Radio frequency energy harvesting system

Abstract

The application discloses a radio frequency energy collection system, which comprises an antenna, an impedance matching circuit, a voltage doubling rectifier circuit and an energy storage module, wherein the antenna, the impedance matching circuit, the voltage doubling rectifier circuit and the energy storage module are sequentially connected; the system further comprises a temperature compensation circuit, which is connected with the voltage doubling rectifier circuit, is used for acquiring an ambient temperature, and compensates input impedance drift of the voltage doubling rectifier circuit according to the ambient temperature. The temperature compensation circuit is connected between the impedance matching circuit and the voltage doubling rectifier circuit, and automatically compensates input impedance drift of the voltage doubling rectifier circuit at high temperature or low temperature, so that the comprehensive energy conversion efficiency of the radio frequency energy collection system is improved.

Description

Technical Field

[0001] This invention relates to the field of energy harvesting technology, and in particular to a radio frequency energy harvesting system. Background Technology

[0002] The main problem with related radio frequency energy harvesting systems lies in their low energy conversion efficiency. Improving the energy conversion efficiency of radio frequency energy harvesting systems is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide a radio frequency energy harvesting system that improves the overall energy conversion efficiency of the radio frequency energy harvesting system.

[0004] To achieve the above objectives, a first aspect of the present invention provides a radio frequency energy harvesting system, the system comprising: an antenna, an impedance matching circuit, a voltage doubler rectifier circuit, and an energy storage module, wherein the antenna, the impedance matching circuit, the voltage doubler rectifier circuit, and the energy storage module are connected in sequence; the system further comprises: a temperature compensation circuit, the temperature compensation circuit being connected to the voltage doubler rectifier circuit, for acquiring the ambient temperature and compensating for the input impedance drift of the voltage doubler rectifier circuit based on the ambient temperature.

[0005] According to an embodiment of the present invention, a temperature compensation circuit is connected between the impedance matching circuit and the voltage doubler rectifier circuit to automatically compensate for the input impedance drift of the voltage doubler rectifier circuit at high or low temperatures, thereby improving the overall energy conversion efficiency of the radio frequency energy harvesting system.

[0006] In addition, the radio frequency energy harvesting system proposed in the above embodiments of the present invention may also have the following additional technical features:

[0007] According to one embodiment of the present invention, the temperature compensation circuit includes: a voltage generating module, a voltage dividing resistor, a thermistor, a switching transistor, and a reactive element. A first terminal of the voltage generating module is connected to the output terminal of the energy storage module. A second terminal of the voltage generating module is connected to the first terminal of the voltage dividing resistor. The second terminal of the voltage dividing resistor is connected to the first terminal of the thermistor. The second terminal of the thermistor is grounded. The second terminal of the voltage dividing resistor is connected to the control terminal of the switching transistor. The first terminal of the switching transistor is grounded. The second terminal of the switching transistor is connected to the first terminal of the reactive element. The second terminal of the reactive element is connected to the voltage doubler rectifier circuit. The energy storage module provides voltage to the voltage generating module, which provides an output reference voltage. The thermistor provides different voltage divisions to the control terminal of the switching transistor based on the ambient temperature. When the voltage division is greater than the on-state voltage of the switching transistor, the reactive element is connected between the impedance matching circuit and the voltage doubler rectifier circuit to compensate for the input impedance drift of the voltage doubler rectifier circuit.

[0008] According to one embodiment of the present invention, the temperature compensation circuit further includes a first capacitor, one end of which is connected to the output terminal of the voltage generating module, and the other end of which is grounded.

[0009] According to one embodiment of the present invention, the reactive element is a capacitor or an inductor.

[0010] According to one embodiment of the present invention, the thermistor is a thermistor with a positive temperature coefficient or a thermistor with a negative temperature coefficient.

[0011] According to one embodiment of the present invention, if the thermistor is a positive temperature coefficient thermistor, when the ambient temperature rises and is higher than a first preset temperature, the resistance of the thermistor increases, causing the switching transistor to conduct. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit, so that the input impedance of the voltage doubler rectifier circuit after compensation by the reactive element still meets the output impedance of the impedance matching circuit.

[0012] According to one embodiment of the present invention, if the thermistor is a negative temperature coefficient thermistor, when the ambient temperature decreases and is lower than a second preset temperature, the resistance of the thermistor increases, causing the switching transistor to conduct. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit, so that the input impedance of the voltage doubler rectifier circuit after compensation by the reactive element still meets the output impedance of the impedance matching circuit.

[0013] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a radio frequency energy harvesting system according to an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of impedance matching values ​​according to an embodiment of the present invention;

[0016] Figure 3 This is a circuit diagram of a voltage doubler rectifier circuit according to an embodiment of the present invention. Detailed Implementation

[0017] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0018] The radio frequency energy harvesting system of the present invention will be described in detail below with reference to the instructions in sections 1-3 and specific implementation methods.

[0019] Figure 1 This is a schematic diagram of a radio frequency energy harvesting system according to an embodiment of the present invention. Figure 1 As shown, the radio frequency energy harvesting system 100 may include: an antenna 10, an impedance matching circuit 20, a voltage doubler rectifier circuit 30, and an energy storage module 40, which are connected in sequence. The radio frequency energy harvesting system 100 may also include: a temperature compensation circuit 50, which is connected to the voltage doubler rectifier circuit 30 and is used to acquire the ambient temperature and compensate for the input impedance drift of the voltage doubler rectifier circuit 30 according to the ambient temperature.

[0020] For a specific frequency, the signal received by the antenna 10 is first input to the impedance matching circuit 20, then through the voltage doubler rectifier circuit 30, and finally sent to the energy storage module 40.

[0021] In an embodiment of the present invention, the antenna 10 is used to receive energy. The received energy is input to the voltage doubler rectifier circuit 30 after passing through the impedance matching circuit 20. The voltage doubler rectifier circuit 30 rectifies the input energy and outputs DC energy, which is finally stored by the energy storage module 40. The impedance matching circuit 20 is used to perform impedance matching between the antenna 10 and the voltage doubler rectifier circuit 30 to improve the overall energy conversion efficiency.

[0022] Since the voltage doubler rectifier circuit 30 is composed of nonlinear devices such as diodes, in outdoor application scenarios such as deserts and Gobi, the large temperature difference between day and night causes significant changes in parameters such as transistor junction voltage and reverse current, leading to input impedance drift in the voltage doubler rectifier circuit 30. The impedance matching circuit 20 can only match the input impedance of the voltage doubler rectifier circuit 30 at room temperature, and cannot simultaneously meet the impedance matching requirements at both high and low temperatures. When the ambient temperature is too high or too low, the input impedance mismatch of the voltage doubler rectifier circuit 30 will cause most of the energy to be reflected back to the antenna 10, reducing the overall energy conversion efficiency.

[0023] In order to improve the overall energy conversion efficiency of the radio frequency energy harvesting system 100 and to ensure that the overall energy conversion efficiency of the radio frequency energy harvesting system 100 is not affected by the large temperature difference, a temperature compensation circuit 50 is connected between the impedance matching circuit 20 and the voltage doubler rectifier circuit 30 in this embodiment of the invention.

[0024] The temperature compensation circuit 50 in this embodiment of the invention is used to obtain the ambient temperature and compensate the input impedance drift of the voltage doubler rectifier circuit 30 according to the ambient temperature, so as to improve the overall energy conversion efficiency of the radio frequency energy harvesting system 100 and make the overall energy conversion efficiency of the radio frequency energy harvesting system 100 unaffected by changes in ambient temperature.

[0025] In one embodiment of the present invention, such as Figure 1 As shown, the temperature compensation circuit 50 may include: a voltage generation module 51, a voltage divider resistor R1, a thermistor RT, a switching transistor, and a reactive element. The first end of the voltage generation module 51 is connected to the output end of the energy storage module 40. The second end of the voltage generation module 51 is connected to the first end of the voltage divider resistor R1. The second end of the voltage divider resistor R1 is connected to the first end of the thermistor RT. The second end of the thermistor is grounded. The second end of the voltage divider resistor R1 is connected to the control end of the switching transistor. The first end of the switching transistor is grounded. The second end of the switching transistor is connected to the first end of the reactive element. The second end of the reactive element is connected to the voltage doubler rectifier circuit 30. The energy storage module 40 is used to provide a reference voltage for the voltage generation module 51. The voltage generation module 51 is used to provide an output reference voltage. The thermistor RT is used to provide different voltage divisions to the control end of the switching transistor according to the ambient temperature. When the voltage division is greater than the conduction voltage of the switching transistor, the reactive element is connected between the impedance matching circuit 20 and the voltage doubler rectifier circuit 30 to compensate for the input impedance drift of the voltage doubler rectifier circuit 30.

[0026] In this embodiment, the reactive element is either a capacitor or an inductor.

[0027] In this embodiment, the switching transistor is an NPN type switching transistor.

[0028] Specifically, the energy storage module 40 stores the collected energy. A voltage signal can be drawn from the energy storage module 40 to supply the voltage generation module 51, causing the voltage generation module 51 to output a fixed voltage (reference voltage). The reference voltage is divided by two resistors (voltage divider resistor R1 and thermistor RT) and then connected to the control terminal (base) of the NPN switching transistor. The first terminal (emitter) of the NPN switching transistor is grounded, and the second terminal (collector) of the NPN switching transistor is connected between the impedance matching circuit 20 and the voltage doubler rectifier circuit 30 in the main path through a reactive element (inductor or capacitor).

[0029] In one embodiment of the present invention, the temperature compensation circuit 50 further includes a first capacitor C1, one end of which is connected to the output terminal of the voltage generation module 51, and the other end of which is grounded.

[0030] Specifically, the first capacitor C1 is connected between ground and the output terminal of the voltage generation module 51 to reduce the influence of voltage pulses on the reference voltage output by the voltage generation module 51.

[0031] In embodiments of the present invention, the thermistor RT can be a thermistor with a positive temperature coefficient or a thermistor with a negative temperature coefficient.

[0032] Specifically, the thermistor RT can be either a thermistor with a positive temperature coefficient or a thermistor with a negative temperature coefficient.

[0033] In one embodiment of the present invention, if the thermistor RT is a positive temperature coefficient thermistor, when the ambient temperature rises and is higher than the first preset temperature, the resistance of the thermistor RT increases, causing the NPN switch to conduct. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit 30, so that the input impedance of the voltage doubler rectifier circuit 30 after compensation by the reactive element still meets the output impedance of the impedance matching circuit.

[0034] Specifically, the thermistor RT is a positive temperature coefficient thermistor. When the ambient temperature is low, the preset output impedance of the impedance matching circuit 20 meets the input impedance requirements of the voltage doubler rectifier circuit 30. At this time, the resistance of the thermistor RT is small, and the voltage drop at the control terminal of the NPN switching transistor will not turn on the NPN switching transistor. As the ambient temperature rises, the preset output impedance of the impedance matching circuit 20 can no longer meet the input impedance requirements of the voltage doubler rectifier circuit 30, and the input impedance of the voltage doubler rectifier circuit 30 drifts. At the same time, the resistance of the thermistor RT in the temperature compensation circuit of this embodiment gradually increases with the rise of the ambient temperature, and the voltage drop at the control terminal of the NPN switching transistor increases. When the ambient temperature rises and exceeds the first preset temperature, the voltage drop across the control terminal of the NPN switching transistor exceeds the NPN switching transistor's turn-on voltage. The collector and emitter of the switching transistor are turned on, and the reactive element is connected between the impedance matching circuit 20 and the voltage doubler rectifier circuit 30 in the main path. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit 30 caused by the rise in ambient temperature.

[0035] In one embodiment of the present invention, if the thermistor RT is a thermistor with a negative temperature coefficient, then when the ambient temperature decreases and is lower than the second preset temperature, the resistance of the thermistor increases, causing the switching transistor to conduct. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit, so that the input impedance of the voltage doubler rectifier circuit 30 after compensation by the reactive element still meets the output impedance of the impedance matching circuit.

[0036] Specifically, the thermistor RT is a negative temperature coefficient thermistor. At higher ambient temperatures, the preset output impedance of the impedance matching circuit 20 meets the input impedance requirements of the voltage doubler rectifier circuit 30. At this time, the thermistor RT has a small resistance, and the voltage drop across the control terminal of the NPN switching transistor will not turn it on. As the ambient temperature decreases, the preset output impedance of the impedance matching circuit 20 can no longer meet the input impedance requirements of the voltage doubler rectifier circuit 30, causing the input impedance of the voltage doubler rectifier circuit 30 to drift. Simultaneously, in this embodiment, the resistance of the thermistor RT in the temperature compensation circuit gradually increases as the ambient temperature decreases, leading to a larger voltage drop across the control terminal of the NPN switching transistor. When the ambient temperature decreases and falls below the second preset temperature, the voltage drop across the control terminal of the NPN switching transistor exceeds the NPN switching transistor's turn-on voltage. This causes the collector and emitter of the switching transistor to conduct, and the reactive element is connected between the impedance matching circuit 20 and the voltage doubler rectifier circuit 30 in the main path. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit 30 caused by the decrease in ambient temperature.

[0037] It should be noted that the first preset temperature and the second preset temperature in the embodiments of the present invention are set by the staff through debugging according to the environment in which the radio frequency energy harvesting system is located in the actual scenario.

[0038] As a specific example, the antenna frequency is set to 2400mHz, and the thermistor RT is selected as a negative temperature coefficient (NTC) thermistor.

[0039] When the RF energy harvesting system 100 is not connected to the temperature compensation circuit 50, during the day when the temperature is high, if the input impedance of the voltage doubler rectifier circuit 30 is... (that is, looking to the right from point A) (see...) Figure 1 That is, looking from point A towards the voltage doubler rectifier circuit 30, the impedance is 20 - j * 10. However, when the temperature is low at night, the input impedance of the voltage doubler rectifier circuit 30 drifts to 20 + j * 10 (looking to the right from point A), at which point the power reflection increases.

[0040] When the RF energy harvesting system 100 is connected to the temperature compensation circuit 50, as the ambient temperature decreases, the resistance of the NTC thermistor increases (as the ambient temperature decreases, the resistance of the negative temperature coefficient (NTC) thermistor increases), and the voltage across the base of the switching transistor increases. When the ambient temperature decreases and is below the second preset temperature, the voltage across the base of the switching transistor exceeds the transistor's turn-on voltage, turning on the transistor's collector and emitter. The reactive component is then connected to the main signal path (between the impedance matching circuit 20 and the voltage doubler rectifier circuit 30). The input impedance of the voltage doubler rectifier circuit 30 (viewed from point A to the right) is 20 + j * 10. After passing through a grounded 2.7pF capacitor (reactive component), the input impedance of the voltage doubler rectifier circuit 30 (viewed from point B to the right) becomes 20 - j * 10, which matches the initial setting value of the impedance matching circuit 20, thus avoiding signal mismatch caused by impedance drift of the voltage doubler rectifier circuit 30.

[0041] In this embodiment, when the ambient temperature is within the initially set range, the main path of the radio frequency energy harvesting system 100 is a normal radio frequency energy harvesting circuit, and the energy is stored in the energy storage module. The reference voltage output by the voltage generation module 51, after being divided by a resistor, is lower than the turn-on voltage of the switching transistor, so the switching transistor does not conduct. When the temperature drops, the input impedance of the voltage doubler rectifier circuit 30 drifts, the resistance of the NTC thermistor increases sharply, the base voltage of the switching transistor increases, the switching transistor conducts, and the reactive component is connected to the main path to compensate for the input impedance at low temperatures.

[0042] See Figure 2 Point 1 in the circle diagram represents the input impedance of point A at low temperature. By connecting a 2.7pF capacitor in parallel, the input impedance of point B becomes the position of point 2 in the circle diagram. After passing through the impedance matching circuit 20, the impedance becomes 50 ohms, which matches the antenna perfectly.

[0043] In this embodiment of the invention, the input impedance at high or low temperatures is automatically compensated by two resistors (voltage divider resistor R1 and thermistor RT), a switching transistor, and a reactive component, thereby improving the overall energy conversion efficiency of the radio frequency energy harvesting system.

[0044] The main feature of this invention is that the voltage doubler rectifier circuit 30 operates under two different input impedance states at high and low temperatures. Within a relatively large temperature fluctuation range, it can achieve good consistency and effectively prevent the problem that a large amount of energy input to the voltage doubler rectifier circuit 30 is reflected back to the antenna 10 and not utilized when impedance mismatch occurs.

[0045] In an embodiment of the present invention, the voltage doubler rectifier circuit 30 may be a Greinacher circuit, see [link to relevant documentation]. Figure 3 The Greinacher circuit consists of two diodes and a capacitor.

[0046] The radio frequency energy harvesting system of this invention incorporates a temperature compensation circuit between the impedance matching circuit and the voltage doubler rectifier circuit. This circuit can automatically compensate for the drift impedance of the voltage doubler rectifier circuit at high or low temperatures, thereby improving the overall energy conversion efficiency of the radio frequency energy harvesting system.

[0047] In the description of this specification, 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.

[0048] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0049] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0050] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0052] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A radio frequency energy harvesting system, characterized in that, The system includes: an antenna, an impedance matching circuit, a voltage doubler rectifier circuit, and an energy storage module, wherein the antenna, the impedance matching circuit, the voltage doubler rectifier circuit, and the energy storage module are connected in sequence; The system further includes a temperature compensation circuit, which is connected to the voltage doubler rectifier circuit and is used to acquire the ambient temperature and compensate for the input impedance drift of the voltage doubler rectifier circuit based on the ambient temperature. The temperature compensation circuit includes a voltage generation module, voltage divider resistors, a thermistor, a switching transistor, and reactive components. The first terminal of the voltage generating module is connected to the output terminal of the energy storage module; the second terminal of the voltage generating module is connected to the first terminal of the voltage dividing resistor; the second terminal of the voltage dividing resistor is connected to the first terminal of the thermistor; the second terminal of the thermistor is grounded; the second terminal of the voltage dividing resistor is connected to the control terminal of the switching transistor; the first terminal of the switching transistor is grounded; the second terminal of the switching transistor is connected to the first terminal of the reactive element; and the second terminal of the reactive element is connected to the voltage multiplier rectifier circuit. The energy storage module provides voltage to the voltage generation module, which in turn provides an output reference voltage. The thermistor provides different voltage divisions to the control terminal of the switching transistor based on the ambient temperature. When the voltage division is greater than the on-state voltage of the switching transistor, the reactive element is connected between the impedance matching circuit and the voltage doubler rectifier circuit to compensate for the input impedance drift of the voltage doubler rectifier circuit.

2. The radio frequency energy harvesting system according to claim 1, characterized in that, The temperature compensation circuit also includes a first capacitor, one end of which is connected to the output terminal of the voltage generation module, and the other end of which is grounded.

3. The radio frequency energy harvesting system according to claim 1, characterized in that, The reactive element is either a capacitor or an inductor.

4. The radio frequency energy harvesting system according to claim 1, characterized in that, The thermistor is either a positive temperature coefficient thermistor or a negative temperature coefficient thermistor.

5. The radio frequency energy harvesting system according to claim 4, characterized in that, If the thermistor is a positive temperature coefficient thermistor, then when the ambient temperature rises and is higher than the first preset temperature, the resistance of the thermistor increases, causing the switching transistor to conduct. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit, so that the input impedance of the voltage doubler rectifier circuit after compensation by the reactive element still meets the output impedance of the impedance matching circuit.

6. The radio frequency energy harvesting system according to claim 4, characterized in that, If the thermistor is a negative temperature coefficient thermistor, then when the ambient temperature decreases and is lower than the second preset temperature, the resistance of the thermistor increases, causing the switching transistor to conduct. The reactive element compensates for the input impedance drift of the voltage doubler rectifier circuit, so that the input impedance of the voltage doubler rectifier circuit after compensation by the reactive element still meets the output impedance of the impedance matching circuit.

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