Radio frequency energy acquisition assembly and radio frequency energy acquisition system

Abstract

The invention provides a radio frequency energy collection assembly and system. The radio frequency energy collection assembly comprises at least two radio frequency rectification modules, an energy storage module and a DC-DC conversion module. The at least two radio frequency rectification modules are connected in parallel with each other, are connected with the energy storage module, and are used for outputting energy to the energy storage module; the energy storage module is connected with the DC-DC conversion module and is used for providing energy for the DC-DC conversion module; wherein each radio frequency rectification module comprises a rectifier and a controller, the rectifier comprises a transistor set, and the controller is used for disconnecting the transistor set when electric leakage of the rectifier is detected so as to stop electric leakage of the rectifier. According to the invention, the problem that different channels influence each other when the power is unbalanced can be solved.

Description

Technical Field

[0001] The present application relates to the field of radio frequency circuit technology, and in particular to a radio frequency energy harvesting component and a radio frequency energy harvesting system. Background Art

[0002] Massive wireless IoT (Internet of Things) devices with RF energy harvesting capabilities are widely used in smart homes, smart cities, and industrial Internet due to their diverse application scenarios, rich functions, high flexibility, and low cost. However, electromagnetic waves decay rapidly in space, and antenna gain is directional, resulting in low and unreliable harvested energy. Multiple antennas are an effective way to increase the available power or directional range.

[0003] A key issue in multi-antenna energy harvesting is power combining. Two commonly used combining methods are RF (Radio Frequency, RF) combining and direct current (Direct Current, DC) combining. The RF combining method has a higher peak efficiency, while the DC combining method allows the RF channels to be independent of each other, so the peak efficiency is lower, but there is no interference problem. DC combining can be achieved by simply connecting the outputs of the RF rectifiers of multiple channels in parallel to improve directivity. However, this method is inefficient, and if the power is unbalanced, the channels will affect each other, resulting in leakage in the high-power RF channel. Summary of the invention

[0004] The present application provides a radio frequency energy harvesting component and a radio frequency energy harvesting system, which can solve the problem of mutual influence between different channels when the power is unbalanced.

[0005] In a first aspect, the present application provides a radio frequency energy harvesting component, comprising at least two radio frequency rectifier modules, an energy storage module and a direct current to direct current (DC-DC) conversion module;

[0006] The at least two radio frequency rectifier modules are connected in parallel to each other and to the energy storage module, and are used to output energy to the energy storage module;

[0007] The energy storage module is connected to the DC-DC conversion module and is used to provide energy for the DC-DC conversion module;

[0008] Each of the radio frequency rectifier modules includes a rectifier and a controller, the rectifier includes a transistor set, and the controller is used to disconnect the transistor set when detecting leakage of the rectifier to stop the leakage of the rectifier.

[0009] Optionally, a gate of a first transistor in the transistor set is connected to a first RF switch for receiving a first AC signal from the first RF switch; a gate of a second transistor in the transistor set is connected to a second RF switch for receiving a second AC signal from the second RF switch, and the first AC signal and the second AC signal are inverse phase signals to each other;

[0010] The gate of the first transistor and the gate of the second transistor are also connected to resistors respectively, and receive direct current voltage signals through the resistors respectively;

[0011] An anti-leakage switch is also provided between the gate of the first transistor and the gate of the second transistor;

[0012] The controller is used to adjust the DC voltage signals respectively provided to the gate of the first transistor and the gate of the second transistor in the rectifier to 0V signals when detecting leakage of the rectifier, and to close the anti-leakage switch to cut off the first transistor and the second transistor in the rectifier.

[0013] Optionally, the controller is used to detect the voltage of the drain of the first transistor and the voltage of the drain of the second transistor in the rectifier;

[0014] When the controller detects that the voltage of the drain of the first transistor and the voltage of the drain of the second transistor meet a preset condition, it is determined that leakage of the rectifier is detected;

[0015] When the controller detects that the voltage of the drain of the first transistor and the voltage of the drain of the second transistor do not meet the preset conditions, the anti-leakage switch is disconnected, and the DC voltage signal provided to the gate of the first transistor and the gate of the second transistor is restored from 0V to a preset value.

[0016] Optionally, the controller includes a first resistor and a second resistor connected between the drain of the first transistor and the drain of the second transistor, and a first capacitor connected between the first resistor and the second resistor; the first resistor and the first capacitor are grounded via a third resistor and a second capacitor;

[0017] When the controller detects that the voltage between the third resistor and the second capacitor is higher than 1 / 2 of the output voltage of the at least two RF rectifier modules, it is determined that the rectifier is leaking.

[0018] Optionally, the controller includes a comparison module and a level converter;

[0019] The comparison module is used to compare the voltage between the third resistor and the second capacitor with 1 / 2 of the output voltage of the at least two RF rectifier modules, and output a comparison result;

[0020] The level converter is used to generate a control signal of the anti-leakage switch according to the comparison result, so that when the voltage between the third resistor and the second capacitor is higher than 1 / 2 of the output voltage of the at least two RF rectifier modules, the anti-leakage switch is turned on.

[0021] In a second aspect, the present application provides a radio frequency energy harvesting system, comprising:

[0022] The RF energy harvesting component according to any one of the preceding claims, wherein the RF energy harvesting component comprises at least two RF rectification modules, an energy storage module and a DC-DC conversion module, and the DC-DC conversion module comprises at least one transistor;

[0023] An output power matching component is used to detect a load voltage and adjust a control level signal of at least one transistor in the DC-DC conversion module according to the load voltage so that the output voltage of the at least two RF rectifier modules maintains a target output voltage, and the target output voltage is the output voltage corresponding to the at least two RF rectifier modules at maximum output power.

[0024] Optionally, the output power matching component includes a maximum power tracking module, a comparison module and a switch control module;

[0025] The maximum power tracking module is used to obtain the target output voltage by scanning the output voltages corresponding to the at least two RF rectifier modules at different output powers;

[0026] The comparison module is used to compare the target output voltage with the current output voltages of the at least two RF rectifier modules;

[0027] The switch control module is used to control at least one transistor in the DC-DC conversion module according to the comparison result of the comparison module, so that the output voltage of the at least two RF rectification modules is maintained at the output voltage corresponding to the current maximum output power.

[0028] Optionally, the maximum power tracking module includes a controllable voltage reference source and a voltage controller;

[0029] The controllable voltage reference source is used to output a reference voltage to the at least two RF rectifier modules;

[0030] The voltage controller is used to:

[0031] detecting the load voltage;

[0032] When a drop in the load voltage is detected, controlling the controllable voltage reference source to increase the output reference voltage;

[0033] When it is detected that the load voltage rises, the reference voltage output by the controllable voltage reference source is used as the target output voltage.

[0034] Optionally, the DC-DC conversion module includes an inductor L, a transistor S1 and a transistor S2, and the voltage difference corresponding to the hysteresis window of the comparison module is ΔV;

[0035] The switch control module is used for:

[0036] When the current output voltage of the at least two RF rectifier modules is higher than the sum of the target output voltage and ΔV, controlling the transistor S1 to be turned on so that the energy in the energy storage module flows into the inductor L;

[0037] When the current output voltage of the at least two RF rectifier modules drops to the difference between the target output voltage and ΔV, controlling the transistor S1 to be turned off and the transistor S2 to be turned on, so that the energy in the inductor L flows into the load; and

[0038] After the energy in the inductor L flows into the load, the switch control module is used to control the transistor S2 to be turned off to prevent the energy of the load from flowing back to the inductor L;

[0039] Wherein, after the transistor S1 and the transistor S2 are turned off, the energy generated by the at least two radio frequency rectification modules is accumulated in the energy storage module.

[0040] Optionally, one end of the DC-DC conversion module connected to the load is also connected to a load capacitor;

[0041] After the transistor S1 and the transistor S2 are turned off, the load is powered by the load capacitor.

[0042] In an embodiment of the present application, at least two RF rectifier modules are connected in parallel to achieve DC merging, and after merging, they are connected to the energy storage module to output energy to the energy storage module. In this way, different RF rectifier modules share one energy storage module, which can save material costs and control complexity, and can improve directionality. However, this will introduce leakage problems caused by power imbalance among different RF rectifier modules. Therefore, in an embodiment of the present application, the structure of the RF rectifier module is set so that the RF rectifier module includes a controller for disconnecting a transistor set in the rectifier when leakage of the rectifier in the RF rectifier module is detected to stop leakage of the rectifier, thereby solving the problem of mutual influence between different channels when power is unbalanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the topological structure of an embodiment of the radio frequency energy harvesting component of the present application;

[0044] Figure 2 The output power P of the RF rectifier module 1 in case 1 and case 2 is shown. OUT and output voltage V RECT relationship.

[0045] Figure 3 It is a schematic diagram of the topological structure of an embodiment of a rectifier in a radio frequency rectifier module of the present application;

[0046] Figure 4 It is a schematic diagram of the topological structure of an embodiment of the radio frequency rectifier module of the present application;

[0047] Figure 5 It is a schematic diagram of the topological structure of an embodiment of the radio frequency energy receiving system of the present application;

[0048] Figure 6 yes Figure 5 A specific embodiment of the topological structure diagram of the radio frequency energy receiving system shown;

[0049] Figure 7 shows the measured power conversion efficiency of the system when using a single antenna as input;

[0050] Figure 8 shows the measured power conversion efficiency of the system when using dual antennas as input;

[0051] Fig. 9 Shows the output power of the RF energy harvesting system measured during wireless tests with different numbers of antennas at different angles in the room. DETAILED DESCRIPTION

[0052] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0053] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0054] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0055] like Figure 1 As shown, Figure 1 Schematic diagram of the topological structure of an embodiment of the radio frequency energy harvesting component of the present application. The radio frequency energy harvesting component 10 includes at least two radio frequency rectification modules 1, an energy storage module 2 and a direct current to direct current (DC-DC) conversion module 3.

[0056] The at least two RF rectifier modules 1 are connected in parallel to each other and to the energy storage module 2 , so as to output energy to the energy storage module 2 . Figure 1 In the example, the RF energy collection component 10 includes two RF rectifier modules 11 and 12. In one example, the energy storage module 2 is specifically an energy storage capacitor C b The energy storage module 2 is connected to the DC-DC conversion module 3 to provide energy to the DC-DC conversion module 3. The DC-DC conversion module 3 can be connected to the load 4 to convert the DC voltage from at least two RF rectifier modules 1 into another suitable DC voltage and then supply power to the load 4. Optionally, the RF energy harvesting component 10 also includes a load capacitor 5 for reducing the voltage ripple at the load end and supplying power to the load.

[0057] The at least two RF rectifier modules 1 have a low cost by combining them through DC, but power loss will occur when the channels are unbalanced. The principle of power loss in the RF energy harvesting component 10 is as follows: Figure 2 shown. Figure 2 The output power P of the RF rectifier module 1 in case 1 and case 2 is shown. OUT and output voltage V RECT relationship.

[0058] Case 1 refers to the case where the output voltage VMPP corresponding to the at least two RF rectifier modules at the maximum output power is less than the open circuit voltage VOC2 of the low power channel. In case 1, both RF rectifier modules 11 and 12 can output power, but since the two channels of the RF rectifier modules 11 and 12 share a working point, when the output power of the two channels is unbalanced, there will be a loss caused by the compromised maximum power tracking. However, compared with the total output power of the two RF rectifier modules 11 and 12, the maximum power point power loss under condition 1 can be ignored.

[0059] Case 2 refers to the case where the output voltage VMPP corresponding to the at least two RF rectifier modules at the maximum output power is greater than the open circuit voltage VOC2 of the low power channel and less than the open circuit voltage VOC1 of the high power channel. In case 2, only the high power channel can output power P IN，1 , and part of the power will leak to the low power channel P IN，2 Therefore, in the embodiment of the present application, the structure of the RF rectifier module is also set so that when leakage occurs in the high-power channel, the transistor in the RF rectifier module is cut off to suppress leakage.

[0060] The radio frequency rectifier module includes a rectifier and a controller, wherein the rectifier includes a transistor set, and the controller is used to disconnect the transistor set when detecting that the energy of the rectifier flows to other radio frequency rectifier modules, so as to cut off the energy of the rectifier from flowing to other radio frequency rectifier modules.

[0061] like Figure 3 As shown, Figure 3 It is a schematic diagram of the topological structure of an embodiment of a rectifier in the radio frequency rectifier module of the present application.

[0062] The structure of the rectifier 21 is a differential mutual coupling structure, and the transistor set in the rectifier 21 includes a first transistor 211, a second transistor 212, a third transistor 213 and a fourth transistor 214. The first transistor 211 and the second transistor 212 are N-type transistors, and the third transistor 213 and the fourth transistor 214 are P-type transistors.

[0063] The drain of the first transistor 211, the drain of the third transistor 213 and the gate of the fourth transistor 214 meet at a connection point A, and the connection point A is connected to the first RF switch through a capacitor for receiving a first AC signal V from the first RF switch. RF+ The gate of the second transistor 212 is connected to the connection point A via a capacitor C1.

[0064] The drain of the second transistor 212, the drain of the fourth transistor 214 and the gate of the third transistor 213 meet at a connection point B, which is connected to the second RF switch via a capacitor for receiving a second AC signal V from the second RF switch. RF- The second AC signal V RF- and the first AC signal V RF+ The gate of the first transistor 211 is connected to the connection point B through a capacitor C2.

[0065] An anti-leakage switch SW is also provided between the gate of the first transistor 211 and the gate of the second transistor 212. The gate of the first transistor 211 is connected to a DC voltage signal V E The gate of the second transistor 212 is connected to the DC voltage signal V through the resistor R2. E The connection point between the resistor R1 and the resistor R2 is also grounded via the capacitor C3.

[0066] The source of the first transistor 211 and the gate-source of the second transistor 212 are grounded respectively. The source of the third transistor 213 and the gate-source of the fourth transistor 214 are respectively used to connect to the DC-DC conversion module to output the voltage signal V RECT .

[0067] When the energy of one of the RF rectifier modules is higher than the energy of the other RF rectifier modules, the gate voltages of the first transistor 211 and the second transistor 212 in the rectifier in the high power channel are high voltages, resulting in V RECT The energy at the terminal will flow through the first transistor 211 and the second transistor 212 to the ground, causing leakage and energy waste.

[0068] When the controller detects that the rectifier 21 is leaking, the DC voltage signal V is provided to the gate of the first transistor 211 and the gate of the second transistor 212 respectively. E Adjust to 0V signal; and close the leakage protection switch so that the first AC signal V RF+ and the second AC signal V RF- They cancel each other out to 0. That is, the DC component and the AC component of the gate of the first transistor 211 and the gate of the second transistor 212 are both 0, so that the first transistor 211 and the second transistor 212 are turned off, so that the leakage current is suppressed.

[0069] There are many ways for the controller to detect and cut off the leakage of the rectifier. In one example, the controller 22 samples the DC voltage of the rectifier 21 and determines whether the rectifier is leaking according to the sampled voltage. When the sampled DC voltage is higher than a preset value, it is determined that the rectifier is leaking. Figure 4 As shown, Figure 4 Schematic diagram of the topological structure of an embodiment of the RF rectifier module of the present application. The controller of the RF rectifier module 40 includes a first resistor R3 and a second resistor R4 connected between a connection point A and a connection point B, and a first capacitor C4 connected between the first resistor R3 and the second resistor R4; the connection between the first resistor R3 and the first capacitor C4 is also grounded through a third resistor R5 and a second capacitor C5.

[0070] exist Figure 4 In the embodiment, the controller detects the voltage V between the third resistor R5 and the second capacitor C5. SNS To sample the DC voltage of the rectifier. When the controller detects that the voltage V between the third resistor R5 and the second capacitor C5 SNS When the voltage of the drain of the first transistor and the voltage of the drain of the second transistor meet the preset condition, it is determined that the rectifier 21 is leaking. RECT The value is determined by, for example, 0.5V RECT .

[0071] Specifically, Figure 4 As shown, the controller 22 further includes a comparison module 221 for comparing the voltage V collected between the third resistor R5 and the second capacitor C5 SNS With 0.5V RECT to compare and at V SNS Above 0.5V RECT Output level signal to close the leakage protection switch SW.

[0072] Optionally, the comparison module 221 does not compare the collected V SNS With 0.5V RECT Instead of comparing, they compare based on a certain frequency. Figure 4 As shown, the controller further includes a register 222 and a frequency divider 223. The frequency divider 223 is used to input a frequency signal P1 to the comparison module 221, so that the comparison module starts to compare the voltage V according to the frequency signal P1. SNS With 0.5V RECT The comparison is performed and the comparison result is stored in the register 222. When the comparison result stored in the register corresponds to the voltage V SNS Greater than 0.5V RECT When the comparison result is , the leakage protection switch SW is turned off.

[0073] In practical applications, there may be a mismatch between the comparison result and the voltage used to turn off the leakage protection switch SW. Therefore, a level conversion module is also provided between the register 222 and the leakage protection switch SW to convert the corresponding voltage V SNSGreater than 0.5V RECT The comparison result is converted into a voltage that can turn off the leakage protection switch SW.

[0074] In an embodiment of the present application, at least two RF rectifier modules are connected in parallel to achieve DC merging, and after merging, they are connected to the energy storage module to output energy to the energy storage module. In this way, different RF rectifier modules share one energy storage module, which can save material costs and control complexity, and can improve directionality. However, this will introduce leakage problems caused by power imbalance among different RF rectifier modules. Therefore, in an embodiment of the present application, the structure of the RF rectifier module is set so that the RF rectifier module includes a controller for disconnecting a transistor set in the rectifier when leakage of the rectifier in the RF rectifier module is detected to stop leakage of the rectifier, thereby solving the problem of mutual influence between different channels when power is unbalanced.

[0075] In one example, the maximum power point tracking (MPPT) is also implemented by using a DC-DC conversion module to improve efficiency and achieve load regulation. Figure 5 As shown, Figure 5 is a schematic diagram of the topological structure of an embodiment of the radio frequency energy receiving system of the present application. The radio frequency energy receiving system 50 includes at least two antennas ( Figure 5 In the example, three antennas are used as examples), a radio frequency energy collection component 52 and an output power matching component 53. A load 55 may be connected to the radio frequency energy collection component 52 to supply power to the load 55.

[0076] The RF energy collection component 52 includes at least two RF rectifier modules (three RF rectifier modules are used as an example in the figure), an energy storage module and a DC-DC conversion module. Each RF rectifier module can be as described above. Figure 1-Figure 4 The RF rectifier module described above will not be described in detail here. Figure 5 In the embodiment shown, the energy storage module 2 includes an energy storage capacitor C b ; DC-DC conversion module 3 includes inductor L, load capacitor C LOAD and at least one transistor.

[0077] The output power matching component 53 is used to detect the load voltage and adjust the control level signal of at least one transistor in the DC-DC conversion module 3 according to the load voltage, so that the output voltage of the at least two RF rectifier modules 1 maintains the target output voltage, which refers to the output voltage corresponding to the at least two RF rectifier modules at the maximum output power.

[0078] In one example, the output power matching component 53 includes a maximum power tracking module 531, a comparison module 532 and a switch control module 533. The maximum power tracking module 531 is used to obtain the target output voltage by scanning the output voltages corresponding to the at least two RF rectifier modules at different output powers. The comparison module 532 is used to compare the target output voltage with the current output voltage V of the at least two RF rectifier modules. RECT The switch control module 533 is used to control at least one transistor in the DC-DC conversion module 3 according to the comparison result of the comparison module 532, so that the output voltage V RECT Maintain the output voltage corresponding to the current maximum output power.

[0079] exist Figure 5 In the example shown, the RF energy receiving system 50 may further include feedback resistors R6 and R7. The feedback resistors R6 and R7 are connected in series and connected to the load voltage output point. The maximum power tracking module 531 in the output power matching component 53 is connected to the connection between the feedback resistors R6 and R7 to detect the load voltage V LOAD .

[0080] In one example, the maximum power tracking module 531 includes a controllable voltage reference source 5311 and a voltage controller 5312. The controllable voltage reference source 5311 is used to output a reference voltage to the at least two RF rectifier modules. The voltage controller 5312 is used to detect the load voltage, and when the load voltage drops, the controllable voltage reference source is controlled to increase the reference voltage output, and when the load voltage rises, the reference voltage output by the controllable voltage reference source is used as the target output voltage. Thus, the controllable voltage reference source 5311 is used to generate a signal VMPP from the load voltage V detected by the maximum power tracking module 531. LOAD The change trend of the load voltage V LOAD The reference voltage V corresponding to the maximum power point can be determined by the changing trend of the output MPP .

[0081] The controllable voltage reference source 5311 converts the voltage V MPP Output to the comparison module 534. The comparison module 534 is used to compare the voltage V MPP and the output voltage V of each RF rectifier module 1 RECT The comparison is performed and the comparison result is output to the switch control module 535. The switch control module 535 adjusts at least one transistor in the DC-DC conversion module 3 according to the comparison result to adjust the output voltage V RECTThe voltage value VMPP corresponding to the current maximum output power is maintained. Thus, MPPT is achieved by using a DC-DC conversion module.

[0082] The output power matching component 53 also includes a digital-to-analog conversion module 535, which is used to provide a DC voltage signal V for the transistors of the rectifiers in each RF rectifier module. E , and when leakage is detected in the RF rectifier module, the DC voltage signal V E Change to 0V.

[0083] Optionally, the RF energy receiving system 50 further includes a starting component 54, which is used to detect the current state of the RF energy receiving system 50 and determine a corresponding working mode according to the state. The switch controller is also used to generate a control level signal of at least one transistor in the corresponding DC-DC conversion module 3 according to the determined working mode. Figure 5 In the example shown, the startup component 54 includes a startup detection module 541, a mode selection module 542 and a comparison module 543. The startup detection module 541 is used to detect the load voltage V LOAD The comparison module 543 is used to compare the collected voltage between the feedback resistors R6 and R7 with the reference voltage V REF The comparison is performed and the comparison result is output to the mode selection module 542. The mode selection module 542 detects the load voltage V detected by the startup detection module 541. LOAD The corresponding working mode is selected based on the comparison result output by the comparison module 543.

[0084] like Figure 6 As shown, Figure 6 yes Figure 5 The topological structure diagram of the radio frequency energy receiving system is shown in FIG. 60. Specifically, in the radio frequency energy receiving system 60, the DC-DC conversion module includes an inductor L, a load capacitor C LOAD and four transistors S1, S2, S3 and S4. The control level signals of the gates of transistors S1 and S2 come from the switch control module 533. Specifically, the switch control module 533 adjusts the duty cycle of the control level signal P1 of transistor S1 according to the comparison result of the comparison module, and controls the duty cycle of the control level signal P2 of transistor S2 according to the zero current detection (ZCD) circuit control. The input of the ZCD circuit is the voltage Vx at the source of transistor S1 and the load voltage V LOAD ; When Vx is greater than V LOAD When Vx is less than V LOAD When the switch control module 5 immediately turns off the transistor S2.

[0085] exist Figure 6 In the example shown, the comparison module is used to determine whether the rectifier is leaking if the two input voltages to be compared are the voltage V collected between the third resistor R5 and the second capacitor C5. SNS , and V RECT *2 / 3, and at V SNS Higher than V RECT *2 / 3 outputs a level signal to close the leakage protection switch SW. The voltage V input by the comparison module RECT *2 / 3 can be output by a voltage divider connected to the controller.

[0086] exist Figure 6 In the example shown, the operating modes of the RF energy receiving system 60 include a cold start mode and a steady-state operating mode.

[0087] When the RF energy receiving system 60 is started, the load voltage V LOAD is 0, the output voltage V RECT = is a lower voltage, the mode selection module 542 determines that the working mode is the cold start mode. The switch control module 533 changes the duty cycle of the control level signal of the transistors S1 and S2 according to the cold start mode so that the load voltage V LOAD Boost from 0V to high voltage.

[0088] This low voltage can drive the ring oscillator and charge pump and boost the voltage. After boosting, the energy is stored in the on-chip capacitor C QP On, so that the voltage V QP The control voltage required by the RF energy receiving system 60 is reached. At this time, the switch control module permanently disconnects the transistor S2, and the current is conducted by the diode. The control level signal CS_P1 (Cold Start_P1) of the transistor S1 in the cold start mode is generated by the frequency divider and the pulse generator. The DC-DC conversion module implements the boost function to provide the load voltage V LOAD Charging. When the load voltage V LOAD When the start voltage is reached, the CS_DIS (Cold Start Disable) signal rises to a high level, the cold start circuit is turned off, and the RF energy receiving system 60 enters a steady-state working mode.

[0089] In the steady-state working mode, the RF energy receiving system 60 switches back and forth between the MPPT mode and the overvoltage idle mode, and the steady-state regulation is achieved by switching between the two modes. After entering the steady-state working mode, when in the MPPT mode, the switch control module changes the duty cycle of the control level signals P1 and P2 of the transistors S1 and S2 according to the output result of the comparison module 534, so as to adjust the output voltage V RECTMaintain the voltage value VMPP corresponding to the current maximum output power, and then enter the overvoltage idle mode. In the overvoltage idle mode, the DC-DC conversion module does not work, and the load is only supplied by the load capacitor C S powered by.

[0090] In one example, when in MPPT mode, the RF energy receiving system uses a hysteresis control method to adjust the output voltage V RECT The voltage value VMPP corresponding to the current maximum output power is maintained, and the feedback is controlled by the voltage controller using the Perturb and Observe (P&O) algorithm. Specifically, ΔV is the hysteresis window of the comparison module. When the output voltage V RECT Higher than V MPP +ΔV, the comparison result output by the comparison module causes the switch control module to control the transistor S1 to turn on, and the energy in Cb quickly flows into the inductor, causing V RECT Rapidly decreases. At V RECT Drop to V MPP -ΔV, the switch control module controls the transistor S1 to be cut off, and Vx is greater than V LOAD , the switch control module controls the transistor S2 to turn on, and the energy in the inductor L can flow into the load with almost no loss. When the inductor energy transfer is completed, the voltage Vx shows a value lower than V LOAD , S2 is turned off at this time to ensure that energy does not flow back. When both transistors S1 and S2 are turned off, the energy generated by the rectifier gradually accumulates in Cb, VRECT gradually rises, and the above process is repeated, and finally VRECT always fluctuates around the VMPP voltage.

[0091] The VMPP voltage is generated by a controllable voltage reference source 5311. Optionally, the controllable voltage reference source 5311 is implemented by a resistor-based digital-to-analog converter (DAC), with an output range of 0.3V to 1.2V and a current of approximately 100nA. When the system enters the MPPT mode, the initial value of VMPP is preset to 0.3V, and VRECT will be fixed at around 0.3V by the feedback system. If the output power corresponding to 0.3V cannot meet the load, V LOAD will drop, the controllable voltage reference source will increase the output to 0.35V, and the voltage controller observes V LOAD If it continues to drop, then increase it to 0.4V until V LOAD After starting to rise, the VMPP voltage value is fixed.

[0092] After the controllable voltage reference source finds the maximum output power from the output powers of each RF rectifier module, V LOADIt will continue to rise until the preset upper limit, and the RF energy receiving system 60 will work in the overvoltage idle mode, the MPPT mode is turned off, and the transistor S1 and the transistor S2 remain in the off state. In this way, the DC-DC conversion module does not work, and the load is only composed of the load capacitor C s Power supply until V LOAD When it drops to the preset lower limit, the MPPT restarts.

[0093] Optionally, in the RF energy receiving system 60, each RF rectifier module, DC-DC conversion module and all control circuits are located on the chip, and each antenna, each matching network, energy storage capacitor C b , inductance L, load capacitance C LOAD The feedback resistors R6 and R7 are located outside the chip. Optionally, the rectifiers in each RF rectifier module are different and connected in parallel with the energy storage capacitor C b connection; and the controllers in each RF rectifier module share the same controller to control different rectifiers respectively.

[0094] In one example, the RF rectifier system is implemented in 180nm CMOS process with a chip area of ​​0.89mm2. Three RF rectifier modules are on three sides of the chip, and the power stage is placed on the fourth side to connect the inductor and capacitor. The chip can be wire bonded to FR4PCB. A balun with an insertion loss of 1dB is used to convert the 50Ω single-ended input to a 200Ω differential input. The RF inductor is 33nH and the DC resistance is 230mΩ. The rectifier energy storage capacitor (Cb) and the load capacitor C LOAD They are 1μF and 2.2μF respectively, and the package size is 0603. The power inductor L is 22μH, the DC resistance is 0.7Q, and the package size is 1210. The output feedback resistors R1 and R2 are 3.9MΩ and 7.8MΩ respectively.

[0095] Figure 7 The power conversion efficiency (PCE) of the system measured when a single antenna is used as input is shown. The RF rectifier module RF1 of one channel is connected to the RF source, and the other two channels are left floating with no input power. The input power range of the RF rectifier module is -14dBm to +4dBm, and the peak PCE can be measured to be 44%.

[0096] Figure 8The PCE measured by the system when using dual antennas as input is shown. In order to verify whether the proposed rectifier is working properly, a multiplexer is set for each rectifier to select the signal to control the RF switch, either from the leakage detection circuit or always off. The red curve and indicate that the anti-leakage switch SW of all rectifiers is closed. The blue curve indicates that the switch signal comes from the leakage detection circuit. The input power of the RF rectifier module RF2 of one channel is fixed to 0dBm, and the input power of RF1 is -17dBm to -1dBm. Channel RF3 is in a floating state and no input power is applied. It can be observed that from -17dBm to -10dBm, the leakage is suppressed by AVC, so the output power shows a straight line without increasing or decreasing; from -10dBm to -5dBm, enabling the switch SW can further suppress the leakage in this range, while not enabling the switch SW will cause leakage to reduce the output power, thus proving that the leakage suppression function is effective.

[0097] Fig. 9 The output power of the RF energy harvesting system measured by wireless tests with different numbers of antennas at different angles in the room is shown. When the antenna angle is +45°, the output power of the single antenna and dual antennas is 140.6μW and 370μW respectively, which is a 163% improvement over the system PCE in the prior art.

[0098] The above is only a preferred embodiment of the present disclosure, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Without departing from the scope and spirit of the described embodiments, many modifications and changes are obvious to those of ordinary skill in the art. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein. Various elements in the embodiments or examples may be omitted or replaced by their equivalent elements. In addition, the steps may be performed in an order different from that described in the present disclosure. Further, the various elements in the embodiments or examples may be combined in various ways. It is important that with the evolution of technology, many elements described herein may be replaced by equivalent elements that appear after the present disclosure. That is, any equivalent structure or equivalent process transformation made according to the claims, specifications, and drawings of the present disclosure, or directly or indirectly applied in other related technical fields, are all included in the scope of protection of the claims of this patent.

Claims

1. A radio frequency energy harvesting component, characterized in that: It includes at least two radio frequency rectifier modules, an energy storage module and a direct current to direct current (DC-DC) conversion module; The at least two radio frequency rectifier modules are connected in parallel to each other and to the energy storage module, and are used to output energy to the energy storage module; The energy storage module is connected to the DC-DC conversion module and is used to provide energy for the DC-DC conversion module; Each of the radio frequency rectifier modules includes a rectifier and a controller, the rectifier includes a transistor set, and the controller is used to disconnect the transistor set when detecting leakage of the rectifier to stop the leakage of the rectifier.

2. The radio frequency energy harvesting component according to claim 1, characterized in that: A gate of a first transistor in the transistor set is connected to a first RF switch for receiving a first AC signal from the first RF switch; a gate of a second transistor in the transistor set is connected to a second RF switch for receiving a second AC signal from the second RF switch, and the first AC signal and the second AC signal are mutually inverted signals; The gate of the first transistor and the gate of the second transistor are also connected to resistors respectively, and receive direct current voltage signals through the resistors respectively; An anti-leakage switch is also provided between the gate of the first transistor and the gate of the second transistor; The controller is used to adjust the DC voltage signals respectively provided to the gate of the first transistor and the gate of the second transistor in the rectifier to 0V signals when detecting leakage of the rectifier, and to close the anti-leakage switch to cut off the first transistor and the second transistor in the rectifier.

3. The radio frequency energy harvesting component according to claim 2, characterized in that: The controller is used to detect the voltage of the drain of the first transistor and the voltage of the drain of the second transistor in the rectifier; When the controller detects that the voltage of the drain of the first transistor and the voltage of the drain of the second transistor meet a preset condition, it is determined that leakage of the rectifier is detected; When the controller detects that the voltage of the drain of the first transistor and the voltage of the drain of the second transistor do not meet the preset conditions, the anti-leakage switch is disconnected, and the DC voltage signal provided to the gate of the first transistor and the gate of the second transistor is restored from 0V to a preset value.

4. The radio frequency energy harvesting component according to claim 2, characterized in that: The controller includes a first resistor and a second resistor connected between a drain of the first transistor and a drain of the second transistor, and a first capacitor connected between the first resistor and the second resistor; The first resistor and the first capacitor are connected to ground via a third resistor and a second capacitor; When the controller detects that the voltage between the third resistor and the second capacitor is higher than a preset voltage, it is determined that the rectifier is leaking, wherein the preset voltage is determined according to the output voltages of the at least two RF rectifier modules.

5. The radio frequency energy harvesting component according to claim 4, characterized in that: The controller includes a comparison module and a level converter; The comparison module is used for comparing the voltage between the third resistor and the second capacitor with the preset voltage, and outputting a comparison result; The level converter is used to generate a control signal of the leakage protection switch according to the comparison result, so that when the voltage between the third resistor and the second capacitor is higher than the preset voltage, the leakage protection switch is turned on.

6. A radio frequency energy collection system, characterized in that: include: The RF energy harvesting component according to any one of claims 1 to 5, wherein the RF energy harvesting component comprises at least two RF rectifier modules, an energy storage module and a DC-DC conversion module, and the DC-DC conversion module comprises at least one transistor; An output power matching component is used to detect a load voltage and adjust a control level signal of at least one transistor in the DC-DC conversion module according to the load voltage so that the output voltage of the at least two RF rectifier modules maintains a target output voltage, and the target output voltage is the output voltage corresponding to the at least two RF rectifier modules at maximum output power.

7. The radio frequency energy harvesting system according to claim 6, characterized in that: The output power matching component includes a maximum power tracking module, a comparison module and a switch control module; The maximum power tracking module is used to obtain the target output voltage by scanning the output voltages corresponding to the at least two RF rectifier modules at different output powers; The comparison module is used to compare the target output voltage with the current output voltages of the at least two RF rectifier modules; The switch control module is used to control at least one transistor in the DC-DC conversion module according to the comparison result of the comparison module, so that the output voltage of the at least two RF rectification modules is maintained at the output voltage corresponding to the current maximum output power.

8. The radio frequency energy harvesting system according to claim 7, characterized in that: The maximum power tracking module includes a controllable voltage reference source and a voltage controller; The controllable voltage reference source is used to output a reference voltage to the at least two RF rectifier modules; The voltage controller is used to: detecting the load voltage; When a drop in the load voltage is detected, controlling the controllable voltage reference source to increase the output reference voltage; When it is detected that the load voltage rises, the reference voltage output by the controllable voltage reference source is used as the target output voltage.

9. The radio frequency energy harvesting system according to claim 7, characterized in that: The DC-DC conversion module includes an inductor L, a transistor S1 and a transistor S2, and the voltage difference corresponding to the hysteresis window of the comparison module is ΔV; The switch control module is used for: When the current output voltage of the at least two RF rectifier modules is higher than the sum of the target output voltage and ΔV, controlling the transistor S1 to be turned on so that the energy in the energy storage module flows into the inductor L; When the current output voltage of the at least two RF rectifier modules drops to the difference between the target output voltage and ΔV, controlling the transistor S1 to be turned off and the transistor S2 to be turned on, so that the energy in the inductor L flows into the load; and After the energy in the inductor L flows into the load, the switch control module is used to control the transistor S2 to be turned off to prevent the energy of the load from flowing back to the inductor L; Wherein, after the transistor S1 and the transistor S2 are turned off, the energy generated by the at least two radio frequency rectification modules is accumulated in the energy storage module.

10. The radio frequency energy harvesting system according to claim 6, characterized in that: One end of the DC-DC conversion module connected to the load is also connected to a load capacitor; After the transistor S1 and the transistor S2 are turned off, the load is powered by the load capacitor.

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