Input power adaptive split radio frequency energy harvesting circuit

Abstract

The present application relates to input power adaptive shunt radio frequency energy acquisition circuit, comprising: electromagnetic wave receiving module, adaptive impedance matching module, rectifier module, maximum power point tracking module and energy storage module connected in turn;The electromagnetic wave receiving module is used for receiving radio frequency signal, and it is converted into first input power signal or second input power signal;Adaptive impedance matching module is used for adaptive matching impedance according to the received first input power signal or second input power signal, to obtain first output power signal or second output power signal;The rectifier module is used for converting the received first output power signal or second output power signal based on the resistance of real-time adjustment, obtains first direct current signal or second direct current signal;Through maximum power point tracking module, the direct current signal obtained by conversion is stored in energy storage module.The method can effectively improve the conversion efficiency, meet the equipment demand.

Description

Technical Field

[0001] This invention belongs to the field of power supply circuit technology, specifically relating to a radio frequency energy harvesting circuit with adaptive input power shunting. Background Technology

[0002] For devices that cannot be connected to traditional power sources, such as remote sensors, implantable wearable devices, smart home devices, and industrial monitoring sensors, frequent battery replacements not only increase maintenance costs but may also affect the reliability and lifespan of the equipment. However, by incorporating radio frequency energy harvesting circuits into these devices, the principle of electromagnetic induction can be used to receive electromagnetic waves from the transmitter via a receiving coil and then convert them into electrical energy. This provides power to devices that cannot be connected to traditional power sources, significantly improving the autonomy and sustainability of the equipment.

[0003] However, existing radio frequency energy harvesting circuits suffer from low conversion efficiency, failing to meet equipment requirements. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides an input power adaptive shunt radio frequency energy harvesting circuit. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] This invention provides an input power adaptive shunt radio frequency energy harvesting circuit, comprising: an electromagnetic wave receiving module, an adaptive impedance matching module, a rectification module, a maximum power point tracking module, and an energy storage module connected in sequence; the electromagnetic wave receiving module is used to receive radio frequency signals and convert the radio frequency signals into a first input power signal or a second input power signal, wherein the power value of the first input power signal is less than the power value of the second input power signal; the adaptive impedance matching module is used to adaptively adjust the resistance value between the output terminal of the electromagnetic wave receiving module and the input terminal of the rectification module according to the received first input power signal or second input power signal, so as to obtain a corresponding first output power signal or second output power signal; the rectification module is used to convert the received first output power signal or second output power signal based on the resistance value adjusted in real time by the maximum power point tracking module, to obtain a first DC signal or a second DC signal; the maximum power point tracking module is also used to generate a third DC signal or a fourth DC signal using the first DC signal or the second DC signal; the energy storage module is used to store the third DC signal or the fourth DC signal and to supply power to external devices.

[0006] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0007] To address the problem of low conversion efficiency in existing radio frequency (RF) energy harvesting circuits, which fail to meet device requirements, this invention provides an RF energy harvesting circuit with adaptive input power shunting. This device acquires RF signals with a wide power range through an electromagnetic wave receiving module, reducing energy loss. Based on the power value, the RF signal is converted into a first or second input power signal. Subsequently, an adaptive impedance matching module automatically selects the power flow path to adaptively adjust impedance matching, reducing signal transmission loss. A rectifier module then converts the signal to a first or second DC signal. A maximum power point tracking (MPPT) module adjusts the resistance of the rectifier module in real time, and uses the first or second DC signal to obtain a third or fourth DC signal. This third or fourth DC signal is then stored in an energy storage module to complete wireless charging. The RF energy harvesting circuit with adaptive input power shunting provided by this invention can effectively improve conversion efficiency, reduce signal transmission loss, and achieve wide-range RF signal acquisition, meeting device requirements. Attached Figure Description

[0008] Figure 1 This is a structural block diagram of the radio frequency energy harvesting circuit with adaptive input power shunting provided in an embodiment of the present invention;

[0009] Figure 2 This is a circuit connection diagram of the adaptive impedance matching module provided in an embodiment of the present invention;

[0010] Figure 3 This is a circuit connection diagram of the first rectifier submodule provided in an embodiment of the present invention;

[0011] Figure 4 This is a circuit connection diagram of the second rectifier submodule provided in an embodiment of the present invention;

[0012] Figure 5 This is a schematic diagram of the structural connection of the maximum power point tracking module provided in an embodiment of the present invention;

[0013] Figure 6 This is a schematic diagram of the structural connection of the open-loop Buck-Boost submodule provided in an embodiment of the present invention;

[0014] Figure 7 This is a simulation example diagram of the radio frequency energy harvesting circuit that adaptively shunts the input power according to an embodiment of the present invention;

[0015] Figure 8 This is an example diagram of the simulation results of the radio frequency energy harvesting circuit that adaptively shunts the input power, provided in an embodiment of the present invention. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0017] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0018] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0019] The radio frequency energy harvesting circuit with adaptive input power shunting proposed in this invention will now be described in detail with reference to the accompanying drawings.

[0020] Figure 1 This is a structural block diagram of the radio frequency energy harvesting circuit with adaptive input power shunting provided in an embodiment of the present invention. Figure 1 As shown, the device includes: an electromagnetic wave receiving module, an adaptive impedance matching module, a rectification module, a maximum power point tracking module, and an energy storage module connected in sequence; the electromagnetic wave receiving module is used to receive radio frequency signals and convert the radio frequency signals into a first input power signal or a second input power signal, wherein the power value of the first input power signal is less than the power value of the second input power signal; the adaptive impedance matching module is used to adaptively adjust the resistance value between the output terminal of the electromagnetic wave receiving module and the input terminal of the rectification module according to the received first input power signal or second input power signal, so as to obtain the corresponding first output power signal or second output power signal; the rectification module is used to convert the received first output power signal or second output power signal based on the resistance value adjusted in real time by the maximum power point tracking module, so as to obtain a first DC signal or a second DC signal; the maximum power point tracking module is also used to generate a third DC signal or a fourth DC signal using the first DC signal or the second DC signal; the energy storage module is used to store the third DC signal or the fourth DC signal and to supply power to external devices.

[0021] Here, the first input power signal is a low-power signal, and the second input power signal is a high-power signal, both of which are high-frequency AC signals. The electromagnetic wave receiving module is an antenna; this antenna is connected to an adaptive impedance matching module and can convert radio frequency signals of different power ranges, widening the input power range of the radio frequency signal. Specifically, the antenna can acquire radio frequency signals with a wide input power range of 915MHz in the environment, convert the acquired radio frequency signals into input power signals, and compare the input power signals with preset values ​​to classify them into either the first input power signal or the second input power signal.

[0022] Figure 2 This is a circuit connection diagram of the adaptive impedance matching module provided in an embodiment of the present invention. Figure 2 As shown, the adaptive impedance matching module includes: inductor L1, inductor L2 and capacitor C1; the first end of inductor L1 is connected to the output end of the electromagnetic wave receiving module, the second end is connected to the first end of inductor L2, the first end of capacitor C1 and the input end of the first rectifier submodule respectively, the second end of capacitor C1 is grounded, and the second end of inductor L2 is connected to the input end of the second rectifier submodule.

[0023] It should be noted that the inductors L1 and L2 and capacitor C1 were determined by impedance matching based on the Smith chart, and the corresponding matching points will vary depending on the circuit being applied.

[0024] Here, inductor L1, capacitor C1, and inductor L2 form a low-power input path, while inductor L1 and capacitor C1 form a high-power input path. For example, initially, the antenna outputs a power signal, which may be a first power signal or a second power signal. This power signal enters the first and second rectifier submodules via two paths, or it may only enter either the first or second rectifier submodule. The maximum power point tracking module obtains the output values ​​of the first and / or second rectifier submodules and adjusts their resistance values ​​in real time. Due to the change in resistance values ​​of the first and / or second rectifier submodules, and the different power values ​​of the antenna output power signal, to match the resistance between the antenna output terminal and the input terminal of the rectifier module, the power signal spontaneously flows into either the low-power input path or the high-power input path. Specifically, when a first input power signal is received, the first input power signal enters the first rectifier submodule via inductor L1, capacitor C1, and inductor L2; when a second input power signal is received, the second input power signal enters the second rectifier submodule via inductor L1 and capacitor C1.

[0025] It should be noted that when matching a low-power input path, the high-power input path is open; and when matching a high-power input path, the low-power input path is open.

[0026] Compared to traditional RF energy harvesting circuits that can only process a single, narrow range of power signals, in this embodiment of the invention, by using an adaptive impedance matching module, the power flow path can be automatically selected according to different power signals to match different impedance networks, thereby achieving wide-range RF signal collection, reducing energy loss, and effectively improving conversion efficiency.

[0027] Here, the rectifier module includes: a first rectifier submodule and a second rectifier submodule; wherein, the first rectifier submodule operates within a power range consisting of a first preset value and a second preset value, and the second rectifier submodule operates within a power range consisting of a third preset value and a fourth preset value, wherein the first preset value is less than the second preset value, the third preset value is less than the fourth preset value, and the third preset value is greater than or equal to the second preset value; the first rectifier submodule is used to convert the received first output power signal into a first DC signal based on the resistance value adjusted in real time by the maximum power point tracking module; the second rectifier submodule is used to convert the received second output power signal into a second DC signal based on the resistance value adjusted in real time by the maximum power point tracking module.

[0028] In one possible implementation, the first rectifier submodule is a cross-coupled rectifier, and the second rectifier submodule is a Dixon charge pump rectifier. In this implementation, the cross-coupled rectifier has higher rectification efficiency for low input power conditions, while the Dixon charge pump rectifier has higher rectification efficiency for high input power conditions. Using this combination can improve the overall rectification efficiency across the power input range. It should be understood that other types of rectifiers can also be used in embodiments of the present invention. Exemplarily, when the rectifier module receives a first output power signal, it uses the first rectifier submodule to convert the first output power signal to obtain a first DC signal; when the rectifier module receives a second output power signal, it uses the second rectifier submodule to convert the second output power signal to obtain a second DC signal.

[0029] Figure 3 This is a circuit connection diagram of the first rectifier submodule provided in an embodiment of the present invention. Figure 3As shown, the first rectifier submodule includes: inductor L3, inductor L4, capacitor C2, capacitor C3, capacitor C4, PMOS transistor MP1, PMOS transistor MP2, NMOS transistor MN1, and NMOS transistor MN2; the first terminal of inductor L3 is grounded, and the second terminal is connected to the first terminal of capacitor C1; inductor L3 and inductor L4 are electromagnetically coupled, and the first terminal of inductor L4 is connected to the first terminal of capacitor C2; the second terminal of capacitor C2 is connected to the source of NMOS transistor MN1, the source of PMOS transistor MP1, and the source of PMOS transistor MP2, respectively. The gate of the NMOS transistor MN1 is connected to the gate of the NMOS transistor MN2; the second terminal of capacitor C1 is connected to the source of NMOS transistor MN2, the source of PMOS transistor MP2, the gate of NMOS transistor MN1, and the gate of PMOS transistor MP1, respectively; the drain of NMOS transistor MN1 and the drain of NMOS transistor MN2 are grounded, and the drain of PMOS transistor MP1 and the drain of PMOS transistor MP2 are both connected to the first terminal of capacitor C3, which is connected to the first input terminal of the maximum power point tracking module; the second terminal of capacitor C3 is grounded.

[0030] Figure 4 This is a circuit connection diagram of the second rectifier submodule provided in an embodiment of the present invention. Figure 4 As shown, the second rectifier submodule includes: capacitors C5, C6, C7, and C8; diodes D1, D2, D3, and D4; the second terminal of inductor L1 in the adaptive impedance matching module is connected to the first terminal of capacitor C5 and the first terminal of capacitor C7; the second terminal of capacitor C5 is connected to the negative terminal of diode D1 and the positive terminal of diode D2, with the positive terminal of diode D1 grounded; the negative terminal of diode D2 is connected to the positive terminal of diode D3 and the first terminal of capacitor C6, with the second terminal of capacitor C6 grounded; the second terminal of capacitor C7 is connected to the negative terminal of diode D3 and the positive terminal of diode D4, with the negative terminal of diode D4 connected to the second input terminal of the maximum power point tracking module; the negative terminal of diode D4 is also connected to the first terminal of capacitor C8, with the second terminal of capacitor C8 grounded.

[0031] Here, the maximum power point tracking module acquires the outputs of the first and second rectifiers in real time and adjusts their internal resistances accordingly, enabling the first rectifier to efficiently convert the input first output power signal, and the second rectifier to efficiently convert the input second output power signal. Now, combined with... Figure 5 The structure of the maximum power point tracking module is described. Figure 5 This is a schematic diagram of the structural connection of the maximum power point tracking module provided in an embodiment of the present invention. Figure 5As shown, the maximum power point tracking module includes: a power estimator, a sample-and-hold circuit, a comparator, an up-and-down counter, an open-loop Buck-Boost submodule, and an on-time generator. The first input of the power estimator is connected to the output of the first rectifier submodule, the second input is connected to the output of the second rectifier submodule, and the output is connected to the input of the sample-and-hold circuit and the negative input of the comparator. The output of the sample-and-hold circuit is connected to the positive input of the comparator, the output of the comparator is connected to the input of the up-and-down counter, the four outputs of the up-and-down counter are connected to the four inputs of the on-time generator, the output of the on-time generator is connected to the input of the open-loop Buck-Boost submodule, and the output of the open-loop Buck-Boost submodule is connected to the input of the energy storage module.

[0032] The power estimator is used to acquire the first voltage or the second voltage corresponding to the i-th preset period. The first voltage is generated using the first DC signal output by the first rectifier submodule, and the second voltage is generated using the second DC signal output by the second rectifier submodule, where i is a positive integer greater than 1. The sample-and-hold circuit is used to provide the first voltage or the second voltage corresponding to the (i-1)-th preset period to the comparator, and to acquire and hold the first voltage or the second voltage corresponding to the i-th preset period. The comparator is used to compare the first voltage or the second voltage corresponding to the i-th preset period and the first voltage or the second voltage corresponding to the (i-1)-th preset period, and to output the comparison result. The up-and-down counter is used to determine the counting signal based on the comparison result output by the comparator. The on-time generator is used to generate the corresponding on-control signal using the counting signal. The open-loop Buck-Boost submodule is used to change the on-time of its internal switch in response to the on-control signal, so as to change the resistance value of the first rectifier submodule or the second rectifier submodule in real time.

[0033] The following example illustrates the operation of the maximum power point tracking (MPPT) module by demonstrating how it adjusts the resistance of the first rectifier in real time. Specifically, the power estimator acquires the first DC signal output from the first rectifier and its corresponding voltage value multiple times within a preset period to calculate the power of the first DC signal and outputs this power value as a first voltage. Assuming there are Q preset periods, the number of corresponding first voltages is also Q. Within the i-th preset period, the power estimator outputs the i-th first voltage to both the comparator and the sample-and-hold circuit. The sample-and-hold circuit holds the i-th first voltage. Simultaneously, the comparator compares the i-th first voltage with the (i-1)-th first voltage output by the sample-and-hold circuit. If the (i-1)-th first voltage is greater than the i-th first voltage, the comparator outputs a high-level signal; otherwise, it outputs a low-level signal. Here, the up / down counter includes D flip-flops and digital logic gates. The initial count signal for the up / down counter is 1111, corresponding to the maximum resistance, ensuring the circuit can start normally during power-up. The up-and-down counter reads the comparator's output in each preset cycle and performs an up-and-down calculation. If a high-level signal is read, the 4-bit signal of the up-and-down counter controls the programmable capacitor array to generate a 4-bit count signal (this count signal is obtained by adding 1 to the initial count signal, with an upper limit of 4'b1111). If a low-level signal is read, the 4-bit signal of the up-and-down counter controls the programmable capacitor array to generate a 4-bit count signal (this count signal is obtained by subtracting 1 from the initial count signal, with a lower limit of 4'b0000). These 4-bit count signals Q0, Q1, Q2, and Q3 are sent to the on-time generator to generate 4 on-control signals. These 4 on-control signals are used to control the on-time of the switches inside the open-loop Buck-Boost submodule.

[0034] Figure 6 This is a schematic diagram of the structural connection of the open-loop Buck-Boost submodule provided in an embodiment of the present invention. Figure 6 As shown, the open-loop Buck-Boost submodule includes: inductor L5, switch S1, switch S2, switch S3 and switch S4; the first terminal of switch S1 is connected to the output terminal of the conduction time generator, the second terminal is connected to the first terminal of inductor L5 and the first terminal of switch S2 respectively, the second terminal of switch S2 is grounded, the second terminal of inductor L5 is connected to the first terminal of switch S3 and the first terminal of switch S4 respectively, the second terminal of switch S3 is grounded, and the second terminal of switch S4 is connected to the input terminal of the energy storage module.

[0035] Here, the open-loop Buck-Boost submodule operates in DCM mode. Four-bit counter signals Q0, Q1, Q2, and Q3 are sent to the on-time generator to generate four on-control signals. These four on-control signals control the opening and closing of switches S1, S2, S3, and S4 within the open-loop Buck-Boost submodule. Within each cycle, switches S1, S2, S3, and S4 sequentially experience: Stage ①: Switches S1 and S3 are on, while switches S2 and S4 are off; Stage ②: Switches S2 and S4 are on, while switches S1 and S3 are off; Stage ③: All switches S1, S2, S3, and S4 are off. The resistance of the first or second rectifier submodule is changed by controlling the duration of Stage ①. Under low power input conditions, the on-time is shorter and the resistance is higher. Under high input power conditions, the on-time is longer and the resistance is lower.

[0036] In one possible implementation, the first or second DC signal output by the first or second rectifier submodule is an average current value. This first or second DC signal flows to the energy storage module via a maximum power point tracking module. Specifically, the first or second DC signal sequentially passes through a power estimator, a sample-and-hold circuit, a comparator, an up / down counter, an open-loop Buck-Boost submodule, and an on-time generator, attenuating to a third or fourth DC signal, which is then stored in the energy storage module. The energy storage module is a lithium battery.

[0037] Here, the first DC signal or the second DC signal flowing out of the open-loop Buck-Boost submodule can be represented as: The resistance value of the corresponding first or second rectifier submodule can be expressed as: Among them, I in,avg I represents the value of either the third or fourth DC signal. pk For peak inductor current, DT and T on All are the durations of phase ①, where D is the duty cycle, T is the preset period, and V is the duration of phase ①. in Where is the input voltage, L is the power inductance, and R is the input voltage. in,avg This is the resistance value of the first or second rectifier submodule.

[0038] Please continue to refer to Figure 5 The maximum power point tracking module also includes a clock signal generation module. This clock signal generation module is connected to the on-time generator to generate a pulse signal with a constant period to control the operating frequency of the circuit. The length of the pulse signal determines the length of the preset period.

[0039] It should be noted that, Figure 5 The power estimator, sample-and-hold circuit, comparator, up / down counter, clock signal generation module, and on-time generator are all existing circuit modules. For the sake of simplicity, the circuit connections of these existing modules will not be described in detail here.

[0040] To address the problem of low conversion efficiency in existing radio frequency (RF) energy harvesting circuits, which fail to meet device requirements, this invention provides an RF energy harvesting circuit with adaptive input power shunting. This device acquires RF signals with a wide power range through an electromagnetic wave receiving module, reducing energy loss. Based on the power value, the RF signal is converted into a first or second input power signal. Subsequently, an adaptive impedance matching module automatically selects the power flow path to adaptively adjust impedance matching, reducing signal transmission loss. A rectifier module then converts the signal to a first or second DC signal. A maximum power point tracking (MPPT) module adjusts the resistance of the rectifier module in real time, and uses the first or second DC signal to obtain a third or fourth DC signal. This third or fourth DC signal is then stored in an energy storage module to complete wireless charging. The RF energy harvesting circuit with adaptive input power shunting provided by this invention can effectively improve conversion efficiency, reduce signal transmission loss, and achieve wide-range RF signal acquisition, meeting device requirements.

[0041] To verify the conversion effect of the input power adaptive shunt RF energy harvesting circuit provided in this invention, the circuit was placed in a simulation environment with an input power range of -15dBm to 15dBm and a signal frequency of 915MHz, and simulation results were obtained. Figure 7 As shown, the antenna receives radio frequency signals in space and converts them into power signals. These power signals pass through an adaptive impedance matching module to a cross-coupled rectifier and / or a Dickson rectifier, then through a maximum power point tracking module, and are finally stored in a lithium battery. Figure 8 As shown, the maximum conversion efficiency of the input power adaptive shunt RF energy acquisition circuit is close to 70%, and the minimum conversion efficiency is greater than 20%, indicating that the input power adaptive shunt RF energy acquisition circuit provided by the present invention can effectively improve the conversion efficiency and realize the acquisition of RF signals over a wide power range.

[0042] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A radio frequency energy harvesting circuit with adaptive input power shunt, characterized in that, include: The electromagnetic wave receiving module, adaptive impedance matching module, rectifier module, maximum power point tracking module and energy storage module are connected in sequence. The electromagnetic wave receiving module is used to receive radio frequency signals and convert the radio frequency signals into a first input power signal or a second input power signal, wherein the power value of the first input power signal is less than the power value of the second input power signal. The adaptive impedance matching module is used to adaptively adjust the resistance between the output terminal of the electromagnetic wave receiving module and the input terminal of the rectifier module according to the received first input power signal or second input power signal, so as to obtain the corresponding first output power signal or second output power signal. The rectifier module is used to convert the received first output power signal or second output power signal based on the resistance value adjusted in real time by the maximum power point tracking module, so as to obtain a first DC signal or a second DC signal. The maximum power point tracking module is further configured to generate a third DC signal or a fourth DC signal using the first DC signal or the second DC signal; The energy storage module is used to store the third DC signal or the fourth DC signal, and to supply power to external devices; The rectifier module includes: a first rectifier submodule and a second rectifier submodule; wherein the first rectifier submodule operates within a power range consisting of a first preset value and a second preset value, and the second rectifier submodule operates within a power range consisting of a third preset value and a fourth preset value, wherein the first preset value is less than the second preset value, the third preset value is less than the fourth preset value, and the third preset value is greater than or equal to the second preset value; The first rectifier submodule is used to convert the received first output power signal into the first DC signal based on the resistance value adjusted in real time by the maximum power point tracking module. The second rectifier submodule is used to convert the received second output power signal into the second DC signal based on the resistance value adjusted in real time by the maximum power point tracking module; The adaptive impedance matching module includes: inductor L1, inductor L2, and capacitor C1; The first end of the inductor L1 is connected to the output end of the electromagnetic wave receiving module, and the second end is connected to the first end of the inductor L2, the first end of the capacitor C1, and the input end of the second rectifier submodule. The second end of the capacitor C1 is grounded, and the second end of the inductor L2 is connected to the input end of the first rectifier submodule. The maximum power point tracking module includes: a power estimator, a sample-and-hold circuit, a comparator, an up-and-down counter, an open-loop Buck-Boost submodule, and an on-time generator; The first input terminal of the power estimator is connected to the output terminal of the first rectifier submodule, the second input terminal is connected to the output terminal of the second rectifier submodule, and the output terminal is connected to the input terminal of the sample-and-hold circuit and the negative input terminal of the comparator, respectively. The output terminal of the sample-and-hold circuit is connected to the positive input terminal of the comparator, the output terminal of the comparator is connected to the input terminal of the up-and-down counter, the four output terminals of the up-and-down counter are connected to the four input terminals of the on-time generator, the output terminal of the on-time generator is connected to the input terminal of the open-loop Buck-Boost submodule, and the output terminal of the open-loop Buck-Boost submodule is connected to the input terminal of the energy storage module. The power estimator is used to obtain a first voltage or a second voltage corresponding to the i-th preset period. The first voltage is generated using the first DC signal output by the first rectifier submodule, and the second voltage is generated using the second DC signal output by the second rectifier submodule. i is a positive integer greater than 1. The sample-and-hold circuit is used to provide the comparator with a first voltage or a second voltage corresponding to the (i-1)th preset period, and to acquire and hold the first voltage or the second voltage corresponding to the i-th preset period. The comparator is used to compare the first voltage or the second voltage corresponding to the i-th preset period and the first voltage or the second voltage corresponding to the (i-1)-th preset period, and output the comparison result. The up-and-down counter is used to determine the counting signal based on the comparison result output by the comparator; The conduction time generator is used to generate a corresponding conduction control signal using the counting signal; The open-loop Buck-Boost submodule is used to change the on-time of its internal switch in response to the on-control signal, so as to change the resistance value of the first rectifier submodule or the second rectifier submodule in real time.

2. The RF energy harvesting circuit with adaptive input power shunting according to claim 1, characterized in that, The first rectifier submodule includes: inductor L3, inductor L4, capacitor C2, capacitor C3, capacitor C4, PMOS transistor MP1, PMOS transistor MP2, NMOS transistor MN1 and NMOS transistor MN2; The first end of the inductor L3 is grounded, and the second end serves as the input terminal of the first rectifier submodule; the inductor L3 and the inductor L4 are electromagnetically coupled, and the first end of the inductor L4 is connected to the first end of the capacitor C2, and the second end is connected to the first end of the capacitor C3; The second terminal of capacitor C2 is connected to the source of NMOS transistor MN2, the source of PMOS transistor MP2, the gate of PMOS transistor MP1, and the gate of NMOS transistor MN1, respectively. The second terminal of capacitor C3 is connected to the source of NMOS transistor MN1, the source of PMOS transistor MP1, the gate of NMOS transistor MN2, and the gate of PMOS transistor MP2, respectively. The drains of NMOS transistors MN1 and MN2 are grounded, and the drains of PMOS transistors MP1 and MP2 are both connected to the first terminal of capacitor C4. The first terminal of capacitor C4 is connected to the first input terminal of the maximum power point tracking module; the second terminal of capacitor C4 is grounded.

3. The RF energy harvesting circuit with adaptive input power shunting according to claim 1, characterized in that, The second rectifier submodule includes: capacitor C5, capacitor C6, capacitor C7, capacitor C8, diode D1, diode D2, diode D3, and diode D4; The second terminal of the inductor L1 in the adaptive impedance matching module is connected to the first terminal of the capacitor C5 and the first terminal of the capacitor C7, respectively. The second terminal of capacitor C5 is connected to the negative terminal of diode D1 and the positive terminal of diode D2, respectively. The positive terminal of diode D1 is grounded. The negative terminal of diode D2 is connected to the positive terminal of diode D3 and the first terminal of capacitor C6, respectively. The second terminal of capacitor C6 is grounded. The second terminal of capacitor C7 is connected to the negative terminal of diode D3 and the positive terminal of diode D4. The negative terminal of diode D4 is connected to the second input terminal of the maximum power point tracking module. The negative terminal of diode D4 is also connected to the first terminal of capacitor C8. The second terminal of capacitor C8 is grounded.

4. The RF energy harvesting circuit with adaptive input power shunting according to claim 1, characterized in that, The open-loop Buck-Boost submodule includes: inductor L5, switch S1, switch S2, switch S3 and switch S4; The first end of switch S1 is connected to the output end of the conduction time generator, and the second end is connected to the first end of inductor L5 and the first end of switch S2 respectively. The second end of switch S2 is grounded. The second end of inductor L5 is connected to the first end of switch S3 and the first end of switch S4 respectively. The second end of switch S3 is grounded. The second end of switch S4 is connected to the input end of the energy storage module.

5. The RF energy harvesting circuit with adaptive input power shunting according to claim 1, characterized in that, The energy storage module is a lithium battery.

6. The RF energy harvesting circuit with adaptive input power shunting according to claim 1, characterized in that, The first rectifier submodule is a cross-coupled rectifier, and the second rectifier submodule is a Dickson charge pump rectifier.

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