Fixed frequency resonant power regulating wireless charging system and transmitting end

Abstract

This disclosure relates to the field of wireless charging technology, and discloses a fixed-frequency resonant power-regulating wireless charging system and a transmitter. During power regulation, the inverter unit of the transmitter outputs a fixed-frequency drive signal to excite the transmitting resonant circuit. The adjustable resonant network changes the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit through the state switching of a controlled switch. The modulation unit of the receiver changes the equivalent impedance of the receiver according to a preset encoding rule, causing the electrical parameters of the transmitting resonant circuit to generate amplitude fluctuations characterizing the power regulation command. The signal demodulation unit of the transmitter decodes the power regulation command and controls the state of the controlled switch accordingly, thereby regulating the transmitting power while maintaining a fixed frequency. This disclosure avoids resonant circuit detuning caused by frequency conversion, balancing transmission efficiency and power regulation accuracy.

Description

Technical Field

[0001] This disclosure relates to the field of wireless charging technology, and in particular to a fixed-frequency resonant power modulation wireless charging technology. Background Technology

[0002] The descriptions in this section are intended to provide background information for the embodiments of this disclosure and should not be construed as an admission or implication that they constitute prior art.

[0003] With the widespread adoption of smart wearables, personal care products, and portable small electronic devices, magnetic induction wireless charging technology has been widely used due to its convenience, safety, and reliability. During wireless charging, the load state of the receiver and the coupling state between the transmitting and receiving coils will change depending on the usage. To ensure the stability of the receiver's output voltage and charging current, the transmitting power of the transmitter needs to be adjusted accordingly.

[0004] In related technologies, magnetic induction wireless charging systems typically adjust the transmission power by changing the operating frequency of the inverter unit to adapt to changes in load and coupling state. However, for small devices such as smart wearables, the size of their transceiver coils is small, the quality factor of the resonant circuit is high, and the effective resonant bandwidth is narrow. Even a small shift in the operating frequency can cause significant detuning of the resonant circuit, leading to increased reactive power loss and decreased transmission efficiency, making it difficult to meet the transmission efficiency requirements of such small coil applications. Summary of the Invention

[0005] This disclosure provides a fixed-frequency resonant power-adjustable wireless charging system and transmitter. One of the technical problems it solves is how to ensure the transmission efficiency of wireless charging while achieving power adjustment in application scenarios such as small coils and narrow resonant bandwidth.

[0006] According to one aspect of this disclosure, a fixed-frequency resonant power modulation wireless charging system is provided, including a wireless charging transmitter and a wireless charging receiver. The transmitter includes a transmitter control unit, an inverter unit, a transmitter resonant circuit, an adjustable resonant network, and a signal demodulation unit; The inverter unit is controlled and connected to the transmitter control unit, and is used to output a drive signal with a constant frequency to excite the transmitter resonant circuit. The frequency of the drive signal remains fixed during power regulation. The transmitting resonant circuit includes a transmitting coil and a resonant capacitor; The tunable resonant network includes at least one tuning branch equipped with a controlled switch. The tuning branch is connected to the transmitting resonant circuit and is used to change the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit when the state of the controlled switch is switched. The receiving end includes a receiving end control unit, a receiving resonant circuit, a rectifier output unit, a sampling unit, and a modulation unit; The receiving coil in the receiving resonant circuit is magnetically coupled to the transmitting coil, and the resonant frequency of the receiving resonant circuit is matched with the frequency of the driving signal. The rectifier output unit is used to convert the AC power coupled by the receiving resonant circuit into DC power to supply the load. The sampling unit is used to collect the operating parameters of the receiving end and transmit them to the receiving end control unit; The modulation unit is controlled to be connected to the receiver control unit. The receiver control unit generates a power adjustment command according to the operating parameters and controls the modulation unit to change the equivalent impedance of the receiver according to a preset coding rule, so that the electrical parameters of the transmitting resonant circuit generate amplitude fluctuations that characterize the power adjustment command. The signal demodulation unit is used to detect amplitude fluctuations in the electrical parameters of the transmitting resonant circuit and decode the power adjustment command, which is then transmitted to the transmitting end control unit. The transmitter control unit controls the state of the controlled switch according to the power adjustment command. While keeping the frequency of the drive signal fixed, the transmitter power is adjusted by changing the equivalent capacitance and / or equivalent inductance of the transmitter resonant circuit.

[0007] In a preferred embodiment, the tunable resonant network includes a controllable capacitor matrix; The controllable capacitor matrix includes multiple parallel capacitor tuning branches, and each capacitor tuning branch includes a compensation capacitor and the controlled switch connected in series. The transmitter control unit changes the equivalent capacitance connected to the transmitter resonant circuit by controlling the on / off state of the controlled switches in each of the capacitor tuning branches.

[0008] In a preferred embodiment, the tunable resonant network further includes a multi-tap inductor switching matrix; The multi-tap inductor switching matrix includes an inductor winding with multiple taps and multiple tap selection switches connected one-to-one with each of the taps. The tap selection switches are controlled to be connected to the transmitter control unit. The inductor winding is connected in series between the output terminal of the inverter unit and the transmitter coil. The transmitter control unit controls the on / off state of the tap selection switch to select different taps, thereby changing the equivalent inductance connected to the transmitter resonant circuit.

[0009] In a preferred embodiment, the controllable capacitor matrix and the multi-tap inductor switching matrix work independently or in conjunction.

[0010] In a preferred embodiment, the modulation unit includes a load modulation branch and / or a capacitor modulation branch; The load modulation branch includes a modulation load connected in series and a first modulation switch. The receiving end control unit controls the first modulation switch to switch the modulation load to change the equivalent impedance of the receiving end. The capacitor modulation branch includes a modulation capacitor and a second modulation switch connected in series. The receiver control unit controls the second modulation switch to switch the modulation capacitor to change the equivalent impedance of the receiver.

[0011] In a preferred embodiment, the preset encoding rule is as follows: the receiving end control unit controls the modulation unit to periodically change the equivalent impedance of the receiving end at the modulation frequency, and encodes the power adjustment command by at least one of the modulation frequency, modulation duty cycle and modulation timing to distinguish different power adjustment commands; The signal demodulation unit acquires the current signal and / or voltage signal of the transmitting resonant circuit, and sequentially filters, shapes and decodes the acquired signals to obtain the power adjustment command.

[0012] In a preferred embodiment, the transmitting end further includes a primary-side parameter sampling unit, which is used to collect the current, voltage, and voltage-current phase difference of the transmitting resonant circuit and transmit them to the transmitting end control unit. The transmitting end control unit determines the target switching state of the tunable resonant network according to the power adjustment command, corrects the target switching state according to the parameters collected by the primary side parameter sampling unit, and controls each of the controlled switches according to the corrected switching state.

[0013] In a preferred embodiment, when the signal demodulation unit fails to decode the power adjustment command within a preset time period, or when the decoding result does not conform to the preset encoding rule, the transmitting end control unit autonomously controls the state of the controlled switch according to the parameters collected by the primary side parameter sampling unit, so as to maintain power adjustment or stop power transmission.

[0014] In a preferred embodiment, the adjustable resonant network has multiple gears defined by different on / off state combinations of each of the controlled switches; the transmitting control unit pre-stores the mapping relationship between the power adjustment command and the gears, the transmitting control unit determines the target gear according to the decoded power adjustment command and the mapping relationship, and controls the state of the controlled switches according to the target gear.

[0015] In a preferred embodiment, the transmitting end further includes a cancellation capacitor matrix, which comprises multiple parallel cancellation capacitor branches. Each cancellation capacitor branch includes a cancellation capacitor and a controlled switch connected in series. Each controlled switch is controlled to connect to the transmitting end control unit. The cancellation capacitor branches are connected to the transmitting resonant circuit in the same manner as the transmitting resonant circuit. The minimum equivalent capacitance adjustment step of the cancellation capacitor matrix is ​​smaller than the equivalent capacitance adjustment step corresponding to the capacitor tuning branch used for power regulation in the tunable resonant network, thereby functionally decoupling the cancellation capacitor matrix from the tunable resonant network. The tunable resonant network is used to perform power regulation in response to the power regulation command, and the cancellation capacitor matrix is ​​used to compensate for parasitic capacitance introduced by the dielectric to restore the resonant frequency. The transmitter control unit is configured to: extract the voltage-current phase difference collected by the primary side parameter sampling unit as the baseline phase during non-communication periods when the signal demodulation unit does not detect the uplink modulation signal; when the offset of the voltage-current phase difference collected by the primary side parameter sampling unit relative to the baseline phase is greater than a preset phase threshold, and the duration of the offset is greater than a preset duration, and the signal demodulation unit does not decode the power adjustment command within the duration, it is determined to be a static resonance offset introduced by the medium and enters the baseline calibration mode; otherwise, it is determined to be a coupling change or normal modulation and does not enter the baseline calibration mode. In the baseline calibration mode, the transmitter control unit switches the corresponding cancellation capacitor branch in the cancellation capacitor matrix in the direction that reduces the offset of the voltage-current phase difference, so as to adjust the resonant frequency of the transmitter resonant circuit to match the frequency of the drive signal, and uses the state of each controlled switch determined by this switching as the reference state for subsequent power adjustment.

[0016] In a preferred embodiment, the signal demodulation unit includes a synchronous sampling module, a coherent accumulation module, a bandpass filtering module, and a decision module; The synchronous sampling module is phase-locked to the drive signal output by the inverter unit, and samples the current signal and / or voltage signal of the transmitting resonant circuit at a preset phase point within each drive signal cycle; the coherent accumulation module accumulates and averages the sampling results of the synchronous sampling module within one uplink symbol cycle; the center frequency of the bandpass filter module is set to the modulation frequency used by the preset encoding rule; at the end of the uplink symbol cycle, the decision module performs amplitude determination based on the outputs of the coherent accumulation module and the bandpass filter module to obtain the power adjustment command; The uplink symbol period is not less than a preset multiple of the envelope time constant of the transmitting resonant circuit, wherein the envelope time constant is... ,in The quality factor of the transmitting resonant circuit is denoted as . The angular frequency of the driving signal; The modulation frequency is greater than the power control loop bandwidth of the transmitter control unit, so that the impedance modulation generated by the modulation unit is separated from the load change in the frequency domain.

[0017] According to another aspect of this disclosure, a fixed-frequency resonant power modulation wireless charging transmitter is provided, including a transmitter control unit, an inverter unit, a transmitting resonant circuit, an adjustable resonant network, and a signal demodulation unit; The inverter unit is controlled and connected to the transmitter control unit, and is used to output a drive signal with a constant frequency to excite the transmitter resonant circuit. The frequency of the drive signal remains fixed during power regulation. The transmitting resonant circuit includes transmitting coils and resonant capacitors connected in series or in parallel. The tunable resonant network includes at least one tuning branch equipped with a controlled switch. The tuning branch is connected to the transmitting resonant circuit and is used to change the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit when the state of the controlled switch is switched. The signal demodulation unit is used to detect the amplitude fluctuation of the electrical parameters of the transmitting resonant circuit, and decode the power adjustment command generated by the wireless charging receiver by changing its equivalent impedance modulation, and transmit it to the transmitting end control unit. The transmitter control unit controls the state of the controlled switch according to the power adjustment command. While keeping the frequency of the drive signal fixed, the transmitter power is adjusted by changing the equivalent capacitance and / or equivalent inductance of the transmitter resonant circuit.

[0018] In the embodiments of this disclosure, by enabling the inverter unit at the transmitting end to output a drive signal with a fixed frequency throughout the power regulation process, and by setting up an adjustable resonant network connected to the transmitting resonant circuit that can change the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit under controlled switch state switching, and by having the modulation unit at the receiving end change the equivalent impedance of the receiving end according to a preset coding rule, the electrical parameters of the transmitting resonant circuit generate amplitude fluctuations characterizing the power regulation command. The signal demodulation unit at the transmitting end then decodes the power regulation command and controls the state of the controlled switch accordingly. This allows for closed-loop regulation of the transmitting power while maintaining a fixed operating frequency, thereby avoiding resonant circuit detuning and reactive power loss caused by frequency conversion, and balancing transmission efficiency in application scenarios such as small coils, narrow resonant bandwidth, and weak coupling. At the same time, with the help of the uplink modulation feedback at the receiving end, the transmitting end can accurately know the load demand and coupling state of the receiving end. Compared with the method of passively judging the operating state by relying solely on the primary side parameters, this significantly improves the response speed and control accuracy of power regulation under complex operating conditions such as load changes, weak coupling, and coil offset.

[0019] Furthermore, by setting the tunable resonant network as a controllable capacitor matrix including multiple parallel capacitor tuning branches, and by having the transmitter control unit control the on / off state of the controlled switches in each capacitor tuning branch to change the equivalent capacitance connected to the transmitter resonant circuit, small-span, fine-tuned transmitter power adjustment can be achieved.

[0020] Furthermore, by adding a multi-tap inductor switching matrix including a multi-tap inductor winding and a tap selection switch corresponding to each tap, and by having the transmitter control unit select different taps to change the equivalent inductance connected to the transmitter resonant circuit, a wide range and broad span of transmitter power adjustment can be achieved.

[0021] Furthermore, by enabling the controllable capacitor matrix and the multi-tap inductor switching matrix to work independently or in conjunction, it is possible to balance fine adjustment over small spans with wide-range adjustment over large spans, thereby expanding the power adjustment range and increasing the gear density.

[0022] Furthermore, by setting the modulation unit as a load modulation branch including a modulation load and a first modulation switch and / or a capacitor modulation branch including a modulation capacitor and a second modulation switch, and by having the receiver control unit switch the modulation load or modulation capacitor to change the equivalent impedance of the receiver, uplink signal feedback can be completed without a separate carrier modulation chip, simplifying the receiver circuit structure and reducing cost and size.

[0023] Furthermore, by encoding the change process of the equivalent impedance at the receiving end using different modulation frequencies and / or modulation duty cycles to distinguish different power adjustment commands, and by having the signal demodulation unit sequentially filter, shape and decode the acquired current and / or voltage signals, multiple power adjustment commands can be accurately distinguished and identified.

[0024] Furthermore, by adding a primary-side parameter sampling unit to collect the current, voltage, and voltage-current phase difference of the transmitting resonant circuit, and having the transmitting control unit correct the target switching state determined by the power adjustment command based on the primary-side sampling parameters, the receiving modulation feedback and primary-side parameter sampling can be combined to form a dual calibration, further improving the accuracy and stability of power adjustment.

[0025] Furthermore, when the signal demodulation unit fails to decode the power adjustment command within a preset time or the decoding result does not conform to the preset encoding rules, the transmitter control unit can autonomously control the state of the controlled switch according to the primary side sampling parameters. This can automatically degrade to maintain power adjustment when modulation feedback is missing or abnormal, thereby improving the system's fault tolerance and avoiding charging interruption. Alternatively, according to a separate agreement from the transmitter, the control unit can stop transmitting power.

[0026] Furthermore, by limiting the adjustable resonant network to multiple gears corresponding to different on / off combinations of each controlled switch, and by pre-storing the mapping relationship between power adjustment commands and gears in the transmitter control unit to determine the target gear, fast and accurate matching of power adjustment commands to gears can be achieved.

[0027] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Various aspects and embodiments of this disclosure can be combined in different ways. This summary section is not intended to identify key or essential features of the claimed subject matter, nor is it intended to aid in determining the scope of the claimed subject matter. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall architecture of a fixed-frequency resonant power modulation wireless charging system according to an embodiment of the present disclosure; Figure 2 This is a circuit diagram of a transmitter using a series resonant topology and an adjustable resonant network according to an embodiment of the present disclosure; Figure 3 This is another circuit diagram of a transmitter using a series resonant topology and an adjustable resonant network according to an embodiment of the present disclosure; Figure 4 This is a circuit diagram of a transmitter using a parallel resonant topology and an adjustable resonant network according to an embodiment of the present disclosure; Figure 5 This is another circuit diagram of a transmitter using a parallel resonant topology and an adjustable resonant network according to an embodiment of the present disclosure; Figure 6 This is a schematic diagram of the circuit principle of a fixed-frequency resonant power modulation wireless charging system according to an embodiment of the present disclosure; Figure 7 This is a schematic diagram of the circuit principle of a fixed-frequency resonant power modulation wireless charging system according to another embodiment of the present disclosure.

[0029] Explanation of reference numerals in the attached figures 31—Transmitting coil, 32—Resonant capacitor, 41—Controllable capacitor matrix, 411—Compensation capacitor, 412—Controlled switch, 42—Multi-tap inductor switching matrix, 421—Inductor winding, 422—Tap, 423—Tap selection switch. Detailed Implementation

[0030] In the following description, numerous technical details are presented to enable the reader to better understand this disclosure. However, those skilled in the art will understand that the technical solutions claimed in this disclosure can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0031] Example 1 This embodiment provides a fixed-frequency resonant power modulation wireless charging system, the overall architecture of which is as follows: Figure 1 As shown, the device comprises two parts: a wireless charging transmitter and a wireless charging receiver. Wireless power transmission between the transmitter and receiver is achieved through magnetic field coupling between their transmitting and receiving coils. Power regulation information is transmitted back from the receiver to the transmitter by modulating the amplitude of the coupled magnetic field. The transmitter includes a transmitter control unit, an inverter unit, a transmitting resonant circuit, an adjustable resonant network, and a signal demodulation unit, and is equipped with a power supply circuit to provide operating power to each unit. The receiver includes a receiver control unit, a receiving resonant circuit, a rectifier output unit, a sampling unit, and a modulation unit. The specific structure, connection relationships, and working principles of each component are explained below.

[0032] The inverter unit is connected to the transmitter control unit and is used to output a constant-frequency drive signal to excite the transmitter resonant circuit. In this embodiment, the transmitter control unit uses a microcontroller with a built-in fixed clock source. The fixed clock source is divided to obtain a single-frequency pulse-width modulated drive signal, which is then amplified by the driver stage to control the power switching devices in the inverter unit. The inverter unit can adopt one of the following inverter topologies: full-bridge, half-bridge, or single-transistor. In full-bridge and half-bridge topologies, the power transistors of the upper and lower bridge arms are alternately turned on at a fixed frequency to convert the DC voltage provided by the power supply circuit into an alternating voltage. In a single-transistor topology, a single power transistor is switched at a fixed frequency, working with the resonant network to establish an alternating current on the transmitter coil. It should be particularly noted that the frequency of the drive signal... The power remains constant throughout the entire power regulation process. Generally slightly deviating from the natural resonant center frequency of the transmitting resonant circuit. ,in , These are the nominal inductance and nominal capacitance of the transmitting resonant circuit, respectively. The system does not perform any frequency conversion, frequency sweep, or frequency stretching operations; all power regulation is completed at this fixed frequency. For magnetic induction applications with small coils and narrow resonant bandwidths, It can be taken from tens of kilohertz to several megahertz, for example, a fixed value between 100 kHz and 300 kHz.

[0033] The transmitting resonant circuit includes a transmitting coil and a resonant capacitor, which together form a circuit operating at a fixed frequency. The resonant LC reference circuit provides a stable fixed-frequency operating reference for the system. The transmitting coil and resonant capacitor can be connected in series to form a series resonant circuit or in parallel to form a parallel resonant circuit. The specific form is determined by the inverter topology and design requirements. In practice, the circuit operating point is set near the resonant point and biased towards the inductive detuning side. Slightly deviated This allows for bidirectional adjustment of the transmit power within a small detuning range near the resonant point via a controlled switch, and maintains high transmission efficiency by keeping the operating point as close to the resonant point as possible when the load is stable and no significant adjustment is required.

[0034] The tunable resonant network includes at least one tuning branch equipped with a controlled switch, which is connected to the transmitting resonant circuit. The controlled switch in each tuning branch can be a power MOSFET, analog switch, or relay—a device that can be controlled by an electrical signal to switch on and off. When the controlled switch switches between on and off states, the tuning element connected in series with it is connected to or disconnected from the transmitting resonant circuit, thereby changing the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit. Since the inverter unit always operates at a fixed frequency... Changes in the equivalent capacitance or equivalent inductance can cause a controllable capacitive or inductive micro-detuning in the transmitting resonant circuit relative to a fixed driving frequency. Taking a series resonant circuit as an example, its frequency... The loop impedance at point can be expressed as ,in , The equivalent inductance and equivalent capacitance after connecting to the tuning branch, This is the equivalent series resistance of the circuit. When , When the nominal value is taken such that the imaginary part is zero, the circuit is in perfect resonance, the impedance is minimum, the excitation current of the transmitting coil is maximum, and the energy of the coupled magnetic field is strongest; when the controlled switch switches... or When the value deviates from the nominal value, the imaginary part of the circuit is no longer zero, the impedance increases, the excitation current decreases, and the magnetic field energy weakens. Therefore, the transmitter control unit only needs to control the on / off combination of the controlled switches to continuously adjust the transmission power without changing the frequency.

[0035] In the receiving resonant circuit of the receiving end, the receiving coil and the transmitting coil are magnetically coupled. The resonant frequency of the receiving resonant circuit matches the frequency of the inverter unit's drive signal, thus ensuring that the receiving end can efficiently pick up coupled energy under fixed-frequency operation. The rectifier output unit is used to convert the AC power coupled from the receiving resonant circuit into DC power to supply the load. It can use a synchronous rectifier circuit, including synchronous full-bridge rectification (4 MOSFETs, or 2 MOSFETs plus 2 diodes, or 4 diodes), half-bridge rectification, or dual-diode rectification. The diodes can be ordinary diodes or Schottky single diodes, and are used in conjunction with a voltage regulator and filter circuit to output rectified voltage. This provides power to the downstream low-dropout linear regulator, DC-DC converter, or charging management circuit. The sampling unit collects the operating parameters of the receiver and transmits them to the receiver control unit. The collected operating parameters include the rectified output voltage. System power supply voltage Battery voltage One or more of the following can be sampled: load current and rectified current. Sampling can be achieved through a voltage divider circuit or a sampling resistor in conjunction with an analog-to-digital converter.

[0036] The modulation unit is controlled and connected to the receiver control unit. The receiver control unit generates a power adjustment command based on the operating parameters acquired by the sampling unit and controls the modulation unit to change the equivalent impedance of the receiver according to a preset coding rule. This causes the electrical parameters of the transmitting resonant circuit to exhibit amplitude fluctuations characterizing the power adjustment command. Specifically, because the transmitting and receiving ends are magnetically coupled, the periodic changes in the receiver's equivalent impedance are reflected back to the transmitting end via the magnetic field, causing corresponding periodic fluctuations in the current or voltage amplitude of the transmitting resonant circuit. These fluctuations carry the power adjustment command.

[0037] The signal demodulation unit is used to detect amplitude fluctuations in the electrical parameters of the transmitting resonant circuit, decode the power adjustment command, and transmit it to the transmitting control unit. The signal demodulation unit can also acquire current or voltage signals from the transmitting resonant circuit, extract the amplitude envelope changes, and thus reconstruct the power adjustment command sent by the receiving end.

[0038] Based on this, a complete fixed-frequency power regulation closed loop is formed: the receiving end control unit determines whether to increase, decrease, or maintain the power based on the operating parameters, for example, detecting during the constant current charging stage. When the load current decreases and approaches the lower limit at which the subsequent circuit can operate normally, a power-up command is generated; when the load current decreases, When the power increase exceeds the expected value, a power reduction command is generated. The receiver control unit then controls the modulation unit to change the receiver's equivalent impedance. The signal demodulation unit detects amplitude fluctuations at the transmitter and decodes the command. The transmitter control unit then controls the state of each controlled switch in the adjustable resonant network according to the power adjustment command. While keeping the drive signal frequency fixed, the transmitter power is increased or decreased by changing the equivalent capacitance and / or equivalent inductance of the transmitter resonant circuit, bringing the receiver's operating parameters back to the target range, thereby achieving high-precision adaptive power adjustment. With the cooperation of the transmitter control unit, inverter unit, transmitter resonant circuit, adjustable resonant network, signal demodulation unit, and receiver control unit, receiver resonant circuit, rectifier output unit, sampling unit, and modulation unit, those skilled in the art can completely implement a wireless charging system with a fixed frequency throughout and precise power control via receiver modulation feedback.

[0039] The following describes several optional improvements to this solution.

[0040] In some optional implementations, the modulation unit can consist of a load modulation branch and / or a capacitor modulation branch. The load modulation branch includes a modulation load connected in series and a first modulation switch. The receiver control unit switches the modulation load by controlling the first modulation switch to change the equivalent impedance of the receiver. The capacitor modulation branch includes a modulation capacitor connected in series and a second modulation switch. The receiver control unit switches the modulation capacitor by controlling the second modulation switch to change the equivalent impedance of the receiver. It should be noted that the load modulation branch and the capacitor modulation branch can be selected individually or simultaneously, with the receiver control unit choosing the preferred option. Both can generate an impedance disturbance at the receiver that can be recognized by the primary side. When the passive switching method described above is not used, a similar reflection modulation effect can be achieved by adjusting the equivalent input impedance of the rectifier output unit.

[0041] As a preferred but not mandatory improvement, the preset encoding rules can be implemented by encoding the change in equivalent impedance through different modulation frequencies and / or modulation duty cycles to distinguish different power adjustment commands. For example, a higher modulation frequency corresponds to a power increase command, and a lower modulation frequency corresponds to a power decrease command, or different duty cycles distinguish different modulation step sizes. Accordingly, the signal demodulation unit acquires the current signal and / or voltage signal of the transmitting resonant circuit, and sequentially filters, shapes, and decodes the acquired signals to obtain the power adjustment command: filtering is used to remove the operating frequency component and retain the envelope component near the modulation frequency; shaping is used to organize the envelope into a logic level that is easy to distinguish; and decoding is used to restore the meaning of the command according to the preset encoding rules. In addition to the above frequency / duty cycle encoding, other encoding methods such as preset timing or frame format can also be used, which can be flexibly selected by those skilled in the art according to the noise environment and response speed requirements.

[0042] Building upon the above scheme, a further mapping relationship between power adjustment commands and power levels can be established. The adjustable resonant network can have multiple power levels defined by different combinations of on / off states of each controlled switch. Each power level corresponds to a set of defined equivalent capacitance and / or equivalent inductance values, thus corresponding to a defined transmit power level. The transmitting control unit pre-stores the mapping relationship between power adjustment commands and power levels, and determines the target power level by looking up the table based on the decoded power adjustment command. Then, it controls the state of each controlled switch according to the target power level. Using pre-stored mapping allows the transmitting end to quickly adjust the power level after receiving the command, shortening the response time. When pre-stored mapping is not used, the transmitting control unit can also calculate the target equivalent parameters in real time based on the command before determining the switch state, achieving power adjustment in the same way.

[0043] Example 2 This embodiment is based on Embodiment 1, combined with Figures 2 to 5The specific structure of the tunable resonant network at the transmitter and the series and parallel configurations of the transmitter resonant circuit are further explained. Figure 2 , Figure 3 This illustrates the case where the transmitting coil 31 and the resonant capacitor 32 are connected in series to form a series resonant circuit. Figure 4 , Figure 5 The diagram illustrates the case where the transmitting coil 31 and the resonant capacitor 32 are connected in parallel to form a parallel resonant circuit. In the circuits described above, the transmitting coil 31 is a coil that is magnetically coupled to the receiving coil and transmits energy. The resonant capacitor 32 is a fixed, constantly connected capacitor without a controlled switch. The transmitting coil 31 and the resonant capacitor 32 together determine the reference resonant center frequency of the transmitting resonant circuit, and the fixed drive frequency of the inverter unit is locked to this center frequency.

[0044] In some alternative implementations, the tunable resonant network includes a controllable capacitor matrix 41. For example... Figure 2 , Figure 5 As shown, the controllable capacitor matrix 41 includes multiple parallel capacitor tuning branches. Each capacitor tuning branch includes a compensation capacitor 411 connected in series and a controlled switch 412. Each controlled switch 412 is controlled to connect to the transmitter control unit. The transmitter control unit controls the on / off state of the controlled switches 412 in each capacitor tuning branch to connect or disconnect the corresponding compensation capacitor 411 from the transmitter resonant circuit, thereby changing the equivalent capacitance of the connected circuit. At this time, the equivalent capacitance of the connected circuit is approximately the sum of the resonant capacitor 32 and the compensation capacitors 411 of each conducting branch. The compensation capacitors 411 can be configured with three to six branches using differentiated capacitance values. For example, the compensation capacitors 411 of each branch can be assigned values ​​according to binary weights or arithmetic progressions, so that different on / off combinations of the controlled switches 412 cover a relatively dense range of capacitance values, adapting to fine power adjustment over small spans. It should be noted that the connection form between the compensation capacitors 411 and the controlled switches 412 is not unique, such as... Figure 3 , Figure 4 As shown, the controllable capacitor matrix 41 can also be constructed by using multiple compensation capacitors 411 selectively connected in series or bypassed by the controlled switch 412, which can also change the equivalent capacitance of the circuit. When a multi-branch capacitor matrix is ​​not used, it can be replaced with a single digital adjustable capacitor or a mechanically variable capacitor to adjust the equivalent capacitance.

[0045] In a variation of this embodiment, the tunable resonant network may further include a multi-tap inductor switching matrix 42. For example... Figures 2 to 5As shown, the multi-tap inductor switching matrix 42 includes an inductor winding 421 with multiple taps 422 and multiple tap selection switches 423 connected one-to-one with each tap 422. The tap selection switches 423 are controlled to connect to the transmitter control unit. The inductor winding 421 is connected in series between the output terminal of the inverter unit and the transmitter coil 31. The transmitter control unit controls the on / off state of the tap selection switches 423 to select different taps 422, thereby changing the effective number of turns of the inductor winding 421 connected in series in the circuit, and thus changing the equivalent inductance connected to the transmitter resonant circuit. The inductor winding 421 can be equipped with three to five taps 422. Since the change in inductance has a relatively large impact on the circuit impedance, the multi-tap inductor switching matrix 42 is suitable for power regulation over a wide range and a wide span. By separating the inductor winding 421, which is responsible for tuning, from the externally coupled transmitting coil 31, the equivalent inductance of the circuit can be changed while maintaining the coupling relationship between the transmitting coil 31 and the receiving coil, making the power adjustment process more controllable. When an integrated multi-tap winding is not used, the inductor winding 421 can also be replaced by multiple discrete inductors that are switched in series and parallel by a switch to adjust the equivalent inductance.

[0046] Optionally, the controllable capacitor matrix 41 and the multi-tap inductor switching matrix 42 can operate independently or in conjunction. When they operate independently, the controllable capacitor matrix 41 can handle fine-range adjustment, or the multi-tap inductor switching matrix 42 can handle wide-range adjustment; when they operate in conjunction, for example... Figures 2 to 5 The scenario shown, where both the controllable capacitor matrix 41 and the multi-tap inductor switching matrix 42 are simultaneously configured, allows for coarse adjustment first using the multi-tap inductor switching matrix 42, followed by fine adjustment using the controllable capacitor matrix 41. This results in higher tuning resolution over a wider power range. It should be noted that the controllable capacitor matrix 41 and the multi-tap inductor switching matrix 42 do not necessarily need to be configured simultaneously. Even with only one of them configured, the transmitter can still achieve power regulation by changing the equivalent capacitance or equivalent inductance under fixed-frequency conditions.

[0047] Regardless of the method Figure 2 , Figure 3 The series resonance mode is still Figure 4 , Figure 5 In the parallel resonance mode, after the transmitter control unit changes the state of the controlled switch 412 in the controllable capacitor matrix 41 or the tap selection switch 423 in the multi-tap inductor switching matrix 42, the transmitter resonant circuit generates controllable capacitive or inductive micro-detuning relative to the fixed driving frequency, thereby changing the excitation current and coupled magnetic field energy of the transmitter coil 31, and realizing power regulation under fixed frequency conditions.

[0048] Example 3 This embodiment, based on the aforementioned embodiments, further explains the redundancy and fault-tolerant control method at the transmitting end. Its position in the system is described in [reference needed]. Figure 1 .

[0049] To further improve adaptability under complex operating conditions, a primary-side parameter sampling unit can be added at the transmitter. This unit collects the current, voltage, and voltage-current phase difference of the transmitting resonant circuit and transmits them to the transmitter control unit. For example, it obtains the circuit current through a precision sampling resistor, the circuit voltage through a voltage divider circuit, and the phase difference between the current and voltage through a phase detection circuit. With the primary-side parameter sampling unit, the transmitter control unit first determines the target switching state of the adjustable resonant network based on the decoded power adjustment command. Then, it corrects the target switching state based on the parameters collected by the primary-side parameter sampling unit and finally controls each controlled switch according to the corrected switching state. For example, when the actual excitation current collected by the primary side deviates from the expected current at the target level, the transmitter control unit can make a fine adjustment near the target level to make the actual power closer to the target value. It should be noted that the primary-side parameter sampling unit is not a necessary condition for implementing this scheme. Even without this unit, the system can still perform power adjustment normally by controlling the controlled switches solely based on the demodulation command from the receiver.

[0050] Building upon the aforementioned scheme, a degradation-tolerance mechanism can be further implemented. When the signal demodulation unit fails to decode the power adjustment command within a preset time period, or when the decoding result does not conform to the preset encoding rules, the transmitting end control unit autonomously controls the state of the controlled switch based on the parameters collected by the primary-side parameter sampling unit to maintain power adjustment. This preset time period can be a value between tens and hundreds of milliseconds. With this mechanism, under conditions such as strong interference with the modulated signal, receiver malfunction, or temporary lack of feedback, the transmitting end can automatically and smoothly switch from a working mode primarily based on the receiver's demodulation command to a working mode that autonomously adjusts the power level based on the primary-side current, voltage, and phase difference, thereby preventing power runaway or charging interruption. Alternatively, without this degradation mechanism, it can be replaced by maintaining the previous effective power level or switching to a reduced power protection state during demodulation failure.

[0051] Example 4 This embodiment provides a specific implementation of the aforementioned system, and its overall block diagram is as follows: Figure 6 As shown.

[0052] At the transmitting end, the transmitting control unit integrates a drive circuit. One output is a fixed-frequency pulse-width modulation signal to drive the inverter unit, and the other outputs a matrix switch control signal to control the on / off state of each controlled switch in the adjustable resonant network. The inverter unit can adopt a full-bridge, half-bridge, or single-transistor topology. The transmitting resonant circuit and the adjustable resonant network together constitute the resonant and matrix part of the transmitting end, consisting of a transmitting coil, a resonant capacitor, and capacitor tuning branches and inductor switching branches with controlled switches. The transmitting end is equipped with a signal demodulation unit to detect amplitude fluctuations in the electrical parameters of the transmitting resonant circuit, and may further include a primary-side parameter sampling unit to collect circuit current, voltage, and voltage-current phase difference, both of which provide feedback to the transmitting control unit.

[0053] At the receiving end, the receiving resonant circuit supplies power to the subsequent stage via a rectifier output unit. The rectifier output unit can use a full-bridge, half-bridge, single-tube, or single-diode rectification. The rectified voltage output is then supplied to the load and battery via a DC-DC converter, a low-dropout linear regulator, or a charging management circuit. The receiving end control unit collects parameters such as rectified current, rectified output voltage, supply voltage, battery voltage, and load current, and outputs two modulation control signals accordingly. These signals control the capacitor modulation branch and the load modulation branch in the modulation unit to switch the modulation capacitor or load according to a preset code, thereby changing the equivalent impedance of the receiving end and generating an uplink feedback signal.

[0054] In this embodiment, the topology selection of inverter and rectifier, the setting of capacitor modulation branch and load modulation branch, and the setting of primary side parameter sampling unit can all be flexibly selected according to product needs and are not necessary for implementing the aforementioned system. Those skilled in the art can select specific devices based on this block diagram to realize a wireless charging system with fixed frequency throughout and precise control by modulation feedback from the receiving end.

[0055] Example 5 This embodiment provides a complete and specific circuit example to illustrate the collaborative working process of the above-mentioned parts in an actual product. The circuit principle is as follows: Figure 7 As shown. In this case, the inverter unit at the transmitting end adopts a half-bridge topology, and the transmitting resonant circuit adopts a series resonant configuration with the transmitting coil and resonant capacitor connected in series. The adjustable resonant network is connected in series to adjust the equivalent capacitance and equivalent inductance of the circuit. The rectifier output unit at the receiving end uses a single Schottky diode or a single power transistor for rectification, and the rectified output voltage... After voltage regulation, it supplies power to the subsequent DC-DC converter, low-dropout linear regulator, or charging management circuit.

[0056] After the system is powered on, the transmitter control unit operates at a fixed frequency. Two complementary pulse-width modulated (PWM) signals are output to drive the upper and lower power transistors of the half-bridge, respectively. To avoid shoot-through caused by simultaneous conduction of the upper and lower power transistors, a dead zone is provided between the two drive signals to form non-overlapping signals. The upper and lower power transistors conduct alternately at a fixed frequency, establishing an alternating current on the transmitting coil of the series resonant circuit, thereby generating an alternating magnetic field. After the receiving coil couples this magnetic field, it is rectified by a single diode or a single transistor to obtain the desired signal. It supplies power to the downstream load.

[0057] Under conditions of increased load current, the system operates at a fixed frequency resonance. The voltage will gradually decrease as the load current increases. If no adjustment is made, the subsequent circuits may fail to operate normally due to the low supply voltage. The receiving control unit detects this through the sampling unit. With changes in charging current, After the voltage drop, a power-up command is generated, and the modulation unit is controlled to change the equivalent impedance of the receiver by switching the load or capacitor, causing the current in the transmitting resonant circuit to fluctuate to carry the amplitude of the command. After the signal demodulation unit at the transmitting end demodulates the power-up command, the transmitting control unit increases the power through a switching matrix. This can be achieved in several ways: one is to reduce the equivalent capacitance of the circuit separately; another is to reduce the equivalent inductance of the circuit separately; and a further step is to reduce both the equivalent inductance and equivalent capacitance simultaneously for finer energy control. Reducing the equivalent inductance and equivalent capacitance decreases the impedance of the series resonant circuit at a fixed frequency, increases the excitation current of the transmitting coil, enhances the energy of the coupled magnetic field, and consequently increases the energy received by the receiving resonant circuit. Rebound The charging current is increased until the target requirement is met.

[0058] Under operating conditions with reduced load current, also due to fixed-frequency resonance, The voltage will gradually increase as the load current decreases. Excessive voltage can affect the safety of downstream loads and reduce conversion efficiency. The receiver control unit detects this. With normal charging current, If the power level rises above the expected value, a power reduction command is generated and fed back to the transmitter via the modulation unit. After demodulating the power reduction command, the transmitter reduces the power through a switching matrix. This can be achieved by individually increasing the equivalent capacitance or equivalent inductance of the circuit, or by simultaneously increasing both the equivalent inductance and capacitance for finer energy control. Increasing the equivalent inductance and capacitance increases the circuit impedance, reduces the excitation current of the transmitting coil, weakens the coupling magnetic field energy, and decreases the energy received by the receiving resonant circuit. pullback As the charging current stabilizes until the target requirement is met, the overall conversion efficiency is improved due to the reduction of reactive power loss caused by excessive transmission.

[0059] As can be seen from the above process, when the load is stable, the system operates at a fixed frequency in a near-perfect resonant state, corresponding to high transmission efficiency. When there are sudden load changes, voltage fluctuations, or coupling shifts, the receiver's modulation feedback triggers the transmitter to quickly adjust the frequency, which makes up for the problem of response lag and insufficient accuracy when relying solely on passive sensing at the primary side. Since the operating frequency is not changed throughout the process, the circuit always operates near the designed narrow resonant bandwidth, avoiding serious detuning and efficiency degradation caused by frequency shift.

[0060] Example 6 This embodiment provides a fixed-frequency resonant power-modulated wireless charging transmitter, which can be manufactured and used independently and can be used in conjunction with a receiver of any resonant frequency to complete wireless charging. The transmitter includes a transmitter control unit, an inverter unit, a transmitting resonant circuit, an adjustable resonant network, and a signal demodulation unit. Its specific configuration and switching matrix under both series and parallel resonant topologies are described in [reference needed]. Figures 2 to 5 .

[0061] The inverter unit is controlled and connected to the transmitter control unit, used to output a constant-frequency drive signal to excite the transmitter resonant circuit. The frequency of the drive signal remains fixed during power regulation. The transmitter resonant circuit includes transmitter coils 31 connected in series or parallel and resonant capacitors 32. Figure 2 , Figure 3 As shown, when a series configuration is used, the transmitting coil 31 and the resonant capacitor 32 are connected in series at the output terminal of the inverter unit. The circuit exhibits low impedance and high current characteristics at resonance. Figure 4 , Figure 5 As shown, in the parallel configuration, the transmitting coil 31 and the resonant capacitor 32 are connected in parallel to the output of the inverter unit, and the circuit exhibits high impedance characteristics at resonance. Both configurations are designed to resonate at a fixed drive frequency, and those skilled in the art can choose between them based on the inverter topology and power level. The adjustable resonant network includes at least one tuning branch with a controlled switch, which is connected to the transmitting resonant circuit. This tuning branch is used to change the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit under the state switching of the controlled switch. It can be embodied in one or both of the aforementioned controllable capacitor matrix 41 and multi-tap inductor switching matrix 42. The signal demodulation unit is used to detect the amplitude fluctuation of the electrical parameters of the transmitting resonant circuit and decode the power adjustment command generated by the wireless charging receiver by changing its equivalent impedance modulation, and transmit it to the transmitting end control unit. The transmitting end control unit controls the state of the controlled switch according to the power adjustment command, and adjusts the transmitting power by changing the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit while keeping the frequency of the drive signal fixed.

[0062] Since the transmitter itself includes complete capabilities for fixed-frequency excitation, resonant matrix tuning, and uplink signal demodulation, it can function as a standalone product as a universal wireless charging transmitter base. Any receiver whose resonant frequency matches the transmitter's fixed operating frequency and possesses equivalent impedance modulation capability can work with it. Optionally, the transmitter can further incorporate improvements such as the primary-side parameter sampling unit, controllable capacitor matrix, multi-tap inductor switching matrix, and degradation fault-tolerant mechanism described in the aforementioned embodiments to enhance tuning accuracy and operational stability. Even without these improvements, the transmitter can still independently perform power regulation under fixed-frequency conditions.

[0063] Example 7 This embodiment is based on the system of the aforementioned embodiment (see...). Figure 1 To address the issue that fixed-frequency systems cannot track frequencies under varying dielectric constants, an improvement based on primary-side phase baseline monitoring for environmental parasitic capacitance cancellation is proposed.

[0064] As an optional improvement, a cancellation capacitor matrix is ​​further incorporated at the transmitting end. The cancellation capacitor matrix consists of multiple parallel cancellation capacitor branches. Each branch includes a cancellation capacitor connected in series with a controlled switch, and each controlled switch is connected to the transmitting end control unit. The cancellation capacitors employ differentiated capacitance values ​​at the picofarad level, such as a binary weighted design or a non-uniform weighting based on the sensitivity near the resonant point. Their minimum switching step is significantly smaller than the step of the capacitor tuning branch used for power regulation in the controllable capacitor matrix, thus functionally decoupling the cancellation capacitor matrix from the power modulation: the controllable capacitor matrix is ​​responsible for power adjustment in response to receiver commands, while the cancellation capacitor matrix is ​​dedicated to restoring the static resonant point. The cancellation capacitor branches are connected to the circuit according to the series or parallel topology of the transmitting resonant circuit. To further enhance adaptability to temperature drift, a temperature sensing unit can be placed near the transmitting coil or magnetic components, with its output connected to the transmitting end control unit; when no temperature sensing unit is provided, this embodiment can still achieve cancellation solely through phase monitoring.

[0065] In systems with narrow resonant bandwidth and fixed frequency operation, changes in the dielectric constant of the medium between the transmitter and receiver (e.g., equipment exposed to water or sweat, probe inserted into biological tissue) will introduce parasitic capacitance in the picofarad range into the transmitter circuit, causing the actual resonant center frequency of the transmitter resonant circuit to deviate from the fixed driving frequency. This results in a phase difference between the primary voltage and current. A persistent offset occurs, leading to a decrease in transmission efficiency. Since the system lacks frequency tracking capabilities, this offset cannot be eliminated through frequency conversion. This embodiment addresses this problem by leveraging the existing phase detection capability of the primary-side parameter sampling unit. One challenge is distinguishing between environmental medium drift and coupling changes caused by coil displacement, avoiding misinterpreting coupling changes as medium offset and incorrectly canceling them out.

[0066] There are two bases for differentiation. First, the difference in time scale: medium wetting or tissue contact is a gradual and long-term process, causing a phase shift that accumulates slowly over a period of seconds or more and remains constant, while coil displacement exhibits an event-driven, step-like abrupt change. Second, cross-verification with receiver feedback: coil displacement primarily alters the mutual inductance between the transmitting and receiving coils, simultaneously affecting the rectified output voltage at the receiver. Upon a sudden change in synchronization, the receiving control unit immediately reports the corresponding power adjustment command via the modulation unit. However, under weak coupling conditions, changes in the dielectric primarily alter the equivalent capacitance and resonant frequency of the transmitting circuit itself, having a relatively small impact on mutual inductance. Therefore, this manifests as a continuous drift in the primary-side phase. There is no corresponding mutation, nor is there a corresponding power adjustment command.

[0067] Accordingly, the discrimination logic of the transmitter control unit is as follows: extract the static baseline phase only during non-communication periods when the signal demodulation unit does not detect the uplink modulation signal. When the sampled phase offset satisfies Greater than the preset phase threshold (For example (Take a range of 3° to 5°), and the duration must be greater than the preset duration. (For example The timeframe is 0.5s to 2s. If the signal demodulation unit fails to decode the corresponding power adjustment command within this timeframe, it is determined to be a static parasitic offset introduced by the environmental medium, and the system enters the environmental baseline calibration mode. Otherwise, it is determined to be a coupling change or normal modulation, and cancellation is not triggered. Since the baseline phase is only extracted during non-communication periods, the phase disturbance caused by the uplink modulation itself will not contaminate the baseline, which helps to ensure the accuracy of offset determination.

[0068] After entering the environmental baseline calibration mode, the transmitter control unit estimates the equivalent parasitic capacitance introduced by the environment based on the direction and amplitude of the current phase shift, and switches the branch corresponding to the capacitance value in the cancellation capacitor matrix in the direction of zero phase difference, thus pulling the actual equivalent resonant frequency of the transmitter resonant circuit back to normal. The system converges in small steps, aiming to minimize the phase difference between the primary and secondary sides. The switch combination determined after cancellation serves as the new reference resonant setting for subsequent power adjustment. The system then executes power increase / decrease commands from the receiver on top of this new reference, forming a two-layer superposition: static cancellation to restore the resonant reference, followed by dynamic power adjustment. These two layers do not interfere with each other. When setting the temperature sensing unit, the transmitter control unit can also perform feedforward pre-compensation for the offset caused by temperature drift based on a pre-stored temperature-resonance drift characteristic curve, switching the cancellation capacitor setting before the closed-loop response to accelerate convergence.

[0069] During actual operation, the system first starts at a fixed frequency, the tunable resonant network is set to the initial resonance setting, and the static baseline phase is recorded during non-communication periods. Subsequently, the primary side parameter sampling unit monitors the phase difference in real time. And calculate the offset. Then, according to the above time scale and Cross-validation conditions are used to determine the source of the offset; if it is determined to be environmental medium drift, the capacitor matrix is ​​iteratively switched to cancel it out. return The reference profile is then updated nearby; finally, the power tuning of the receiver modulation feedback is performed on the updated reference profile, and the baseline phase is periodically refreshed.

[0070] With the aforementioned improvements, the cancellation capacitor matrix, separate from the controllable capacitor matrix, assumes the function of static impedance repair, compensating for the inability of the fixed-frequency scheme to track frequencies in environments with varying dielectric constants. Since the minimum switching step of the cancellation capacitor matrix is ​​smaller than the step of the capacitor tuning branch used for power regulation in the controllable capacitor matrix, the two are functionally decoupled. Fine tuning during cancellation will not disturb the predetermined power level, and power regulation will not damage the repaired resonant point. Furthermore, the picofarad-level fine step allows for more precise compensation of parasitic capacitance introduced by the dielectric. By cross-judging the phase shift, duration, and absence of power regulation commands during that period, the coupling changes caused by environmental dielectric drift and coil displacement can be distinguished, significantly reducing the probability of false triggering and erroneous cancellation, and improving the reliability of the cancellation action. Finally, under conditions where dielectric effects are significant and persistent, such as waterproof equipment being exposed to water and sweat, or miniature medical probes contacting or penetrating biological tissue, the resonant operating point can be stably locked back. This avoids a significant drop in transmission efficiency and eliminates the need for additional independent frequency control hardware.

[0071] Example 8 This embodiment, based on the previous embodiments, further improves the signal demodulation unit to address the issues of low quality factor of small coils, weak uplink feedback signal under weak coupling conditions, and slow resonant cavity envelope tuning. All improvements are concentrated at the transmitting end; the modulation unit, receiving resonant circuit, and rectifier output unit structures at the receiving end remain unchanged. No additional carrier chip or high-frequency modulation and demodulation hardware is required, and the cost and size of the receiving end circuit and materials do not increase.

[0072] As an optional improvement, the signal demodulation unit includes a synchronous sampling module, a coherent accumulation module, a bandpass filter module, and a decision module. The synchronous sampling module is phase-locked to the pulse width modulation drive signal of the inverter unit, the coherent accumulation module accumulates and averages the sampling results within one uplink symbol period, and the center frequency of the bandpass filter module is set to the modulation frequency. The decision module performs amplitude decision at the end of the symbol period to obtain the power adjustment command.

[0073] Because the system is locked to a single fixed frequency throughout the entire process In operation, the transmitter itself serves as the phase reference for the uplink carrier, and its phase is completely known. Based on this, the synchronous sampling module synchronously samples the primary-side current at a fixed phase point in each pulse width modulation cycle (e.g., near the peak or zero-crossing point of the transmit resonant current); the coherent accumulation module samples the primary-side current within one symbol period. The cumulative averaging of each sampling point is equivalent to lock-in amplification or matched filtering, causing the signal-to-noise ratio to increase approximately by the number of accumulation cycles. This improves the performance, thereby extracting the subtle reflection impedance fluctuations that are masked by background noise under weak coupling. For example, by taking the quality factor. , At that time, the pulse width modulation period is approximately 5 μs; when the accumulation within one symbol period... During each cycle, the signal-to-noise ratio is improved by about 10 times (about 20dB), thus enabling stable demodulation even under weak coupling conditions with large coil offset, unlike simple peak detection methods which are susceptible to background noise and physical movement of equipment.

[0074] Considering the envelope time constant of a high-quality factor resonant cavity (in The amplitude jump caused by modulation is relatively large, and it takes several cycles to stabilize. If the symbol period is too short, inter-symbol interference will occur. Therefore, the uplink symbol period can be reduced. Designed for cavity time constant Integer multiples of, i.e. , Choose values ​​from 3 to 5 to fully adjust the envelope within each symbol before the decision module makes a decision. (Still using...) , For example, Correspondingly The time interval is approximately 0.5ms to 0.8ms. This design binds the uplink communication rate to the physical characteristics of the resonant cavity according to quantitative rules, which can reduce the decision error caused by the high quality factor and slow envelope.

[0075] Regarding encoding and frequency band, the receiver control unit controls the modulation unit to encode the power adjustment command into frequency. Tonal bursts can be achieved, for example, by using on / off keying or frequency shift keying. satisfy , where m is a multiple of the aforementioned symbol period and envelope time constant (taken as 3 to 5). This refers to the bandwidth of the transmitter's power control loop (e.g., below 100Hz). The transmitter passes through a bandpass filter module... The uplink command is extracted from the center, while the power control loop only responds at frequencies lower than [the specified frequency]. The slow variable thus separates the modulation disturbance at the receiver from the actual load change in the frequency domain, preventing the power control loop from misinterpreting periodic modulation as a load change and making incorrect adjustments; whereby The available window is narrower due to quality factor constraints, and can be specifically set according to the above upper and lower limits.

[0076] To accommodate different coupling strengths, the receiver control unit can also adjust the parameters based on the measurements taken by the sampling unit. Based on this estimated coupling strength, the switching amount of the modulation unit can be adaptively adjusted: in weak coupling, i.e. When the impedance is too low or the estimated mutual inductance is small, increase the switching modulation load or modulation capacitance to increase the reflection impedance change and ensure demodulation at the transmitter; reduce the switching amount in strong coupling to reduce... Ripple, thereby balancing communication reliability and power stability.

[0077] When the decision module fails to obtain a valid decision within a preset number of symbol periods, or when the decoding result does not conform to the preset encoding rules, the transmitter control unit determines that the uplink channel is abnormal and automatically connects to the aforementioned redundancy strategy, downgrading to a pure primary-side mode that autonomously adjusts the phase and current based on the primary-side parameter sampling unit to ensure uninterrupted charging.

[0078] In actual operation, the receiving end control unit presses... The symbol period encodes the power regulation command as The tone bursts and is switched by the modulation unit; the synchronous sampling module is phase-locked to the inverter drive signal and samples the primary current at a fixed phase point in each cycle; the coherent accumulation module accumulates and averages within the symbol period, and the bandpass filter module extracts the signal. The decision module receives the instruction at the end of the symbol and uploads it to the transmitter control unit, which switches the adjustable resonant network's gear according to the mapping relationship between the instruction and the gear. When consecutive decisions fail, the network is downgraded to pure primary-side autonomous gear adjustment according to the above abnormal connection.

[0079] With the above improvements, this embodiment utilizes the characteristic of prior knowledge of the waveform phase in a fixed-frequency architecture to perform synchronous coherent accumulation on the primary-side signal, thereby obtaining approximately The signal-to-noise ratio gain; this gain comes from the known phase reference provided by fixed-frequency operation, which is difficult to obtain directly by frequency conversion schemes that rely on frequency tracking and have variable carrier phases. The uplink symbol period is compared with the envelope time constant of the resonant cavity. according to The quantitative rule binding provides a clear design basis for demodulation reliability, facilitating reproduction under the same rules on products with different quality factors and operating frequencies, and reducing inter-symbol interference and decision errors caused by high quality factors and slow envelopes. Furthermore, the separation of the bandpass filter center frequency and the power control loop bandwidth in the frequency domain ensures that modulation disturbances and actual load changes are not confused, preventing the power control loop from misinterpreting periodic modulation as load changes and incorrectly adjusting the modulation. In summary, this embodiment improves the demodulation reliability and anti-interference capability of uplink feedback under weak coupling, slow envelope, and small coil conditions; since all improvements are concentrated in the transmitter firmware, no changes are required at the receiver, preserving the advantages of low cost and small size.

[0080] The systems and transmitters in the various embodiments of this specification do not require high-frequency carrier communication hardware. The circuit structure is simple, the cost is low, and the size is small. At the same time, it takes into account the transmission efficiency under fixed frequency operation and the tuning accuracy brought by modulation feedback. It can be adapted to the wireless charging needs of portable electronic products with small coils and weak coupling, such as smart wearable devices, electric toothbrushes, and shavers.

[0081] It should be noted that in this disclosure, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this disclosure, reference to performing an action according to an element means performing the action at least according to that element, including two cases: performing the action only according to that element, and performing the action according to that element and other elements. Expressions such as "multiple," "repeatedly," and "various" include two, two times, two kinds, and more than two, more than two times, and more than two kinds.

[0082] This specification includes combinations of various embodiments described herein. Individual references to embodiments (e.g., “one embodiment”, “some embodiments”, or “preferred embodiments”) do not necessarily refer to the same embodiment; however, these embodiments are not mutually exclusive unless indicated to be mutually exclusive or are readily apparent to those skilled in the art. It should be noted that the word “or” is used in a non-exclusive sense throughout this specification unless the context explicitly indicates or requires it.

[0083] Furthermore, it should be understood that after reading the contents of this disclosure, those skilled in the art can make various alterations or modifications to this disclosure, and these equivalent forms also fall within the scope of protection claimed by this disclosure.

Claims

1. A fixed-frequency resonant power-regulating wireless charging system, characterized in that, Includes a wireless charging transmitter and a wireless charging receiver; The transmitter includes a transmitter control unit, an inverter unit, a transmitter resonant circuit, an adjustable resonant network, and a signal demodulation unit; The inverter unit is controlled and connected to the transmitter control unit, and is used to output a drive signal with a constant frequency to excite the transmitter resonant circuit. The frequency of the drive signal remains fixed during power regulation. The transmitting resonant circuit includes a transmitting coil and a resonant capacitor; The tunable resonant network includes at least one tuning branch equipped with a controlled switch. The tuning branch is connected to the transmitting resonant circuit and is used to change the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit when the state of the controlled switch is switched. The receiving end includes a receiving end control unit, a receiving resonant circuit, a rectifier output unit, a sampling unit, and a modulation unit; The receiving coil in the receiving resonant circuit is magnetically coupled to the transmitting coil, and the resonant frequency of the receiving resonant circuit is matched with the frequency of the driving signal. The rectifier output unit is used to convert the AC power coupled by the receiving resonant circuit into DC power to supply the load. The sampling unit is used to collect the operating parameters of the receiving end and transmit them to the receiving end control unit; The modulation unit is controlled to be connected to the receiver control unit. The receiver control unit generates a power adjustment command according to the operating parameters and controls the modulation unit to change the equivalent impedance of the receiver according to a preset coding rule, so that the electrical parameters of the transmitting resonant circuit generate amplitude fluctuations that characterize the power adjustment command. The signal demodulation unit is used to detect amplitude fluctuations in the electrical parameters of the transmitting resonant circuit and decode the power adjustment command, which is then transmitted to the transmitting end control unit. The transmitter control unit controls the state of the controlled switch according to the power adjustment command. While keeping the frequency of the drive signal fixed, the transmitter power is adjusted by changing the equivalent capacitance and / or equivalent inductance of the transmitter resonant circuit.

2. The fixed-frequency resonant power modulation wireless charging system according to claim 1, characterized in that, The tunable resonant network includes a controllable capacitor matrix; The controllable capacitor matrix includes multiple parallel capacitor tuning branches, and each capacitor tuning branch includes a compensation capacitor and the controlled switch connected in series. The transmitter control unit changes the equivalent capacitance connected to the transmitter resonant circuit by controlling the on / off state of the controlled switches in each of the capacitor tuning branches.

3. The fixed-frequency resonant power modulation wireless charging system according to claim 2, characterized in that, The tunable resonant network also includes a multi-tap inductor switching matrix; The multi-tap inductor switching matrix includes an inductor winding with multiple taps and multiple tap selection switches connected one-to-one with each of the taps. The tap selection switches are controlled to be connected to the transmitter control unit. The inductor winding is connected in series between the output terminal of the inverter unit and the transmitter coil. The transmitter control unit controls the on / off state of the tap selection switch to select different taps, thereby changing the equivalent inductance connected to the transmitter resonant circuit. The controllable capacitor matrix and the multi-tap inductor switching matrix can work independently or in conjunction.

4. The fixed-frequency resonant power modulation wireless charging system according to claim 1, characterized in that, The modulation unit includes a load modulation branch and / or a capacitor modulation branch; The load modulation branch includes a modulation load connected in series and a first modulation switch. The receiving end control unit controls the first modulation switch to switch the modulation load to change the equivalent impedance of the receiving end. The capacitor modulation branch includes a modulation capacitor and a second modulation switch connected in series. The receiver control unit controls the second modulation switch to switch the modulation capacitor to change the equivalent impedance of the receiver.

5. The fixed-frequency resonant power modulation wireless charging system according to claim 1, characterized in that, The preset encoding rule is as follows: the receiving end control unit controls the modulation unit to periodically change the equivalent impedance of the receiving end at the modulation frequency, and encodes the power adjustment command by at least one of the modulation frequency, modulation duty cycle and modulation timing to distinguish different power adjustment commands; The signal demodulation unit acquires the current signal and / or voltage signal of the transmitting resonant circuit, and sequentially filters, shapes and decodes the acquired signals to obtain the power adjustment command.

6. The fixed-frequency resonant power modulation wireless charging system according to claim 1, characterized in that, The transmitter also includes a primary-side parameter sampling unit, which is used to collect the current, voltage, and voltage-current phase difference of the transmitting resonant circuit and transmit them to the transmitter control unit. The transmitting end control unit determines the target switching state of the tunable resonant network according to the power adjustment command, corrects the target switching state according to the parameters collected by the primary side parameter sampling unit, and controls each of the controlled switches according to the corrected switching state.

7. The fixed-frequency resonant power modulation wireless charging system according to claim 6, characterized in that, When the signal demodulation unit fails to decode the power adjustment command within a preset time period, or when the decoding result does not conform to the preset encoding rule, the transmitter control unit autonomously controls the state of the controlled switch according to the parameters collected by the primary side parameter sampling unit, so as to maintain power adjustment or stop power transmission.

8. The fixed-frequency resonant power modulation wireless charging system according to claim 6, characterized in that, The transmitting end also includes a cancellation capacitor matrix, which comprises multiple parallel cancellation capacitor branches. Each cancellation capacitor branch includes a cancellation capacitor and a controlled switch connected in series. Each controlled switch is controlled to connect to the transmitting end control unit. The cancellation capacitor branches are connected to the transmitting resonant circuit in the same way as the transmitting resonant circuit. The minimum equivalent capacitance adjustment step of the cancellation capacitor matrix is ​​smaller than the equivalent capacitance adjustment step corresponding to the capacitor tuning branch used for power adjustment in the tunable resonant network, thereby decoupling the cancellation capacitor matrix from the tunable resonant network in function. The tunable resonant network is used to adjust power in response to the power adjustment command, and the cancellation capacitor matrix is ​​used to compensate for parasitic capacitance introduced by the dielectric to restore the resonant frequency. The transmitter control unit is configured to: extract the voltage-current phase difference collected by the primary side parameter sampling unit as the baseline phase during non-communication periods when the signal demodulation unit does not detect the uplink modulation signal; when the offset of the voltage-current phase difference collected by the primary side parameter sampling unit relative to the baseline phase is greater than a preset phase threshold, and the duration of the offset is greater than a preset duration, and the signal demodulation unit does not decode the power adjustment command within the duration, it is determined to be a static resonance offset introduced by the medium and enters the baseline calibration mode; otherwise, it is determined to be a coupling change or normal modulation and does not enter the baseline calibration mode. In the baseline calibration mode, the transmitter control unit switches the corresponding cancellation capacitor branch in the cancellation capacitor matrix in the direction that reduces the offset of the voltage-current phase difference, so as to adjust the resonant frequency of the transmitter resonant circuit to match the frequency of the drive signal, and uses the state of each controlled switch determined by this switching as the reference state for subsequent power adjustment.

9. The fixed-frequency resonant power modulation wireless charging system according to claim 5, characterized in that, The signal demodulation unit includes a synchronous sampling module, a coherent accumulation module, a bandpass filtering module, and a decision module; The synchronous sampling module is phase-locked to the drive signal output by the inverter unit, and samples the current signal and / or voltage signal of the transmitting resonant circuit at a preset phase point within each drive signal cycle. The coherent accumulation module accumulates and averages the sampling results of the synchronous sampling module within one uplink symbol period; the center frequency of the bandpass filter module is set to the modulation frequency used by the preset coding rule; at the end of the uplink symbol period, the decision module performs amplitude decision based on the outputs of the coherent accumulation module and the bandpass filter module to obtain the power adjustment command. The uplink symbol period is not less than a preset multiple of the envelope time constant of the transmitting resonant circuit, wherein the envelope time constant is... ,in The quality factor of the transmitting resonant circuit is denoted as . The angular frequency of the driving signal; The modulation frequency is greater than the power control loop bandwidth of the transmitter control unit, so that the impedance modulation generated by the modulation unit is separated from the load change in the frequency domain.

10. A fixed-frequency resonant power-modulated wireless charging transmitter, characterized in that, It includes a transmitter control unit, an inverter unit, a transmitter resonant circuit, an adjustable resonant network, and a signal demodulation unit; The inverter unit is controlled and connected to the transmitter control unit, and is used to output a drive signal with a constant frequency to excite the transmitter resonant circuit. The frequency of the drive signal remains fixed during power regulation. The transmitting resonant circuit includes transmitting coils and resonant capacitors connected in series or in parallel. The tunable resonant network includes at least one tuning branch equipped with a controlled switch. The tuning branch is connected to the transmitting resonant circuit and is used to change the equivalent capacitance and / or equivalent inductance of the transmitting resonant circuit when the state of the controlled switch is switched. The signal demodulation unit is used to detect the amplitude fluctuation of the electrical parameters of the transmitting resonant circuit, and decode the power adjustment command generated by the wireless charging receiver by changing its equivalent impedance modulation, and transmit it to the transmitting end control unit. The transmitter control unit controls the state of the controlled switch according to the power adjustment command. While keeping the frequency of the drive signal fixed, the transmitter power is adjusted by changing the equivalent capacitance and / or equivalent inductance of the transmitter resonant circuit.

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