components of the inverter cannot be separated from the DC / DC converter and still provide their respective functions.

[0039] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0040] Inductors can be adapted to provide a constant DC current.

[0041] The combined DC / DC converter and inverter can be a Class E inverter.

[0042] The combined DC / DC converter and inverter can be load-independent.

[0043] The half-bridge may have a first switching frequency, and the transistors in the pair of circuits may have a second switching frequency.

[0044] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0045] According to another aspect, an inverter with DC / DC conversion function is provided for a transmitter in a wireless power transmission system.

[0046] The inverter includes:

[0047] A pair of circuits, including:

[0048] At least one transistor and at least one capacitor arranged in parallel; and

[0049] At least one inductor arranged in series with a transistor and a capacitor, and

[0050] The inductors in the half-bridge and inverter circuits are electrically connected to the half-bridge.

[0051] Inductors are suitable for storing and releasing energy for DC / DC conversion, and are also suitable for operation as choke coils in inverters.

[0052] Inductors serve as both DC / DC converters and inverters. In other words, inductors have a dual function. This eliminates the need for additional components in DC / DC converters that could affect efficiency, size, and weight. In particular, it eliminates the need for additional inductors and chokes. Since these components are large and contribute to power losses, transmitters in this configuration have reduced weight and size and improved power transfer efficiency compared to conventional transmitters in power delivery systems.

[0053] In other words, the combined DC / DC converter and inverter form an inseparable circuit; that is, the circuit components of the DC / DC converter cannot be separated from the inverter, and similarly, the circuit components of the inverter cannot be separated from the DC / DC converter and still provide their respective functions.

[0054] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0055] Inductors can be adapted to provide a constant DC current.

[0056] The combined DC / DC converter and inverter can be a Class E inverter.

[0057] The combined DC / DC converter and inverter can be load-independent.

[0058] The half-bridge may have a first switching frequency, and the transistors in the pair of circuits may have a second switching frequency.

[0059] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0060] According to another aspect, a method is provided for transmitting power from a transmitter to a receiver in a wireless power transmission system, the transmitter including transmitter elements and an inverter, the inverter including a switch-mode zero-voltage switching (ZVS) amplifier, comprising:

[0061] A pair of circuits, including:

[0062] At least one transistor and at least one capacitor arranged in parallel; and

[0063] At least one inductor arranged in series with the transistor and the capacitor;

[0064] A ZVS inductor, electrically connected to the pair of circuits, operates as a transmitter element of a transmitter to transfer power to a receiver of a wireless power transmission system via magnetic field coupling, the method comprising:

[0065] A receiver element that generates a field via a transmitter element to transmit power to a receiver in a wireless power transmission system.

[0066] A field can be a magnetic field.

[0067] The receiver element may include a coil with multiple windings. The receiver element may be similar to or the same as the transmitter element.

[0068] The transmitter may include at least one capacitor. When a magnetic field is generated, the transmitter elements and the capacitor can resonate. This resonance can improve the degree of freedom and / or efficiency of power transfer between the transmitter and receiver.

[0069] Power can be transferred from the transmitter to the receiver via magnetic field coupling between the transmitter and receiver elements.

[0070] According to another aspect, a method is provided for transmitting power from a transmitter to a receiver in a wireless power transmission system, the transmitter including transmitter elements, and a combined DC / DC converter and inverter.

[0071] The combined DC / DC converter and inverter include:

[0072] A pair of circuits, including:

[0073] At least one transistor and at least one capacitor arranged in parallel; and

[0074] At least one inductor arranged in series with a transistor and a capacitor, and

[0075] The inductors in the half-bridge and inverter circuits are electrically connected to the half-bridge.

[0076] Wherein, the inductor is suitable for storing and releasing energy for DC / DC conversion, and the inductor is suitable for operation as a choke coil in an inverter, the method comprising:

[0077] A receiver element that generates a field via a transmitter element to transmit power to a receiver in a wireless power transmission system.

[0078] The combined inverter and DC / DC converter form an inseparable circuit; that is, the circuit components of the DC / DC converter cannot be separated from the inverter, and similarly, the circuit components of the inverter cannot be separated from the DC / DC converter and still provide their respective functions.

[0079] A field can be a magnetic field.

[0080] The receiver element may include a coil with multiple windings. The receiver element may be similar to or the same as the transmitter element.

[0081] The transmitter may include at least one capacitor. When a magnetic field is generated, the transmitter elements and the capacitor can resonate. This resonance can improve the degree of freedom and / or efficiency of power transfer between the transmitter and receiver.

[0082] Power can be transferred from the transmitter to the receiver via magnetic field coupling between the transmitter and receiver elements.

[0083] The described method already provides any benefits described regarding the transmitter. Additionally, the transmitter in the described method may have any additional features described regarding the transmitter.

[0084] According to another aspect, a rectifier is provided for rectifying an alternating current (AC) signal into a direct current (DC) signal, the rectifier being suitable for use in a receiver of a wireless power transmission system, the rectifier including a capacitor for converting a voltage signal at a receiver element into a current signal.

[0085] A capacitor is connected in parallel to the receiver element of a wireless power transmission system.

[0086] A voltage signal can be induced at the receiver element via magnetic field coupling with the transmitter element of the wireless power transmission system. The voltage signal can be constant.

[0087] The current signal can be constant.

[0088] The rectifier may include an impedance transformation circuit, which includes a capacitor.

[0089] Impedance transformation circuits can have a T-network topology.

[0090] The capacitance of a capacitor can be given by the following equation:

[0091]

[0092] Where C3 is the capacitance of the capacitor.

[0093] Where α is a dimensionless factor such that 1.25 < α ≤ 3.

[0094] Where ω is the operating frequency of the receiver.

[0095] Wherein, LRX2 is part of the inductance of the receiver element, and

[0096] LRX3 is another part of the inductance of the receiver element.

[0097] The value of α allows control over the reflected impedance of the receiver, making it more inductive or capacitive depending on the load at the receiver.

[0098] The inductance of the receiver element can be given by the following equation:

[0099]

[0100] Where LRX is the inductance of the receiver element.

[0101] The rectifier may include:

[0102] A pair of circuits, including:

[0103] At least one diode and at least one capacitor are arranged in parallel; and

[0104] At least one inductor arranged in series with the transistor and the capacitor; and

[0105] The capacitor is electrically connected to the circuit and the receiver element.

[0106] The rectifier can be a Class E rectifier.

[0107] The rectifier can be a push-pull rectifier.

[0108] According to another aspect, a receiver is provided for extracting power from a field generated by a transmitter in a wireless power transmission system. The receiver includes a receiver element electrically connected to a rectifier, the rectifier including a capacitor for converting a voltage signal at the receiver element into a current signal.

[0109] The capacitor is connected in parallel with the receiver element.

[0110] Rectifiers can include full-wave rectifiers.

[0111] A voltage signal can be induced at the receiver element via magnetic field coupling with the transmitter element of the wireless power transmission system. The voltage signal can be constant.

[0112] The current signal can be constant.

[0113] The receiver may include an impedance transformation circuit, which includes a capacitor.

[0114] Impedance transformation circuits can have a T-network topology.

[0115] The capacitance of a capacitor can be given by the following equation:

[0116]

[0117] Where C3 is the capacitance of the capacitor.

[0118] Where α is a dimensionless factor such that 1.25 < α ≤ 3.

[0119] Where ω is the operating frequency of the receiver.

[0120] Wherein, LRX2 is part of the inductance of the receiver element, and

[0121] LRX3 is another part of the inductance of the receiver element.

[0122] The value of α allows control over the reflected impedance of the receiver, making it more inductive or capacitive depending on the load at the receiver.

[0123] The inductance of the receiver element can be given by the following equation:

[0124]

[0125] Where LRX is the inductance of the receiver element.

[0126] The rectifier may include:

[0127] A pair of circuits, including:

[0128] At least one diode and at least one capacitor are arranged in parallel; and

[0129] At least one inductor arranged in series with a transistor and a capacitor; and

[0130] The capacitor is electrically connected to the circuit and the receiver element.

[0131] The rectifier can be a Class E rectifier.

[0132] The rectifier can be a push-pull rectifier.

[0133] According to another aspect, a method is provided for transmitting power from a transmitter to a receiver in a wireless power transmission system, the system including a receiver element electrically connected to a rectifier, the rectifier including a capacitor for converting a voltage signal at the receiver element into a current signal.

[0134] The method involves connecting a capacitor in parallel to the receiver element.

[0135] Power is extracted from the field generated by the transmitter element of the wireless power transmission system via the receiver element.

[0136] Rectifiers can include full-wave rectifiers.

[0137] A voltage signal can be induced at the receiver element via magnetic field coupling with the transmitter element of the wireless power transmission system. The voltage signal can be constant.

[0138] The receiver may also include a capacitor. The capacitor and receiver elements can resonate when power is extracted from the field generated by the transmitter elements. Power can be extracted via magnetic field coupling between the transmitter and receiver elements.

[0139] According to another aspect, a wireless power transmission system is provided, including a transmitter and a receiver.

[0140] The transmitter is used to transfer power to the receiver. The transmitter includes transmitter elements and an inverter. The inverter includes a switch-mode zero-voltage switching (ZVS) amplifier. The switch-mode ZVS amplifier includes:

[0141] A pair of circuits, including:

[0142] At least one transistor and at least one capacitor arranged in parallel; and

[0143] At least one inductor arranged in series with a transistor and a capacitor;

[0144] The ZVS inductor is electrically connected to the pair of circuits. The ZVS inductor operates as a transmitter element of the transmitter to transfer power to the receiver of the wireless power transfer system via magnetic field coupling.

[0145] A receiver is used to extract power from the field generated by the transmitter. The receiver includes a receiver element electrically connected to a rectifier, which includes a capacitor for converting a voltage signal at the receiver element into a current signal.

[0146] The capacitor is connected in parallel with the receiver element.

[0147] According to another aspect, a wireless power transmission system is provided, including a transmitter and a receiver.

[0148] The transmitter is used to transfer power to the receiver. The transmitter includes transmitter elements, an inverter, and a DC / DC converter.

[0149] The inverter includes:

[0150] A pair of circuits, including:

[0151] At least one transistor and at least one capacitor arranged in parallel; and

[0152] At least one inductor arranged in series with a transistor and a capacitor, and

[0153] A DC / DC converter includes a half-bridge and an inverter with a pair of inductors, the inductors being electrically connected to the half-bridge.

[0154] The inductor is suitable for storing and releasing energy for DC / DC conversion, and is also suitable for operation as a choke coil in an inverter; and

[0155] A receiver is used to extract power from the field generated by the transmitter. The receiver includes a receiver element electrically connected to a rectifier, which includes a capacitor for converting a voltage signal at the receiver element into a current signal.

[0156] The capacitor is connected in parallel with the receiver element.

[0157] The inverter and the DC / DC converter form an inseparable circuit; that is, the circuit components of the DC / DC converter cannot be separated from the inverter, and similarly, the circuit components of the inverter cannot be separated from the DC / DC converter and still provide their respective functions.

[0158] Rectifiers can include full-wave rectifiers.

[0159] A voltage signal can be induced at the receiver element via magnetic field coupling with the transmitter element of the wireless power transmission system. The voltage signal can be constant.

[0160] The system described may have any benefits and / or features described regarding the transmitter, receiver, rectifier, and / or method.

[0161] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0162] Inductors can be adapted to provide a constant DC current to an inverter.

[0163] The inverter can be a Class E inverter.

[0164] Inverters can be load-independent.

[0165] The half-bridge can have a first switching frequency, and the inverter can have a second switching frequency.

[0166] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0167] A voltage signal can be constant. In other words, a signal can have a constant voltage level.

[0168] A current signal can be constant. In other words, a signal can have a constant current level.

[0169] The receiver may include an impedance transformation circuit, which includes a capacitor.

[0170] Impedance transformation circuits can have a T-network topology.

[0171] The capacitance of a capacitor can be given by the following equation:

[0172]

[0173] Where C3 is the capacitance of the capacitor.

[0174] Where α is a dimensionless factor such that 1.25 < α ≤ 3.

[0175] Where ω is the operating frequency of the receiver.

[0176] Wherein, LRX2 is part of the inductance of the receiver element, and

[0177] LRX3 is another part of the inductance of the receiver element.

[0178] The value of α allows control over the reflected impedance of the receiver, making it more inductive or capacitive depending on the load at the receiver.

[0179] The inductance of the receiver element can be given by the following equation:

[0180]

[0181] Where LRX is the inductance of the receiver element.

[0182] The rectifier may include:

[0183] A pair of circuits, including:

[0184] At least one diode and at least one capacitor are arranged in parallel; and

[0185] At least one inductor arranged in series with a transistor and a capacitor; and

[0186] The capacitor is electrically connected to the circuit and the receiver element.

[0187] The rectifier can be a Class E rectifier.

[0188] The rectifier can be a push-pull rectifier.

[0189] According to another aspect, a wireless power transmission system is provided, comprising:

[0190] The described transmitter; and

[0191] The receiver described.

[0192] The transmitter can be adapted to transmit power to the receiver via magnetic field coupling.

[0193] According to another aspect, a transmitter is provided for transmitting power to a receiver in a wireless power transmission system. The transmitter includes a transmitter element comprising an air-core coil having a plurality of overlapping flat windings, the transmitter element surrounding the shaft of an electric motor.

[0194] The windings can be around the shaft of the motor. Each winding is typically in a different radial plane than its adjacent windings. The windings can be parallel in the axial plane.

[0195] The transmitter may also include:

[0196] Emitter field cancellation element. The field cancellation element can be adapted to reduce current losses in the shaft of the motor around which the emitter element (i.e., winding) is located.

[0197] At least one of the transmitter element and the transmitter field cancellation element may be positioned around the shaft of the motor.

[0198] The electric motor can be a current-excited synchronous motor.

[0199] The field cancelling element and the emitter element can be coplanar in the radial direction relative to the axis. In other words, the cancelling element and the emitter element can be in the same radial plane.

[0200] The transmitter field elimination element may include a field elimination coil with multiple overlapping flat windings. The windings may be in the opposite direction to the windings of the transmitter element. In this way, due to the opposite windings of the elimination element, losses of current induced in the motor shaft can be prevented.

[0201] Elimination elements may include copper and / or aluminum wound around the rotor shaft adjacent to the emitter element. This wound material can reduce eddy current losses in the shaft.

[0202] The transmitter may also include:

[0203] Inverter, including switch-mode zero-voltage switching (ZVS) amplifier, the switch-mode ZVS amplifier includes:

[0204] A pair of circuits, including:

[0205] At least one transistor and at least one capacitor arranged in parallel; and

[0206] At least one inductor arranged in series with a transistor and a capacitor;

[0207] The ZVS inductor is electrically connected to the pair of circuits. The ZVS inductor operates as a transmitter element of the transmitter to transfer power to the receiver of the wireless power transmission system via magnetic field coupling.

[0208] A transmitter may include a combined DC / DC converter and inverter. The combined DC / DC converter and inverter can provide the functionality of both a DC / DC converter and an inverter, while using fewer components than two separate circuits suitable for performing both tasks. The combined DC / DC converter and inverter may include one or more inductors. The inductor may be a choke inductor. A choke inductor can be used to provide dual DC conversion and inversion. The choke inductor operates as an energy storage component adapted to convert the input DC voltage applied to the inverter to a lower value (to provide DC / DC conversion) and to regulate and control the generated AC output current (to provide inverter functionality). By having a single combined DC converter and inverter that provides both DC / DC conversion and DC signal to AC inversion, the size and weight of the transmitter can be reduced. Furthermore, since multiple inductors are not required in either the DC / DC converter or the inverter, the number of inductors needed is reduced, improving power transfer efficiency, as inductors are typically lossy electrical components.

[0209] The transmitter may also include:

[0210] A DC / DC converter is used to convert the input signal of an inverter to a desired level. The DC / DC converter is electrically connected to the inverter.

[0211] A DC / DC converter may include an inductor in a pair of circuits for a half-bridge and an inverter, with the inductor electrically connected to the half-bridge.

[0212] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0213] The half-bridge can have a first switching frequency, and the inverter can have a second switching frequency.

[0214] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0215] Inductors can be adapted to store and release energy for DC / DC conversion, and inductors can be adapted to operate as chokes in inverters.

[0216] Inductors can be adapted to provide a constant DC current to an inverter.

[0217] The inverter can be a Class E inverter.

[0218] Inverters can be load-independent.

[0219] The transmitter may also include:

[0220] Inverters and DC / DC converters,

[0221] The inverter includes:

[0222] A pair of circuits, including:

[0223] At least one transistor and at least one capacitor arranged in parallel; and

[0224] At least one inductor arranged in series with a transistor and a capacitor, and

[0225] A DC / DC converter includes a half-bridge and an inverter with a pair of inductors, the inductors being electrically connected to the half-bridge.

[0226] Inductors are suitable for storing and releasing energy for DC / DC conversion, and are also suitable for operation as choke coils in inverters.

[0227] The inverter and the DC / DC converter form an inseparable circuit; that is, the circuit components of the DC / DC converter cannot be separated from the inverter, and similarly, the circuit components of the inverter cannot be separated from the DC / DC converter and still provide their respective functions.

[0228] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0229] Inductors can be adapted to provide a constant DC current to an inverter.

[0230] The inverter can be a Class E inverter.

[0231] Inverters can be load-independent.

[0232] The half-bridge can have a first switching frequency, and the inverter can have a second switching frequency.

[0233] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0234] According to another aspect, a receiver is provided for extracting power from a field generated by a transmitter of a wireless power transmission system, the receiver including a receiver element comprising an air-core coil having a plurality of overlapping flat windings, the receiver element surrounding the shaft of an electric motor.

[0235] The windings can be around the shaft of the motor. Each winding is typically in a different radial plane than its adjacent windings. The windings can be parallel in the axial plane.

[0236] The receiver may also include:

[0237] Receiver field cancellation element. Field cancellation elements can be adapted to reduce current losses in the shaft of a motor around which the receiver element (i.e., winding) is located.

[0238] At least one of the receiver element and the receiver field cancellation element may be positioned around the shaft of the motor.

[0239] The electric motor can be a current-excited synchronous motor.

[0240] The cancelling element and the receiver element can be coplanar in the radial direction relative to the axis. In other words, the cancelling element and the receiver element can be in the same radial plane.

[0241] The field cancellation element for the receiver can include a field cancellation coil having multiple overlapping flat windings. The windings can be in the opposite direction to the windings of the receiver element. In this way, due to the opposite windings of the cancellation element, losses of current induced in the motor shaft can be prevented.

[0242] Elimination elements may include copper and / or aluminum wound around the rotor shaft adjacent to the emitter element. This wound material can reduce eddy current losses in the shaft.

[0243] The receiver element can be electrically connected to a rectifier, which includes a capacitor for converting the voltage signal at the receiver element into a current signal.

[0244] The capacitor is connected in parallel with the receiver element.

[0245] Rectifiers can include full-wave rectifiers.

[0246] A voltage signal can be induced at the receiver element via magnetic field coupling with the transmitter element of the wireless power transmission system. The voltage signal can be constant.

[0247] The current signal can be constant.

[0248] The receiver may include an impedance transformation circuit, which includes a capacitor.

[0249] Impedance transformation circuits can have a T-network topology.

[0250] The capacitance of a capacitor can be given by the following equation:

[0251]

[0252] Where C3 is the capacitance of the capacitor.

[0253] Where α is a dimensionless factor such that 1.25 < α ≤ 3.

[0254] Where ω is the operating frequency of the receiver.

[0255] Wherein, LRX2 is part of the inductance of the receiver element, and

[0256] LRX3 is another part of the inductance of the receiver element.

[0257] The value of α allows control over the reflected impedance of the receiver, making it more inductive or capacitive depending on the load at the receiver.

[0258] The inductance of the receiver element can be given by the following equation:

[0259]

[0260] Where LRX is the inductance of the receiver element.

[0261] The rectifier may include:

[0262] A pair of circuits, including:

[0263] At least one diode and at least one capacitor are arranged in parallel; and

[0264] At least one inductor arranged in series with a transistor and a capacitor; and

[0265] The capacitor is electrically connected to the circuit and the receiver element.

[0266] The rectifier can be a Class E rectifier.

[0267] The rectifier can be a push-pull rectifier.

[0268] According to another aspect, a wireless power transmission system is provided, comprising:

[0269] A transmitter, comprising a transmitter element, the transmitter element including an air-core coil having multiple overlapping flat windings; and

[0270] The receiver includes receiver elements for extracting power from a field generated by the transmitter, the receiver elements including an air-core coil having multiple overlapping flat windings.

[0271] The transmitter and receiver elements can surround the shaft of the motor. The transmitter and receiver elements can be in the same radial plane relative to the shaft. The coil of the transmitter element can have a first radius. The coil of the receiver element can have a second radius. The first radius can be greater than or less than the second radius. The coil of the transmitter element can form an inner coil, while the coil of the receiver element forms an outer coil. Alternatively, the coil of the transmitter element can form an outer coil, and the coil of the receiver element can form an inner coil. Both the inner and outer coils can surround the shaft.

[0272] The system may also include:

[0273] One or more shielding elements. Shielding elements can be adapted to limit the field generated by the transmitter, particularly the field generated by the transmitter's air-core coil. Shielding elements can be adapted to prevent unwanted environmental effects from the field generated by the transmitter.

[0274] The shielding element may include a cylindrical shielding element. The shielding element may include a first shielding plate and a second shielding plate. The cylindrical shielding element and plates may surround the hollow coils of the transmitter and receiver. The cylindrical shielding element and plates may form a shell surrounding the core of the transmitter and receiver.

[0275] The transmitter's coil can wrap around the receiver's coil.

[0276] The coil can lie in the same radial plane centered on the axis. The coil can be wrapped around the axis.

[0277] The transmitter coil may have a first radius, and the receiver coil may have a second radius. The first radius may be smaller than the second radius.

[0278] The transmitter may also include:

[0279] Emitter field cancellation element. The field cancellation element can be adapted to reduce current losses in the shaft of the motor around which the emitter element (i.e., winding) is located.

[0280] At least one of the transmitter element and the transmitter field cancellation element may be positioned around the shaft of the motor.

[0281] The electric motor can be a current-excited synchronous motor.

[0282] The field cancelling element and the emitter element can be coplanar in the radial direction relative to the axis. In other words, the cancelling element and the emitter element can be in the same radial plane.

[0283] The transmitter field elimination element may include a field elimination coil with multiple overlapping flat windings. The windings may be in the opposite direction to the windings of the transmitter element. In this way, due to the opposite windings of the elimination element, losses of current induced in the motor shaft can be prevented.

[0284] Elimination elements may include copper and / or aluminum wound around the rotor shaft adjacent to the emitter element. This wound material can reduce eddy current losses in the shaft.

[0285] The receiver may also include:

[0286] Receiver field cancellation element. Field cancellation elements can be adapted to reduce current losses in the shaft of a motor around which the receiver element (i.e., winding) is located.

[0287] At least one of the receiver element and the receiver field cancellation element may be positioned around the shaft of the motor.

[0288] The electric motor can be a current-excited synchronous motor.

[0289] The cancelling element and the receiver element can be coplanar in the radial direction relative to the axis. In other words, the cancelling element and the receiver element can be in the same radial plane.

[0290] The field cancellation element for the receiver can include a field cancellation coil having multiple overlapping flat windings. The windings can be in the opposite direction to the windings of the receiver element. In this way, due to the opposite windings of the cancellation element, losses of current induced in the motor shaft can be prevented.

[0291] Elimination elements may include copper and / or aluminum wound around the rotor shaft adjacent to the emitter element. This wound material can reduce eddy current losses in the shaft.

[0292] The transmitter may also include a power supply.

[0293] The power supply can be a direct current (DC) power supply.

[0294] The receiver may also include a load.

[0295] The load may include the rotor windings of an electric motor.

[0296] The electric motor can be a current-excited synchronous motor.

[0297] The transmitter may also include:

[0298] An inverter comprising a switch-mode zero-voltage switching (ZVS) amplifier, the switch-mode ZVS amplifier including:

[0299] A pair of circuits, including:

[0300] At least one transistor and at least one capacitor arranged in parallel; and

[0301] At least one inductor arranged in series with a transistor and a capacitor;

[0302] The ZVS inductor is electrically connected to the pair of circuits. The ZVS inductor operates as a transmitter element of the transmitter to transfer power to the receiver of the wireless power transmission system via magnetic field coupling.

[0303] A transmitter may include a combined DC / DC converter and inverter. The combined DC / DC converter and inverter can provide the functionality of both a DC / DC converter and an inverter, while using fewer components than two separate circuits suitable for performing both tasks. The combined DC / DC converter and inverter may include one or more inductors. The inductor may be a choke inductor. A choke inductor can be used to provide dual DC conversion and inversion. The choke inductor operates as an energy storage component adapted to convert the input DC voltage applied to the inverter to a lower value (to provide DC / DC conversion) and to regulate and control the generated AC output current (to provide inverter functionality). By having a single combined DC converter and inverter that provides both DC / DC conversion and DC signal to AC inversion, the size and weight of the transmitter can be reduced. Furthermore, since multiple inductors are not required in either the DC / DC converter or the inverter, the number of inductors needed is reduced, improving power transfer efficiency, as inductors are typically lossy electrical components.

[0304] The transmitter may also include:

[0305] A DC / DC converter is used to convert the input signal of an inverter to a desired level. The DC / DC converter is electrically connected to the inverter.

[0306] A DC / DC converter may include an inductor in a pair of circuits for a half-bridge and an inverter, with the inductor electrically connected to the half-bridge.

[0307] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0308] The half-bridge can have a first switching frequency, and the inverter can have a second switching frequency.

[0309] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0310] Inductors can be adapted to store and release energy for DC / DC conversion, and inductors can be adapted to operate as chokes in inverters.

[0311] Inductors can be adapted to provide a constant DC current to an inverter.

[0312] The inverter can be a Class E inverter.

[0313] Inverters can be load-independent.

[0314] The transmitter may also include:

[0315] Inverters and DC / DC converters,

[0316] The inverter includes:

[0317] A pair of circuits, including:

[0318] At least one transistor and at least one capacitor arranged in parallel; and

[0319] At least one inductor arranged in series with a transistor and a capacitor, and

[0320] A DC / DC converter includes a half-bridge and an inverter with a pair of inductors, the inductors being electrically connected to the half-bridge.

[0321] Inductors are suitable for storing and releasing energy for DC / DC conversion, and are also suitable for operation as choke coils in inverters.

[0322] The inverter and the DC / DC converter form an inseparable circuit; that is, the circuit components of the DC / DC converter cannot be separated from the inverter, and similarly, the circuit components of the inverter cannot be separated from the DC / DC converter and still provide their respective functions.

[0323] A half-bridge may include transistors and diodes electrically connected in parallel to the transistors. A half-bridge may include high-side switches / transistors and low-side switches / transistors for synchronous operation, or switches / transistors and diodes for asynchronous operation.

[0324] Inductors can be adapted to provide a constant DC current to an inverter.

[0325] The inverter can be a Class E inverter.

[0326] Inverters can be load-independent.

[0327] The half-bridge can have a first switching frequency, and the inverter can have a second switching frequency.

[0328] The second switching frequency can be greater than the first switching frequency. For example, the second switching frequency can be approximately 80 kHz–10 MHz. The first switching frequency can be 20–200 kHz. Those skilled in the art will understand that these values ​​are exemplary and other frequencies can be used. For example, the first switching frequency can be 50 kHz and the second frequency can be 1 MHz.

[0329] The receiver element can be electrically connected to a rectifier, which includes a capacitor for converting the voltage signal at the receiver element into a current signal.

[0330] The capacitor is connected in parallel with the receiver element.

[0331] Rectifiers can include full-wave rectifiers.

[0332] A voltage signal can be induced at the receiver element via magnetic field coupling with the transmitter element of the wireless power transmission system. The voltage signal can be constant.

[0333] The current signal can be constant.

[0334] The receiver may include an impedance transformation circuit, which includes a capacitor.

[0335] Impedance transformation circuits can have a T-network topology.

[0336] The capacitance of a capacitor can be given by the following equation:

[0337]

[0338] Where C3 is the capacitance of the capacitor.

[0339] Where α is a dimensionless factor such that 1.25 < α ≤ 3.

[0340] Where ω is the operating frequency of the receiver.

[0341] Wherein, LRX2 is part of the inductance of the receiver element, and

[0342] LRX3 is another part of the inductance of the receiver element.

[0343] The value of α allows control over the reflected impedance of the receiver, making it more inductive or capacitive depending on the load at the receiver.

[0344] The inductance of the receiver element can be given by the following equation:

[0345]

[0346] Where LRX is the inductance of the receiver element.

[0347] The rectifier may include:

[0348] A pair of circuits, including:

[0349] At least one diode and at least one capacitor are arranged in parallel; and

[0350] At least one inductor arranged in series with a transistor and a capacitor; and

[0351] The capacitor is electrically connected to the circuit and the receiver element.

[0352] The rectifier can be a Class E rectifier.

[0353] The rectifier can be a push-pull rectifier.

[0354] It should be understood that any feature described with respect to one aspect, example, or embodiment may also be used with respect to any other aspect, example, or embodiment of this disclosure. Other advantages of this disclosure will become apparent to those skilled in the art from the detailed description taken in conjunction with the following drawings. Attached Figure Description

[0355] The embodiments will now be described more fully with reference to the accompanying drawings, in which:

[0356] Figure 1 This is a block diagram of a wireless power transmission system;

[0357] Figure 2 This is another block diagram of a wireless power transmission system;

[0358] Figure 3 This is a schematic layout of a transmitter for a wireless power transmission system according to one aspect of this disclosure;

[0359] Figure 4a yes Figure 3 A graph showing the current at the inverter of the transmitter;

[0360] Figure 4b yes Figure 3 A graph showing the voltage across the transistor of the transmitter;

[0361] Figure 5a This is a schematic layout of a receiver for a wireless power transmission system according to one aspect of this disclosure;

[0362] Figure 5b It includes Figure 3 The transmitter and Figure 5a A schematic layout of the receiver's wireless power transmission system;

[0363] Figure 6a This is a schematic layout of another receiver in a wireless power transmission system according to one aspect of this disclosure;

[0364] Figure 6b yes Figure 6a An equivalent schematic layout of a portion of the receiver;

[0365] Figure 7 It includes Figure 3 The transmitter and Figure 6a A schematic layout of the receiver's wireless power transmission system;

[0366] Figure 8 This is a schematic layout of another transmitter in a wireless power transmission system according to one aspect of this disclosure;

[0367] Figure 9 It includes Figure 8 The transmitter and Figure 6a A schematic layout of the receiver's wireless power transmission system;

[0368] Figure 10a yes Figure 9 A graph showing the voltage across the transistor of the transmitter in the system;

[0369] Figure 10b yes Figure 9 A graph showing the voltage across the diode in the receiver of the system.

[0370] Figure 11 This is a schematic layout of another transmitter in a wireless power transmission system according to one aspect of this disclosure;

[0371] Figure 12a This is a schematic layout of another receiver in a wireless power transmission system according to one aspect of this disclosure;

[0372] Figure 12b This is a schematic layout of another receiver in a wireless power transmission system according to one aspect of this disclosure;

[0373] Figure 13 This is a block diagram of an electric motor;

[0374] Figure 14a It is part of a transmitter for wireless power transmission of an electric motor according to one aspect of this disclosure;

[0375] Figure 14b This is based on one aspect of the disclosure. Figure 14a A portion of the transmitter and a receiver for wireless power transmission to the electric motor; and

[0376] Figure 15 It is part of another wireless power transmission for an electric motor according to one aspect of this disclosure. Detailed Implementation

[0377] The foregoing description of the invention and the following detailed description of certain examples will be better understood when read in conjunction with the accompanying drawings. As used herein, an element or feature introduced in the singular and preceded by the word "a" or "an" should be understood to not necessarily exclude multiple elements or features. Furthermore, references to "an example" or "an embodiment" are not intended to be construed as excluding the existence of additional examples or embodiments that also include the described elements or features. Moreover, unless expressly stated to the contrary, instances or embodiments of elements or features having a particular property, or multiple elements or features, may include additional elements or features that do not have said property. Furthermore, it should be understood that the terms "comprising," "having," and "including" mean "including but not limited to," and the terms "comprising," "having," and "including" have equivalent meanings. It should also be understood that throughout the specification and drawings, the same reference numerals will be used to refer to the same elements.

[0378] As used herein, the terms “suitable” and “configured” mean that an element, component, or other subject matter is designed and / or intended to perform a given function. Therefore, the use of the terms “suitable” and “configured” should not be construed as meaning that a given element, component, or other subject matter is merely “capable” of performing a given function, but rather that the element, component, and / or other subject matter is specifically selected, created, implemented, utilized, and / or designed for the purpose of performing that function. Element, component, and / or other subject matter described as suitable for performing a particular function may additionally or alternatively be described as configured to perform that function, and vice versa, also within the scope of this application. Similarly, subject matter described as configured to perform a particular function may additionally or alternatively be described as operable to perform that function.

[0379] It should be understood that when a component is referred to as being "on", "attached" to, "connected" to, "coupled" to, or "in contact" with another component, it can be directly on, attached to, connected to, coupled to, or in contact with another component, or there may be an intermediate component.

[0380] It should be understood that, unless otherwise stated, the use of the word “exemplary” means “as an example” or “an example”, and does not mean a preferred or best design or implementation.

[0381] Now go to Figure 1 This diagram illustrates a wireless power transfer system generally identified by reference numeral 100. The wireless power transfer system 100 includes a transmitter 110 and a receiver 120. The transmitter 110 includes a power source 112 electrically connected to a transmitter element 116, and the receiver 120 includes a receiver element 124 electrically connected to a load 128. Power is transferred from the power source 112 to the transmitter element 116. Power is then transferred from the transmitter element 116 to the receiver element 124 via resonant or non-resonant electric or magnetic field coupling. Power is then transferred from the receiver element 124 to the load 128. Exemplary wireless power transfer systems 100 include high-frequency inductive wireless power transfer systems as described in the applicant's U.S. Provisional Application No. 62 / 899165, or resonant capacitively coupled wireless power transfer systems as described in the applicant's U.S. Patent No. 9653948B2, relevant portions of which are incorporated herein by reference.

[0382] In the wireless power transmission system 100, power is transmitted from transmitter element 116 to receiver element 124. The exemplary wireless power transmission system 100 includes a high-frequency inductive wireless power transmission system as described in U.S. Patent Application No. 17 / 018,328, relevant portions of which are incorporated herein by reference.

[0383] Now go to Figure 2 Another embodiment of a wireless power transmission system is illustrated, generally identified by reference numeral 200. The wireless power transmission system 200 includes a power supply 212, a DC / DC converter 214, circuitry 216, and a transmitter element 222. The power supply 212 is electrically connected to the DC / DC converter 214. The DC / DC converter 214 is electrically connected to the circuitry 216. The circuitry 216 is electrically connected to the transmitter element 222.

[0384] Power supply 212 is used to generate an input power signal for transmitting power. In this embodiment, the input power signal is a direct current (DC) power signal.

[0385] DC / DC converter 214 is used to convert a received DC voltage signal into a desired voltage level. The received DC voltage may come from power supply 212. System 200 is shown as including DC / DC converter 214, and those skilled in the art will understand that other configurations are possible. In another embodiment, no DC / DC converter is present.

[0386] In the illustrated arrangement, circuit 216 includes an inverter and an output stage. The output stage matches the output impedance of circuit 216 to the optimal impedance of the wireless link 230 between the transmitter and receiver. The output stage also filters high-frequency harmonic components of the inverter. As those skilled in the art will understand, circuit 216 may include only an inverter, without an output stage.

[0387] Transmitter element 222 includes one or more inductive elements, i.e., inductors. Inductive elements may include one or more coils. Coils may include boost or shielded coils, such as those described in the applicant's U.S. Patent Application No. 17 / 193539, the relevant portions of which are incorporated herein by reference.

[0388] In another arrangement, transmitter element 222 includes one or more capacitive elements, such as capacitive electrodes. Capacitive electrodes may be laterally spaced elongated electrodes; however, those skilled in the art will understand that other configurations are possible, including but not limited to concentric, coplanar, circular, elliptical, disk-shaped, etc. Other suitable electrode configurations are described in the applicant's U.S. Patent No. 9,979,206B2, the relevant portions of which are incorporated herein by reference. As those skilled in the art will understand, transmitter element 222 may include a combination of inductive and capacitive elements.

[0389] Power supply 212 provides a DC input power signal to DC / DC converter 214, which converts the signal to a desired voltage level. Inverter circuit 216 receives the converted DC power signal and inverts it to generate a magnetic and / or electric field at transceiver element 222 for power transmission via electric or magnetic field coupling. Specifically, transmitter element 222 generates a magnetic / electric field to transmit power to receiver via magnetic / electric field coupling. Power supply 212, DC / DC converter 214, circuit 216, and transmitter element 222 can collectively form transmitter 210. As previously mentioned, DC / DC converter 214 may not be present in transmitter 210.

[0390] The wireless power transmission system 200 also includes a load 228, a DC / DC converter 226, circuitry 224, and a receiver element 229. The load 228 is electrically connected to the DC / DC converter 226. The DC / DC converter 226 is electrically connected to the circuitry 224. The circuitry 224 is electrically connected to the receiver element 229.

[0391] In the arrangement shown, load 228 is a DC load. Load 228 can be static or variable.

[0392] DC / DC converter 226 is used to convert a received DC voltage signal into a desired voltage level. The received DC voltage may originate from circuit 224. Although system 200 includes DC / DC converter 226, those skilled in the art will understand that other configurations are possible. In another embodiment, DC / DC converter 226 is not present.

[0393] Circuit 224 includes an input stage and a rectifier, such as a diode rectifier or a synchronous rectifier. The input stage is configured to ensure optimal impedance presented to receiver element 229 at full power of wireless power transmission system 200. The input stage also maintains quasi-voltage source behavior of receiver element 229, so that the output of the synchronous rectifier presents a stable DC voltage from no-load to full-load conditions. As those skilled in the art will understand, circuit 224 may include only a rectifier without an input stage.

[0394] Receiver element 229 includes one or more inductive elements, i.e., inductors. Receiver element 229 may include one or more coils. Coils may include boost or shielded coils, such as those described in the applicant's U.S. Patent Application No. 17 / 193539, the relevant portions of which are incorporated herein by reference.

[0395] In another arrangement, transmitter element 222 includes one or more capacitive elements, such as capacitive electrodes. Capacitive electrodes may be laterally spaced elongated electrodes; however, those skilled in the art will understand that other configurations are possible, including but not limited to concentric, coplanar, circular, elliptical, disk-shaped, etc. Other suitable electrode configurations are described in the applicant's U.S. Patent No. 9,979,206B2, the relevant portions of which are incorporated herein by reference. As those skilled in the art will understand, transmitter element 222 may include a combination of inductive and capacitive elements.

[0396] The transmitter and receiver elements 222 and 229 of system 200 form a wireless link 230. Elements 222 and 229 are separated by a wireless gap. The wireless gap can be formed by the atmosphere (i.e., air) or a physical medium (e.g., a wall, glass, liquid, wood, insulating material, etc.). Power is transmitted across the wireless link 230 from one element to another via resonant or non-resonant magnetic and / or electric field coupling (i.e., electro-induction or magnetic induction).

[0397] During operation, receiver element 229 extracts power from the magnetic and / or electric fields generated by transmitter element 222. Circuit 224 acts as a rectifier, such as a diode rectifier or synchronous rectifier, and rectifies the received power signal. DC / DC converter 226 converts the rectified power signal to the desired power level received by load 228. In this way, receiver element 229 extracts power emitted by transmitter element 222 (transmitter 210), such that electrical power is transferred to load 228 via magnetic / electric field coupling. Load 228, DC / DC converter 226, circuit 224, and receiver element 229 can collectively form receiver 220. As previously mentioned, DC / DC converter 226 may not be present in receiver 220.

[0398] In magnetic field coupling, the inverter (DC / AC inverter) of circuit 216 of transmitter 210 is configured to convert the DC power signal from DC / DC converter 214 into a sinusoidal RF power signal. The sinusoidal RF power signal is output from the DC / AC converter to transmitter element 222. In the case of magnetic field coupling, transmitter element 222 includes coils, i.e., multiple windings forming at least one coil.

[0399] The DC / AC inverter of circuit 216 drives the transmitter coil with sinusoidal alternating current (AC). The transmitter coil is configured to generate an induced (magnetic) field and transfer power via coupling through the induced (magnetic) field. The DC / AC inverter takes a DC input voltage and converts it into AC current to drive the transmitter coil.

[0400] Now go to Figure 3 The diagram illustrates a specific arrangement of a transmitter 300 (e.g., transmitter 210 including circuitry 216) in a wireless power transmission system 200, the circuitry including a load-independent DC / AC inverter. In this arrangement, transmitter 300 includes a power supply (in this embodiment, DC power supply 302), a DC / AC inverter, and transmitter elements. The DC / AC inverter has a current-mode output. The current-mode output indicates that the DC / AC inverter has an AC output with a constant amplitude and phase independent of the load value.

[0401] The DC / AC inverter includes a switch-mode ZVS amplifier as described below. The amplifier is a radio frequency (RF) amplifier. Figure 3As shown, the switch-mode amplifier includes series inductors 304 and 314, each having inductances L1 and L2, which receive an input voltage from a power supply 302. Each inductor 304, 314 is connected in series with a combination of transistors 306 and 316 (Q1 and Q2) (or switches) and capacitors 308 and 318. Capacitors 308 and 318 have capacitances C1 and C2, respectively. Specifically, transistor 306 and capacitor 308 are arranged in parallel and connected to inductor 304. Transistor 316 and capacitor 318 are arranged in parallel and connected to inductor 314. Transistor 306 and capacitor 308 are grounded, and transistor 316 and capacitor 318 are also grounded.

[0402] Inductor 320 (ZVS inductor) is connected in parallel between inductors 304 and 314. Resistor 322, with resistance Rload, is connected in series with inductor 320. Resistor 320 represents the reflected load of the receiver element (e.g., the receiver coil of receiver 220).

[0403] Inductor 320 operates both as a ZVS inductor and as a transmitter element of transmitter 300 (e.g., 222 of transmitter 210). In this way, fewer components are required on transmitter 300, allowing the transmitter to be smaller and lighter. Furthermore, power transfer efficiency is improved because additional capacitors and / or inductors are required to provide the transmitter element, as described in the applicant's own U.S. Patent Application Publication No. 2021 / 0083634A1, the contents of which are incorporated herein by reference.

[0404] In operation, the output signal from power supply 302 is DC, providing a DC voltage input to the inverter. The current in inductor 320 is Ac with a constant amplitude. Inductors 304 and 314 operate as chokes. Therefore, their inductance is chosen such that the current flowing through them is almost DC. In one arrangement, transistors 306 and 316 are NMOS transistors. Transistors 306 and 316 can be silicon, GaN, or silicon carbide. Transistors 306 and 316 can be driven by 50% duty cycle pulses and are 180 degrees out of phase with each other. The values ​​of capacitors 308 and 318 and inductor 320 are chosen to achieve load-independent operation.

[0405] As described in more detail in the applicant's own U.S. Patent Application Publication No. 2021 / 0083634A1, the resonant factor (q) of the transmitter element (i.e., inductor 320) of transmitter 300 is given by the following Formula 1:

[0406] Equation 1

[0407] Lzvs is the inductance of inductor 320.

[0408] Czvs refers to capacitors 308 and 318.

[0409] The resonance factor (q) typically indicates how close the resonant frequencies of inductor 320 (inductor LZVS) and capacitors 308, 318 (capacitor CZVS) are to the operating frequency of transmitter 300. A resonance factor value of 1 indicates that the inverter's frequency is equal to the resonant frequencies of inductor 320 and capacitors 308, 318, which would mean that the inverter is a "resonant inverter".

[0410] The current in inductor 320 is given by the following equation 2:

[0411] Equation 2

[0412] Vin is the input voltage, which is the output voltage of power supply 302.

[0413] w is the operating frequency of transmitter 300.

[0414] like Figure 4a As shown, the current at ZVS inductor 320 is alternating current (AC). The voltage at transistors 306 and 316 is... Figure 4b As shown in the figure, when transistors 306 and 316 are 180 degrees out of phase, the voltage alternates between high and low in opposite ways between transistors 306 and 316.

[0415] Now go to Figure 5a The image shows a receiver 400 used with the transmitter 300. The receiver 400 includes a receiver element, which is arranged in the form of an inductor 402 having an inductance LRX, i.e. Figure 2 Receiver element 229 in receiver 210. Capacitor 404 operates to tune inductor 402 for transmitter 300.

[0416] Inductor 402 is connected in series with capacitor 404, which has capacitance C3. Inductor 402 (receiver element) is connected to a full-wave rectifier including diodes 406, 408, 410, and 412. Diodes 406 and 408 are connected in series. This diode pair is connected in parallel with diodes 410 and 412, which are connected in series. The full-wave rectifier is connected in parallel with capacitor 414, which has capacitance C4. Capacitor 414 is a decoupling capacitor with capacitance C4, which is selected such that the output voltage of receiver 300 is DC. Capacitor 414 is connected in parallel with resistor 416, which has a resistance RLOAD representing the load.

[0417] When the inverter of transmitter 300 drives the TX coil (i.e., inductor 320) with a constant current, the induced voltage at the RX coil (i.e., inductor 302) will be constant. The full-wave rectifier will provide a constant DC output voltage independent of the load value.

[0418] Transmitter 300 and receiver 400 are shown as forming together. Figure 5b The wireless power transmission system 440 is described above. In operation, transmitter 300 transmits power to receiver 400 via magnetic coupling between inductor 320 of transmitter 300 and inductor 402 of receiver 400. The coupling coefficient between transmitter 300 and receiver 400 is denoted as k.

[0419] Now go to Figure 6a An alternative arrangement of the receiver is shown. The receiver is identified by reference numeral 460. Receiver 460 includes an inductor 462 with an inductance of LRX, which forms the receiver element or coil, namely receiver element 229 of receiver 220. Inductor 462 is connected to a rectifier, which is connected to a load at receiver 460. Specifically, inductor 462 is connected in parallel with capacitor 464 having a capacitance C3. Instead, receiver 460 is a Class E inverter. Transistors (e.g., transistors 306, 316 of emitter 300) have been replaced with diodes 470, 480.

[0420] Capacitor 464 is connected in series with diodes 470 and 480 (D1 and D2) and a combination of capacitors 472 and 482. Capacitors 472 and 482 have capacitances C4 and C5, respectively. Specifically, diode 470 and capacitor 472 are arranged in parallel and connected to inductor 474 with inductance L3. Diode 480 and capacitor 482 are arranged in parallel and connected to inductor 484 with inductance L4. Inductors 474 and 484 are connected in parallel to capacitor 490 with capacitance C6, and capacitor 490 is connected to resistor 492 with load RLoad representing the load of receiver 460.

[0421] In operation, inductors 474 and 484 serve as chokes. Inductors L3 and L4 are chosen to be sufficiently high such that the current flowing through them is DC. Capacitors 472 and 482 have a similar function to capacitors 308 and 318 in transmitter 300. Capacitors 472 and 482 shape the voltage across diodes 470 and 480 so that the rectifier at receiver 460 operates with a 50% (±10%) duty cycle.

[0422] Capacitor 464 is placed across (parallel to) inductor 462 (receiver element / coil). Capacitor 462 is part of a T-impedance transformation circuit, whose main function is to convert the induced voltage at inductor 462 from a constant voltage to a constant current. The T-impedance transformation circuit of the rectifier is shown in [the diagram]. Figure 6b As shown in the image.

[0423] like Figure 6b As shown, the rectifier is represented by its equivalent input impedance, which is a series RL circuit represented by inductors 426 and 428 with inductances Lrec1 and Lrec2 respectively, and resistor 430 with resistance Rrec. Inductor 462 (receiver coil) is divided into three inductors 420, 422, and 424 with inductances LRX1, LRX2, and LRX3 respectively. The combination of inductors 420, 422, and 424, capacitor 464, and inductors 426 and 428 forms the T impedance transformation circuit.

[0424] The values ​​of the rectifier components are selected such that the inductance Lrec1 of inductor 426 is equal to the inductance LRX2 of inductor 422, and the inductance Lrec2 of inductor 428 is equal to the inductance LRX3 of inductor 424.

[0425] The capacitance C3 of capacitor 464 is given by the following equation 3:

[0426] Equation 3

[0427] w is the operating frequency of the receiver 460, and α is a dimensionless factor such that 1.25 < α ≤ 3.

[0428] The value of α allows control over the reflected impedance of receiver 460, making it more inductive or capacitive depending on the value of the load 492 at receiver 460.

[0429] Transmitter 300 and receiver 460 are shown as forming together. Figure 7 The wireless power transmission system 494 is described above. In operation, transmitter 300 transmits power to receiver 460 via magnetic coupling between inductor 320 of transmitter 300 and inductor 462 of receiver 460. The coupling coefficient between transmitter 300 and receiver 460 is denoted as k.

[0430] For various applications, such as charging the batteries of electric vehicles (EVs) or powering the rotor of an electric motor such as a synchronous motor, the output current of the transmitter must be regulated and controlled.

[0431] Current regulation is required because the load resistance can change. For example, the load resistance can change as the rotor windings of the motor heat up. Furthermore, the input power signal voltage can vary because it can be supplied by a battery. For instance, a 400V nominal EV battery can drop to 300V when the battery is at its lowest charge level. Therefore, the transmitter's output power needs to be controllable and adjustable.

[0432] Class E inverters (such as those associated with transmitter 300) can be difficult to control because ZVS may lose its operating frequency and the duty cycle of the switching cycle may be adjusted. Alternatively, the input DC voltage to the inverter at transmitter 300 can be changed by introducing a DC / DC converter into transmitter 300. However, adding additional electrical components will increase the size and weight of transmitter 300. Furthermore, power transfer efficiency may decrease. In particular, adding energy storage inductors and chokes can lead to power losses and increase size and weight due to the relatively large size of these components.

[0433] Now go to Figure 8 This diagram illustrates an alternative arrangement of transmitter 500 that at least partially addresses these issues. In this arrangement, a DC / DC converter (i.e., DC / DC converter 214) has been added to transmitter 500. The DC / DC converter is used to convert the received DC voltage signal to the desired voltage level. However, instead of adding a completely independent DC / DC conversion function, the DC / DC converter is created using inductors 504 and 514 of the inverter. Inductors 504 and 514 now have a dual purpose / function; firstly, they act as energy storage and release components typically present in switch-mode DC / DC converters, and secondly, they act as chokes feeding a constant DC current to the Class E inverter.

[0434] The transmitter 500 is described in more detail. The transmitter 500 includes a battery model 530, which includes a power supply 532 (DC power supply) connected in series with a resistor 534 and an inductor 536. The battery model 530 is connected to a half-bridge. The half-bridge includes a capacitor 540 connected in parallel with a diode 544 (D3), and a transistor 542 (Q3) is located between the capacitor 540 and the diode 544.

[0435] The half-bridge is connected to an inverter similar to the one described with transmitter 300. The inverter includes a switch-mode ZVS amplifier as an RF amplifier. The switch-mode amplifier includes series inductors 504 and 514, each having inductances L1 and L2, respectively. Each inductor 504, 514 is connected in series to a combination of transistors 506 and 516 (Q1 and Q2) (or switches) and capacitors 508 and 518, respectively. Capacitors 508 and 518 have capacitances C1 and C2, respectively. Specifically, transistor 506 and capacitor 508 are arranged in parallel and connected to inductor 504. Transistor 516 and capacitor 518 are arranged in parallel and connected to inductor 514. Transistor 506 and capacitor 508 are grounded, and transistor 516 and capacitor 518 are also grounded.

[0436] Inductor 520 (ZVS inductor) is connected in parallel between inductors 504 and 514 along with resistor 522 having a resistance R_Load. Inductor 520 operates as both a ZVS inductor of emitter 500 and an emitter element (e.g., 222 of emitter 210). In this way, fewer components are required on emitter 500, allowing the emitter to be smaller and lighter. Furthermore, power transfer efficiency is improved because additional capacitors and / or inductors are required to provide the emitter element, as described in the applicant's own U.S. Patent Application Publication No. 2021 / 0083634A1, the contents of which are incorporated herein by reference.

[0437] The transmitter 500 has two distinct switching frequencies throughout the circuit. The first switching frequency is the half-bridge switching frequency, providing buck conversion. The second switching frequency is the Class E inverter switching frequency. The first switching frequency will be much lower, on the order of tens of kHz, while the second switching frequency will be on the order of 100 kHz to several MHz.

[0438] Transmitter 500 and receiver 460 are shown as forming together. Figure 9 The wireless power transmission system 550 is described above. In operation, transmitter 500 transmits power to receiver 460 via magnetic coupling between inductor 520 of transmitter 500 and inductor 462 of receiver 460. The coupling coefficient between transmitter 500 and receiver 460 is denoted as k.

[0439] During operation, the voltages at transistors 506 and 516 of transmitter 500 are out of phase by 180 degrees, such as... Figure 10a As shown. Similarly, the voltages at diodes 470 and 480 of receiver 460 are out of phase, as... Figure 10b As shown.

[0440] Although a specific transmitter has been described, those skilled in the art will understand that variations are possible. Now turn to Figure 11This illustrates another arrangement of the transmitter. In this arrangement, unless otherwise stated, transmitter 800 includes the same elements as transmitter 500. An additional identical element "300" is added.

[0441] Emitter 800 includes transistor 844 connected to transistor 842, instead of diode 544 (D3) connected to transistor 542 as in emitter 500. With this modification, the emitter operates as a "synchronous buck" DC / DC converter. Transistor 844 operates in a complementary manner to transistor 842.

[0442] Although a specific receiver has been described, those skilled in the art will understand that variations are possible. Now turn to Figure 12a and Figure 12b This illustrates other arrangements of the receiver. Figure 12a In the arrangement shown, unless otherwise specified, receiver 1460 includes elements as in receiver 460. The same element "1000" is added. Specifically, receiver 1460 includes MOSFETs 1470 and 1480 instead of diodes 470 and 480. This improves the power transmission efficiency of receiver 1460 when compared to receiver 460 and / or wireless power transmission systems that include receiver 1460. Additionally or alternatively, replacing diodes with MOSFETs can reduce losses, such as ohmic losses.

[0443] exist Figure 12b In the arrangement shown, unless otherwise specified, receiver 2460 includes elements similar to those in receiver 460. The same element "2000" is added. Specifically, receiver 2460 does not include a capacitor connected in parallel with inductor 1462 (i.e., connected to the same two nodes). In this arrangement, the capacitor (i.e., capacitor 464 with capacitor C3) is completely omitted. This results in a simpler receiver circuit because the number of required components is reduced. Therefore, the size (e.g., shape factor) of receiver 2460 can be reduced. Thus, receiver 2460 can be suitable for applications where size constraints are critical.

[0444] However, receiver 2460 may lose its ability to provide a constant DC current across the entire load range. In other words, when compared to receiver 460, receiver 2460 can provide a constant DC current output over a smaller range. For example, receiver 2460 may only be suitable for load resistances varying by approximately ±25% from its nominal value, while receiver 460 can be suitable for larger variations.

[0445] The capacitances C4 and C5 of capacitors 2472 and 2482 are given by the following equation 4:

[0446] Equation 4

[0447] ω is the operating frequency of receiver 2460, α is a dimensionless factor such that 0.75 < α < 1.25, and LRX is the inductance of the receiver element. α is used to set receiver 2460 to output a certain current value based on the load resistance.

[0448] The described transmitter and receiver can be used in a variety of applications. For example, powering the rotor in an electric motor. Electric motors are used in a wide range of applications, including electric vehicles (EVs). While the electric motor can be a permanent magnet synchronous motor, using rare earth metals to provide the required permanent magnets can have negative environmental impacts and put pressure on the supply chain of such metals. Therefore, there is a trend in industry to replace permanent magnets with electromagnets in the rotor of electric motors. The rotor now requires external power. Such a motor can be called an externally current-excited synchronous motor.

[0449] Go to Figure 13 An exemplary electric motor 600 is shown. The motor 600 includes a stator 610 having windings 612 forming electromagnets. In the arrangement shown, there are four sets of windings 612, and they are equidistant within the stator 610. The stator 610 surrounds a rotor 604, which surrounds a central shaft 602. The rotor 604 includes magnetic elements 606. As described, in the case of a permanent magnet synchronous motor, the magnetic elements 606 include permanent magnets. These permanent magnets can be replaced with electromagnets, such that the motor 600 is an externally current-excited synchronous motor.

[0450] When rotor 604 rotates, slip rings or brushes are used to transfer current to the electromagnet. However, slip rings and brushes suffer wear and therefore require regular maintenance and / or replacement. This increases the cost of motor 600 and potential downtime. An alternative is needed.

[0451] The described wireless power transfer system can be used to provide electrical power to the magnetic element 606 of the stator 604. In the exemplary arrangement, the rotor typically requires a current of up to 20A. The current must be adjustable, controllable, and modifiable. The rotor rotates at extremely high speeds, such as up to 20,000 RPM. The rotor's input voltage can be 400V; however, it is expected to reach 800V in the future. Therefore, the wireless power transfer system will have an input voltage of 400V and then provide an output voltage of 400V. The transmitter of the system will be stationary and not rotating, while the receiver will rotate because it is associated with the rotor 604 and the magnetic element 606.

[0452] Now go to Figure 14aThe figure shows a portion of a transmitter used with this motor 600. As shown, the transmitter includes transmitter elements in the form of a transmitter coil 620, which includes multiple overlapping windings around the shaft 602 of the motor 600. The windings are centered on the rotor 602 and are in the same axial plane. As previously described, the windings generate a magnetic field to transmit power to the receiver.

[0453] A magnetic field can induce eddy currents in shaft 602, resulting in losses. Therefore, the transmitter also includes a field cancellation coil 622, which comprises multiple windings around shaft 602. The windings of the cancellation coil 622 are centered on rotor 602 and lie in the same axial plane. The windings of the cancellation coil 622 are parallel to the windings of the transmitter coil 620 in the radial plane of shaft 602 of motor 600. The field generated by transmitter coil 620 is cancelled by cancellation coil 622, which reduces losses from induced eddy currents.

[0454] The transmitter also includes a shield, which in this arrangement takes the form of a plate 624 surrounding and perpendicular to axis 602. Plate 624 protects the transmitter coil 620 and the cancelling coil 622 from environmental influences.

[0455] Now go to Figure 14b The diagram illustrates a transmitter combined with a receiver. Similar to the transmitter, the receiver includes a receiver coil 630, a field cancellation coil 632, and a plate 634. These components are oriented in the same manner as the transmitter components. The receiver coil 630 is positioned close to the transmitter coil 620, and so is the receiver's cancellation coil 632 relative to the transmitter's cancellation coil 622. The receiver's plate 634 is positioned opposite the transmitter coil 630, such that the transmitter coil 620, the receiver coil 630, and the associated cancellation coils 622, 632 are surrounded by plates 624, 634 in an axial plane defined by shaft 602.

[0456] The transmitter is stationary and transmits power to the rotating receiver. During operation, power is transferred from the stationary transmitter coil 620 to the rotating receiver coil 630 to power the magnetic elements 606 of the stator 604.

[0457] right Figure 14b The transmitter and receiver shown are used in a simulation. In this simulation, the inductance of the transmitter coil 620 is found to be 4.2uH, and the Q factor is 250 at an operating frequency of 1MHz.

[0458] Although the cancelling coils 622 and 632 have been described, those skilled in the art will understand that other configurations are possible. In another arrangement, the shaft 602 is wound around copper or aluminum to provide a lower resistance loop for inducing eddy currents.

[0459] Now go to Figure 15 An alternative arrangement of the transmitter coil and receiver coil is shown. In this arrangement, the transmitter coil 730 surrounds the receiver coil 720, which in turn surrounds the shaft 602 of the motor 600. Those skilled in the art will understand that the transmitter coil 730 may alternatively be surrounded by the receiver coil 720. The coils 720 and 730 are axially fixed in place while allowing the receiver coil 720 to rotate about the shaft 602 via a separating material 750. The coils 720 and 730 are enclosed by a housing defined by shielding plates 742 and 744 and a cylindrical shielding plate 740. The shielding housing protects the coils 720 and 730 from environmental influences.

[0460] Simulate using the following parameters Figure 15 The arrangement is as follows: The cylindrical shield 740 has a height of 65 mm, while the total diameter of the circular shields 742, 744, and shaft 602 is 150 mm. The splitter material 750 is 20 mm thick on either axial side of coils 720 and 730. Under these conditions, the inductance of transmitter coil 730 is 4.2 μH, and the inductance of receiver coil 720 is 4.53 μH. The RF power transmission efficiency was found to be 97%.

[0461] During operation, power is transferred from the stationary transmitter coil 730 to the rotating receiver coil 720 to power the magnetic element 606 of the stator 604.

[0462] Although embodiments have been described above with reference to the accompanying drawings, those skilled in the art will understand that variations and modifications may be made without departing from the scope defined by the appended claims.

Claims

1. A transmitter for transmitting power to a receiver in a wireless power transmission system, the transmitter comprising transmitter elements and an inverter, the inverter comprising a switch-mode zero-voltage switching (ZVS) amplifier, the switch-mode ZVS amplifier comprising: A pair of circuits, including: At least one transistor and at least one capacitor arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor; ZVS inductor, which is electrically connected to the pair of circuits, operates as the transmitter element of the transmitter to transfer power to the receiver of the wireless power transmission system via magnetic field coupling.

2. The transmitter according to claim 1, wherein, The inverter includes a combined DC / DC converter and inverter for converting an input DC signal to a desired level and inverting the DC signal into AC.

3. The transmitter according to claim 2, wherein, The combined DC / DC converter and inverter includes a half-bridge and an inductor in the pair of circuits of the inverter, the inductor being electrically connected to the half-bridge.

4. The transmitter according to claim 3, wherein, The half-bridge includes a transistor and a diode connected in parallel to the transistor.

5. The transmitter according to claim 3 or 4, wherein, The half-bridge has a first switching frequency, and the transistors of the pair of circuits have a second switching frequency.

6. The transmitter according to claim 5, wherein, The second switching frequency is greater than the first switching frequency.

7. The transmitter according to any one of claims 2 to 6, wherein, The inductor is adapted to store and release energy for DC / DC conversion, and the inductor is adapted to operate as a choke coil of the inverter.

8. The transmitter according to claim 2 or 7, wherein, The inductor is adapted to provide a constant DC current.

9. The transmitter according to any one of claims 1 to 8, wherein, The combined DC / DC converter and inverter are Class E inverters.

10. The transmitter according to any one of claims 1 to 9, wherein, The combined DC / DC converter and inverter are load-independent.

11. A transmitter for transmitting power to a receiver in a wireless power transmission system, the transmitter comprising transmitter elements and a combined DC / DC converter and inverter. The combined DC / DC converter and inverter include: A pair of circuits, including: At least one transistor and at least one capacitor arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor, and The inductor of the pair of circuits of the half-bridge and the inverter, the inductor being electrically connected to the half-bridge. The inductor is adapted to store and release energy for DC / DC conversion, and the inductor is adapted to operate as a choke coil of the inverter.

12. An inverter operating with a DC / DC conversion function for use as a transmitter in a wireless power transmission system. The inverter includes: A pair of circuits, including: At least one transistor and at least one capacitor arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor, and The inductor of the pair of circuits of the half-bridge and the inverter, the inductor being electrically connected to the half-bridge. The inductor is adapted to store and release energy for DC / DC conversion, and the inductor is adapted to operate as a choke coil of the inverter.

13. A method for transmitting power from a transmitter to a receiver in a wireless power transfer system, the transmitter including transmitter elements and an inverter, the inverter including a switch-mode zero-voltage switching (ZVS) amplifier, the switch-mode ZVS amplifier comprising: A pair of circuits, including: At least one transistor and at least one capacitor arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor; A ZVS inductor, electrically connected to the pair of circuits, the ZVS inductor operating as the transmitter element of the transmitter to transfer power to a receiver of a wireless power transfer system via magnetic field coupling, the method comprising: A receiver element generates a field via the transmitter element to transmit power to the receiver of the wireless power transmission system.

14. A method for transmitting power from a transmitter to a receiver in a wireless power transmission system, the transmitter comprising transmitter elements, and a combined DC / DC converter and inverter. The combined DC / DC converter and inverter include: A pair of circuits, including: At least one transistor and at least one capacitor arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor, and The inductor of the pair of circuits of the half-bridge and the inverter, the inductor being electrically connected to the half-bridge. Wherein, the inductor is adapted to store and release energy for DC / DC conversion, and the inductor is adapted to operate as a choke coil of the inverter, the method comprising: A receiver element generates a field via the transmitter element to transmit power to the receiver of the wireless power transmission system.

15. A rectifier for rectifying an alternating current (AC) signal into a direct current (DC) signal, the rectifier being adapted for use in a receiver of a wireless power transmission system, the rectifier including a capacitor for converting a voltage signal at a receiver element into a current signal. The capacitor is connected in parallel to the receiver element of the receiver in the wireless power transmission system.

16. A receiver for extracting power from a field generated by a transmitter of a wireless power transmission system, the receiver comprising a receiver element electrically connected to a rectifier, the rectifier including a capacitor for converting a voltage signal at the receiver element into a current signal. The capacitor is electrically connected in parallel with the receiver element.

17. The receiver according to claim 16, wherein, The voltage signal is constant.

18. The receiver according to claim 16 or 17, wherein, The current signal is constant.

19. The receiver according to any one of claims 16 to 18, wherein, The receiver includes an impedance transformation circuit, which includes the capacitor.

20. The receiver according to claim 19, wherein, The impedance transformation circuit has a T-network topology.

21. The receiver according to any one of claims 16 to 20, wherein, The capacitance of the capacitor is: Where C3 is the capacitance of the capacitor. α is a dimensionless factor such that 1.25 < α ≤ 3. Wherein, ω is the operating frequency of the receiver. Wherein, LRX2 is part of the inductance of the receiver element, and LRX3 is another part of the inductance of the receiver element.

22. The receiver according to claim 21, wherein, The inductance of the receiver element is: Wherein, LRX is the inductance of the receiver element.

23. The receiver according to any one of claims 16 to 22, wherein, The rectifier includes: A pair of circuits, including: At least one diode and at least one capacitor are arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor; and The capacitor is electrically connected to the pair of circuits and the receiver element.

24. The receiver according to any one of claims 16 to 23, wherein, The rectifier is a Class E rectifier.

25. The receiver according to any one of claims 16 to 24, wherein, The rectifier is a push-pull rectifier.

26. A method for transmitting power from a transmitter to a receiver in a wireless power transmission system, comprising a receiver element electrically connected to a rectifier, the rectifier including a capacitor for converting a voltage signal at the receiver element into a current signal. The capacitor is connected in parallel to the receiver element, and the method includes: Power is extracted from the field generated by the transmitter element of the transmitter of the wireless power transmission system via the receiver element.

27. A wireless power transmission system, comprising a transmitter and a receiver, The transmitter is used to transmit power to the receiver, the transmitter includes transmitter elements and an inverter, the inverter includes a switch-mode zero-voltage switching (ZVS) amplifier, the switch-mode ZVS amplifier includes: A pair of circuits, including: At least one transistor and at least one capacitor arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor; A ZVS inductor, electrically connected to the pair of circuits, operates as the transmitter element of the transmitter to transfer power to the receiver of the wireless power transfer system via magnetic field coupling; and The receiver is used to extract power from the field generated by the transmitter. The receiver includes a receiver element electrically connected to a rectifier, the rectifier including a capacitor for converting a voltage signal at the receiver element into a current signal. The capacitor is electrically connected in parallel with the receiver element.

28. A wireless power transmission system, comprising a transmitter and a receiver, The transmitter is used to transmit power to the receiver, and the transmitter includes transmitter elements, an inverter, and a DC / DC converter. The inverter includes: A pair of circuits, including: At least one transistor and at least one capacitor arranged in parallel; and At least one inductor arranged in series with the transistor and the capacitor, and The DC / DC converter includes a half-bridge and an inductor in the pair of circuits of the inverter, the inductor being electrically connected to the half-bridge. The inductor is adapted to store and release energy for DC / DC conversion, and the inductor is adapted to operate as a choke coil of the inverter; and The receiver is used to extract power from the field generated by the transmitter. The receiver includes a receiver element electrically connected to a rectifier, the rectifier including a capacitor for converting a voltage signal at the receiver element into a current signal. The capacitor is electrically connected in parallel with the receiver element.

29. A wireless power transmission system, comprising: The transmitter according to any one of claims 1 to 11; and The receiver according to any one of claims 16 to 25.

30. A transmitter for transmitting power to a receiver in a wireless power transmission system, the transmitter including a transmitter element comprising an air-core coil having a plurality of overlapping flat windings, the transmitter element surrounding a shaft of an electric motor.

31. The transmitter according to claim 30, further comprising: Emitter field cancellation element.

32. The transmitter according to claim 31, wherein, At least one of the transmitter element and the transmitter field cancellation element surrounds the shaft of the motor.

33. The transmitter according to claim 32, wherein, The motor is a current-driven synchronous motor.

34. The transmitter according to claim 32 or 33, wherein, The transmitter field cancellation element and the transmitter element are coplanar in the radial direction relative to the axis.

35. The transmitter according to any one of claims 31 to 34, wherein, The transmitter field elimination element includes a field elimination coil having multiple overlapping flat windings.

36. A receiver for extracting power from a field generated by a transmitter of a wireless power transmission system, the receiver comprising a receiver element including an air-core coil having a plurality of overlapping flat windings, the receiver element surrounding a shaft of an electric motor.

37. The receiver of claim 36, further comprising: Receiver field elimination element.

38. The receiver according to claim 37, wherein, At least one of the receiver element and the receiver field cancellation element surrounds the shaft of the motor.

39. The receiver according to claim 38, wherein, The motor is a current-driven synchronous motor.

40. The receiver according to claim 38 or 39, wherein, The receiver field cancellation element and the receiver element are coplanar in the radial direction relative to the axis.

41. The receiver according to any one of claims 37 to 40, wherein, The receiver field elimination element includes a field elimination coil having multiple overlapping flat windings.

42. A wireless power transmission system, comprising: A transmitter, the transmitter including a transmitter element, the transmitter element including an air-core coil having a plurality of overlapping flat windings; and The receiver includes a receiver element for extracting power from a field generated by the transmitter, the receiver element including an air-core coil having a plurality of overlapping flat windings.

43. The system according to claim 42, wherein, The transmitter's coil surrounds the receiver's coil.

44. The system according to claim 42 or 43, wherein, The coils are located in the same radial plane centered on the axis, and the coils are arranged around the axis.

45. The system according to any one of claims 42 to 44, wherein, The transmitter's coil has a first radius, and the receiver's coil has a second radius, wherein the first radius is smaller than the second radius.

46. ​​The system according to any one of claims 42 to 45, further comprising: One or more shielding elements.

47. The system according to claim 46, wherein, The shielding element includes a cylindrical shielding element, a first shielding plate, and a second shielding plate, wherein the cylindrical shielding element and the plates form a shell surrounding the core of the transmitter and the receiver.

48. The system according to any one of claims 42 to 47, wherein, The transmitter also includes a transmitter field elimination element.

49. The system according to claim 48, wherein, At least one of the transmitter element and the transmitter field cancellation element surrounds the shaft of the motor.

50. The system according to claim 49, wherein, The motor is a current-driven synchronous motor.

51. The system according to claim 49 or 50, wherein, The transmitter field cancellation element and the transmitter element are coplanar in the radial direction relative to the axis.

52. The system according to any one of claims 48 to 51, wherein, The transmitter field elimination element includes a field elimination coil having multiple overlapping flat windings.

53. The system according to any one of claims 42 to 52, wherein, The receiver also includes a receiver field elimination element.

54. The system according to claim 53, wherein, At least one of the receiver element and the receiver field cancellation element surrounds the shaft of the motor.

55. The system according to claim 54, wherein, The motor is a current-driven synchronous motor.

56. The system according to claim 54 or 55, wherein, The receiver field cancellation element and the receiver element are coplanar in the radial direction relative to the axis.

57. The system according to any one of claims 53 to 56, wherein, The receiver field elimination element includes a field elimination coil having multiple overlapping flat windings.

58. The system according to any one of claims 42 to 57, wherein, The transmitter also includes a power source.

59. The system according to claim 58, wherein, The power source is a direct current (DC) power source.

60. The system according to any one of claims 42 to 59, wherein, The receiver also includes a payload.

61. The system according to claim 60, wherein, The load includes the rotor windings of the electric motor.

62. The system according to claim 61, wherein, The motor is a current-driven synchronous motor.

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