A mobile magnetic resonance wireless power transmission system based on frequency tracking control

Abstract

This invention discloses a mobile magnetic resonant wireless power transmission system based on frequency tracking control, belonging to the field of wireless power transmission technology. Its resonant energy transmitter includes a DC power supply, a frequency tracking control system, a high-frequency signal generation circuit, a drive circuit, a power amplifier, and a transmitting coil and resonant compensation capacitor module. The frequency tracking control system includes a current sampling circuit, an amplitude detection module, and a control circuit. The resonant energy receiver includes a load, a rectifier circuit, and a receiving coil and resonant compensation capacitor module connected in sequence. The frequency tracking control system can obtain current feedback signals from the transmitting coil and resonant compensation capacitor module, adjust the output signal frequency of the high-frequency signal generator, thereby changing the resonant frequency of the system. Both the resonant energy transmitter and receiver are installed on a mobile carrier, allowing for simultaneous movement and charging. It has a large operating range, requires no specific track construction, and is cost-effective.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and more specifically, to a mobile magnetic resonant wireless power transmission system based on frequency tracking control. Background Technology

[0002] Wireless power transfer technology, unlike traditional power transmission methods, is a power transmission technology that does not rely on wires and uses magnetic fields, ultrasound, lasers, etc., to transfer electrical energy. Wireless power transfer is free from the constraints of wires, making it a safer, more flexible, and reliable power transmission method. Based on the movement of the electrical device during charging, wireless charging methods for mobile loads are mainly divided into:

[0003] (1) Static wireless charging. A wireless charging transmitter is installed at a specific location. The device needs to stop moving and align the receiving coil on the device with the transmitting coil of the power supply end before charging.

[0004] (2) Dynamic wireless charging. The device runs on a track or road with a specially laid transmitting coil, and charges while moving.

[0005] Both methods have their advantages, but in the field, in the air, and in military scenarios, the range of movement of electrical equipment is relatively large. Using static charging requires the equipment to stop working and return to the charging location after a period of time, which limits its working time. Using dynamic charging requires the construction of specific tracks, which limits its working range, and the cost of this method is also higher. Summary of the Invention

[0006] The present invention provides a mobile magnetic resonant wireless power transmission system based on frequency tracking control, which can alleviate the above-mentioned problems.

[0007] To alleviate the above problems, the technical solution adopted by the present invention is as follows:

[0008] This invention provides a mobile magnetic resonant wireless power transmission system based on frequency tracking control, including a resonant energy transmitter and a resonant energy receiver installed on a mobile carrier;

[0009] The resonant energy transmitter includes a DC power supply, a frequency tracking control system, a high-frequency signal generation circuit, a drive circuit, a power amplifier, a transmitting coil, and a resonant compensation capacitor module. The frequency tracking control system includes a current sampling circuit, an amplitude detection module, and a control circuit. The DC power supply, power amplifier, current sampling circuit, transmitting coil, and resonant compensation capacitor module are electrically connected in sequence. The current sampling circuit, amplitude detection module, control circuit, high-frequency signal generation circuit, drive circuit, and power amplifier are electrically connected in sequence.

[0010] The resonant energy receiver includes a load, a rectifier circuit, and a receiving coil and a resonant compensation capacitor module connected in sequence. The receiving coil and the resonant compensation capacitor module are matched with the transmitting coil and the resonant compensation capacitor module.

[0011] The frequency tracking control system can obtain current feedback signals from the transmitting coil and the resonant compensation capacitor module, adjust the output signal frequency of the high-frequency signal generator, and thus change the resonant frequency of the system.

[0012] In a preferred embodiment of the present invention, the transmitting coil of the transmitting coil and the receiving coil of the resonant compensation capacitor module, and the receiving coil of the receiving coil and the resonant compensation capacitor module, are spatial spiral coils made of copper wire of the same diameter, and have the same number of turns, radius and turn spacing.

[0013] In a preferred embodiment of the present invention, the resonant compensation capacitor of the transmitting coil and the resonant compensation capacitor module and the resonant compensation capacitor of the receiving coil and the resonant compensation capacitor module have the same structure.

[0014] In a preferred embodiment of the present invention, the current sampling circuit includes a sampling resistor, a low-pass filter, and a differential amplifier circuit;

[0015] The sampling resistor and the transmitting coil are connected in series to obtain a first current signal flowing through the transmitting coil based on the voltage across the sampling resistor;

[0016] The low-pass filter is used to filter out the high-frequency components in the first current signal to obtain the second current signal;

[0017] The differential amplifier circuit is used to amplify the second current signal to obtain the current feedback signal.

[0018] In a preferred embodiment of the present invention, the method for adjusting the output signal frequency of the high-frequency signal generator by the frequency tracking control system includes:

[0019] The current sampling circuit obtains the current feedback signal from the transmitting coil;

[0020] The amplitude detection module calculates the effective value of the current based on the disturbance signal and the current feedback signal;

[0021] The control circuit adjusts the output signal frequency of the high-frequency signal generator circuit according to the effective value of the current.

[0022] In a preferred embodiment of the present invention, the amplitude detection module can output a DC level corresponding to the effective value of the current, so as to reflect the magnitude of the effective value of the current.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The current signal of the transmitting resonant coil is sampled and fed back to the control unit. The control circuit adjusts the output signal frequency of the high-frequency signal generator according to the feedback signal, thereby changing the resonant frequency of the system and increasing the output power without communicating with the receiver.

[0025] Meanwhile, the system has a simple structure, does not require the introduction of complex circuit structures in the wireless power transmission system, and does not require communication with the receiving end. It only needs to sample the current signal on the transmitting coil.

[0026] Traditional control methods require monitoring multiple electrical signals. The control process of this invention is simple and reliable, with high accuracy in current signal sampling and processing, and low cost. Frequency adjustment can be achieved based solely on the effective value of the feedback signal.

[0027] Traditional wireless power transmission solutions require that the coils at the transmitting and receiving ends be relatively stationary. This invention broadens the application scenarios of wireless power transmission, enabling efficient power transmission even when both the power supply and receiving ends are in motion. It eliminates the need for specific tracks, ensuring a large operating range for the system, and is also cost-effective.

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, embodiments of the present invention are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a system configuration diagram provided in the implementation method.

[0031] Figure 2 This is a schematic diagram of a spatial spiral coil provided in the implementation method.

[0032] Figure 3 This is a schematic diagram of the transmitter circuit of the wireless power transmission system provided in the implementation method.

[0033] Figure 4 This is a schematic diagram of the receiver circuit of the wireless power transmission system provided in the implementation method.

[0034] Figure 5 This is a diagram showing the relationship between system output power, coupling coefficient, and operating frequency in the implementation method.

[0035] Figure 6 This is a flowchart of the frequency tracking control provided in the implementation method. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0037] Please refer to Figures 1-6 This embodiment discloses a mobile magnetic resonant wireless power transmission system based on frequency tracking control, including a resonant energy transmitter and a resonant energy receiver;

[0038] The resonant energy transmitter includes a DC power supply, a frequency tracking control system, a high-frequency signal generation circuit, a drive circuit, a power amplifier, a transmitting coil, and a resonant compensation capacitor module. The frequency tracking control system includes a current sampling circuit, an amplitude detection module, and a control circuit. The DC power supply, power amplifier, current sampling circuit, and transmitting coil and resonant compensation capacitor module are electrically connected in sequence. The current sampling circuit, amplitude detection module, control circuit, high-frequency signal generation circuit, drive circuit, and power amplifier are electrically connected in sequence.

[0039] The resonant energy receiver includes a load, a rectifier circuit, and a receiving coil and a resonant compensation capacitor module connected in sequence. The receiving coil and the resonant compensation capacitor module are matched with the transmitting coil and the resonant compensation capacitor module.

[0040] In this embodiment, the power amplifier is an IRF540, a common N-channel enhancement-mode MOSFET used for very fast switching operations and amplification processes. Compared to general transistors, the IRF540 has a significantly higher input impedance, making it highly sensitive.

[0041] In this embodiment, the resonant compensation capacitors of the transmitting coil and resonant compensation capacitor module, as well as the resonant compensation capacitors of the receiving coil and resonant compensation capacitor module, have the same structure. The inherent resonant frequencies of the transmitting resonant circuit and the receiving resonant circuit are the same, and energy exchange occurs in the form of coil resonance.

[0042] In this embodiment, the transmitting coil of the transmitting coil and the receiving coil of the resonant compensation capacitor module, as well as the receiving coil of the receiving coil and the resonant compensation capacitor module, are spatial spiral coils made of copper wire of the same diameter, and have the same number of turns, radius and turn spacing.

[0043] In this embodiment, a high-frequency signal generator, a drive circuit, and a power amplifier constitute a high-frequency inverter; the high-frequency inverter can convert the input energy of DC power supply into high-frequency AC energy.

[0044] In this embodiment, when the mobile carrier is in motion and the relative positions of the transmitting coil and the receiving coil change, the frequency tracking control system adjusts the output signal frequency of the high-frequency signal generator according to the current feedback signal, thereby changing the resonant frequency of the system and increasing the output power without communicating with the receiving end.

[0045] In this embodiment, the method for adjusting the output signal frequency of the high-frequency signal generator by the frequency tracking control system includes: a current sampling circuit acquiring a current feedback signal from the transmitting coil; an amplitude detection module calculating the effective value of the current based on the disturbance signal and the current feedback signal, and outputting a corresponding DC level signal, transmitting the effective value of the sampled current to the control circuit; and the control circuit adjusting the output signal frequency of the high-frequency signal generator based on the effective value of the current.

[0046] In this embodiment, the rectifier circuit converts the high-frequency AC power received by the receiving coil into DC power to supply the load.

[0047] In this embodiment, both the transmitting coil and the receiving coil are as follows: Figure 2 The spatial spiral coil shown is wound with copper wire of diameter a = 1 mm, coil radius r = 100 mm, number of turns n = 6, and turn spacing s = 2 mm. The self-inductance of the transmitting and receiving coils can be measured to be approximately 15.9 uH using a bridge tester. The transmitting and receiving coils are connected in series with a CPB capacitor of approximately 1.59 nF, each forming a transmitting resonant circuit and a receiving resonant circuit with a natural resonant frequency of approximately 1 MHz.

[0048] The high-frequency signal generator produces a square wave signal with a duty cycle of 0.5 and an amplitude of approximately 2V, with an initial frequency of 1MHz. After being amplified by the drive circuit, the square wave signal has an amplitude of approximately 14V.

[0049] The output of the drive circuit serves as the gate input voltage of the power amplifier's switching transistor, while the drain is connected to the DC power supply. The power amplifier output is connected in series with the transmitting resonant circuit, converting the DC input energy into high-frequency AC energy to supply the transmitting resonant circuit. The frequency of the high-frequency AC energy is the same as the frequency of the square wave signal; therefore, this frequency is called the system operating frequency. The transmitting coil generates a high-frequency AC magnetic field under AC excitation. Because the inherent resonant frequencies of the transmitting and receiving resonant circuits are the same, the transmitting and receiving coils resonate in the magnetic field, and energy is transferred from the transmitting end to the receiving end along with the resonance.

[0050] like Figure 4 As shown, the energy received by the receiving resonant circuit from the transmitting end is high-frequency AC power, which can be converted into DC power by a full-bridge rectifier circuit and then supplied to the load.

[0051] In this embodiment, the resonant energy transmitter and receiver are mounted on different movable carriers. The movement of the carriers may cause changes in the relative positions of the transmitting and receiving coils, resulting in a change in the coupling k between the coils. The maximum output power of the system is achieved when the operating frequency equals the system's natural resonant frequency, ω. s It is related to the coupling coefficient k. When k is less than the critical coupling coefficient, ω s Approximately equal to the system operating frequency of 1MHz, but when k is greater than the critical coupling coefficient, the system's natural resonant frequency has two values, and satisfies ω s1 <1MHz<ω s2 Therefore, the maximum output power is also obtained at these two frequencies. The relationship between output power, coupling coefficient, and operating frequency is as follows: Figure 5 As shown in the figure, when the coupling coefficient is greater than the critical coupling coefficient, the output power will decrease rapidly if the system operating frequency remains unchanged. Therefore, the wireless power transmission system introduces a frequency tracking control system at the transmitting end.

[0052] In this embodiment, the current sampling circuit includes a sampling resistor, a low-pass filter, and a differential amplifier circuit.

[0053] like Figure 3 As shown, the voltage difference across resistor R8 enters differential amplifier U7 through resistors R28 and R29. After being amplified by differential amplifier U7, the current information of the corresponding circuit branch is collected.

[0054] The signal sampled by differential amplifier U7 is output to coupling capacitor C21. After passing through coupling capacitor C21, it enters signal RMS value calculator U8. The RMS value of the sampled sine signal is output through pin 7 of signal RMS value calculator U8.

[0055] The transmitting coil L2 and capacitor C11 form a transmitting resonant circuit, and energy is transmitted to the receiving end through the transmitting coil L2. The PWM control signal of the driver U4 is transmitted to the switching transistor Q1 to control the switching on and off of the switching transistor Q1. The coil L1, capacitor C9, and switching transistor Q1 form a voltage regulation circuit to provide a stable voltage for the system operation.

[0056] Resistors R4 and R1 form a resistor voltage divider circuit. The PWM signal generated by the controller enters the resistor voltage divider circuit through interface P1, generating a corresponding drive waveform. It then enters the driver U4 through pin 2, which generates a corresponding drive signal for the switching transistor Q1. The signal is then output to the gate of the switching transistor Q1 through the current-limiting resistor R6.

[0057] In this system, a 0.01Ω sampling resistor R8 is connected in series between the switching transistor Q1 and the transmitting resonant circuit. The voltage across the sampling resistor R8 reflects the current information of the transmitting resonant circuit. The current flowing through the sampling resistor R8 is the current in the transmitting coil L2, i.e., the first current signal. According to the definition of a resonant circuit, when the first current signal in the transmitting coil L2 reaches its maximum value, the system is in a resonant state, and therefore the output power reaches its corresponding maximum value. The voltage across the sampling resistor R8 characterizes the magnitude of the current in the transmitting coil L2, serving as the feedback signal for the control scheme. Then, the first current signal is filtered by a first-order RC low-pass filter circuit to remove high-frequency components, resulting in a second current signal. This second current signal is then amplified by a differential amplifier circuit to a range recognizable by the amplitude detection module, yielding the current feedback signal. The amplitude detection module calculates the effective value of the current feedback signal and outputs a corresponding DC level to reflect the magnitude of the effective value of the input signal current. After receiving the effective current value, the control circuit automatically adjusts the frequency of the square wave signal output by the high-frequency signal generator according to the control flow, thereby achieving the function of adjusting the system's operating frequency.

[0058] The frequency tracking control method flow provided in this embodiment is as follows: Figure 6 As shown, the current sampling frequency is f c =200kHz, the perturbation frequency is f N =100Hz, the system initial operating frequency is f = f0 = 1MHz, the initial feedback signal current effective value is I0, ΔI0 = 0. The specific control flow is as follows:

[0059] S1: The control circuit adds a frequency disturbance signal Δf = f in a random direction to the system. NS =10kHz, the current operating frequency of the system becomes f = f0 + Δf after the disturbance.

[0060] S2: Current detection, i.e., the current sampling circuit obtains the current feedback signal from the transmitting coil, and the amplitude detection module determines the amplitude based on the disturbance signal Δf = f NS =10kHz and the current feedback signal are used to calculate the effective value of the current after the disturbance, I1.

[0061] S3: If ΔI1 = 0, then Δf = 0, and the frequency adjustment ends. If ΔI1 ≠ 0, the control circuit determines the frequency change Δf in the next frequency adjustment based on the comparison result of I1 and I0, and then jumps to step S2.

[0062] The method for determining the frequency change Δf in the next frequency adjustment is as follows:

[0063] If ΔI1=I1-I0<0, then the frequency change is Δf=-0.5·Δf;

[0064] If ΔI1 > 0 and ΔI0 > 0, then Δf = Δf;

[0065] If ΔI1 > 0 and ΔI0 <= 0, then Δf = 0.5·Δf.

[0066] S5: Time T elapsed N Regardless of the value of ΔI1, proceed to step S1.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A frequency tracking control based mobile magnetic resonance wireless power transmission system, characterized by, This includes a resonant energy transmitter and a resonant energy receiver installed on a movable carrier; The resonant energy transmitter includes a DC power supply, a frequency tracking control system, a high-frequency signal generation circuit, a drive circuit, a power amplifier, a transmitting coil, and a resonant compensation capacitor module. The frequency tracking control system includes a current sampling circuit, an amplitude detection module, and a control circuit. The DC power supply, power amplifier, current sampling circuit, transmitting coil, and resonant compensation capacitor module are electrically connected in sequence. The current sampling circuit, amplitude detection module, control circuit, high-frequency signal generation circuit, drive circuit, and power amplifier are electrically connected in sequence. The resonant energy receiver includes a load, a rectifier circuit, and a receiving coil and a resonant compensation capacitor module connected in sequence. The receiving coil and the resonant compensation capacitor module are matched with the transmitting coil and the resonant compensation capacitor module. The frequency tracking control system can obtain current feedback signals from the transmitting coil and the resonant compensation capacitor module, adjust the output signal frequency of the high-frequency signal generating circuit, and thus change the resonant frequency of the system. The frequency tracking control method for the mobile magnetic resonant wireless power transmission system specifically includes the following steps: S1: Add a frequency perturbation signal with a random direction to the control circuit. The system's current operating frequency becomes after the disturbance. , Initialize the system's operating frequency, initialize ; S2: Current detection, i.e., the current sampling circuit obtains the current feedback signal from the transmitting coil, and the amplitude detection module detects the current based on the disturbance signal. and the effective value of the initial current feedback signal The effective value of the current after the disturbance is calculated. ; S3: If ,but End the frequency modulation; otherwise, the control circuit will adjust the frequency based on the effective value of the current. and the effective value of the current feedback signal The comparison results determine the amount of frequency change in the next frequency adjustment. In determining the change in frequency Then, update the variables. as well as Then proceed to step S2; Determine the amount of frequency change in the next frequency adjustment. The method is as follows: like The change in frequency is ; like ,and ,but ; like ,and ,but ; Over time ,regardless What is the value of ? Proceed to step S1. The frequency is the disturbance frequency.

2. The mobile magnetic resonant wireless power transmission system based on frequency tracking control according to claim 1, characterized in that... The transmitting coil of the transmitting coil and the receiving coil of the resonant compensation capacitor module, as well as the receiving coil of the receiving coil and the resonant compensation capacitor module, are spatial spiral coils made of copper wire of the same diameter, and have the same number of turns, radius and turn spacing.

3. The mobile magnetic resonant wireless power transmission system based on frequency tracking control according to claim 2, characterized in that... The resonant compensation capacitor of the transmitting coil and resonant compensation capacitor module and the resonant compensation capacitor of the receiving coil and resonant compensation capacitor module have the same structure.

4. The mobile magnetic resonant wireless power transmission system based on frequency tracking control according to claim 3, characterized in that... The current sampling circuit includes a sampling resistor, a low-pass filter, and a differential amplifier circuit. The sampling resistor and the transmitting coil are connected in series to obtain a first current signal flowing through the transmitting coil based on the voltage across the sampling resistor; The low-pass filter is used to filter out the high-frequency components in the first current signal to obtain the second current signal; The differential amplifier circuit is used to amplify the second current signal to obtain the current feedback signal.

5. The mobile magnetic resonant wireless power transmission system based on frequency tracking control according to claim 1, characterized in that... The method for adjusting the output signal frequency of the high-frequency signal generation circuit by the frequency tracking control system includes: The current sampling circuit obtains the current feedback signal from the transmitting coil; The amplitude detection module calculates the effective value of the current based on the disturbance signal and the current feedback signal; The control circuit adjusts the output signal frequency of the high-frequency signal generator circuit according to the effective value of the current.

6. The mobile magnetic resonant wireless power transmission system based on frequency tracking control according to claim 5, characterized in that... The amplitude detection module can output a DC level corresponding to the effective value of the current to reflect the magnitude of the effective value of the current.

Images