Multi-mode triple composite vibration energy acquisition device based on frequency division technology and self-powered sensing system

Abstract

The invention provides a multi-mode triple composite vibration energy acquisition device based on a frequency division technology and a self-powered sensing system. The multi-mode triple composite vibration energy acquisition device comprises a shell, an electromagnetic power generation element, an elastic piezoelectric power generation element and a friction nano power generation element, the electromagnetic power generation element comprises a magnet vibrator and a coil, electromechanical coupling control switches are arranged on the two sides of the magnet vibrator respectively, and each electromechanical coupling control switch is connected with one side of the magnet vibrator through a first elastic unit and an inerter which are connected in parallel. A coil is arranged on the shell on the outer side of the magnet vibrator, and electric energy is generated through reciprocating motion of the magnet vibrator; a friction nanometer power generation element is arranged between the magnet vibrator and the electromechanical coupling control switch, and electric energy is generated by changing the distance between the magnet vibrator and the electromechanical coupling control switch; and an elastic piezoelectric power generation element is arranged between the electromechanical coupling control switch and the wall surface of the shell. Automatic switching of electromagnetic power generation, friction power generation and piezoelectric power generation can be realized under excitation of different frequencies.

Description

Technical Field

[0001] The present invention relates to the field of Internet of Things energy supply or the field of automatic energy supply equipment or the field of vibration energy conversion, and in particular to a multi-mode triple-combination vibration energy harvesting device and a self-powered sensing system based on frequency division technology. Background Art

[0002] With the development of Internet of Things (IoT) technology and the requirements of energy conservation and emission reduction, collecting energy from the environment to power the many sensor units in the IoT system and avoiding the current technical bottleneck of trillions of widely distributed sensor systems that consumes manpower and material resources due to battery installation, replacement, and recycling, the development of self-powered sensor systems has extremely important research value and strategic significance.

[0003] Mechanical vibrations in the environment are ubiquitous and are ideal potential recyclable energy. At present, there are three main ways to harvest vibration energy: electromagnetic generator (EMG), piezoelectric generator (PEG) and triboelectric nanogenerator (TENG). Electromagnetic power generation technology is mature and widely used. Its working principle is based on the electromagnetic induction phenomenon. When a conductor moves in a magnetic field, an induced electromotive force will be generated and an electric current will be excited. Common thermal generators, hydroelectric generators, and wind turbines mostly use electromagnetic power generation. Even nuclear power plants are built based on the principle of electromagnetic power generation, which is the only choice for large-scale power generation. The basic principle of piezoelectric power generation is the positive piezoelectric effect of piezoelectric materials. Mechanical vibration causes stress inside the piezoelectric material, which generates positive piezoelectric effect to generate charge and output electrical energy. Among them, piezoelectric power generation devices have many advantages such as high energy density, no electromagnetic interference, easy processing, and easy to achieve miniaturization and integration. They have very broad application prospects and are currently a hot topic of research. The friction nanogenerator is a disruptive technology proposed by Academician Wang Zhonglin in recent years based on friction electrification and Maxwell displacement current. It has unprecedented high-efficiency output performance. Compared with the classical electromagnetic generator, the high efficiency of the friction nanogenerator at low frequency is unmatched by similar technologies. At the same time, it can also be used as a self-driven sensor to sense the information of static and dynamic processes generated by mechanical triggering. It is widely used in mechanical energy recovery such as human activities, vibration wind energy, ocean energy, and water flow.

[0004] Traditional energy harvesting technology can usually only obtain higher output power under resonance conditions, while the power generation performance in non-resonance conditions is very poor, which is also an important reason why energy harvesting devices are difficult to be put into practical use on a large scale. In order to explore new methods to improve the power generation performance of energy harvesting devices, there are currently two main ideas: first, adjust the parameters of the energy harvesting device, or introduce nonlinear characteristics to broaden the resonant frequency band of the device to ensure that the device can achieve efficient energy harvesting in a wide frequency range. However, even if mechanical or circuit methods are used for improvement, the bandwidth of the resonant frequency band is still very limited; second, combine two or more different power generation technologies together to generate electricity simultaneously. Compared with the first idea, the second composite vibration energy harvesting method has a more significant improvement in energy harvesting efficiency due to the superposition of a new energy recovery method. However, due to the different underlying principles of power generation in different power generation modes, simply designing them in a composite way can improve the energy collection efficiency, but because it fails to consider the differences in the power generation modes of each mode under different working conditions, and does not consider the laws of mutual coupling and interaction between multi-mode power generation, it cannot effectively exert the optimal power generation state of each mode under different input profiles, and in some working conditions, it is easy to have the problem that the energy generated by a certain power generation mode is too little and cannot be applied. It may even cause mutual interference between the power generation modes, resulting in the power generation efficiency of certain frequency bands in the composite mode being inferior to the power generation efficiency after adjusting the optimal parameters in the single mode. For example, under low-frequency (usually 0.5-5Hz) vibration input, the performance of friction nano power generation is much better than that of electromagnetic power generation. The extremely small output voltage of electromagnetic power generation at low frequency makes it almost impossible to use it to drive any electronic device that requires a certain threshold voltage (0.2-4V), thus wasting most of the harvested energy. At high frequencies, electromagnetic power generation efficiency has an absolute advantage. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a multi-mode triple composite vibration energy harvesting device and a self-powered sensing system based on frequency division technology, an energy harvesting device integrating electromagnetic power generation, friction power generation and piezoelectric power generation, and applied to the self-powered sensing system, and designs a corresponding frequency division control mechanism based on the dynamic response characteristics of the composite energy harvesting system, and designs a mechanical network device based on the electromechanical similarity theory to realize the frequency division function, so as to ensure that the device can be in the best power generation state under the excitation conditions of different frequencies, and designs a matching self-powered sensing system. The problems of poor matching, mutual influence and mutual constraint between the power generation modes of the traditional multiple composite vibration energy harvesting device are solved, and the power generation efficiency of the energy harvesting device is further improved.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A multi-mode triple composite vibration energy harvesting device based on frequency division technology, comprising a housing, an electromagnetic power generation element, an elastic piezoelectric power generation element and a friction nano power generation element;

[0008] The electromagnetic power generation element includes a magnet vibrator and a coil. The magnet vibrator is located in a shell. Electromechanical coupling control switches are respectively provided on both sides of the magnet vibrator. Each of the electromechanical coupling control switches is connected to one side of the magnet vibrator through a first elastic unit and an inertia capacitor connected in parallel. A coil is provided on the shell outside the magnet vibrator, and electric energy is generated by the reciprocating movement of the magnet vibrator. A friction nano-power generation element is provided between the magnet vibrator and the electromechanical coupling control switch, and electric energy is generated by the change in the distance between the magnet vibrator and the electromechanical coupling control switch. An elastic piezoelectric power generation element is provided between the electromechanical coupling control switch and the wall of the shell.

[0009] Furthermore, the friction nano-power generation element includes a first friction unit and a second friction unit, the first friction unit is installed on one side of the electromechanical coupling control switch, and the second friction unit is installed on one end of the magnet vibrator, and electric energy is generated by changing the distance between the first friction unit and the second friction unit.

[0010] Furthermore, the first friction unit and the second friction unit are made of materials with opposite electron gain and loss properties. The material of the first friction unit is polyoxymethylene or ethyl cellulose; the material of the second friction unit is polytetrafluoroethylene or polydimethylsiloxane.

[0011] Furthermore, the elastic piezoelectric generating element includes a second elastic unit and a piezoelectric element, the piezoelectric element is installed on the wall of the shell, and a second elastic unit is provided between the piezoelectric element and the electromechanical coupling control switch; the stiffness of the second elastic unit is greater than the stiffness of the first elastic unit.

[0012] Furthermore, the elastic piezoelectric generating element is a piezoelectric spring, and the stiffness of the piezoelectric spring is greater than the stiffness of the first elastic unit.

[0013] Furthermore, the inertia coefficient of the inertia capacity is determined according to the operating frequency, the stiffness of the first elastic unit, and the stiffness of the elastic body in the elastic piezoelectric generating element.

[0014] Furthermore, it also includes a conductive device, which connects the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element to the power-consuming end respectively.

[0015] Furthermore, the conductive device includes a conductive slide rail, a conductive sheet and a brush. Conductive slide rails are provided on both sides of the shell, and the conductive slide rails are conductively connected to the coil; brushes are provided at both ends of the electromechanical coupling control switch. When the electromechanical coupling control switch is in an unbalanced position, the brushes contact the conductive slide rails to connect the electromagnetic generating element to the power-consuming end; the elastic piezoelectric generating element and the friction nano generating element are respectively provided with conductive sheets, and the conductive sheets are connected to the power-consuming end.

[0016] A self-powered sensing system comprises the multi-mode triple composite vibration energy harvesting device based on frequency division technology and a load; the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element are respectively connected to the load.

[0017] Furthermore, it also includes a rectifier module and a capacitor; the electromagnetic power generation element, elastic piezoelectric power generation element and friction nano power generation element are respectively connected to the corresponding rectifier modules, and several rectifier modules are connected in parallel at both ends of the capacitor, and the capacitor is connected to the load.

[0018] The beneficial effects of the present invention are:

[0019] 1. The multi-mode triple-composite vibration energy harvesting device based on frequency division technology described in the present invention integrates electromagnetic power generation, friction power generation and piezoelectric power generation, and can be applied to self-powered sensing systems. The device of the present invention has a stable structure and flexible size. Large or miniature energy harvesting devices can be designed according to actual needs. It can be used in distributed sensing systems in various occasions, including but not limited to railway or highway networks, remote areas, farmlands and dangerous places, etc., and one-time installation avoids the manpower and material resources of later maintenance and battery replacement and even potentially dangerous construction conditions.

[0020] 2. The multi-mode triple-composite vibration energy harvesting device based on frequency division technology described in the present invention can realize automatic switching among electromagnetic power generation, friction power generation and piezoelectric power generation under the excitation of different frequencies, which can effectively solve the problems of poor matching, mutual influence and mutual constraint among the power generation modes of traditional multiple composite vibration energy harvesting devices, further improve the power generation efficiency of the energy harvesting device, and provide ideas for the further development of composite vibration energy harvesting devices and self-powered sensing systems.

[0021] 3. The multi-mode triple composite vibration energy harvesting device based on frequency division technology described in the present invention has three power generation modes at the same time, and the device is adaptable to a wide range of environments. The combination of multiple power generation modes ensures the reliability of the energy harvesting device. If one or even two generators fail, the remaining generators can maintain the normal operation of the most important basic components, or send alarm signals and location sharing information for timely maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For ordinary technicians in this field, it is obvious that other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a front view of the multi-mode triple composite vibration energy harvester based on the frequency division technology described in the present invention.

[0024] Figure 2 for Figure 1 Top view of the .

[0025] Figure 3 Schematic diagram of electromechanical coupling control switch.

[0026] Figure 4 The schematic diagram of the circuit of the conductive device of the present invention is shown in FIG.

[0027] Figure 5 It is another schematic diagram of an implementation of the multi-mode triple composite vibration energy harvester based on the frequency division technology described in the present invention.

[0028] Figure 6 Comparison of the output efficiency of the friction nanogenerator and the electromagnetic generator under different frequency inputs.

[0029] Figure 7 This is the force analysis diagram under low frequency excitation.

[0030] Figure 8 This is the force analysis diagram under high frequency excitation frequency.

[0031] In the figure:

[0032] 1-housing; 2-piezoelectric element; 3-hard spring; 4-electromechanical coupling control switch; 5-first friction unit; 6-soft spring; 7-inertia; 8-second friction unit; 9-coil; 10-magnet vibrator; 11-conductive slide rail; 12-conductive sheet; 13-brush; 14-conducting wire; 15-rectifier module; 16-capacitor; 17-load; 18-piezoelectric spring. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "axial", "radial", "vertical", "horizontal", "inner", "outer" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] like Figure 1 and Figure 2 As shown, the multi-mode triple composite vibration energy harvesting device based on frequency division technology described in the present invention includes a housing 1, an electromagnetic power generation element, an elastic piezoelectric power generation element and a friction nano power generation element; the electromagnetic power generation element includes a magnet vibrator 10 and a coil 9, the magnet vibrator 10 is located in the housing 1, and the left and right sides of the magnet vibrator 10 are respectively provided with an electromechanical coupling control switch 4, and the electromechanical coupling control switch 4 on each side is connected to one side of the magnet vibrator 10 through a parallel soft spring 6 and an inertia 7; the housing 1 outside the magnet vibrator 10 is provided with a coil 9, and electric energy is generated by the reciprocating movement of the magnet vibrator 10; a friction nano power generation element is provided between the magnet vibrator 10 and the electromechanical coupling control switch 4, and electric energy is generated by the change in the distance between the magnet vibrator 10 and the electromechanical coupling control switch 4; an elastic piezoelectric power generation element is provided between the electromechanical coupling control switch 4 and the wall surface of the housing 1. It can be seen from the figure that the friction nano power generation elements are respectively provided on the left and right sides of the magnet vibrator 10. The shell 1 encapsulates the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element therein, and the shell 1 is made of a hard insulating material to prevent accidents such as leakage.

[0037] The friction nano-electricity generating element includes a first friction unit 5 and a second friction unit 8, wherein the first friction unit 5 is mounted on one side of the electromechanical coupling control switch 4, and the second friction unit 8 is mounted on one end of the magnet vibrator 10, that is, the first friction unit 5 and the second friction unit 8 are respectively provided on the facing surfaces of the electromechanical coupling control switch 4 and the magnet vibrator 10, and electric energy is generated by the change in the distance between the first friction unit 5 and the second friction unit 8. The structure of the friction unit is a friction layer and a conductive layer, wherein the friction layer is used for contact electrification, and the conductive layer is used for connecting the wire to transmit electric energy to the circuit. In addition, the first friction unit 5 and the second friction unit 8 are made of materials with opposite properties of gaining and losing electrons, wherein the material of the first friction unit 5 is polyoxymethylene or ethyl cellulose; and the material of the second friction unit 8 is polytetrafluoroethylene or polydimethylsiloxane.

[0038] The elastic piezoelectric generating element includes a hard spring 3 and a piezoelectric element 2, wherein the piezoelectric element 2 is mounted on the wall of the housing 1, and a hard spring 3 is provided between the piezoelectric element 2 and the electromechanical coupling control switch 4; the stiffness of the hard spring 3 is greater than the stiffness of the soft spring 6. The inertia coefficient of the inertia capacity 7 of the present invention is determined according to the operating frequency, the stiffness of the hard spring 3 and the stiffness of the soft spring 6.

[0039] like Figure 3 and Figure 4 As shown, the present invention also includes a conductive device, which connects the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element to the power end respectively. The conductive device includes a conductive rail 11, a conductive sheet 12 and a brush 13. The upper and lower sides of the housing 1 are provided with conductive rails 11, and the conductive rails 11 are conductively connected to the coil 9; brushes 13 are provided at both ends of the electromechanical coupling control switch 4. When the electromechanical coupling control switch 4 is in an unbalanced position, the brush 13 contacts the conductive rail 11 to connect the electromagnetic power generation element to the power end; when the electromechanical coupling control switch 4 is in a balanced position, the brush 13 does not contact the conductive rail 11, and the coil 9 is in a disconnected state. The elastic piezoelectric power generation element and the friction nano power generation element are respectively provided with conductive sheets 12, and the conductive sheets 12 are connected to the power end.

[0040] like Figure 2 , the coil 9 is located above and below the magnet vibrator 10 when the balance position. The conductive rail 11 is installed on the upper and lower walls of the housing 1. The conductive rail 11 is in the shape of a rectangular sheet, and there are 4 sheets arranged on the upper left, lower left, upper right and lower right of the housing 1. A rectangular space is opened in the middle to achieve the separation of the brush 13 and the conductive rail 11 when the balance position is in place, so as to avoid the electromagnetic power generation device dissipating the collected vibration energy under low-frequency excitation.

[0041] like Figure 4The circuit schematic diagram of the conductive device shows that there are six groups of rectifier units 15, which are respectively connected to three types of generator modules that are symmetrical on the left and right. Specifically, one end of the wire of the electromagnetic power generation element is connected to the conductive sheet, and the other end is connected to the conductive slide rail 11; one end of the wire of the friction nano power generation element is connected to the first friction unit 5, and the other end is connected to the second friction unit 8; the wire of the elastic piezoelectric power generation element is respectively connected to the opposite sides of the piezoelectric element 2. The circuit after rectification by the rectifier unit 16 is divided into positive (+) and negative (-) circuits. The six positive circuits are connected, the six negative circuits are connected, and then connected to the load 17. At the same time, in order to play the role of voltage stabilization and energy storage, a capacitor 16 is connected in parallel.

[0042] like Figure 5 As shown, in another embodiment of the present invention, the elastic piezoelectric generating element is a piezoelectric spring 18, and the stiffness of the piezoelectric spring 18 is greater than the stiffness of the first elastic unit.

[0043] like Figure 6 The output power of the friction nano-generator and the electromagnetic generator under different frequency inputs is compared. Under low-frequency input, the output power of the friction nano-generator is large and the power generation performance is good, while the output power of the electromagnetic generator is small. Under ultra-low frequency input, due to the internal resistance of the actual model, it cannot output effective power, which is why energy is wasted in the ultra-low frequency band. As the frequency increases, the output power of the friction nano-generator increases linearly, while the output power of the electromagnetic generator increases quadratically. When the frequency is higher than f, the output power of the electromagnetic generator exceeds that of the friction nano-generator. Although the output power of the friction nano-generator also increases, the large friction force at this time will hinder the further improvement of the energy collection efficiency of the electromagnetic generator. Therefore, for high-frequency input, the introduction of the friction nano-generator may cause a decrease in the overall output performance of the device.

[0044] like Figure 7 It is a force analysis diagram under low frequency excitation frequency. Assuming the sine wave excitation Asin(ωt), A is the amplitude, ω is the frequency, and the force at both ends of the soft spring 6 can be expressed as:

[0045] F s =kAsin(ωt)

[0046] Wherein, k is the stiffness coefficient of the soft spring 6.

[0047] The forces at both ends of the inertia capacitor 7 can be expressed as:

[0048] F b =-bω 2 Asin(ωt)

[0049] Where b is the inertia coefficient of the inertia capacity.

[0050] Under low-frequency excitation, it can be seen that the elastic force of the soft spring 6 is significantly greater than the inertia force, so at this time, the magnet vibrator 10 is mainly reciprocated by the force of the soft spring 6, and the friction power generation element works. Since the hard spring 3 is connected in series with the soft spring 6, the force it receives is equal to the sum of the elastic force and the inertia force of the soft spring 6. At this time, the inertia force is relatively small and can be ignored, so the displacement of the hard spring 3 can also be ignored, but because the force exists and cannot be ignored, the piezoelectric element 2 still works.

[0051] like Figure 8 It is a force analysis diagram under high-frequency excitation frequency. Under high-frequency excitation, it can be seen that the elastic force of the soft spring 6 is significantly smaller than the inertia force. At this time, the hard spring 6 begins to show obvious compression and stretching, so the magnetic vibrator 10 and the electromechanical coupling control switch 4 can be regarded as a rigid connection at this time, and the friction power generation element is disconnected. Since the hard spring 3 is connected in series with the inertia, its force is equal to the sum of the elastic force of the soft spring 6 and the inertia force. At this time, the inertia force accounts for the main part and is much larger than the elastic force of the hard spring 3. Therefore, the force of the hard spring 3 drives the magnetic vibrator 10 and the electromechanical coupling control switch 4 to reciprocate together, and the electromagnetic power generation element and the piezoelectric element 2 work at the same time.

[0052] A self-powered sensing system includes the multi-mode three-combination vibration energy harvesting device based on frequency division technology, a load 17, a rectifier module 15 and a capacitor 16; the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element are respectively connected to the load 17; the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element are respectively connected to the corresponding rectifier modules 15, and several rectifier modules 15 are connected in parallel at both ends of the capacitor 16, and the capacitor 16 is connected to the load 17.

[0053] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0054] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-mode triple composite vibration energy harvesting device based on frequency division technology, characterized in that: It comprises a housing (1), an electromagnetic power generation element, an elastic piezoelectric power generation element and a friction nano power generation element; The electromagnetic power generation element comprises a magnetic vibrator (10) and a coil (9). The magnetic vibrator (10) is located in a housing (1). Electromechanical coupling control switches (4) are respectively provided on both sides of the magnetic vibrator (10). Each electromechanical coupling control switch (4) is connected to one side of the magnetic vibrator (10) through a first elastic unit and an inertia (7) connected in parallel. A coil (9) is provided on the housing (1) outside the magnetic vibrator (10), and electric energy is generated by the reciprocating movement of the magnetic vibrator (10). A friction nano-power generation element is provided between the magnetic vibrator (10) and the electromechanical coupling control switch (4), and electric energy is generated by the change in the distance between the magnetic vibrator (10) and the electromechanical coupling control switch (4). An elastic piezoelectric power generation element is provided between the electromechanical coupling control switch (4) and the wall surface of the housing (1).

2. The multi-mode triple composite vibration energy harvesting device based on frequency division technology according to claim 1 is characterized in that: The friction nano-electricity generating element comprises a first friction unit (5) and a second friction unit (8), wherein the first friction unit (5) is mounted on one side of an electromechanical coupling control switch (4), and the second friction unit (8) is mounted on one end of a magnet vibrator (10), and electric energy is generated by a change in the distance between the first friction unit (5) and the second friction unit (8).

3. The multi-mode triple composite vibration energy harvesting device based on frequency division technology according to claim 2 is characterized in that: The first friction unit (5) and the second friction unit (8) are made of materials with opposite electron gain and loss properties. The material of the first friction unit (5) is polyoxymethylene or ethyl cellulose; the material of the second friction unit (8) is polytetrafluoroethylene or polydimethylsiloxane.

4. The multi-mode triple composite vibration energy harvesting device based on frequency division technology according to claim 1 is characterized in that: The elastic piezoelectric generating element comprises a second elastic unit and a piezoelectric element (2); the piezoelectric element (2) is mounted on the wall of the housing (1); a second elastic unit is provided between the piezoelectric element (2) and the electromechanical coupling control switch (4); and the stiffness of the second elastic unit is greater than the stiffness of the first elastic unit.

5. The multi-mode triple composite vibration energy harvesting device based on frequency division technology according to claim 1 is characterized in that: The elastic piezoelectric generating element is a piezoelectric spring (18), and the stiffness of the piezoelectric spring (18) is greater than the stiffness of the first elastic unit.

6. The multi-mode triple composite vibration energy harvesting device based on frequency division technology according to claim 1 is characterized in that: The inertia coefficient of the inertia capacitor (7) is determined according to the operating frequency, the stiffness of the first elastic unit and the stiffness of the elastic body in the elastic piezoelectric generating element.

7. The multi-mode triple composite vibration energy harvesting device based on frequency division technology according to claim 1 is characterized in that: It also includes a conductive device, which connects the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element to the power consumption end respectively.

8. The multi-mode triple composite vibration energy harvesting device based on frequency division technology according to claim 7 is characterized in that: The conductive device comprises a conductive slide rail (11), a conductive sheet (12) and a brush (13); the conductive slide rails (11) are provided on both sides of the housing (1); the conductive slide rails (11) are conductively connected to the coil (9); brushes (13) are provided at both ends of the electromechanical coupling control switch (4); when the electromechanical coupling control switch (4) is in an unbalanced position, the brush (13) contacts the conductive slide rail (11) to connect the electromagnetic power generation element to the power-using end; the elastic piezoelectric power generation element and the friction nano power generation element are respectively provided with conductive sheets (12), and the conductive sheets (12) are connected to the power-using end.

9. A self-powered sensing system, characterized in that: It comprises a multi-mode triple composite vibration energy harvesting device based on frequency division technology as described in any one of claims 1 to 8 and a load (17); the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element are respectively connected to the load (17).

10. The self-powered sensing system according to claim 1, characterized in that: It also includes a rectifier module (15) and a capacitor (16); the electromagnetic power generation element, the elastic piezoelectric power generation element and the friction nano power generation element are respectively connected to the corresponding rectifier modules (15), a plurality of rectifier modules (15) are connected in parallel at both ends of the capacitor (16), and the capacitor (16) is connected to a load (17).

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