A multi-section lithium battery wireless charging module and a wireless charging method

Abstract

The application relates to the technical field of wireless charging and discloses a multi-section lithium battery wireless charging module and a wireless charging method, the module comprising a receiving coil assembly, a rectification and voltage stabilization unit, a battery management system unit, a local magnetic flux gain trace, a Hall sensor unit and a main control processing unit. The local magnetic flux gain trace is connected in series in an equalization circuit of the battery management system, and the wiring is spirally arranged around the Hall sensor unit; the method uses a local magnetic field generated when an equalization current flows through the trace, calculates a measured sensitivity by collecting a differential voltage when an equalization switch is turned on and turned off, and corrects a background magnetic field measurement value; further, a coil coupling coefficient is derived by combining a rectification voltage, and real-time equivalent thermal resistance and coil equivalent internal resistance are mapped. The application realizes online self-calibration of the sensor without increasing hardware cost, can dynamically adjust an upper limit of the current based on a coupling state, and realizes self-adaptive continuous charging for preventing overheating.

Description

Technical Field

[0001] This invention relates to the field of wireless charging technology, specifically to a multi-cell lithium battery wireless charging module and a wireless charging method. Background Technology

[0002] With the widespread application of wireless charging technology in multi-cell lithium battery-powered devices such as drones, power tools, and service robots, the market has placed higher demands on the integration, detection accuracy, and thermal management capabilities of receiver modules. In wireless power transmission systems, the coupling alignment of the receiving coil and the transmitting coil directly determines the transmission efficiency and heat generation level. Therefore, it is necessary to introduce magnetic field detection elements such as Hall sensors to assist in judging the alignment status or for feedback control. However, with the increasing miniaturization of receiver devices, PCB board space is extremely limited. Adding independent drive circuits or additional calibration coils to ensure sensor accuracy will increase hardware costs and occupy valuable wiring space, making it difficult to meet the design requirements of high integration density.

[0003] Meanwhile, as a sensitive element, the Hall sensor's measurement accuracy is easily affected by the operating environment. During the high-power transmission of wireless charging, the temperature rise effect inside the module can cause the Hall element's sensitivity to drift, and the permeability of surrounding magnetic shielding materials such as ferrite will also fluctuate with temperature changes or long-term aging. Existing magnetic field detection schemes use an open-loop reading method, which cannot detect and compensate for measurement errors caused by ambient temperature and material property drift in real time. This leads to distortion of the magnetic field data acquired by the system under long-term operation or high-temperature conditions, thus affecting the accuracy of the control system's judgment.

[0004] Furthermore, thermal management during wireless charging is a core aspect of ensuring system safety. The coupling state of the coil not only affects the power reception efficiency but also directly alters the coil's equivalent internal resistance and the overall heat dissipation path of the system. Current technologies rely on a fixed temperature threshold for passive protection when dealing with heat generation issues; that is, the charging circuit is forcibly disconnected when the temperature exceeds a safe threshold and restarted after the temperature returns to normal. This intermittent start-stop operation not only reduces charging efficiency and causes drastic fluctuations in device temperature but also lacks the ability to actively adjust power based on the current coupling deviation and actual heat dissipation conditions, failing to maintain continuous and efficient power transmission while ensuring the device does not overheat. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a multi-cell lithium battery wireless charging module and a wireless charging method. It solves the problem that existing wireless charging receivers cannot simultaneously achieve low hardware cost and online self-testing function of sensors within a limited space, and also solves the problem that the measurement accuracy of magnetic field detection elements decreases over long-term operation due to changes in ambient temperature and material properties.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a wireless charging module for multiple lithium batteries, namely a wireless power receiver.

[0008] This wireless charging module integrates an energy receiving link and a signal detection and control link in its hardware architecture. The energy receiving link includes a receiving coil assembly and a rectification and voltage regulation unit, used to convert the energy of the spatial magnetic field into electrical energy and supply power to subsequent stages. To achieve high-precision closed-loop control, the wireless charging module integrates a battery management system unit, a local magnetic flux gain trace, a Hall sensor unit, and a main control processing unit.

[0009] In terms of specific circuit connections, the battery management system unit integrates an equalization resistor and an equalization switch for cell voltage balancing. A key improvement of this invention lies in utilizing a local magnetic flux gain trace connected in series between the equalization resistor and the equalization switch. This local magnetic flux gain trace is physically located within the sensing region of the Hall sensor unit, for example, extending spirally around the sensing center of the Hall sensor unit, thus forming a planar coil structure.

[0010] When the battery management system unit performs an equalization operation or closes the equalization switch in response to a master control command, the equalization current flows through the local flux gain trace. Due to the specific wiring pattern of this local flux gain trace, the current generates a local magnetic field with a concentrated vertical component at the sensing surface of the Hall sensor unit. The master control processing unit connects the Hall sensor unit and the battery management system unit, enabling coordinated control of the switching operation and signal acquisition, thereby achieving adaptive adjustment of the wireless charging process.

[0011] Furthermore, this wireless charging module employs parameter identification logic based on active perturbation. The main control processing unit establishes a magnetic field quiescent window to control the switching of the equalization switch in the absence of external transmitted magnetic field interference. By acquiring Hall voltage signals before and after the switch action and calculating the differential voltage, combined with the known equalization current value, the wireless charging module can calculate the measured magnetoelectric response sensitivity of the Hall sensor unit in real time. By comparing this measured value with the reference sensitivity under standard operating conditions, a sensitivity deviation factor can be obtained. This factor can characterize and compensate for sensor measurement errors caused by factors such as ambient temperature drift and changes in the properties of magnetic shielding materials, thereby significantly improving the accuracy of background magnetic field measurement.

[0012] Based on this, the main control processing unit uses the corrected magnetic field data and rectified voltage data to infer the coil coupling coefficient between the receiving coil assembly and the transmitting end through a preset model. This coil coupling coefficient is directly related to the system's heat generation and heat dissipation characteristics. The main control processing unit internally stores the AC equivalent internal resistance characteristic curve of the receiving coil assembly and the module's equivalent heat transfer model. Based on the identified coupling coefficient, it dynamically maps the current coil equivalent AC internal resistance and the system's real-time equivalent thermal resistance. The wireless charging module then calculates the maximum allowable charging current boundary value under the current heat dissipation conditions to maintain the target control temperature, and uses this as the upper limit to clamp the actual charging current, achieving proactive safety management to prevent device overheating.

[0013] A second aspect of the present invention provides a method for wireless charging of multiple lithium batteries.

[0014] This wireless charging method is applied to the aforementioned wireless charging module. By performing physical field perturbation, signal calculation, and boundary control in stages, it achieves safe and efficient wireless power transmission.

[0015] The wireless charging method first performs an active magnetic field excitation step. The main control processing unit sends a command to the battery management system unit to control the equalization switch to close. At this time, the current path originally used for battery equalization is reused as a signal excitation source. The current flows through the local magnetic flux gain trace, generating a deterministic superimposed magnetic field at the Hall sensor unit.

[0016] The sensitivity self-calibration step is then performed. The system synchronously acquires Hall voltage signals in both the on and off states of the equalization switch. Common-mode interference is eliminated using the voltage difference between the two signals, and combined with the current equalization current value, the measured magnetoelectric response sensitivity under the current operating condition is calculated. By comparing the measured sensitivity with the pre-stored reference sensitivity, a sensitivity deviation factor is determined. This factor is used to normalize and correct subsequent background magnetic field measurements, eliminating measurement errors caused by sensor temperature drift and aging.

[0017] Next, the system performs a multi-physical parameter derivation step. Using the corrected background magnetic field strength and rectified output voltage, the system calculates the coil coupling coefficient, characterizing the coil alignment state. Based on this coupling coefficient, the system consults preset characteristic curves and heat transfer models to determine the equivalent AC internal resistance of the receiving coil and the real-time equivalent thermal resistance of the entire module under the current state. This process transforms thermal parameters, which are difficult to measure directly, into calculable electromagnetic parameters.

[0018] Finally, the dynamic boundary control step is executed. Based on the difference between the set target control temperature and the current ambient temperature, combined with the previously determined real-time equivalent thermal resistance and coil equivalent AC internal resistance, the system calculates the maximum charging current boundary value. This boundary value represents the upper limit of the current that the system can withstand without overheating under the current alignment position and heat dissipation environment. The main control processing unit limits the actual charging current within this boundary value range and sends adjustment commands to the transmitter as needed to ensure that the charging process always remains within the thermally safe range.

[0019] This invention provides a multi-cell lithium battery wireless charging module and a wireless charging method. It has the following beneficial effects:

[0020] 1. This invention achieves high reuse of hardware functions by connecting the local magnetic flux gain trace in series in the equalization circuit of the battery management system and making it extend in a spiral shape around the Hall sensor unit in physical layout. By using the battery equalization current as a deterministic excitation source, a local magnetic field with a concentrated vertical component can be applied to the Hall sensor unit without adding an independent drive circuit or an additional calibration coil. This enables the sensor to perform online self-testing within a limited PCB space, reducing hardware costs and increasing the integration density of the module.

[0021] 2. This invention adopts a sensitivity self-calibration mechanism based on active perturbation. By collecting the differential voltage signal before and after the equalization switch tube operates, the sensitivity deviation factor is calculated, and the background magnetic field measurement value is corrected in real time. This eliminates the measurement error of the Hall element caused by changes in ambient temperature and drift of magnetic shielding material characteristics, ensuring that the wireless charging module can obtain high-precision magnetic field data under different temperature conditions and aging cycles. This solves the technical problem of long-term operation accuracy decline of traditional open-loop detection methods.

[0022] 3. This invention establishes a dynamic thermal management model based on the coil coupling coefficient, which can map the equivalent AC internal resistance of the receiving coil and the equivalent thermal resistance of the system in real time according to the identified coupling state, and then deduce the maximum charging current boundary value. Compared with the existing technology that only relies on a fixed temperature threshold for intermittent protection, this invention can actively limit the upper limit of the current according to the current alignment deviation and heat dissipation capacity, clamping the actual charging current within the thermal safety boundary, thereby preventing the equipment from overheating while realizing continuous and efficient power transmission. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of a multi-cell lithium battery wireless charging module according to the present invention;

[0024] Figure 2 This is a schematic diagram of the overall process of a wireless charging method for multiple lithium batteries according to the present invention.

[0025] Figure 3 This is a block diagram of the thermal resistance mapping and maximum charging current calculation based on the coil coupling coefficient in this invention.

[0026] Figure 4 This is a comparison and verification curve showing the change of the algorithm-estimated value of the coil coupling coefficient and the instrument-measured value with the lateral offset in an embodiment of the present invention.

[0027] Figure 5 This is a graph showing the change in charging current versus equipment temperature rise when overheat protection is performed using only a fixed temperature threshold in existing technologies.

[0028] Figure 6 The graph shows the relationship between charging current and device temperature rise under the maximum charging current boundary value control strategy in this embodiment of the invention.

[0029] Among them, 10 is the wireless power transmitter; 11 is the transmission control unit; 12 is the transmission coil assembly; 20 is the wireless power receiver; 21 is the receiver coil assembly; 22 is the rectifier and voltage regulator unit; 23 is the main control processing unit; 24 is the battery management system unit; 25 is the battery pack; 26 is the Hall sensor unit; and 27 is the local magnetic flux gain trace. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] See attached document Figure 1 The wireless charging system provided by this invention includes a wireless power transmitter 10 and a wireless power receiver 20. The wireless power transmitter 10 transmits electrical energy to the wireless power receiver 20 through an alternating magnetic field, and an energy transmission channel is established between the two through electromagnetic induction.

[0032] The wireless power transmitter 10 includes a transmission control unit 11 and a transmission coil assembly 12. The transmission control unit 11 is configured to adjust the drive frequency or duty cycle in the transmission coil assembly 12 to change the transmission power and to demodulate the signal fed back from the wireless power receiver 20.

[0033] The wireless power receiver 20 includes a receiving coil assembly 21, a rectifier and voltage regulator unit 22, a main control processing unit 23, a battery management system unit 24, a battery pack 25, a Hall effect sensor unit 26, and a local magnetic flux gain trace 27. The receiving coil assembly 21 is electrically connected to the rectifier and voltage regulator unit 22 to convert the induced alternating magnetic field into direct current (DC) power. The output of the rectifier and voltage regulator unit 22 is connected to the battery management system unit 24 to ultimately charge the battery pack 25.

[0034] The main control processing unit 23 serves as the core computing and control center, establishing signal connections with the rectifier and voltage regulator unit 22, the battery management system unit 24, and the Hall sensor unit 26. The main control processing unit 23 incorporates an analog-to-digital converter and a pulse width modulation controller, used to acquire system voltage and current parameters and output control signals.

[0035] The battery management system unit 24 is connected between the rectifier and voltage regulator unit 22 and the battery pack 25. The battery management system unit 24 integrates an equalizing resistor and an equalizing switch. The control terminal of the equalizing switch is connected to the general-purpose input / output port of the main control processing unit 23, enabling the main control processing unit 23 to independently control the conduction and cutoff of the equalizing switch, thereby controlling the connection or disconnection of the equalizing resistor to the battery circuit.

[0036] The Hall sensor unit 26 is disposed on the printed circuit board of the wireless power receiver 20, and is located in or near the projection area of ​​the receiving coil assembly 21. The Hall sensor unit 26 is used to detect the ambient magnetic field strength and output the corresponding analog voltage signal to the main control processing unit 23. The local flux gain trace 27 is a section of conductive copper foil on the printed circuit board that connects the equalization resistor and the equalization switch. The local flux gain trace 27 extends physically below or around the sensing area of ​​the Hall sensor unit 26, so that the current flowing through the equalization resistor can generate a local magnetic field excitation for the Hall sensor unit 26.

[0037] See attached document Figure 2 The present invention also provides a wireless charging method, which is executed by the main control processing unit 23, for realizing adaptive charging control under sealed and limited heat dissipation conditions.

[0038] In step S1, the system performs a power-on handshake and initialization. When the wireless power receiver 20 enters the effective charging range of the wireless power transmitter 10, the receiving coil assembly 21 senses a voltage and wakes up the main control processing unit 23. The main control processing unit 23 establishes a communication link with the transmitting control unit 11 and reads the current voltage value of the battery pack 25. The main control processing unit 23 determines whether the voltage of the battery pack 25 is higher than a preset minimum calibration threshold; if the condition is met, the calibration process begins.

[0039] In step S2, a magnetic field quiescent window is established. The main control processing unit 23 sends a lock request command to the transmission control unit 11 via load modulation or in-band communication. In response to the command, the transmission control unit 11 locks the operating frequency and duty cycle of the transmission coil assembly 12 within a preset time window and suspends the transmission of frequency shift keying data, so that the background magnetic field generated by the wireless power transmitter 10 remains constant.

[0040] In step S3, active perturbation sampling is performed. During the magnetic field quiescent window, the main control processing unit 23 sends a control signal to the battery management system unit 24 to control the equalization switch to close. At this time, the equalization current flows through the local magnetic flux gain trace 27, generating a superimposed magnetic field at the Hall sensor unit 26. The main control processing unit 23 acquires the voltage signal output by the Hall sensor unit 26 when the equalization switch is closed and open, respectively, and calculates the differential voltage value.

[0041] In step S4, multiphysics parameter calculations are performed. The main control processing unit 23 calculates the current magnetoelectric response sensitivity based on the differential voltage value obtained in step S3 and the known equalization current value. Subsequently, the main control processing unit 23, in conjunction with the rectified voltage output from the rectifier and voltage regulator unit 22, uses a preset algorithm model to calculate the coil coupling coefficient of the receiving coil assembly 21 relative to the transmitting coil assembly 12, and determines the real-time equivalent thermal resistance of the system accordingly.

[0042] In step S5, closed-loop power regulation is performed. The main control processing unit 23 calculates the maximum allowable charging current under the current operating conditions based on the calculated real-time equivalent thermal resistance and the preset temperature upper limit. The main control processing unit 23 limits the charging current requested by the battery management system unit 24 to the maximum charging current range and sends a power adjustment command to the transmitter control unit 11, completing the closed-loop control of the charging process. When the magnetic field silence window ends, the main control processing unit 23 notifies the transmitter control unit 11 to resume the normal dynamic adjustment mode.

[0043] The circuit topology of the wireless power receiver 20 mainly consists of a resonant network, an energy conversion circuit, a battery equalization control circuit, and a magnetic field detection interface circuit.

[0044] The receiving coil assembly 21 includes a receiving coil. and series resonant capacitor Receiving coil It is made of Litz wire and is used to induce alternating magnetic fields and generate high-frequency alternating current. Series resonant capacitor. The capacitance value is matched according to the driving frequency of the transmitter, so that the circuit operates in a resonant state to reduce impedance. The output of the resonant network is connected to the rectifier and voltage regulator unit 22. For the specific topology of the full-bridge synchronous rectifier circuit and the subsequent DC-DC buck circuit inside the rectifier and voltage regulator unit 22, those skilled in the art can refer to the typical application circuit of a general wireless charging receiver chip, which is well known in the art and will not be described in detail here.

[0045] The battery management system unit 24 adopts an architecture where the analog front-end and the main control processing unit 23 are separate or integrated. This is based on the first cell in a multi-cell series-connected battery pack 25. For example, its corresponding battery balancing control circuit includes balancing resistors. and equalization switching transistor Equalizing resistors One end is connected to the first battery cell The positive terminal node. Equalizing resistance. The other end is connected to the input of the local flux gain trace 27. The output of the local flux gain trace 27 is connected to the equalization switch. The drain of the equalization switch. The source is connected to the first cell. The negative terminal node is the system's analog ground.

[0046] Equalization switch An N-channel metal-oxide-semiconductor field-effect transistor is used, with its gate connected to the general-purpose input / output pin of the main control processing unit 23 via a current-limiting resistor. To prevent false turn-on during switching, a pull-down resistor is connected in parallel between the gate and source. The main control processing unit 23 directly controls the equalization switching transistor by outputting high and low level signals. It operates in the saturation conduction or cutoff region, without relying on the overvoltage automatic triggering logic inside the battery management chip. When the equalization switch... When turned on, the first cell The voltage across the equalizing resistor Local flux gain trace 27 and equalization switch tube A balanced current with a definite amplitude is formed in the series circuit. .

[0047] The Hall sensor unit 26 uses a linear Hall sensor chip. Its power supply pin is connected to the system's regulated power rail (e.g., 3.3V), and its ground pin is connected to analog ground. The signal output pin of the Hall sensor unit 26 is connected to the analog-to-digital converter input channel of the main control processing unit 23. A filter capacitor is connected in parallel between this output pin and ground. The cutoff frequency of this filter capacitor is set higher than the driving frequency of the wireless power transmitter 10 to preserve the fundamental characteristics of the background magnetic field while filtering out higher-frequency switching noise interference. The analog voltage output by the linear Hall sensor... It is linearly proportional to the perpendicular component of the magnetic flux density passing through its induction surface. This is due to the equalization current. The magnetic field vector generated by the current flowing through the local magnetic flux gain trace 27 is superimposed on the background magnetic field and is captured by the linear Hall sensor and converted into a voltage signal and transmitted to the main control processing unit 23.

[0048] To address the problem that the weak battery equalization current makes it difficult to capture the magnetic field generated by conventional layouts, this invention features a specific design for the trace topology of the printed circuit board at the physical level.

[0049] The printed circuit board of the wireless power receiver 20 carries a Hall sensor unit 26 and a local flux gain trace 27. The local flux gain trace 27 and the Hall sensor unit 26 maintain a preset distance in the vertical direction of the printed circuit board, and the two have an overlapping area in the horizontal projection plane. The wiring trajectory of the local flux gain trace 27 is configured to extend in a spiral or folded shape around the sensing center of the Hall sensor unit 26, thereby forming a closed or semi-closed planar coil structure around the Hall sensor unit 26.

[0050] This planar helical coil structure constitutes a miniature air-core inductor in a physical sense. According to Ampere's law, when the equalizing current... When the magnetic flux through the local flux gain trace 27 flows, a concentrated vertical component of magnetic induction intensity is generated along the central axis of the spiral. Since the sensing surface of the Hall sensor unit 26 is in close contact with this concentrated magnetic field region, even with equalization current... Even with a small amplitude (e.g., on the order of 50mA to 100mA), a distinguishable voltage response can be generated at the output of the Hall sensor unit 26.

[0051] The local magnetic flux gain trace 27 produces the local magnetic flux density increment. With equalization current The relationship between them follows a specific geometric relationship derived from the Biot-Savart law. In a simplified model that neglects the influence of the printed circuit board dielectric permeability, this relationship is expressed as:

[0052] ;

[0053] in, Represents the vacuum permeability constant; This indicates the effective number of turns of the local flux gain trace 27 around the Hall sensing unit 26; This represents the equivalent average radius of a planar helical coil; This indicates the vertical distance between the center of the sensing element inside the Hall sensing unit 26 and the layer where the local magnetic flux gain trace 27 is located. This is the geometric attenuation factor for interlayer coupling.

[0054] By increasing the effective number of turns Or reduce the vertical distance This can improve the geometric gain coefficient. In actual PCB design, to maximize this gain, the linewidth of the local flux gain trace 27 is designed to meet the minimum current carrying capacity, thereby increasing the winding density per unit area. For the manufacturing process and interlayer alignment accuracy control of multilayer printed circuit boards, those skilled in the art can use conventional electronic design automation software and PCB manufacturing processes, which are well-known technologies in the field and will not be elaborated further here.

[0055] This structural design reuses the BMS equalization loop as a high-precision in-situ magnetic field generator. Due to geometric parameters , and Once the printed circuit board is manufactured, it becomes a fixed physical quantity that does not drift with temperature, humidity or time. Therefore, the ratio of the magnetic field to the current generated by the local magnetic flux gain trace 27 has extremely high stability, providing a reliable physical reference for subsequent elimination of sensor temperature drift.

[0056] In order to achieve high-precision extraction of weak equilibrium current magnetic fields in a strong background magnetic field environment, this invention constructs a dedicated communication protocol and transmission control logic in the time domain.

[0057] The main control processing unit 23 is configured to send a calibration request command to the wireless power transmitter 10 via the in-band communication mechanism of the wireless charging link. This calibration request command is encoded into a data packet of a specific format, such as a proprietary data packet conforming to the wireless charging standard protocol or a configuration packet with specific numerical definitions. The main control processing unit 23 drives the communication modulation circuit to perform amplitude shift keying (ASK) modulation on the voltage or current across the receiving coil assembly 21, transmitting the calibration request command to the wireless power transmitter 10. For the specific circuit implementation of ASK modulation and demodulation, those skilled in the art can refer to existing wireless charging communication standards; it is well-known in the field and will not be described further here.

[0058] Upon receiving and decoding the calibration request command, the wireless power transmitter 10 immediately suspends its internal power closed-loop control algorithm (PID Control Loop) and enters a state-locked mode. In state-locked mode, the wireless power transmitter 10 maintains a constant current drive frequency and duty cycle value for the full-bridge inverter circuit, and no longer adjusts the transmission power based on feedback signals. Simultaneously, the wireless power transmitter 10 is prohibited from sending any form of frequency shift keying (FSK) data packets or performing foreign object detection (FOD) frequency scanning during this period.

[0059] From the moment the wireless power transmitter 10 enters the state-locked mode, the system enters a state-locked mode for a duration of [duration missing]. The magnetic field silent window. During the time period, since the transmission parameters are constant and there is no superposition of modulation signals, the main background magnetic field generated by the transmitting coil assembly 12 is At the receiving end, it manifests as a steady-state AC magnetic field with a single frequency and a constant amplitude envelope. In this case, the main background magnetic field does not experience amplitude jumps caused by communication modulation or power adjustment, providing a stable electromagnetic background environment for signal sampling at the receiving end.

[0060] The main control processing unit 23 has a timer set inside for monitoring. The duration. The value of is set to the time length required to satisfy at least one complete active perturbation sampling sequence, typically in the tens of milliseconds range (e.g., 20ms to 50ms). When the timer overflows or the calibration sequence is completed, the main control processing unit 23 sends a recovery command or a normal control error packet to the wireless power transmitter 10, triggering the wireless power transmitter 10 to exit the state-locked mode and resume dynamic closed-loop regulation of the transmission power. Through this timing control, the system transforms the difficult-to-filter dynamic background noise into a static background quantity that is easily eliminated through differential operations.

[0061] After establishing the magnetic field quiescent window, the main control processing unit 23 takes over the control of the equalization switch transistor in the battery management system unit 24. It achieves microsecond-level real-time control and executes high-frequency differential sampling sequences.

[0062] The main control processing unit 23 first executes the reference sampling step. The main control processing unit 23 then controls the equalization switching transistor. When the circuit is in the off state, no current flows through the local flux gain trace 27. The main control processing unit 23 waits for a preset circuit stabilization time. After the parasitic capacitance has balanced, it triggers the analog-to-digital converter to sample the output signal of the Hall sensor unit 26 to obtain the reference voltage sample value. It should be noted that, since the background magnetic field is an AC signal, the reference voltage sampling value here... It is the DC component (average value) extracted by integrating and averaging the high-speed sampling sequence, or the DC level obtained after low-pass filtering in hardware. It mainly reflects the static zero-point voltage and low-frequency drift of the Hall sensor unit 26. In addition, the main control processing unit 23 also simultaneously calculates the AC amplitude characteristics (such as RMS or peak value) of the sampling sequence, denoted as the background magnetic field induced voltage. This is used for subsequent coupling state calculations.

[0063] Subsequently, the main control processing unit 23 performs the disturbance sampling step. The main control processing unit 23 sends data to the equalization switch transistor... A high-level signal is sent to the gate of the battery to control it to enter the conduction state. At this time, the battery voltage is applied to the equalization circuit, generating an equalization current. The magnetic flux flows through the local flux gain trace 27, establishing a superimposed magnetic field at the Hall sensor unit 26. The main control processing unit 23 performs a delay operation with a long delay time. The LR time constant is set to be greater than that of the equalization circuit to ensure that the current and magnetic field reach a steady state. After the delay ends, the main control processing unit 23 triggers the analog-to-digital converter again to sample and obtain the disturbance voltage sample value. .

[0064] To eliminate random quantization noise and improve the signal-to-noise ratio, the main control processing unit 23 continuously repeats the process within a single magnetic field quiescent window. The above-mentioned cycle sequence of disconnection, sampling, closure, and sampling is repeated. The main control processing unit 23 performs digital averaging filtering on the multiple sets of acquired data and calculates the current measured magnetoelectric response sensitivity according to the following formula. :

[0065] ;

[0066] ;

[0067] in, This represents the equalization current flowing through the local flux gain trace 27, in amperes (A). : This indicates the current battery cell voltage value collected by the main control processing unit 23, in volts (V). This indicates the equalization resistance, with the unit being ohms (Ω). This represents the drain-source on-resistance of the equalization switch in saturation conduction mode, expressed in ohms (Ω). This represents the calculated measured magnetoelectric response sensitivity under the current operating conditions, expressed in volts per ampere (V / A). Indicates the number of sampling cycles, which is a positive integer; Indicates the first The disturbance voltage sampled during the equalization switch closing in the next cycle is in volts (V). Indicates the first The reference voltage sample value when the equalization switch is turned off in the next cycle is in volts (V). Indicates to From 1 to Summing up all the terms.

[0068] Through this differential calculation method, although the background magnetic field is high-frequency alternating, its average value over a complete signal cycle is zero (or a fixed constant). Because... and The sampling and processing methods are consistent (both extract the DC average component), and both are within the magnetic field silence window. The AC background magnetic field components and temperature drift components of both are considered equal and cancel each other out during the subtraction operation. Therefore, This only reflects the system's response to the magnetic field generated by the local equalization current, thus achieving in-situ calibration of the actual sensitivity of the Hall sensor unit 26. The specific code implementation of the analog-to-digital converter's sampling frequency configuration and digital filtering algorithm can be carried out by those skilled in the art according to conventional microprocessor programming manuals; these are well-known technologies in the field and will not be elaborated upon here.

[0069] This invention reverse-engineers the coupling state of a macroscopic wireless charging system by comparing the response characteristics of local microscopic magnetic fields.

[0070] The reference sensitivity is pre-stored in the non-volatile memory inside the main control processing unit 23. The reference sensitivity The value of the unit current magnetic field response of the local magnetic flux gain trace 27 is obtained through calibration testing under standard laboratory conditions, with the wireless power receiver 20 at room temperature (e.g., 25°C) and the receiving coil assembly 21 and the transmitting coil assembly 12 in perfect alignment (center to center).

[0071] The main control processing unit 23 calls the measured magnetoelectric response sensitivity calculated in the aforementioned steps. and compared it with the reference sensitivity Compare and calculate the sensitivity deviation factor. The sensitivity deviation factor The overall sensitivity drift of the Hall sensor unit 26 under current operating conditions is characterized. This drift is caused by the thermal drift due to changes in ambient temperature and the combined effect of the magnetic shielding material (such as a ferrite sheet) on the magnetic field line distribution due to coil position offset. Deviation factor The calculation formula is defined as follows:

[0072] ;

[0073] in, This indicates the current measured magnetoelectric response sensitivity, expressed in volts per ampere (V / A). This indicates the pre-stored reference sensitivity, expressed in volts per ampere (V / A).

[0074] After obtaining the deviation factor, the main control processing unit 23 uses this factor to correct the background reference voltage collected during the magnetic field silence window, in order to restore the true external emitted magnetic field strength. The main control processing unit 23 reads the background magnetic field induced voltage obtained in the disconnected state in the aforementioned steps. This voltage value represents the original AC response excited on the Hall sensing unit 26 by the background magnetic field generated by the wireless power transmitter 10.

[0075] The main control processing unit 23, in conjunction with the rectifier and voltage regulator unit 22, outputs the rectified voltage DC value. The current coil coupling coefficient is calculated using a multivariable mapping function. The calculation process is based on the physical characteristics of wireless power transmission: under the same transmit power, the rectified voltage at the receiver mainly depends on the turns ratio and the coupling coefficient, while the leakage magnetic field strength exhibits a nonlinear trend as the coupling coefficient decreases (i.e., the offset increases). The main control processing unit 23 uses the corrected magnetic field characteristics and voltage characteristics as input vectors and substitutes them into the preset coupling coefficient estimation model.

[0076] The coupling coefficient estimation model is expressed as follows:

[0077] ;

[0078] ;

[0079] in, Indicates the sensitivity deviation factor; This represents the normalized external magnetic field characterization value after sensitivity correction and zero-point calibration, in volts (V), and its value is proportional to the actual magnetic induction intensity. This indicates the background magnetic field induced voltage (RMS or peak value PK) extracted by the main control processing unit 23 from the output signal of the Hall sensor unit 26 when the equalization switch is off within the magnetic field silence window. This value reflects the intensity of the background alternating magnetic field. This represents the estimated coil coupling coefficient between the receiving coil assembly 21 and the transmitting coil assembly 12, with a value ranging from 0 to 1. This indicates the DC value of the rectified voltage output by the rectifier and voltage regulator unit 22, in volts (V). This represents a pre-defined nonlinear mapping function or a two-dimensional lookup table. This functional relationship is constructed by fitting experimental data and describes the coupling state under different combinations of voltage and magnetic field strengths.

[0080] for The specific construction method can be achieved by those skilled in the art through multinomial regression analysis or data table creation on system data under different offset positions and load conditions during the R&D phase. This is a well-known technique in the field and will not be elaborated here. Through the above processing, the system can achieve quantitative evaluation of coil coupling quality using only existing BMS circuits and Hall elements without adding additional positioning sensors.

[0081] See attached document Figure 3 After obtaining the coupling coefficient that characterizes the degree of positional offset, this invention further establishes a position-based thermal and electrical coupling integrated physical constraint model to calculate the maximum safe charging current under the current heat dissipation conditions.

[0082] The main control processing unit 23 internally stores the AC equivalent internal resistance characteristic curve of the receiving coil assembly 21. The loss characteristics of the receiving coil assembly 21 under a high-frequency magnetic field are not constant; its equivalent AC internal resistance... It varies with the operating frequency and magnetic coupling state. When the coil coupling coefficient... When power is reduced, the wireless power transmitter 10 typically adjusts its drive parameters to maintain power transmission, leading to increased eddy current losses and proximity effect losses on the receiving coil assembly 21. The main control processing unit 23 calculates the coil coupling coefficient based on the aforementioned steps. The equivalent AC internal resistance under the current operating condition is determined by looking up a table or by interpolation. .

[0083] Meanwhile, the main control processing unit 23 determines the coil coupling coefficient based on the coil coupling coefficient. The equivalent heat transfer model of the reconstructed system is used. In a small, hermetically sealed electronic device, thermal resistance primarily depends on the heat conduction path from the heat source (coil and PCB) to the housing surface. When the receiving coil assembly 21 experiences alignment misalignment, its heat-generating center shifts away from the heat dissipation structure or closer to areas where heat dissipation is poor due to structural limitations. Therefore, the overall thermal resistance of the system is modeled as a function of the coupling coefficient. The main control processing unit 23 calculates the current real-time equivalent thermal resistance based on a preset linear or nonlinear thermal resistance model.

[0084] Based on the principle of thermal balance, in order to ensure that the temperature of key components inside the wireless power receiver 20 does not exceed the safety threshold, the total Joule heat loss generated by the system must be limited within the heat dissipation capacity. The main control processing unit 23, based on the current ambient temperature parameters and the set target temperature control upper limit, combined with the real-time equivalent thermal resistance and equivalent AC internal resistance, derives the maximum allowable charging current boundary value. .

[0085] This maximum charging current boundary value The calculation formula is expressed as follows:

[0086] ;

[0087] in, This represents the maximum boundary value of the charging current that the system is allowed to apply to the battery under the current coupling state and heat dissipation conditions, in amperes (A). This indicates the system's preset maximum allowable operating temperature or target control temperature (e.g., the surface temperature of the printed circuit board should not exceed 55°C), in degrees Celsius (°C). This indicates the current ambient temperature in degrees Celsius (°C). This value is acquired in real time by the main control processing unit 23 through the onboard thermistor, or a preset safety default value (such as 35°C) can be used when there is no auxiliary temperature measuring element. This represents the coil coupling coefficient estimated by the aforementioned steps; This represents the real-time equivalent thermal resistance of the system from the heat source to the external environment, as mapped based on the current coupling coefficient, and is expressed in degrees Celsius per watt (°C / W). This represents the equivalent AC internal resistance of the receiving coil assembly 21 and the rectifier circuit, as mapped according to the current coupling coefficient, in ohms (Ω).

[0088] The main control processing unit 23 will calculate the results. This serves as a dynamic clamping threshold. In subsequent charging control loops, regardless of the current value requested by the battery management system unit 24 based on the battery charging curve (CC / CV curve), the main control processing unit 23 actually executes the charging current setpoint. None higher than this Value. Through this calculation mechanism, the system operates without any alignment offset ( When the current is relatively large and the heat dissipation is good, high-current fast charging is allowed; however, when offset occurs ( When the thermal resistance increases and coil losses increase due to a smaller current limit, the current limit is automatically reduced, thus solving the risk of overheating of the device caused by blindly pursuing charging speed at the physical level.

[0089] After determining the current boundary that takes thermal safety into account, the main control processing unit 23 executes dual-loop or multi-loop feedback control to precisely regulate the electrical energy transmitted to the battery pack 25.

[0090] The main control processing unit 23 first executes the current command arbitration logic. The main control processing unit 23 obtains the standard charging current requested by the current battery charging curve from the battery management system unit 24. The standard charging current is typically determined by the constant current or constant voltage charging phase of the battery. Subsequently, the main control processing unit 23 compares the requested value with the maximum charging current boundary value. The two values ​​are compared, and the smaller value is selected as the final target current for execution. .

[0091] The mathematical expression of this arbitration logic is as follows:

[0092] ;

[0093] in, This represents the operational logic of the function that takes the minimum value, that is, the system in... and The smaller value between the two will be automatically selected as the basis for execution.

[0094] After determining the target current, the system enters the closed-loop negative feedback regulation stage. The main control processing unit 23 obtains the actual charging current flowing to the battery pack 25 in real time through the sampling circuit. The main control processing unit 23 calculates the deviation between the target current and the actual charging current, and generates adjustment commands using a proportional-integral (PI) control algorithm or a proportional-integral-derivative (PID) control algorithm.

[0095] In the wireless power transmission architecture, the regulation command is mainly manifested as a Control Error Packet (CEP) sent to the wireless power transmitter 10. The main control processing unit 23 calculates the control error value based on the current deviation. This value quantifies the difference between the current received power and the target power.

[0096] Control error value The calculation formula is defined as follows:

[0097] ;

[0098] in, This indicates the target current for execution determined after thermal boundary arbitration, in amperes (A). This indicates the standard charging current requested by the battery management system based on the lithium battery charging characteristic curve, in amperes (A). This represents the maximum charging current boundary value calculated based on the dynamic thermal resistance model, in amperes (A). This represents the actual charging current collected in real time by the current sensor, and the unit is ampere (A). This represents the calculated control error value, which will be encoded and sent to the transmitter via the communication link. This represents the proportional control gain coefficient, used to set the instantaneous response speed of the system to errors; This represents the integral control gain coefficient, used to eliminate steady-state error; The definite integral operator symbol indicates the time from the start of the control process. Up to the current sampling time The integration operation over the time interval is used to calculate the historical cumulative amount of current error; It represents the time differential variable, that is, the tiny time increment unit in integral operations.

[0099] The main control processing unit 23 will calculate the results. The signal is encoded according to a preset communication protocol and transmitted to the wireless power transmitter 10 via an ASK modulation circuit. The wireless power transmitter 10 receives the signal... Then, based on the sign and magnitude of this value, the switching frequency or duty cycle of the inverter bridge is adjusted accordingly. When When the value is positive, it indicates that the actual current is too low, and the wireless power transmitter 10 adjusts the drive parameters to increase the transmission power; conversely, when... When the value is negative, the wireless power transmitter 10 reduces the transmission power.

[0100] In addition, when battery pack 25 enters the constant voltage charging stage, The degradation will naturally decrease exponentially as the battery voltage increases. At this point, the main control processing unit 23 continues to execute the aforementioned arbitration and feedback logic. If the degradation... Less than The system will then automatically and smoothly transition from thermally limited mode to standard constant voltage charging mode. The specific software implementation of PI parameter tuning and communication coding can be carried out by those skilled in the art using conventional automatic control theory and standard communication library functions; these are well-known technologies in the field and will not be elaborated upon here.

[0101] Through the aforementioned closed-loop regulation mechanism, the system not only achieves precise control of the battery charging process, but more importantly, it forcibly applies the calculated physical field boundary conditions (thermal boundary) to the control loop. This ensures that, even under conditions where coupling offset leads to increased thermal resistance, the actual charging power is strictly limited. Within the defined safety envelope, the device is protected from damage due to localized overheating.

[0102] Specific application examples:

[0103] In one specific application embodiment, the wireless power receiver is configured as a smartwatch, as shown in the attached diagram. Figure 5 and attached Figure 6 At the start of the timeline (charging time is 0), the ambient temperature and initial battery temperature are approximately 28°C, and the battery pack voltage is... The voltage is 3.8V, and the inductance of the receiving coil is 10.5μH. The system first uses the local flux gain trace 27 for parameter calibration. When the main control processing unit 23 controls the equalization switch to turn on, due to the equalization resistor... The drain-source on-resistance is 82Ω. Approximately 0.5Ω, the equalization current is calculated according to Ohm's law, i.e. The 46mA current generates a local magnetic field at the Hall sensor, which is collected by the main control processing unit 23. The Hall voltage difference within each sampling period, assuming a cumulative average difference of 2.9mV (0.0029V), is substituted into the sensitivity calculation formula. If the pre-stored ideal alignment reference sensitivity If the value is 0.066V / A, then calculate the deviation factor. The existence of this deviation factor means that due to the increase in temperature or the drift of the properties of the magnetic shielding material, the current Hall sensor’s response to the magnetic field has decreased by about 5%. If no compensation is made, the subsequent measurement of the emitted magnetic field will be biased.

[0104] Assuming the user places the watch randomly, causing a lateral offset of approximately 4.5mm between the centers of the receiving coil and the transmitting coil, the main control processing unit 23 reads the background magnetic field induced voltage. To eliminate the impact of the aforementioned decrease in sensor sensitivity, the system first normalizes and corrects the voltage using a deviation factor, i.e., it calculates... This allows for the reconstruction of the true magnetic field strength. Subsequently, the corrected magnetic field data is... Substitute the rectified voltage into the estimation model. Refer to the appendix. Figure 4 The horizontal axis represents the "lateral offset of the receiving coil (mm)," and the vertical axis represents the "coil coupling coefficient." Observing the data point at the horizontal axis X=4.5mm, the vertical axis Y value corresponding to the estimated value of the algorithm of this invention, shown by the solid line in the figure, is approximately 0.41. The vertical axis Y value corresponding to the instrument's measured value, shown by the circle in the figure, is also approximately 0.41, and the two highly overlap (the data point at X=4.5mm was selected for comparison because this position is in the range where the coupling coefficient changes significantly, and it is also the edge critical region where wireless charging can effectively operate; the fitting accuracy at this point best reflects the algorithm's ability to identify dynamic working conditions). This proves that by introducing a deviation factor... After correcting the measurement data, the algorithm can accurately calculate the coil coupling coefficient with an offset of 4.5mm. If this bias factor is ignored, the calculated coupling coefficient will deviate incorrectly from the true value.

[0105] exist Under these operating conditions, due to the low coupling, the coil eddy current loss increases and the heat dissipation thermal resistance rises. The system, by referring to a table, determines the "comprehensive thermal resistance factor" (i.e., ...) at this point. The thermal safety target temperature is approximately 156 Ω·℃ / W. The current ambient temperature is 44℃. The reading is 28℃. The main control processing unit 23 substitutes the value into the maximum charging current boundary formula for calculation, that is... This means that in order to keep the temperature around 44°C, the physical upper limit of the charging current is calculated to be 0.32A.

[0106] To verify the necessity of this calculation, refer to the appendix. Figure 5 The existing technology on display is in the same Performance under offset conditions. Due to the lack of the aforementioned limitations in current technology... Due to computational limitations and current command arbitration failure, the system blindly executes the 0.5A current request from the battery management system (high level indicated by the dashed line in the diagram). Since the actual current of 0.5A is much greater than the physical limit of 0.32A, according to... The excessive heat generated caused the temperature (solid line in the figure) to rise rapidly from an initial of approximately 33°C, reaching a peak of 62°C at about 4.5 minutes on the timeline. The text "Triggered 60°C overheat protection" and the downward arrow next to it in the figure visually explain the system behavior at this time: when the monitored temperature exceeds the hard-set 60°C safety threshold, the protection mechanism forcibly intervenes. The downward arrow indicates that the charging current (dashed line) immediately drops vertically from 0.5A to 0A. Subsequently, the device enters a sawtooth oscillation cycle of heating, protection, cooling, and restarting, making stable charging impossible.

[0107] In contrast, refer to the appendix Figure 6 The control curves of this invention shown under the same operating conditions verify the effectiveness of the closed-loop control. At this time, the battery requests... However, the main control processing unit 23 calculates according to the aforementioned formula. And substitute it into the arbitration formula Observation Appendix Figure 6 The dotted line in the graph was precisely clamped at the 0.32A level for the first 44 minutes, and the text labeling "Dynamic clamping threshold ≈ 0.32A" perfectly matches the calculated result. Under this control, observe the attached... Figure 6 The solid line in the graph represents a temperature that starts at 28℃ and rises smoothly in a logarithmic curve, gradually flattening out after about 15 minutes and eventually stabilizing between 44℃ and 45℃. This aligns with the preset parameters in the formula. (44℃) Highly compatible. After 44 minutes of charging, the battery voltage rises and enters the constant voltage zone, and the requested current naturally drops below 0.32A, at which point the system automatically exits the thermal limitation mode.

[0108] By comparing the appendix Figure 5 With appendix Figure 6 The measured data, combined with the attached Figure 4 The verification of the coupling coefficient fully demonstrates that the control strategy based on physical formulas proposed in this invention can effectively transform physical parameters under actual working conditions into precise electrical control boundaries, ensuring that the equipment does not overheat.

Claims

1. A wireless charging module for multi-cell lithium batteries, characterized in that, Configured as a wireless power receiver (20), including: A receiving coil assembly (21) is used to convert the magnetic field energy induced from the wireless power transmitter (10) into alternating current energy; A rectifier and voltage regulator unit (22) is used to receive the AC power and perform rectification to supply power to the battery management system unit (24); The battery management system unit (24) is connected to the rectifier and voltage regulator unit (22) and the battery pack (25), and integrates an equalization resistor and an equalization switch to control the generation of equalization current; Local flux gain trace (27) is used to apply a local magnetic field to the Hall sensing unit (26) when the equalization current flows through it; The Hall sensor unit (26) is used to detect the magnetic field signal and send the analog voltage signal to the main control processing unit (23). The main control processing unit (23) is connected to the battery management system unit (24) and the Hall sensor unit (26), and is used to control the operation of the equalization switch and adjust the charging current according to the analog voltage signal; The wiring trace of the local magnetic flux gain trace (27) on the printed circuit board extends in a spiral shape around the sensing center of the Hall sensing unit (26); The planar coil structure formed by the local flux gain trace (27) causes the equalization current flowing through the local flux gain trace (27) to generate a magnetic induction intensity with a vertical component concentration at the sensing surface of the Hall sensing unit (26).

2. The multi-cell lithium battery wireless charging module according to claim 1, characterized in that, The main control processing unit (23) establishes a magnetic field silence window by sending instructions to the transmission control unit (11) of the wireless power transmitter (10) and performs active perturbation sampling logic during the window. The main control processing unit (23) controls the equalization switch to be in the off state and collects the reference voltage sampling value output by the Hall sensor unit (26); The main control processing unit (23) controls the equalization switch to be in the on state and collects the disturbance voltage sampling value output by the Hall sensor unit (26); The main control processing unit (23) calculates the difference between the disturbance voltage sample value and the reference voltage sample value to obtain the differential voltage value.

3. A multi-cell lithium battery wireless charging module according to claim 2, characterized in that, The main control processing unit (23) calculates the measured magnetoelectric response sensitivity based on the ratio of the differential voltage value to the equalization current; The main control processing unit (23) obtains the current voltage value of a single cell in the battery pack (25), and calculates the value of the equalization current based on the current voltage value, the resistance value of the equalization resistor and the on-resistance of the equalization switch.

4. A multi-cell lithium battery wireless charging module according to claim 3, characterized in that, The main control processing unit (23) stores a reference sensitivity, which is the unit current magnetic field response value measured under standard alignment and room temperature conditions. The main control processing unit (23) calculates the quotient of the measured magnetoelectric response sensitivity and the reference sensitivity to obtain the sensitivity deviation factor; The sensitivity deviation factor is used to characterize the change in the response capability of the Hall sensing unit (26) due to changes in ambient temperature and drift of the magnetic shielding material properties.

5. A multi-cell lithium battery wireless charging module according to claim 4, characterized in that, The main control processing unit (23) uses the sensitivity deviation factor to correct the reference voltage sampling value and obtain the normalized external magnetic field characterization value; The main control processing unit (23) obtains the DC value of the rectified voltage output by the rectifier and voltage regulator unit (22); The main control processing unit (23) substitutes the normalized external magnetic field characterization value and the rectified DC voltage value into the preset coupling coefficient estimation model, and calculates the coil coupling coefficient of the receiving coil assembly (21) relative to the transmitting coil assembly (12) in the wireless power transmitting terminal (10) through the mapping function relationship.

6. A multi-cell lithium battery wireless charging module according to claim 5, characterized in that, The main control processing unit (23) internally stores the AC equivalent internal resistance characteristic curve of the receiving coil assembly (21) and the system equivalent heat transfer model; The main control processing unit (23) determines the equivalent AC internal resistance of the receiving coil assembly (21) under the current operating condition based on the coil coupling coefficient; The main control processing unit (23) obtains the real-time equivalent thermal resistance of the wireless charging module from the heat source to the external environment based on the coil coupling coefficient mapping.

7. A multi-cell lithium battery wireless charging module according to claim 6, characterized in that, The main control processing unit (23) sets the target control temperature and obtains the current ambient temperature; The main control processing unit (23) calculates the maximum charging current boundary value, and the calculation logic of the maximum charging current boundary value is as follows: Calculate the difference between the target control temperature and the current ambient temperature, divide the difference by the product of the real-time equivalent thermal resistance and the equivalent AC internal resistance of the receiving coil assembly (21), and perform a square root operation on the resulting quotient. The main control processing unit (23) sets the maximum charging current boundary value as the upper limit of the current allowed to be applied to the battery pack (25) under the current heat dissipation conditions.

8. A multi-cell lithium battery wireless charging module according to claim 7, characterized in that, The main control processing unit (23) executes the current command arbitration logic, specifically as follows: The main control processing unit (23) obtains the standard charging current request value from the battery management system unit (24); The main control processing unit (23) compares the standard charging current request value with the maximum charging current boundary value, and selects the smaller value between the standard charging current request value and the maximum charging current boundary value as the execution target current; The main control processing unit (23) generates an adjustment command based on the deviation between the target current and the actual charging current, and sends it to the transmission control unit (11) for closed-loop adjustment of the transmission power of the transmission coil assembly (12).

9. A method for wireless charging of multiple lithium batteries, characterized in that, The application of a multi-cell lithium battery wireless charging module according to any one of claims 1-8 includes the following steps: The main control processing unit (23) sends a control signal to the battery management system unit (24) to close the equalization switch tube, so that the equalization current flows through the local magnetic flux gain trace (27) and generates a superimposed magnetic field at the Hall sensing unit (26); The main control processing unit (23) collects the voltage signal of the Hall sensor unit (26) in the on and off states of the equalization switch tube, and obtains the measured magnetoelectric response sensitivity by calculating the voltage difference and the equalization current value. The main control processing unit (23) determines the sensitivity deviation factor based on the ratio of the measured magnetoelectric response sensitivity to the pre-stored reference sensitivity, and uses the sensitivity deviation factor to correct the background magnetic field measurement value. The main control processing unit (23) combines the corrected background magnetic field measurement value and the rectified voltage to derive the coil coupling coefficient, and determines the real-time equivalent thermal resistance and equivalent AC internal resistance based on the coil coupling coefficient; The main control processing unit (23) calculates the maximum charging current boundary value based on the target control temperature, ambient temperature, the real-time equivalent thermal resistance and the equivalent AC internal resistance, and limits the actual charging current within the range of the maximum charging current boundary value.

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