Small-sized wireless power supply system based on class-e power amplifier and control method

Abstract

The application provides a small wireless power supply system based on a class-E power amplifier and a control method, which comprises a transmitting end and a receiving end, the transmitting end comprises a power supply, a microcontroller, a current detection amplifier, an output adjustable DC-DC module and a class-E power amplifier module; the receiving end comprises an input resonant circuit, a full-wave rectifier bridge circuit, a DC-DC receiving module and a load which are connected in sequence. The application adopts a class-E power amplifier structure, compared with a traditional inverter and other class power amplifier structures, the circuit complexity is reduced, and the system efficiency is improved. In addition, the magnetic coupling resonant technology is adopted, the energy transmission efficiency is improved under the condition of weak coupling of the coil, and the energy transmission distance is improved compared with the inductive power transmission mode; an open-loop control strategy is adopted, an additional receiving end structure is not needed, the structure is simple, the reaction time is adjustable and the like, and the energy transmission efficiency and the robustness of the system are further improved.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and in particular to the design and control method of a small magnetically coupled resonant wireless power supply system based on a Class E power amplifier. Background Technology

[0002] Wireless power transfer technology is a method of energy transfer using electromagnetic fields, solving the inconvenience and safety issues associated with traditional power transmission using wires. Among the four proposed wireless power transfer methods, magnetically coupled resonant wireless power transfer technology utilizes coupled resonance for efficient energy transfer and is widely used in various fields. Especially in the field of brain-computer interfaces (BCIs), wireless power transfer technology frees implant recipients from the constraints of traditional BCI cables, avoiding the limitations on movement and safety hazards associated with connecting cables. Simultaneously, the size and weight of BCI systems are becoming increasingly miniaturized with the development of wireless power supply technology, greatly promoting the development of this field.

[0003] As an important component of wireless power transmission systems, power amplifiers can obtain energy from DC power supplies to amplify input signals. Among the current categories of power amplifiers, the zero-voltage switching Class E power amplifier is considered to be the most efficient power amplifier because its transistor voltage and current waveforms are interleaved in time, resulting in almost zero switching losses.

[0004] With the miniaturization and increased implantation depth of fully implantable brain-computer interface (BCI) systems, coil size is also shrinking. Currently, wireless power supply systems for fully implantable BCIs still employ large, fixed devices, such as cage-type and helmet-type systems, which suffer from significant system losses and low energy transmission efficiency. Therefore, there is a need to design a small wireless power supply system and control method based on a Class E power amplifier suitable for fully implantable BCIs. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a small wireless power supply system and control method based on a Class E power amplifier.

[0006] To achieve the above objectives, the present invention provides a small wireless power supply system based on a Class E power amplifier, characterized in that it includes a transmitter and a receiver connected in sequence.

[0007] The transmitting end includes a power supply, a microcontroller, a current-sensing amplifier, an adjustable DC-DC module, and a Class E power amplifier module. The power supply is connected to the microcontroller and the Class E power amplifier module. The microcontroller is connected to the current-sensing amplifier, which collects the current and voltage data of the transmitting end through the current-sensing amplifier, uses the calculated output power data as the basis for judging the operating status of the system circuit, and adjusts the output voltage of the transmitting end. The output power of the transmitting end is compared with the set power level. One end of the Class E power amplifier module is connected to the current-sensing amplifier, and the other end is coupled to the receiving end.

[0008] The receiving end includes an input resonant circuit, a full-wave rectifier bridge circuit, a DC-DC receiving module, and a load connected in sequence. The input resonant circuit receives the magnetic energy output from the Class E power amplifier module, converts it into AC power, and outputs it to the full-wave rectifier bridge circuit. It also supplies power to the load through the DC-DC receiving module.

[0009] Preferably, the adjustable DC-DC module is connected to a microcontroller at one end and a current-sensing amplifier at the other end. It includes a digital-to-analog converter (DAC) and a DC-DC module connected in sequence. The microcontroller controls the output signal of the DC-DC module by adjusting the DAC. The DAC includes at least three resistors, and the range and accuracy of the final output voltage are determined by controlling the value of each resistor. The formulas for calculating the output voltage of the DC-DC module and the current in each branch are as follows:

[0010]

[0011] Where I1, I2, and I3 are the magnitudes of the currents flowing through R1, R2, and R3, respectively; V out V is the output voltage of the DC-DC module. DAC V is the output voltage of the digital-to-analog converter. FB This refers to the voltage at the FB pin of the DC-DC module.

[0012] Preferably, the input resonant circuit includes a receiving coil L2 and an impedance matching network. The impedance matching network is an L-shaped structure connected to both ends of the receiving coil L2, used to adjust the resonant frequency and convert the load value at the receiving end into an equivalent load value that maximizes efficiency. The formula for calculating the equivalent load value that maximizes efficiency is as follows:

[0013]

[0014] Among them, R opt The equivalent load value is used to maximize efficiency; ω is the resonant angular frequency of the wireless power supply system; r1 is the internal resistance of the transmitting coil L1; r2 is the internal resistance of the receiving coil L2; L m This is mutual inductance between the coils.

[0015] Preferably, the Class E power amplifier module includes a transistor Q1, a transistor driver chip, a choke inductor L, and an output resonant circuit; one end of the transistor driver chip is connected to the power supply, and the other end is connected to the gate and source of the transistor Q1, and the drain and source of the transistor Q1 are connected to the output resonant circuit; the choke inductor L is connected between the input terminal of the output resonant circuit and the output terminal of the current sensing amplifier; the output terminal of the output resonant circuit is coupled to the input resonant circuit in the receiver.

[0016] Preferably, the maximum drain-source voltage of transistor Q1 is greater than or equal to 100V, the signal waveform generated by the transistor driver chip is a square wave with a frequency of 13.56MHz; the choke inductor L is a surface-mount power inductor greater than or equal to 68uH; the output resonant circuit includes an output resonant capacitor and a transmitting coil L1 connected in sequence to generate 13.56MHz AC power; the Class E power amplifier module converts the acquired DC power into AC power, and then converts the AC power into magnetic energy through the transmitting coil L1 for outward transmission; the minimum choke inductance value of the choke inductor L is calculated using the following formula:

[0017]

[0018] Among them, L fmin R is the minimum choke inductance; R is the equivalent load of the output circuit; f is the circuit operating frequency.

[0019] Preferably, the resonant frequencies of both the output resonant circuit and the input resonant circuit are 13.56MHz.

[0020] Preferably, the power level is determined based on the system's operating status. The power level status includes a low-power state when there is no load, a normal operating state, and a shutdown state due to excessive power consumption.

[0021] Preferably, the power supply includes a first DC-DC power supply, a DC power supply, and a second DC-DC power supply connected in sequence; the first DC-DC power supply is connected to the microcontroller to power the microcontroller; the second DC-DC power supply is connected to the transistor driver chip in the module of the Class E power amplifier to power the transistor driver chip.

[0022] Preferably, the current sensing amplifier is an INA190; the microcontroller is an nRF52832; and the full-wave rectifier bridge circuit includes at least four unidirectional conducting elements connected end-to-end, wherein the unidirectional conducting elements are Schottky diodes.

[0023] This invention also provides a control method for a small wireless power supply system based on a Class E power amplifier, the control method comprising the following steps:

[0024] Step 1: Set the normal operating power threshold and over-power threshold for the transmitter based on the normal operating power consumption of the receiver;

[0025] Step 2: After the transmitter is powered on, the DC-DC module outputs an initial set value of 6V, and the microcontroller starts to collect the transmitter output current through the current sensing amplifier;

[0026] Step 3: Calculate the transmitter output power by collecting the output current and the output voltage of the DC-DC module, and compare it with the pre-set normal operating power threshold. If the output power is less than the normal operating power threshold, it is determined that the circuit is in an unloaded state, and the microcontroller will reduce the output voltage of the DC-DC module to reduce power consumption. If the output power is greater than or equal to the normal operating power threshold, it is determined that there is a load.

[0027] Step 4: Continue to compare with the set over-power threshold. If the output power is greater than the over-power threshold, it is determined that there is a short circuit in the system and the power consumption is too high. The microcontroller will temporarily shut down the DC-DC module output to protect the system from being burned out. If the output power is between the normal operating power threshold and the over-power threshold, the system is considered to be working normally and this output voltage will be maintained until the next comparison.

[0028] Step 5: Delay the circuit for the next time according to the set time.

[0029] This invention provides a small wireless power supply system and control method based on a Class E power amplifier. Compared with existing technologies, its advantages are as follows: Addressing the current trend of miniaturization in wireless implants, it solves the problems of low efficiency and inconvenience associated with large, fixed wireless power supply devices currently used for fully implantable brain-computer interfaces. Furthermore, the wireless power supply system includes a transmitter and a receiver, comprising a power supply, a microcontroller, a current sensing amplifier, an adjustable DC-DC module, and a Class E power amplifier module. The receiver includes an input resonant circuit, a full-wave rectifier bridge circuit, a DC-DC receiver module, and a load connected in sequence. The system circuit uses a Class E power amplifier structure, which reduces circuit complexity and improves system efficiency compared to traditional inverters and other types of power amplifier structures. It also employs magnetic coupling resonant technology, improving energy transmission efficiency even with weak coil coupling, and extending the energy transmission distance compared to inductive energy transmission. The open-loop control strategy eliminates the need for an additional receiver structure, offering advantages such as simple structure and adjustable response time, further improving the system's energy transmission efficiency and robustness. Attached Figure Description

[0030] Figure 1 A system block diagram of a wireless power supply system based on a Class E power amplifier provided by the present invention;

[0031] Figure 2 A schematic diagram of the adjustable DC-DC transmitter output provided by the present invention;

[0032] Figure 3 A circuit diagram of the full-wave rectifier bridge circuit for the receiving end provided by the present invention;

[0033] Figure 4 A control flowchart for a wireless power supply system provided in an embodiment of the present invention. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0035] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0036] In this embodiment of the invention, all directional indicators (such as up, down, left, right, front, back, lateral, longitudinal, etc.) are only used to explain the relative positional relationship and movement of each component in a specific posture. If the specific posture changes, the directional indicator will also change accordingly.

[0037] Due to installation errors and other reasons, the parallel relationship referred to in the embodiments of the present invention may actually be an approximate parallel relationship, and the perpendicular relationship may actually be an approximate perpendicular relationship.

[0038] like Figure 1As shown, this invention provides a small wireless power supply system and control method based on a Class E power amplifier, including a transmitter and a receiver connected in sequence. The transmitter includes a power supply, a microcontroller, a current-sensing amplifier, an adjustable DC-DC module, and a Class E power amplifier module. The power supply is connected to the microcontroller and the Class E power amplifier module, providing power to them. The microcontroller is connected to the current-sensing amplifier, which collects current and voltage data from the transmitter, uses the calculated output power data as a basis for judging the system circuit's operating state, and adjusts the transmitter's output voltage. Furthermore, by comparing the transmitter's output power with a set power level, circuit protection and efficiency optimization are achieved. One end of the Class E power amplifier module is connected to the current-sensing amplifier, and the other end is coupled to the receiver; it is used to convert DC power into magnetic energy and transmit it outwards. The receiving end includes an input resonant circuit, a full-wave rectifier bridge circuit, a DC-DC receiving module, and a load connected in sequence. The input resonant circuit receives the magnetic energy output from the Class E power amplifier module and converts it into DC power, which is then output to the full-wave rectifier bridge circuit. The full-wave rectifier bridge circuit converts AC power into DC power, which is then converted to the required level by the DC-DC receiving module to power the load.

[0039] Specifically, the transmitting coil L1 is a double-layer circular coil, with the two layers located on the top and bottom layers of the PCB respectively, connected by a through-hole. This allows for a more uniform electromagnetic field distribution. The receiving coil L2 is a four-layer square coil, with the four layers located on the top, two middle layers, and the bottom layer of the PCB respectively, connected by a through-hole. Under the same size constraints, this provides more component placement space compared to a circular coil, while also offering stronger anti-offset capability. The transmitting coil L1 and receiving coil L2 are in a coupled resonant state, which improves the energy transmission distance and efficiency. The adjustable DC-DC module connects to a microcontroller at one end and a current-sensing amplifier at the other, providing power to the output circuit of the Class E power amplifier module. It includes a digital-to-analog converter (DAC) and a DC-DC module with a wide output range, connected in sequence. The DC-DC module's output voltage is 4.5-18V, and its model is TPS61288. The microcontroller can control the output voltage of the DC-DC module by adjusting the DAC as needed. The current-sensing amplifier is model INA190, and the microcontroller is model nRF52832. The adjustable output DC-DC module includes at least three resistors, preferably three in number, specifically resistors R1, R2, and R3. Figure 2 As shown, one end of resistor R2 is connected in series with resistor R1 and then grounded, while the other end is connected to the output voltage V of the DC-DC module. out One end of resistor R3 is connected to the diode and receives the output voltage V of the digital-to-analog converter (DAC). DACThe other end is connected between resistors R1 and R2 and to the FB pin of the DC-DC converter. The digital-to-analog converter (DAC) determines the range and accuracy of the final output voltage of the DC-DC module by controlling the value of each resistor, where the output voltage V of the DC-DC module is... out The formulas for calculating the current in each branch (the currents I1, I2, and I3 corresponding to resistors R1, R2, and R3) are as follows:

[0040]

[0041] Where I1, I2, and I3 are the magnitudes of the currents flowing through R1, R2, and R3, respectively; V out V is the output voltage of the DC-DC module. DAC V is the output voltage of the digital-to-analog converter (DAC). FB The voltage at the FB pin of the DC-DC module is fixed at 0.6V.

[0042] The Class E power amplifier module includes a transistor Q1, a transistor driver chip, a choke inductor L, and an output resonant circuit. One end of the transistor driver chip is connected to the power supply, and the other end is connected to the gate and source of transistor Q1. The drain and source of transistor Q1 are connected to the output resonant circuit. The choke inductor L is connected between the input terminal of the output resonant circuit and the output terminal of the current sensing amplifier. The output terminal of the output resonant circuit is coupled to the input resonant circuit in the receiver.

[0043] The maximum drain-source voltage of transistor Q1 is greater than or equal to 100V. The signal waveform generated by the transistor driver chip is a square wave with a frequency of 13.56MHz. The choke inductor L is a surface-mount power inductor greater than or equal to 68uH. The output resonant circuit includes an output resonant capacitor and a transmitting coil L1 connected in sequence to generate 13.56MHz AC power. The Class E power amplifier module converts the acquired DC power into AC power and then converts the AC power into magnetic energy through the transmitting coil L1 for outward transmission. Transistor Q1 is an NMOS transistor made of gallium nitride. The drive signal provided by the transistor driver chip causes the NMOS transistor to switch at a frequency of 13.56MHz. The silicon nitride power NMOS transistor used has a smaller inter-electrode capacitance and a faster switching speed than ordinary silicon transistors, making it suitable for high-frequency applications. In addition, a parallel sensing resistor R is provided at the output of the current sensing amplifier. sense The current sensing amplifier detects the sensing resistor R. sense The voltage is used to obtain the current of the system circuit.

[0044] The 13.56MHz high-frequency AC output from the Class E power amplifier module converts electrical energy into electromagnetic energy through the transmitting coil L1. The current sensing amplifier at the transmitting end detects the output current of the Class E power amplifier module and uses this as a basis for circuit status judgment. At the receiving end, the input resonant circuit includes a receiving coil L2 and an impedance matching network. The impedance matching network is an L-shaped structure connected across the two ends of the receiving coil L2. The L-shaped impedance matching network improves the system's energy transfer efficiency. The input resonant circuit converts the received electromagnetic energy into AC. The full-wave rectifier bridge circuit completes the AC-to-DC conversion and filtering. After conversion by the DC-DC receiving module, the DC-DC power is supplied to the load. The resonant frequencies of both the output and input resonant circuits are 13.56MHz. The impedance matching network is used to adjust the resonant frequency and convert the load value at the receiving end to an equivalent load value that maximizes efficiency. The equivalent load value R that maximizes efficiency... opt The calculation formula is as follows:

[0045]

[0046] Among them, R opt The equivalent load value is used to maximize efficiency; ω is the resonant angular frequency of the wireless power supply system; r1 is the internal resistance of the transmitting coil L1; r2 is the internal resistance of the receiving coil L2; L m Mutual inductance of the coils; proximity refers to the impedance matching network converting the load value at the receiving end into a range that maximizes efficiency as the mutual inductance changes.

[0047] The calculation of relevant parameters for the Class E power amplifier module requires that the output circuit resonant frequency be 13.56MHz, and the drain voltage waveform of transistor Q1 must be a zero-voltage switching waveform. Figure 3 As shown. In this embodiment of the invention, the optimal values ​​of each component parameter are obtained by constructing a simulation circuit and scanning the parameters. The output resonant circuit of the Class E power amplifier module includes a parallel capacitor C and a series capacitor C1. The parallel capacitor C is connected in parallel with the drain and source of transistor Q1, and the series capacitor C1 is connected in series with the transmitting coil L1. The other end of the transmitting coil L1 is connected to one end of the source of transistor Q1. The parallel capacitor C and the series capacitor C1 are calculated by simulation software. By adjusting the values ​​of capacitors C and C1, the drain voltage waveform of transistor Q1 is made into an ideal waveform, achieving zero-voltage switching.

[0048] In this embodiment, the parameters of each component of the transmitter are as follows:

[0049] Choke inductor L: 68uH; parallel capacitor C: 15pF; series capacitor C1: 85pF; transmitting coil L1: 2.25uH.

[0050] The choke inductor L reduces the large ripple generated when transistor Q1 is turned on and off, improving system efficiency. Therefore, the larger the inductance of the choke inductor L, the stronger the suppression of current ripple. The minimum choke inductor L that makes the peak-to-peak value of the current ripple of transistor Q1 less than 10% of the DC current I1 is the minimum value of the choke inductor L. fmin The calculation formula is:

[0051]

[0052] Among them, L fmin R is the minimum choke inductance; R is the equivalent load of the output circuit; f is the circuit operating frequency.

[0053] In this embodiment, when comparing the output power with a set power level, the microcontroller determines the power level status based on the system's operating state. The power level status includes a low-power state with no load, a normal operating state, and a shutdown state due to excessive power consumption. By identifying the power level at which the output power is located, the current operating state of the system is determined, thereby achieving protection of the system circuitry and optimization of efficiency.

[0054] In this embodiment, the power supply includes a first DC-DC power supply, a DC power supply, and a second DC-DC power supply connected in sequence. The first DC-DC power supply is connected to the microcontroller and supplies power to the microcontroller; the second DC-DC power supply is connected to the transistor driver chip in the Class E power amplifier module and supplies power to the transistor driver chip.

[0055] Specifically, the DC power supply is powered by a 3.7V lithium battery, which, after conversion by a first DC-DC power supply and a second DC-DC power supply, powers the microcontroller and the Class E power amplifier module. The first DC-DC power supply has an output voltage of 3.3V and is a TPS62840 chip, while the second DC-DC power supply has an output voltage of 5V and is a TPS61253 chip. In this embodiment, the models of the first DC-DC power supply, the second DC-DC power supply, and the power module are only one example; they can also be other DC-DC chips that meet the corresponding output voltage requirements. This invention does not limit the specific models used.

[0056] In this embodiment, the input resonant circuit includes capacitors C2 and C3. Capacitor C2 is connected in series with the receiving coil L2, and capacitor C3 is connected to the end furthest from the receiving coil L2 and in parallel with the receiving coil L2. Figure 3 As shown, the full-wave rectifier bridge circuit includes at least four unidirectional conducting elements connected end-to-end. The preferred number of unidirectional conducting elements is four. The unidirectional conducting elements are Schottky diodes with lower forward voltage drop, which reduces circuit losses. In this embodiment, if the wireless power supply system does not have high efficiency requirements, other diodes with unidirectional conducting function can be used instead. The specific device used can be replaced according to the actual application scenario.

[0057] In this embodiment, the parameters of each component at the receiving end are as follows: receiving coil L2: 1.3uH; capacitor C2: 330pF; capacitor C3: 130pF.

[0058] like Figure 4 As shown, the present invention also provides a control method for a small magnetically coupled resonant wireless power supply system based on a Class E power amplifier, used to optimize the output of the aforementioned wireless power supply system. The control method includes the following steps:

[0059] Step 1: Set the normal operating power threshold P0 and the over-power threshold P1 of the transmitter based on the normal operating power consumption of the receiver;

[0060] Step 2: After the transmitter is powered on, the DC-DC module outputs the initial set value, and the microcontroller starts to collect the transmitter output current I1 through the current sensing amplifier;

[0061] Step 3: Calculate the transmitter output power P by comparing the collected output current I1 with the DC-DC module output voltage V1, i.e., P = V1 * I1. Compare this power with the pre-set normal operating power threshold P0. If the output power P is less than the normal operating power threshold P0, the circuit is considered to be in an unloaded state, and the microcontroller will reduce the DC-DC module output voltage to reduce power consumption. If the output power is greater than or equal to the normal operating power threshold, the circuit is considered to be under load.

[0062] Step 4: Continue to compare with the set over-power threshold. If the output power P is greater than the over-power threshold P1, it is determined that there is a short circuit in the system and the power consumption is too high. The microcontroller will temporarily shut down the DC-DC module output to protect the system from being burned out. If the output power P is between the normal operating power threshold P0 and the over-power threshold P1, it is considered that the system is working normally and this output voltage is maintained until the next comparison.

[0063] Step 5: Delay the circuit for the next time according to the set time.

[0064] In step 2, the initial setting value is 6V, which can be adjusted arbitrarily according to the operating voltage requirements of the receiving device.

[0065] In summary, this invention provides a small wireless power supply system and control method based on a Class E power amplifier. The system circuit employs a Class E power amplifier structure, which reduces circuit complexity and improves system efficiency compared to traditional inverters and other types of power amplifier structures. Furthermore, it utilizes magnetic coupling resonance technology, improving energy transmission efficiency even with weak coil coupling, and extending the energy transmission distance compared to inductive power transmission. The open-loop control strategy eliminates the need for additional receiver structures, offering advantages such as simple structure and adjustable response time, further enhancing the system's energy transmission efficiency and robustness.

[0066] Although the present invention has been disclosed above by way of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of protection claimed in the claims.

Claims

1. A control method for a small wireless power supply system based on a Class E power amplifier, characterized in that, A small wireless power supply system based on a Class E power amplifier includes a transmitter and a receiver connected in sequence. The transmitting end includes a power supply, a microcontroller, a current-sensing amplifier, an adjustable DC-DC module, and a Class E power amplifier module. The power supply is connected to the microcontroller and the Class E power amplifier module. The microcontroller is connected to the current-sensing amplifier, which collects the current and voltage data of the transmitting end through the current-sensing amplifier. The calculated output power data is used as the basis for judging the operating status of the system circuit. By comparing the output power of the transmitting end with the set power level, the output voltage of the transmitting end is adjusted. One end of the Class E power amplifier module is connected to the current-sensing amplifier, and the other end is coupled to the receiving end. The adjustable output DC-DC module is connected to a microcontroller at one end and a current-sensing amplifier at the other end, providing power to the output circuit of the Class E power amplifier module. It includes a digital-to-analog converter (DAC) and a DC-DC module with a wide output range, connected in sequence. The microcontroller can control the output voltage of the DC-DC module by adjusting the DAC according to actual needs. The adjustable output DC-DC module includes at least three resistors, specifically R1, R2, and R3. The DAC determines the range and accuracy of the final output voltage of the DC-DC module by controlling the value of each resistor. The receiving end includes an input resonant circuit, a full-wave rectifier bridge circuit, a DC-DC receiving module, and a load connected in sequence; the input resonant circuit receives the magnetic energy output from the Class E power amplifier module and converts it into AC power, which is then output to the full-wave rectifier bridge circuit. And power is supplied to the load through a DC-DC receiver module; The control method includes the following steps: Step 1: Set the normal operating power threshold and over-power threshold for the transmitter based on the normal operating power consumption of the receiver; Step 2: After the transmitter is powered on, the DC-DC module outputs the initial set value, and the microcontroller starts to collect the transmitter output current through the current sensing amplifier; Step 3: Calculate the transmitter output power by collecting the output current and the output voltage of the DC-DC module, and compare it with the pre-set normal operating power threshold. If the output power is less than the normal operating power threshold, it is determined that the circuit is in an unloaded state, and the microcontroller will reduce the output voltage of the DC-DC module to reduce power consumption. If the output power is greater than or equal to the normal operating power threshold, it is determined that there is a load. Step 4: Continue to compare with the set over-power threshold. If the output power is greater than the over-power threshold, it is determined that there is a short circuit in the system and the power consumption is too high. The microcontroller will temporarily shut down the DC-DC module output to protect the system from being burned out. If the output power is between the normal operating power threshold and the over-power threshold, the system is considered to be working normally and this output voltage will be maintained until the next comparison. Step 5: Delay the circuit for the next time according to the set time.

2. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 1, characterized in that, The adjustable output DC-DC module is connected to a microcontroller at one end and a current-sensing amplifier at the other end. It includes a digital-to-analog converter (DAC) and a DC-DC module connected in sequence. The microcontroller controls the output signal of the DC-DC module by adjusting the DAC. The adjustable output DC-DC module includes at least three resistors; the range and accuracy of the final output voltage are determined by controlling the value of each resistor. The calculation formulas for the output voltage and the current in each branch of the DC-DC module are as follows: ； Where I1, I2, and I3 are the magnitudes of the currents flowing through R1, R2, and R3, respectively; V out V is the output voltage of the DC-DC module. DAC V is the output voltage of the digital-to-analog converter. FB This refers to the voltage at the FB pin of the DC-DC module.

3. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 1, characterized in that, The input resonant circuit includes a receiving coil L2 and an impedance matching network. The impedance matching network is an L-shaped structure connected to both ends of the receiving coil L2, used to adjust the resonant frequency and convert the receiving load value into an equivalent load value that maximizes efficiency. The formula for calculating the equivalent load value that maximizes efficiency is as follows: ； Among them, R opt The equivalent load value is used to maximize efficiency; ω is the resonant angular frequency of the wireless power supply system; r1 is the internal resistance of the transmitting coil L1; r2 is the internal resistance of the receiving coil L2; L m This is mutual inductance between the coils.

4. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 1, characterized in that, The Class E power amplifier module includes a transistor Q1, a transistor driver chip, a choke inductor L, and an output resonant circuit; one end of the transistor driver chip is connected to the power supply, and the other end is connected to the gate and source of the transistor Q1, and the drain and source of the transistor Q1 are connected to the output resonant circuit. The choke inductor L is connected between the input terminal of the output resonant circuit and the output terminal of the current sensing amplifier; the output terminal of the output resonant circuit is coupled to the input resonant circuit in the receiving terminal.

5. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 4, characterized in that, The maximum drain-source voltage of transistor Q1 is greater than or equal to 100V, and the signal waveform generated by the transistor driver chip is a square wave with a frequency of 13.56MHz; the choke inductor L is a surface-mount power inductor greater than or equal to 68uH; the output resonant circuit includes an output resonant capacitor and a transmitting coil L1 connected in sequence to generate 13.56MHz AC power; the Class E power amplifier module converts the acquired DC power into AC power, and then converts the AC power into magnetic energy through the transmitting coil L1 for outward transmission; the minimum choke inductance value of the choke inductor L is calculated using the following formula: ； Among them, L fmin R is the minimum choke inductance; R is the equivalent load of the output circuit; f is the circuit operating frequency.

6. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 3 or 5, characterized in that, The resonant frequencies of both the output resonant circuit and the input resonant circuit are 13.56MHz.

7. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 1, characterized in that, Based on the operating status of the system, the state of the power level is determined, including the low power consumption state when there is no load, the normal operating state, and the shutdown state when there is excessive power consumption.

8. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 1, characterized in that, The power supply includes a first DC-DC power supply, a DC power supply, and a second DC-DC power supply connected in sequence; the first DC-DC power supply is connected to the microcontroller and supplies power to the microcontroller. The second DC-DC power supply is connected to the transistor driver chip in the Class E power amplifier module to power the transistor driver chip.

9. The control method for a small wireless power supply system based on a Class E power amplifier according to claim 1, characterized in that, The current sensing amplifier is an INA190; the microcontroller is an nRF52832; the full-wave rectifier bridge circuit includes at least four unidirectional conducting elements connected end-to-end, and the unidirectional conducting elements are Schottky diodes.

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