Wireless power transmission system, wireless power transmission device and method

Abstract

A wireless power transmission device, a controller for controlling a switch in a receiver, the receiver comprising a first receiver coil for magnetically coupling to a transmitter coil of a wireless power transmission system, a rectifier circuit coupled to two terminals of the first receiver coil, a second receiver coil, and a first auxiliary switch, wherein the second receiver coil is connected in series with the first auxiliary switch, and the second receiver coil is used to magnetically couple to the transmitter coil; wherein, in response to a low power mode of the device, the controller is used to turn on the first auxiliary switch, so that the first receiver coil and the second receiver coil are connected in series to increase the gain of the wireless power transmission system. The present application also provides a wireless power transmission method and controller. The receiver in the wireless power transmission device of the present application is compatible with different power modes.

Description

[0001] This invention is a divisional application of the invention patent application with application number 202110289122.7 submitted to the State Intellectual Property Office of China on March 17, 2021, and the invention name is "Wireless Power Transmission System, Wireless Power Transmission Device and Method". Technical Field

[0002] The present invention relates to a power transmission system, and in particular to a wireless power transmission system, device and method. Background Art

[0003] With technological advancements, wireless power transmission has become an effective and convenient mechanism for providing power or charging batteries in mobile devices, such as mobile phones, tablets, digital cameras, MP3 players, and / or other similar devices. A wireless power transmission system typically includes a primary-side transmitter and a secondary-side receiver. The primary-side transmitter and the secondary-side receiver are magnetically coupled via magnetic coupling. The magnetic coupling can be implemented as a loosely coupled transformer having a primary-side coil formed in the primary-side transmitter and a secondary-side coil formed in the secondary-side receiver.

[0004] The primary-side transmitter may include a power conversion unit, such as a primary side of a power converter. The power conversion unit is coupled to a power source and is capable of converting electrical energy into a wireless power signal. The secondary-side receiver may receive the wireless power signal via the loosely coupled transformer and convert the received wireless power signal into electrical energy suitable for a load.

[0005] As power consumption becomes increasingly important, there is a need to provide wireless power transmission systems with high power density and high efficiency. In high-power wireless transmission systems, the larger current output will cause the temperature in the receiver coil of the wireless power transmission system to increase, and such temperature increase leads to poor system efficiency. To overcome this disadvantage, a low-inductance receiver coil can be used to reduce the temperature increase in the receiver coil. However, receivers with low-inductance receiver coils can be used in a variety of applications, such as low-power applications (for example, the power of the wireless power transmission system is less than 10W). In low-power applications, receivers with low-inductance receiver coils are not compatible with low-power transmitters (for example, transmitters with low input voltages). Therefore, it is desirable to have a high-performance receiver that exhibits good behavior. For example, an efficient receiver that is compatible with a variety of operating conditions. Summary of the Invention

[0006] These and other problems are generally solved or avoided, and technical advantages are generally achieved, by providing a high-efficiency receiver compatible with a variety of operating conditions as provided by preferred embodiments of the present disclosure.

[0007] According to one embodiment, a wireless power transmission device includes: a controller for controlling a switch in a receiver, the receiver including a first receiver coil for magnetically coupling to a transmitter coil of a wireless power transmission system, a rectifier circuit coupled to two terminals of the first receiver coil, a second receiver coil, and a first auxiliary switch, wherein the second receiver coil is connected in series with the first auxiliary switch and the second receiver coil is used to magnetically couple to the transmitter coil, wherein, in response to a low power mode of the device, the controller is used to turn on the first auxiliary switch so that the first receiver coil and the second receiver coil are connected in series to increase the gain of the wireless power transmission system.

[0008] According to another embodiment, a wireless power transmission method includes: determining, by a controller, an operating mode of a wireless power transmission system, the wireless power transmission system including a transmitter coil, a plurality of receiver coils, a rectifier circuit coupled to the plurality of receiver coils, and an auxiliary switch connected in series with one of the plurality of receiver coils; turning on the auxiliary switch by a signal generated by the controller in response to a low power mode of the wireless power transmission system, wherein, after the auxiliary switch is turned on, at least two of the plurality of receiver coils are connected in series via the turned-on auxiliary switch, thereby increasing the gain of the wireless power transmission system; and turning off the auxiliary switch by a signal generated by the controller in response to a high power mode of the wireless power transmission system, wherein, after the auxiliary switch is turned off, the gain of the wireless power transmission system is reduced.

[0009] According to yet another embodiment, a controller includes circuitry for controlling an auxiliary switch and a switch in a rectifier circuit, wherein the rectifier circuit is coupled to a first receiver coil configured to magnetically couple to a transmitter coil of a wireless power transfer system, and the auxiliary switch and the second receiver coil are connected in series. In response to a low-power mode of the wireless power transfer system, the controller is configured to turn on the auxiliary switch such that the first receiver coil and the second receiver coil are connected in series to increase a gain of the wireless power transfer system.

[0010] The foregoing has generally outlined the features and technical advantages of the present disclosure so that the subsequent detailed description of the present application may be better understood. Additional features and advantages that form the subject matter of the claims of the present application will be described hereinafter. Those skilled in the art will appreciate that the disclosed concepts and specific embodiments may be readily used as a basis for modifying or designing other structures or processes to achieve the same objectives of the present application. Those skilled in the art will also appreciate that such equivalent constructions do not depart from the spirit and scope of the present disclosure as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a better understanding of the technical solutions and effects of the present application, reference is now made to the following description and the accompanying drawings, in which:

[0012] Figure 1 A block diagram of a wireless power transmission system according to various embodiments of the present application is shown;

[0013] Figure 2 Shows the application Figure 1 A schematic diagram of a first embodiment of a receiver of a wireless power transmission system according to various embodiments is shown;

[0014] Figure 3 A schematic diagram illustrating a receiver according to various embodiments of the present application configured to operate in a first stage of a low power mode;

[0015] Figure 4 A schematic diagram illustrating a receiver according to various embodiments of the present application configured to operate in a second phase of a low power mode;

[0016] Figure 5 A schematic diagram illustrating a receiver according to various embodiments of the present application configured to operate in a first phase of a high power mode;

[0017] Figure 6 A schematic diagram illustrating a receiver according to various embodiments of the present application configured to operate in a second phase of a high power mode;

[0018] Figure 7 Implementations of the first receiver coil and the second receiver coil of various embodiments of the present application are shown;

[0019] Figure 8 Various embodiments of the present application are shown Figure 1 A schematic diagram of a second embodiment of a receiver of a wireless power transmission system is shown;

[0020] Figure 9 Various embodiments of the present application are shown Figure 1 A schematic diagram of a third embodiment of a receiver of a wireless power transmission system is shown;

[0021] Figure 10 Various embodiments of the present application are shown Figure 1 A schematic diagram of a first embodiment of a start-up circuit of a receiver of a wireless power transmission system is shown;

[0022] Figure 11 A schematic diagram illustrating a startup circuit according to various embodiments of the present application configured to operate in a first phase;

[0023] Figure 12A schematic diagram illustrating a startup circuit according to various embodiments of the present application configured to operate in the second phase;

[0024] Figure 13 A schematic diagram illustrating a startup circuit according to various embodiments of the present application configured to operate in a first stage of a normal mode;

[0025] Figure 14 A schematic diagram illustrating a startup circuit according to various embodiments of the present application configured to operate in the second stage of the normal mode.

[0026] Figure 15 Various embodiments of the present application are shown Figure 1 A schematic diagram of a second embodiment of a start-up circuit of a receiver of a wireless power transmission system is shown;

[0027] Figure 16 Various embodiments of the present application are shown Figure 15 The schematic diagram of the startup circuit shown is configured to operate in the first stage;

[0028] Figure 17 Various embodiments of the present application are shown Figure 15 A schematic diagram of the startup circuit shown is configured to operate in the second phase; and

[0029] Figure 18 The control of various embodiments of the present application is shown Figure 2 The flowchart of the receiver is shown.

[0030] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated.The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale. DETAILED DESCRIPTION

[0031] The making and using of the preferred embodiments of the present application are discussed in detail below. However, it should be understood that the present disclosure provides many applicable inventive concepts that can be embodied in a variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the present application and do not limit the scope of the present application.

[0032] This application will be described with reference to preferred embodiments in a specific context, namely, a low-gain receiver compatible with various operating conditions. However, the present invention may also be applied to various power conversion devices in wireless power transmission systems. Various embodiments will be described in detail below with reference to the accompanying drawings.

[0033] Figure 1FIG1 shows a block diagram of a low-gain wireless power transmission system (hereinafter referred to as a wireless power transmission system) in various embodiments of the present application. The wireless power transmission system 100 includes a power converter 104 cascaded between an input power source 102 and a load 114 and a wireless power transmission device 101. The wireless power transmission device 101 includes a transmitter 110 and a receiver 120. Figure 1 As shown, the transmitter 110 includes a cascade-connected transmitter circuit 107 and a transmitter coil L1. The input of the transmitter circuit 107 is coupled to the output of the power converter 104. The receiver 120 includes a cascade-connected receiver coil L2 and a rectifier circuit 112. The output of the rectifier circuit 112 is coupled to the load 114.

[0034] When the receiver 120 is placed close to the transmitter 110, the transmitter 110 is magnetically coupled to the receiver 120 via a magnetic field. The transmitter coil L1, which is part of the transmitter 110, and the receiver coil, which is part of the receiver 120, form a loosely coupled transformer 115. Thus, electrical energy can be transferred from the transmitter 110 to the receiver 120.

[0035] In some embodiments, the transmitter 110 may be located in a charging pad. The transmitter coil is placed below the upper surface of the charging pad. The receiver 120 may be embedded in a mobile phone. When the mobile phone is placed close to the charging pad, magnetic coupling between the transmitter coil and the receiver coil is established. In other words, through the power transfer between the transmitter 110 and the receiver 120, the transmitter coil and the receiver coil may form a loosely coupled transformer. The coupling strength between the transmitter coil L1 and the receiver coil L2 may be quantified as a coupling coefficient k. In some embodiments, k ranges from approximately 0.05 to approximately 0.9.

[0036] In some embodiments, after the transmitter coil L1 and the receiver coil L2 establish a magnetic coupling connection, the transmitter 110 and the receiver 120 may form an electrical energy system, through which electrical energy from the input power source 102 may be wirelessly transmitted to the load 114 .

[0037] The input power source 102 may be a power adapter for converting mains voltage into direct current (DC) voltage. In other embodiments, the input power source 102 may be a renewable power source, such as a solar panel. Furthermore, the input power source 102 may also be an energy storage device, such as a rechargeable battery, a fuel cell, and / or other similar energy storage devices.

[0038] The load 114 may represent the power consumed by a mobile device (e.g., a mobile phone) coupled to the receiver 120. In other embodiments, the load 114 may refer to a rechargeable battery and / or multiple rechargeable batteries connected in series or in parallel coupled to the output of the receiver 120.

[0039] According to some embodiments, the transmitter circuit 107 may include multiple primary-side switches of a full-bridge converter. A full-bridge may also be referred to as an H-bridge. In other embodiments, the transmitter circuit 107 may include multiple primary-side switches of other types of converters, such as a half-bridge converter, a push-pull converter, or the like.

[0040] It should be noted that the converters described above are only some examples. Those skilled in the art will appreciate that other suitable power converters, such as a power converter based on a Class E topology (eg, a Class E amplifier), may also be used.

[0041] The transmitter circuit 107 may further include a resonant capacitor. The resonant capacitor and the magnetic induction of the transmitter coil may form a resonant circuit. Depending on design requirements and different applications, the resonant circuit may further include a resonant inductor. In some embodiments, the resonant inductor may be implemented using an external inductor. In other embodiments, the resonant inductor may be implemented using connecting wires.

[0042] The receiver 120 includes the receiver coil L2. When the receiver 120 is placed near the transmitter 110, the receiver coil L2 is magnetically coupled to the transmitter coil L2. Thus, electrical energy can be transferred to the receiver coil and further transmitted to the load 114 via the rectifier circuit 112. The receiver 120 may include a secondary resonant capacitor.

[0043] The rectifier circuit 112 converts the AC polarity waveform received from the receiver coil L2 into a unipolar waveform. In some embodiments, the rectifier circuit 112 can be a synchronous rectifier circuit including four switches. In other embodiments, the rectifier circuit 112 includes a full-wave diode bridge and an output capacitor.

[0044] Furthermore, the synchronous rectification circuit may be formed by any controllable device, such as a metal oxide semiconductor field effect transistor (MOSFET) device, a bipolar junction transistor (BJT) device, a super junction transistor (SJT) device, an insulated gate bipolar transistor (IGBT) device, a gallium nitride (GaN)-based power device, etc. The specific structure of the rectification circuit 112 will be described below in conjunction with Figure 2 Provide explanation.

[0045] The power converter 104 is coupled between the input power source 102 and the input of the wireless power transmission device 101. Depending on design requirements and different applications, the power converter 104 can include a variety of different configurations. In some embodiments, the power converter 104 can be a non-isolated power converter, such as a buck converter. In some embodiments, the power converter 104 can be a linear regulator. In some embodiments, the power converter 104 can be an isolated power converter, such as a forward converter.

[0046] The above-mentioned implementation of the power converter is only an example and should not be used to limit the scope of the claims. Those skilled in the art will be aware of other variations, substitutions and modifications.

[0047] In operation, the wireless power transmission system 100 can be configured to operate in a high-power mode. In high-power mode, the transmitter is a high-power transmitter configured to receive a high input voltage (e.g., 20V). The wireless power transmission system 100 is configured to transmit large amounts of electrical energy. In some embodiments, the maximum power transmitted between the transmitter and the receiver is in the range of approximately 40W to approximately 80W. Alternatively, the wireless power transmission system 100 can be configured to operate in a low-power mode. In low-power mode, the transmitter is a low-power transmitter configured to receive a low input voltage (e.g., 10V). The wireless power transmission system 100 is configured to transmit small amounts of electrical energy, or the input voltage to the wireless power transmission system is low. In some embodiments, the maximum power transmitted between the transmitter and the receiver is in the range of approximately 5W to approximately 10W. It should be noted that the power levels for the high-power mode and the low-power mode described above are merely examples and should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, alternatives, and modifications. For example, depending on different applications and design requirements, in high power mode, the power transferred between the transmitter and the receiver can be greater than 120 W. In addition, in low power mode, the power transferred between the transmitter and the receiver can be in the range of about 30 W to about 40 W.

[0048] In some embodiments, the receiver 120 includes multiple receiver coils. Specifically, the receiver 120 includes at least two receiver coils. The first receiver coil is Figure 1The receiver coil L2 is shown, and a second receiver coil is connected in series with an auxiliary switch. The second receiver coil and the auxiliary switch are configured to make the receiver 120 compatible with different applications. More specifically, when the wireless power transfer system 100 is configured to operate in high-power mode, the receiver 120 and the transmitter 110 form a low-gain wireless power transfer system. In some embodiments, the gain between the receiver and the transmitter is approximately 0.5. For example, when the input voltage of the transmitter is approximately 20V, the output voltage of the receiver is approximately 10V.

[0049] In the high-power mode, the second receiver coil is disconnected from the first receiver coil by opening the auxiliary switch. Power is transferred between the transmitter coil L1 and the first receiver coil L2. The first receiver coil L2 is smaller than the transmitter coil L2. This low inductance helps reduce the impedance of the receiver coil, thereby reducing thermal stress on the receiver 120.

[0050] On the other hand, when the wireless power transmission system 100 is configured to operate in low-power mode, the first and second receiver coils are connected in series by turning on the auxiliary switch. The first and second receiver coils form an equivalent coil with normal inductance. In other words, the receiver 120 and transmitter 110 form a wireless power transmission system with normal gain. In some embodiments, the normal gain between the receiver and transmitter is approximately 0.9. For example, when the input voltage of the transmitter is approximately 20V, the output voltage of the receiver is approximately 18V.

[0051] Figure 2 Various embodiments according to the present disclosure are shown Figure 1 Schematic diagram of a first embodiment of a receiver for a wireless power transmission system is shown in FIG. Figure 1 , the receiver 120 of the wireless power transmission system 100 includes a rectifier circuit 112 connected between the receiver coil L2 and the load 114. In some embodiments, the rectifier circuit 112 is implemented as follows Figure 2 The full-bridge rectifier circuit 112 is coupled to the output (Vo) of the wireless power transmission system 100. The rectifier circuit 112 is configured to convert the received AC polarity waveform into a unipolar waveform. The unipolar waveform is fed to a load such as a battery.

[0052] In order to improve the gain of the wireless power transmission system so that the receiver 120 can work under various working conditions, an additional receiver coil L3 is provided. Figure 2An auxiliary switch Q5 is shown connected to the full-bridge rectifier circuit. The two receiver coils L2 and L3 are magnetically coupled to the transmitter coil to transfer energy in a wireless power transfer system. Throughout this specification, the receiver coil L2 may also be referred to as the first receiver coil, and the receiver coil L3 may also be referred to as the second receiver coil.

[0053] The inductance of the second receiver coil L3 is greater than the inductance of the first receiver coil L2. In some embodiments, the inductance of the second receiver coil L3 is greater than 6uH, and the inductance of the first receiver coil L2 is less than 3uH.

[0054] To improve the efficiency of the wireless power transmission system, a first capacitor C1 is connected in series with the first receiver coil L2. A second capacitor C2 is connected in series with the second receiver coil L3. The first capacitor C1 and the second capacitor C2 are both resonant capacitors.

[0055] The full-bridge rectifier circuit includes four switches Q1, Q2, Q3 and Q4. Figure 2 As shown, a first switch Q1 and a second switch Q2 are connected in series between the output terminal Vo of the wireless power transmission system 100 and ground. Similarly, a third switch Q3 and a fourth switch Q4 are also connected in series between the output terminal Vo of the wireless power transmission system 100 and ground. A common node between the first and second switches Q1 and Q2 is coupled to the first input terminal of the first receiver coil L2 via the first capacitor C1. A common node between the third and fourth switches Q3 and Q4 is coupled to the second input terminal of the first receiver coil L2.

[0056] The second receiver coil L3, second capacitor C2, and auxiliary switch Q5 are connected in series between the common node of the third and fourth switches Q3 and Q4 and ground. During operation, in response to the low-power mode of the wireless power transmission system, the auxiliary switch Q5 is turned on. Due to the turning on of the auxiliary switch, the first and second receiver coils L2 and L3 are connected in series, thereby increasing the gain of the wireless power transmission system. In response to the high-power mode of the wireless power transmission system, the auxiliary switch Q5 is turned off. Due to the turning off of the auxiliary switch Q5, the second receiver coil L3 is disconnected from the first receiver coil L2. Due to the disconnection of the second receiver coil L3 from the first receiver coil L2, the gain of the wireless power transmission system is correspondingly reduced.

[0057] In some embodiments, the switches Q1, Q2, Q3, Q4, and Q5 can each be implemented as a single MOSFET, or multiple MOSFETs connected in parallel, or any combination thereof. In some embodiments, the switching element (e.g., switch S1) can be an IGBT device. In some embodiments, the switches can be any controllable switch, such as an IGCT device, a GTO device, an SCR device, a JFET device, an MCT device, a GaN-based power device, etc.

[0058] It should be noted that although Figure 2 While four switches Q1-Q4 are shown, various embodiments of the present disclosure may include other variations, modifications, and alternatives. For example, a separate capacitor may be connected in parallel with each switch in the rectifier circuit. Such independent capacitors help better control the timing of the rectifier circuit's resonant process.

[0059] In operation, the receiver is configured to operate in two different phases in response to the low power mode of the wireless power transmission system. In the two different phases, the first receiver coil L2 and the second receiver coil L3 are connected in series. The two receiver coils connected in series and the switches Q1-Q4 form a half-bridge rectifier circuit. Figure 3-4 Discuss the detailed operating principles of these two stages.

[0060] Figure 3 Schematic diagram showing a receiver of various embodiments of the present application configured to operate in a first phase of low power mode. In some embodiments, Figure 2 The receiver shown is configured to operate in low power mode. In low power mode, the transmitter is a low power transmitter. For example, the power transmitted between the transmitter and the receiver is in the range of about 5W to about 10W. The input voltage of the transmitter is about 10V. In order to be compatible with low power mode, the gain of the receiver must be increased accordingly. Figure 3 As shown, the auxiliary switch Q5 is turned on. Due to the conduction of the auxiliary switch Q5, the second receiver coil L3 and the first receiver coil L2 are connected in series. In this way, the series connection of the receiver coils L2 and L3 helps to increase the gain of the receiver.

[0061] During the first phase of low-power mode, the second and fourth switches Q2 and Q4 are off, as indicated by the arrows above their respective symbols. The first and third switches Q1 and Q3 are on. Current flows through the auxiliary switch Q5, the second capacitor C2, and the second receiver coil L3, dividing into a first and second conductive paths, respectively. The first conductive path includes the first switch Q1, the first capacitor C1, and the first receiver coil L2. The second conductive path includes the third switch Q3.

[0062] Figure 4 A schematic diagram illustrates a receiver according to various embodiments of the present application configured to operate in the second stage of low-power mode. In the second stage of low-power mode, as indicated by the arrows on the corresponding symbols, the first and third switches Q1 and Q3 are off. The second and fourth switches Q2 and Q4 are on. Current flows through the auxiliary switch Q5, the second capacitor C2, and the second receiver coil L3, and is divided into a third and fourth conductive paths, respectively. The third conductive path includes the second switch Q2, the first capacitor C1, and the first receiver coil L2. The fourth conductive path includes the fourth switch Q4.

[0063] With the above Figure 3-4 One advantage of the described low power mode is that the current is split into two different paths. Due to these two different current paths, the thermal stress on the receiver is reduced compared to a conventional half-bridge rectifier circuit.

[0064] With the above Figure 3-4 Another advantage of the described low-power mode is that the gain of the wireless power transfer system can be adjusted by connecting the second receiver coil L3 in series with the first receiver coil L2. For example, the gain of the wireless power transfer system can be adjusted by selecting the size of the second receiver coil L3. In some embodiments, the size of the second receiver coil L3 can be selected so that the gain of the wireless power transfer system is greater than 1.

[0065] Please refer back to Figure 2 , the receiver can be configured to operate in two different phases in response to the high power mode. In the two different phases, the second receiver coil L3 is disconnected from the first receiver coil L2. The first receiver coil L2 and switches Q1-Q4 form a full-bridge rectifier circuit. Figure 5-6 Discuss the detailed operating principles of these two stages.

[0066] Figure 5 FIG2 is a schematic diagram showing a receiver of various embodiments of the present application configured to operate in a first phase of a high power mode. In some embodiments, Figure 2 The receiver shown is configured to operate in high power mode. In high power mode, the transmitter is a high power transmitter. For example, the power transmitted between the transmitter and the receiver is in the range of about 40W to about 80W. The input voltage of the transmitter is about 20V. In order to be compatible with the high power transmitter, the gain of the receiver must be reduced accordingly. Figure 5As shown, the auxiliary switch Q5 is turned off. Because the auxiliary switch Q5 is turned off, the second receiver coil L3 is disconnected from the first receiver coil L2. In other words, current cannot flow through the second receiver coil L3. The first receiver coil L2 is configured as the only coil to receive power transmitted from the transmitter.

[0067] In the first stage of the high power mode, as indicated by the arrows on the respective symbols, the second switch Q2 and the third switch Q3 are turned off, and the first switch Q1 and the fourth switch Q4 are turned on. Figure 5 As shown by the middle dashed line, current flows through the first switch Q1 , the first capacitor C1 , the first receiver coil L2 and the fourth switch Q4 .

[0068] Figure 6 FIG2 is a schematic diagram showing a receiver of various embodiments of the present application configured to operate in the second stage of the high power mode. In the second stage of the high power mode, as indicated by the arrows on the respective symbols, the first switch Q1 and the fourth switch Q4 are turned off. The second switch Q2 and the third switch Q3 are turned on. Figure 6 As shown by the middle dashed line, the current flows through the second switch Q2, the first capacitor C1, the first receiver coil L2 and the third switch Q3.

[0069] With the above Figure 5-6 One advantage of the high power mode described is that Figure 2 The receiver shown is capable of achieving high efficiency. In particular, the first receiver coil L2 is small in size, and such a small coil has low impedance. Low impedance helps reduce coil temperature, thereby improving the efficiency of the wireless power transfer system.

[0070] Figure 7 1 and 2 show the implementation of the first receiver coil and the second receiver coil of various embodiments of the present application. In some embodiments, the first receiver coil L2 and the second receiver coil L3 are from a continuous coil. Figure 7 As shown, the continuous coil 702 has multiple turns. The continuous coil 702 has three terminals, namely AC1, AC2, and AC3. The first terminal AC1 is connected to the first capacitor C1. The second terminal AC2 is connected to the common node of the third switch Q3 and the fourth switch Q4. The third terminal AC3 is connected to the second capacitor C2.

[0071] Those skilled in the art will recognize that Figure 7 The continuous coil 702 shown is only one embodiment, and those skilled in the art may adopt other configurations for the two receiver coils. For example, the two receiver coils L2 and L3 may be implemented as two separate coils.

[0072] Figure 8Various embodiments of the present application are shown Figure 1 FIG. 1 is a schematic diagram of a second embodiment of a receiver of a wireless power transmission system. Figure 8 The receiver shown is Figure 2 The receiver shown is similar except that a second receiver coil L3, a second capacitor C2 and an auxiliary switch Q5 are connected in series between a common node of the first capacitor C1 and the first receiver coil L2 and ground.

[0073] Figure 9 Various embodiments of the present application are shown Figure 1 FIG. 1 is a schematic diagram of a third embodiment of a receiver of a wireless power transmission system. Figure 9 The receiver shown is Figure 2 The receiver is similar to the one shown in FIG. 1 , except that a second auxiliary switch Q6 is used to further improve the performance of the receiver. Figure 9 As shown, the common node of the first switch Q1 and the second switch Q2 is connected to the first terminal of the first receiver coil L2 via the first capacitor C1. The common node of the third switch Q3 and the fourth switch Q4 is connected to the second terminal of the first receiver coil L2 via the second auxiliary switch Q6. The second auxiliary switch Q6 provides an additional control variable to better control the receiver.

[0074] In operation, a receiver with low gain can successfully establish a bias voltage when magnetically coupled to a high-power transmitter. On the other hand, a receiver with low gain cannot successfully establish a bias voltage when magnetically coupled to a low-power transmitter. Therefore, a startup circuit is required to help the receiver establish a bias voltage under various operating conditions.

[0075] Figure 10 Various embodiments of the present application are shown Figure 1 FIG. 1 is a schematic diagram of a first embodiment of a start-up circuit of a receiver of a wireless power transmission system. The start-up circuit includes a depletion-type switch Q5. Figure 10 As shown, the depletion switch Q5 is connected between the common node of the third switch Q3 and the fourth switch Q4 and the ground. During the startup process, the depletion switch Q5 is turned on before the bias voltage is established. The turned-on depletion switch Q5 helps to establish the bias voltage of the receiver. More specifically, the depletion switch Q5, the body diode of the first switch Q1 and the body diode of Q2 form a half-bridge circuit. The half-bridge circuit is used as a voltage doubler configured to establish the bias voltage at a low voltage gain. Figure 11-12 Discuss the operating principles of a half-bridge circuit.

[0076] Figure 11A schematic diagram illustrates the startup circuit of various embodiments of the present application configured to operate in the first phase. During startup, switches Q1-Q4 are not conducting because the bias voltage has not yet fully established. Since Q5 is a depletion-mode transistor, it is turned on. In some embodiments, depletion-mode switch Q5, the body diode of first switch Q1, the body diode of second switch Q2, and first receiver coil L2 form a half-bridge circuit configured to establish the bias voltage. This half-bridge circuit is configured to operate in two distinct phases.

[0077] In the first stage, as Figure 11 As shown by the dotted line in FIG, current flows through the first switch Q1, the first capacitor C1, the first receiver coil L2, and the body diode of the depletion mode switch Q5. This current is used to charge the bias capacitor (not shown) to establish a bias voltage.

[0078] Figure 12 FIG2 is a schematic diagram showing the startup circuit of various embodiments of the present application configured to operate in the second phase. Figure 12 As shown by the dotted line in FIG, current flows through the body diode of the first switch Q2, the first capacitor C1, the first receiver coil L2, and the depletion mode switch Q5. This current is used to charge the bias capacitor (not shown) to establish a bias voltage.

[0079] After the bias voltage is established, the receiver enters the normal mode. In the normal mode, the depletion switch Q5 is disconnected. The rectifier circuit is configured to operate in the half-bridge mode. The half-bridge mode has two different phases, which will be discussed separately below. Figure 13 and Figure 14 Have a discussion.

[0080] Figure 13 FIG. 1 is a schematic diagram showing the startup circuit of various embodiments of the present application configured to operate in the first stage of normal mode. After the bias voltage is established, as shown in FIG. Figure 13 As shown, the depletion-mode switch Q5 is off. In the first stage of normal mode, as indicated by the arrows on each symbol, the first switch Q1 and the third switch Q3 are off. Current flows through the conductive path formed by the second switch Q2, the first capacitor C1, the first receiver coil L2, and the fourth switch Q4.

[0081] Figure 14 A schematic diagram illustrating the startup circuit of various embodiments of the present application configured to operate in the second phase of normal mode. In the second phase of normal mode, as indicated by the arrows on the corresponding symbols, the second switch Q2 and the third switch Q3 are disconnected. Current flows through the conductive path formed by the first switch Q1, the first capacitor C1, the first receiver coil L2, and the fourth switch Q4.

[0082] Figure 15 Various embodiments of the present application are shown Figure 1 FIG. 1 is a schematic diagram of a second embodiment of a start-up circuit of a receiver of a wireless power transmission system. Figure 15 The startup circuit shown is Figure 2 The circuit shown is similar to that shown in FIG. 1 , except that Q5 is implemented as a depletion-mode transistor. During startup, the depletion-mode switch Q5 is turned on before the bias voltage is established. The turned-on depletion-mode switch Q5 helps establish the bias voltage of the receiver. More specifically, the depletion-mode switch Q5, the body diode of the first switch Q1, and the body diode of the second switch Q2 form a half-bridge circuit. The half-bridge circuit acts as a voltage doubler configured to establish the bias voltage at a low voltage gain between the transmitter and the receiver. Figure 16-17 Discuss the operating principles of a half-bridge circuit.

[0083] Figure 16 Various embodiments of the present application are shown Figure 15 The startup circuit shown is configured for operation in the first phase. During startup, switches Q1-Q4 are not turned on because the bias voltage has not yet fully established. Since Q5 is a depletion-mode transistor, it is turned on. The depletion-mode switch Q5, the body diode of the first switch Q1, the body diode of the second switch Q2, and the first receiver coil L2 form a half-bridge circuit. This half-bridge circuit is configured to operate in two distinct phases.

[0084] In the first stage, as Figure 16 As shown by the dashed line in FIG, current flows through the first switch Q1, the first capacitor C1, the first receiver coil L2, the second receiver coil L3, the second capacitor C2, and the body diode of the depletion-mode switch Q5. This current is used to charge the bias capacitor (not shown) to establish a bias voltage.

[0085] Figure 17 Various embodiments of the present application are shown Figure 15 The startup circuit shown is configured to operate in the second phase. Figure 17 As shown by the dashed line, current flows through the body diode of the second switch Q2, the first capacitor C1, the first receiver coil L2, the second receiver coil L3, the second capacitor C2, and the depletion switch Q5. This current is used to charge the bias capacitor (not shown) to establish the bias voltage.

[0086] In addition to Q5 being a depletion-mode transistor, Figure 15-17 The circuit shown is Figure 2 The circuit shown above is similar. Figure 3-6 The low power mode and high power mode discussed are applicable to Figure 15-17The circuit shown in the figure. Figure 15-17 The circuit shown is configured accordingly.

[0087] Figure 18 The control of various embodiments of the present application is shown Figure 2 The flowchart of the receiver is shown. Figure 18 The flowcharts shown are examples only, which should not unduly limit the scope of the claims. Those skilled in the art will recognize many variations, substitutions, and modifications. For example, the following may be added, removed, replaced, rearranged, and repeated: Figure 18 The steps shown.

[0088] Please refer again Figure 1 , a wireless power transmission system includes a transmitter and a receiver. Depending on the application, the transmitter can be a high-power transmitter. When the receiver (e.g., Figure 2 When the receiver (shown in FIG) is magnetically coupled to the high-power transmitter, the receiver is configured to operate in a high-power mode. On the other hand, when the transmitter is a low-power transmitter, the receiver is configured to operate in a low-power mode.

[0089] The receiver includes a plurality of receiver coils. The plurality of receiver coils are configured differently according to different power modes to make the receiver compatible with different power modes. The receiver is controlled according to the following steps.

[0090] In step 1802, a controller is configured to determine an operating mode of a wireless power transfer system. The wireless power transfer system includes a transmitter coil, a plurality of receiver coils, a rectifier circuit coupled to the plurality of receiver coils, and an auxiliary switch connected in series with one of the plurality of receiver coils. The wireless power transfer system can operate in a low power mode, which requires normal gain between the transmitter and the receiver. Alternatively, the wireless power transfer system can operate in a high power mode, which requires reduced gain between the transmitter and the receiver.

[0091] In step 1804 , in response to the low power mode of the wireless power transmission system, the plurality of receiver coils are configured such that at least two receiver coils of the plurality of receiver coils are connected in series by turning on the auxiliary switch to increase the gain of the wireless power transmission system.

[0092] At step 1806 , in response to the high power mode of the wireless power transfer system, the plurality of receiver coils are configured such that the gain of the wireless power transfer system is reduced by closing the auxiliary switch.

[0093] Although the embodiments of the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.

[0094] Furthermore, the scope of the present application is not intended to be limited to the particular embodiments of the processes, machines, manufactures, compositions of matter, means, methods, and steps described in the specification. One of ordinary skill in the art will readily understand from the disclosure herein that there are currently existing or later developed processes, machines, manufactures, compositions of matter, means, methods, or steps that perform substantially the same functions and that may use the embodiments described with reference to the embodiments of the present application or achieve substantially the same results as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufactures, compositions of matter, means, methods, or steps.

Claims

1. A wireless power transmission device, comprising: a controller for controlling a switch in a receiver, the receiver comprising a first receiver coil for magnetically coupling to a transmitter coil of a wireless power transfer system, a rectifier circuit coupled to two terminals of the first receiver coil, a second receiver coil, and a first auxiliary switch, wherein the second receiver coil is connected in series with the first auxiliary switch, and the second receiver coil is for magnetically coupling to the transmitter coil; wherein, in response to a low power mode of the device, the controller is configured to turn on the first auxiliary switch so that the first receiver coil and the second receiver coil are connected in series to increase the gain of the wireless power transmission system, wherein the low power mode is a mode when the transmitter is a low power transmitter configured to receive a low input voltage; The receiver further includes a first capacitor and a second capacitor, the rectifier circuit includes a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, wherein: A common node between the first switch and the second switch is connected to a first terminal of the first receiver coil via the first capacitor; A common node of the third switch and the fourth switch is connected to a second terminal of the first receiver coil; The second receiver coil, the second capacitor, and the first auxiliary switch are connected in series between a common node of the third switch and the fourth switch and ground.

2. The device according to claim 1, wherein: The first receiver coil and the second receiver coil are magnetically coupled to the transmitter coil to transfer energy in a wireless power transfer system.

3. The device according to claim 1, wherein: In response to a high power mode of the wireless power transmission device, the controller controls the first auxiliary switch to be turned off to disconnect the second receiver coil from the first receiver coil, wherein in the high power mode, the controller configures the rectifier circuit as a full-bridge rectifier circuit.

4. The device according to claim 1, wherein The first and second receiver coils are from a continuous coil having three terminals.

5. The device according to claim 1, wherein the receiver further comprises a first capacitor and a second capacitor, wherein: The rectifier circuit includes a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, wherein: A common node between the first switch and the second switch is connected to a first terminal of a first receiver coil via a first capacitor; A common node of the third and fourth switches is connected to a second terminal of the first receiver coil; and The second receiver coil, the second capacitor and the first auxiliary switch are connected in series between a common node of the first capacitor and the first receiver coil and ground.

6. The apparatus according to claim 1 , wherein the receiver further comprises a first capacitor, a second capacitor, and a second auxiliary switch, wherein: The rectifier circuit includes a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, wherein: A common node between the first switch and the second switch is connected to a first terminal of a first receiver coil via a first capacitor; A common node of the third switch and the fourth switch is connected to a second terminal of the first receiver coil through a second auxiliary switch; and The second receiver coil, the second capacitor and the first auxiliary switch are connected in series between a common node of the third switch and the fourth switch and the ground.

7. The apparatus according to claim 1, wherein: The rectifier circuit includes a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series. In the low-power mode of the wireless power transmission device, the controller is configured to control the rectifier circuit, the first receiver coil, the second receiver coil, and the first auxiliary switch to operate in a half-bridge mode.

8. The apparatus according to claim 7, wherein: In the first stage of the half-bridge mode, the controller controls the first switch and the third switch to be turned on, and controls the second switch and the fourth switch to be turned off; as well as In the second stage of the half-bridge mode, the controller controls the first switch and the third switch to be turned off, and controls the second switch and the fourth switch to be turned on.

9. The apparatus according to claim 1, wherein: The rectifier circuit has an output coupled to a load, wherein the controller is further configured to control a switch in the rectifier circuit to convert an AC polarity waveform into a unipolar waveform.

10. A wireless power transmission method, comprising: determining, by a controller, an operating mode of a wireless power transfer system comprising a transmitter coil, a plurality of receiver coils, a rectifier circuit coupled to the plurality of receiver coils, and an auxiliary switch connected in series with one of the plurality of receiver coils; In response to a low-power mode of the wireless power transmission system, turning on the auxiliary switch by a signal generated by the controller, wherein after the auxiliary switch is turned on, at least two receiver coils among the plurality of receiver coils are connected in series by turning on the auxiliary switch, thereby improving the gain of the wireless power transmission system, wherein the low-power mode is a mode when the transmitter is a low-power transmitter configured to receive a low input voltage; and In response to a high power mode of the wireless power transmission system, turning off the auxiliary switch through a signal generated by the controller, wherein after the auxiliary switch is turned on, the gain of the wireless power transmission system is reduced; The wireless power transmission system further includes a first capacitor and a second capacitor, wherein the rectifier circuit includes a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, wherein: A common node of the first switch and the second switch is connected to a first terminal of a first receiver coil among the plurality of receiver coils via a first capacitor; A common node of the third switch and the fourth switch is connected to a second terminal of a first receiver coil of the plurality of receiver coils; and A second receiver coil among the plurality of receiver coils, a second capacitor, and an auxiliary switch are connected in series between a common node of the third switch and the fourth switch and ground.

11. The method of claim 10, further comprising: In a first stage of the low power mode, the controller configures the rectifier circuit so that the current flows through the auxiliary switch, the second capacitor, and the second receiver coil, and is divided into a first conductive path and a second conductive path, respectively, wherein the first conductive path includes the first switch, the first capacitor, and the first receiver coil, and the second conductive path includes the third switch; and In the second stage of the low-power mode, the controller configures the rectifier circuit so that the current flows through the auxiliary switch, the second capacitor, and the second receiver coil, and is divided into a third conductive path and a fourth conductive path, respectively. The third conductive path includes the second switch, the first capacitor, and the first receiver coil, and the fourth conductive path includes the fourth switch.

12. The method of claim 10, further comprising: In a first stage of the high power mode, the controller configures the rectifier circuit so that current flows through the first switch, the first capacitor, the first receiver coil, and the fourth switch; as well as In a second stage of the high power mode, the controller configures the rectifier circuit to allow current to flow through the second switch, the first capacitor, the first receiver coil, and the third switch.

13. The method according to claim 10, wherein: The auxiliary switch is a depletion-mode transistor.

14. The method of claim 13, further comprising: During a first stage of a startup process, the controller configures the rectifier circuit so that current flows through the first switch, the first capacitor, the first receiver coil, the second receiver coil, the second capacitor, and the body diode of the auxiliary switch; as well as In a second phase of the startup process, the controller configures the rectifier circuit to allow current to flow through the second switch, the first capacitor, the first receiver coil, the second receiver coil, the second capacitor, and the body diode of the auxiliary switch.

15. A controller comprising: a circuit for controlling an auxiliary switch and switches in a rectifier circuit, wherein the rectifier circuit is coupled to a first receiver coil, the first receiver coil being configured to magnetically couple to a transmitter coil of a wireless power transfer system, the auxiliary switch and the second receiver coil being connected in series; wherein, in response to a low power mode of the wireless power transmission system, the controller is configured to turn on the auxiliary switch so that the first receiver coil and the second receiver coil are connected in series to increase the gain of the wireless power transmission system, wherein the low power mode is a mode when the transmitter is a low power transmitter configured to receive a low input voltage; The wireless power transmission system further includes a first capacitor and a second capacitor, wherein the rectifier circuit includes a first switch and a second switch connected in series, and a third switch and a fourth switch connected in series, wherein: A common node between the first switch and the second switch is connected to a first terminal of a first receiver coil via a first capacitor; A common node of the third switch and the fourth switch is connected to the second terminal of the first receiver coil; The second receiver coil, the second capacitor and the auxiliary switch are connected in series between a common node of the third switch and the fourth switch and the ground.

16. The controller according to claim 15, wherein: In a first stage of the low power mode, the controller is configured to control the rectifier circuit and the auxiliary switch so that current flows through the auxiliary switch, the second capacitor, and the second receiver coil and is divided into a first conductive path and a second conductive path, respectively, wherein the first conductive path includes the first switch, the first capacitor, and the first receiver coil, and the second conductive path includes the third switch; and In a second stage of the low-power mode, the controller is configured to control the auxiliary switch so that current flows through the auxiliary switch, the second capacitor, and the second receiver coil, and is divided into a third conductive path and a fourth conductive path, respectively. The third conductive path includes the second switch, the first capacitor, and the first receiver coil, and the fourth conductive path includes the fourth switch.

17. The controller according to claim 15, wherein: In a first stage of a high power mode of the system, the controller is configured to control the auxiliary switch so that current flows through the first switch, the first capacitor, the first receiver coil, and the fourth switch; as well as In a second stage of the high power mode of the system, the controller is configured to control the auxiliary switch so that current flows through the second switch, the first capacitor, the first receiver coil, and the third switch.

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