CN118399614A - Energy harvesting circuit and visible light information and energy simultaneous transmission system - Google Patents

Abstract

The invention discloses an energy acquisition circuit and a visible light information and energy co-transmission system, and relates to the field of photoelectric detection, wherein the energy acquisition circuit comprises a boost circuit, and the boost circuit comprises a maximum power point adjusting unit, an output control unit and an output unit which are all connected with a first chip; and the energy management circuit comprises an energy input unit, an energy storage unit, an energy output unit, a first threshold setting unit and a second threshold setting unit which are all connected with the second chip. The invention can adjust according to the requirements of the maximum power point voltage of different photoelectric conversion devices, so that the photoelectric conversion devices work at the maximum power point, and further the system keeps higher energy acquisition power, thereby realizing the balance and regulation of the energy acquisition power and the communication rate, the efficient utilization of wireless acquisition energy and the stable self-power supply of the load of the receiving end of the system.

Description

Energy harvesting circuit and visible light information and energy simultaneous transmission system

Technical Field

The present invention relates to the field of photoelectric detection technology, in particular to an energy collection circuit and a visible light information and energy transmission system.

Background technique

In the past decade, light-emitting diodes (LEDs) have developed rapidly. With their light intensity change rate faster than the human eye can recognize, LEDs can realize coded data communication, which provides light source conditions for data transmission using visible light. In addition to the problem of high energy consumption, traditional communication equipment also faces problems such as crowded communication frequency bands and electromagnetic radiation pollution. Therefore, the visible light information and energy transmission system has become a key technology for information transmission and power supply for IoT devices with its advantages of no electromagnetic interference, unlimited frequency bands, high communication speeds and good security.

The emerging photovoltaic technology has shown amazing capabilities in energy collection. It has high power conversion efficiency and good flexibility, and can effectively solve the problem of low photoelectric energy conversion efficiency of photodetectors commonly used in visible light communication. Therefore, solar cells can be used as data receivers in visible light communication, and a new communication system has been developed, which uses solar cells as the receiving end of visible light communication to achieve simultaneous transmission of energy and information. This system can be applied to IoT terminals to provide energy for IoT devices while achieving communication.

The existing visible light information and energy transmission system needs to introduce a DC-DC boost circuit to achieve energy collection, but the DC-DC boost circuit also requires an additional field effect transistor drive circuit, which is complex in design and high in power consumption. If the power collected by the photoelectric conversion device is low, it cannot power this high-power circuit, and an external power supply is required. In addition, the DC-DC boost circuit will bring noise, which has a negative impact on information transmission.

Furthermore, the above circuit design that does not include an energy storage function also requires an external power supply for active devices in signal processing circuits such as amplification, filtering and comparison circuits, and cannot achieve continuous self-power supply.

In addition, existing visible light information and energy transmission systems usually require the introduction of maximum power point tracking circuits to achieve efficient energy collection. At the same time, there are few studies on the management of wirelessly collected electrical energy.

Therefore, the present invention proposes a new circuit design scheme for energy harvesting, so as to enable the photoelectric conversion device to operate at the maximum power harvesting point, effectively manage the collected electric energy, and enable the receiving end to operate normally without an external power supply module, so as to balance and regulate the energy harvesting power and the communication rate. That is, the present invention can simultaneously have the characteristics of maximum power point tracking, low power consumption, electric energy management, and voltage-regulated output.

Summary of the invention

In view of the problems existing in the prior art, the present invention is proposed.

Therefore, the first object of the present invention is to provide an energy harvesting circuit, which can not only realize the storage and management of electrical energy, but also can be adjusted according to the requirements of the maximum power point voltage of different photoelectric conversion devices, so that they all work at maximum power, thereby enabling the system to maintain a higher energy harvesting power.

To solve the above technical problems, the present invention provides the following technical solutions: an energy collection circuit, comprising: a boost circuit, comprising a maximum power point adjustment unit, an output control unit and an output unit, all of which are connected to a first chip, the maximum power point adjustment unit is used to adjust the voltage at the input end of the boost circuit to be at a maximum power collection point; an energy management circuit, comprising an energy input unit, an energy storage unit, an energy output unit and a first threshold setting unit and a second threshold setting unit, all of which are connected to a second chip, the energy input unit is also connected to the output unit, the first threshold setting unit is used to adjust the charge and discharge thresholds of the energy storage unit and the output voltage of the energy output unit.

As a preferred solution of the energy harvesting circuit described in the present invention, the maximum power point adjustment unit includes a first capacitor, a first resistor and a second resistor, the positive electrode of the first capacitor is connected to the input end of the boost circuit and the positive electrode of the first resistor, the negative electrode of the first capacitor is grounded, the positive electrode of the first resistor and the input end of the boost circuit are also connected to the first chip, the negative electrode of the first resistor is connected to the positive electrode of the second resistor, and the negative electrode of the second resistor is grounded.

As a preferred solution of the energy harvesting circuit of the present invention, the output control unit includes a second capacitor and a control module, the second capacitor is used to filter out ripples, and the control module is used to control the output voltage of the output unit.

As a preferred solution of the energy harvesting circuit described in the present invention, wherein: the output unit includes a boost circuit output end and a fourth capacitor, the positive electrode of the fourth capacitor is connected to the boost circuit output end and the first chip, and the negative electrode of the fourth capacitor is grounded.

As a preferred solution of the energy harvesting circuit described in the present invention, wherein: the energy input unit includes a backup power supply module, an energy management circuit input end, a first diode and a fifth capacitor, the backup power supply module is connected to the second chip, the anode of the first diode is connected to the energy management circuit input end, the cathode of the first diode is connected to the second chip, the positive electrode of the fifth capacitor is connected to the cathode of the first diode, and the negative electrode of the fifth capacitor is grounded.

As a preferred solution of the energy harvesting circuit of the present invention, the energy storage unit includes a seventh capacitor and an eighth capacitor connected in parallel, the positive electrodes of the seventh capacitor and the eighth capacitor are both connected to the second chip, the negative electrode of the seventh capacitor is connected to the cathode of the second diode, the negative electrode of the eighth capacitor is connected to the anode of the second diode, and the anode and cathode of the second diode are both grounded.

As a preferred solution of the energy harvesting circuit described in the present invention, wherein: the first threshold setting unit includes a third resistor, a fourth resistor and a fifth resistor, the positive electrodes of the third resistor, the fourth resistor and the fifth resistor are all connected to the second chip, the negative electrode of the third resistor is grounded, the negative electrode of the fourth resistor is connected to the positive electrode of the third resistor, and the negative electrode of the fifth resistor is connected to the positive electrode of the fourth resistor; the second threshold setting unit includes a sixth resistor, a seventh resistor and a tenth capacitor, the sixth resistor is connected to the tenth capacitor in parallel and the positive and negative electrodes are both connected to the second chip, the positive electrode of the seventh resistor is connected to the negative electrode of the sixth resistor and the tenth capacitor, and the negative electrode of the seventh resistor is grounded.

As a preferred solution of the energy harvesting circuit described in the present invention, the energy output unit includes a first output end and a second output end of the energy storage unit connected to the energy storage unit through the second chip, and an output end of a low voltage difference linear regulator directly connected to the second chip.

Another object of the present invention is to provide a visible light information and energy transmission system, which can achieve the balance and regulation of energy collection power and communication rate that cannot be achieved in the prior art, the efficient use of wireless collection energy and the stable self-power supply of the system receiving end load.

In order to solve the above technical problems, the present invention provides the following technical solutions: a visible light information and energy transmission system, which includes a transmitting end, which includes a first microprocessor, an LED driving circuit, and an LED module, the output end of the first microprocessor is connected to the input end of the LED driving circuit, and the output end of the LED driving circuit is connected to the input end of the LED module; a receiving end, which includes a photoelectric conversion device, an information and energy decoupling circuit, the energy collection circuit, a signal processing circuit and a second microprocessor, the input end of the photoelectric conversion device receives visible light from the LED module, and the output end of the photoelectric conversion device is connected to the input end of the information and energy decoupling circuit.

As a preferred solution of the visible light information and energy transmission system described in the present invention, the information and energy decoupling circuit includes an energy collection branch for collecting electrical energy, which includes an eighth resistor; a current control branch, which includes a ninth resistor; an information transmission branch for transmitting electrical signals, which includes a fourteenth capacitor and a tenth resistor connected in series, and an output unit connected in parallel with the tenth resistor; the current control branch is used to control the current flowing into the information transmission branch; the output end of the energy collection branch is connected to the input end of the energy collection circuit, and the energy collection circuit supplies power to the signal processing circuit.

The beneficial effects of the present invention are as follows: the present invention can be adjusted according to the requirements of the maximum power point voltage of different photoelectric conversion devices so that they all work at the maximum power, thereby enabling the system to maintain a relatively high energy collection power, thereby achieving the balance and regulation of energy collection power and communication rate, as well as the efficient use and management of wireless collection energy and the stable self-power supply of the system receiving end load.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

FIG1 is a schematic diagram of a boost circuit in an energy harvesting circuit.

FIG2 is a schematic diagram of an energy management circuit of an energy harvesting circuit.

FIG3 is a schematic diagram of a voltage stabilization circuit in an energy harvesting circuit.

FIG4 is a block diagram showing the principle of a visible light information and energy transmission system.

FIG5 is a circuit diagram for decoupling information and energy in a visible light information and energy co-transmission system.

FIG6 is a schematic diagram of the switch closure of the information and energy decoupling circuit in the energy harvesting mode.

FIG. 7 is a schematic diagram of the switch closure of the information and energy decoupling circuit in the information transmission mode.

FIG8 is a schematic diagram of the switch closure of the information and energy decoupling circuit in the information and energy co-transmission mode.

FIG9 is a graph showing how the output voltage-current characteristics of a photoelectric conversion device vary with transmission distance.

FIG10 is a graph showing the output voltage-power characteristics of a photoelectric conversion device as a function of transmission distance.

FIG. 11 is a curve showing the relationship between the second resistor and the output voltage of the photoelectric conversion device.

FIG. 12 is a curve showing the relationship between the output voltage of the photoelectric conversion device and the charging time of the seventh capacitor when the capacitor is 10 mF.

FIG. 13 is a curve showing the influence of the boost circuit on the output current of the photoelectric conversion device.

FIG. 14 is a curve showing the influence of the output voltage of the photoelectric conversion device on the current of each branch.

FIG15 shows the effect of the output voltage of the photoelectric conversion device on the power and signal-to-interference ratio.

In the figure: 100, boost circuit; 101, maximum power point adjustment unit; 102, output control unit; 103, output unit; 200, energy management circuit; 201, energy input unit; 202, energy storage unit; 203, energy output unit; 204, first threshold setting unit; 205, second threshold setting unit; 300, voltage stabilization circuit; 400, transmitter; 401, first microprocessor; 402, LED drive circuit; 403, LED module; 500, receiver; 501, photoelectric conversion device; 502, information and energy decoupling circuit; 502a, energy collection branch; 502b, current control branch; 502c, information transmission branch; 503, signal processing circuit; 504, second microprocessor; R ₁ , first resistor; R ₂ , second resistor; R ₃ , third resistor;

R ₄ , fourth resistor; R ₅ , fifth resistor; R ₆ , sixth resistor; R ₇ , seventh resistor; R ₈ , eighth resistor;

R ₉ , ninth resistor; R ₁₀ , tenth resistor; C ₁ , first capacitor; C ₂ , second capacitor; C ₃ , third capacitor;

C ₄ , fourth capacitor; C ₅ , fifth capacitor; C ₆ , sixth capacitor; C ₇ , seventh capacitor; C ₈ , eighth capacitor;

_C9 , the ninth capacitor; _C10 , the tenth capacitor; _C11 , the eleventh capacitor; _C12 , the twelfth capacitor; _C13 , the thirteenth capacitor; _C14 , the fourteenth capacitor; IC1, the first chip; IC2, the second chip; IC3, the third chip; S1, the first switch; S2, the second switch; S3, the third switch; S4, the fourth switch; S5, the fifth switch; Port1, the input end of the boost circuit; Port2, the output end of the boost circuit; Port3, the input end of the energy management circuit; Port4, the first output end of the energy storage unit; Port5, the second output end of the energy storage unit; Port6, the output end of the low voltage difference linear regulator; Port12, the input end of the voltage stabilizing circuit; Port13, the output end of the voltage stabilizing circuit.

Detailed ways

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

Example 1

1 to 3 , which are the first embodiment of the present invention, provide an energy harvesting circuit. The energy harvesting circuit includes a boost circuit 100 , an energy management circuit 200 and a voltage stabilizing circuit 300 .

Specifically, as shown in FIG. 1 , the boost circuit 100 includes a first chip IC1 , a maximum power point adjustment unit 101 , an output control unit 102 and an output unit 103 .

Preferably, the first chip IC1 is an energy harvesting chip, and the maximum power point adjustment unit 101 includes a first capacitor _C1 , a first resistor _R1 , a second resistor _R2 , and a boost circuit input terminal Port1, wherein the second resistor _R2 is a variable resistor. The positive electrode of the first capacitor _C1 is connected to the boost circuit input terminal Port1 and the positive electrode of the first resistor _R1 , and the negative electrode of the first capacitor _C1 is grounded. The positive electrode of the first resistor _R1 is connected to the pin VIN of the first chip IC1, and the negative electrode is connected to the pin RUN of the first chip IC1 and the positive electrode of the second resistor _R2 , and the negative electrode of the second resistor _R2 is grounded.

The first resistor _R1 , the second resistor _R2 and the first capacitor _C1 form a maximum power point adjustment unit 101. By adjusting the ratio of the first resistor _R1 to the second resistor _R2 , the output voltage U _DC1 of the photoelectric conversion device can be adjusted so that the photoelectric conversion device is maintained at the maximum power point U _DC1 , that is, the maximum energy collection power is maintained. The adjustment is based on the formula:

Wherein, U _DC1 is the output voltage of the photoelectric conversion device, R1 is the resistance value of the first resistor _R1 , and R2 is the resistance value of the second resistor _R2 .

Preferably, the output control unit 102 includes a second capacitor _C2 and a control module 102a, the positive electrode of the second capacitor _C2 is connected to the pin PRI and the pin MPP of the first chip IC1, and the negative electrode is grounded, for filtering ripples. The control module 102a is connected to the pin OS1 and the pin OS2 of the first chip IC1, and the output voltage of the output unit 103 depends on the connection conditions of the two pins OS1 and OS2, as shown in Table 1.

Table 1 shows the relationship between the output voltage and the connection status of pins OS1 and OS2.

OS1 OS2 Output voltage(V) GND GND 1.8 GND VCC 2.2 VCC GND 3.3 VCC VCC 5.0

Preferably, the output unit 103 comprises a boost circuit output terminal Port2 and a fourth capacitor C ₄ , wherein the fourth capacitor C ₄ has a positive electrode connected to the pin VOUT of the first chip IC1 and the boost circuit output terminal Port2 , and a negative electrode connected to ground.

In addition, in the boost circuit 100, the positive electrode of the third capacitor _C3 is connected to the pin VAUX of the first chip IC1, and the negative electrode is grounded.

The positive electrode of the first inductor _L1 is connected to the pin SW1 of the first chip IC1, and the negative electrode is connected to the pin SW2.

When the circuit is just turned on, the third capacitor _C3 is first fully charged, and then supplies energy to the entire internal circuit of the first chip IC1, so that the chip starts working;

After the first chip IC1 starts working, the photoelectric conversion device converts the electrical energy obtained by light energy into the boost circuit 100 through the boost circuit input terminal Port1 to charge the first capacitor C1. After the first capacitor _C1 is fully charged, the first inductor _L1 is charged, and then the fourth capacitor _C4 is charged.

After the fourth capacitor _C4 is fully charged, it outputs electric energy to the subsequent circuit through the boost circuit output terminal Port2. When the voltage across the fourth capacitor _C4 is less than the output voltage controlled by the output control unit 102, the first inductor _L1 charges the fourth capacitor _C4 .

In addition, the first chip IC1 pins VSTORE, VCAP, ENVSTR, VCC, ILIMSEL, SS1, SS2, GND, GND and NC are all grounded.

Preferably, the first chip IC1 is an energy harvesting chip LTC3106 produced by ADI, with a static operating current of 1.6 μA and a boost mode when the input voltage is greater than 850 mV.

The preferred capacitance of the first capacitor _C1 is 22μF, the preferred resistance of the first resistor _R1 is 1MΩ, the preferred inductance of the first inductor _L1 is 22μH, the preferred capacitance of the second capacitor _C2 is 0.01μF, the preferred capacitance of the _third capacitor C3 is 2.2μF, and the preferred capacitance of the fourth capacitor _C4 is 47μF.

Specifically, as shown in FIG. 2 , the energy management circuit 200 includes an energy input unit 201 , an energy storage unit 202 , an energy output unit 203 , a first threshold setting unit 204 , a second threshold setting unit 205 , and a second chip IC2 .

Preferably, the energy input unit 201 includes a backup power module 201a, an energy management circuit input terminal Port3, a first diode _D1 , and a fifth capacitor _C5 . The positive electrode of the backup power module 201a is connected to the pin VBAT of the second chip IC2, and the negative electrode is grounded. The energy management circuit input terminal Port3 is connected to the anode of the first diode _D1 , the cathode of the first diode _D1 is connected to the positive electrode of the fifth capacitor _C5 and the pin VDD of the second chip IC2, and the negative electrode of the fifth capacitor _C5 is grounded.

The electric energy output by the boost circuit 100 is input into the energy management circuit 200 through the energy management circuit input terminal Port3. The first diode _D1 can prevent the input electric energy from flowing back, and the fifth capacitor _C5 is used to filter out ripples.

When the external light condition is weak or there is no light, the external input electric energy cannot turn on the second chip IC2, and the backup power module 201a can provide energy for the energy management circuit 200 at this time.

Preferably, the energy storage unit 202 includes a seventh capacitor _C7 and an eighth capacitor _C8 connected in parallel, the cathode of the seventh capacitor _C7 is connected to the cathode of the second diode _D2 , and the anode is connected to the pin VSTORE1 of the second chip IC2, the cathode of the eighth capacitor _C8 is connected to the anode of the second diode _D2 , and the anode is connected to the pin VSTORE2 of the second chip IC2, and the anode and cathode of the second diode _D2 are both grounded.

The seventh capacitor _C7 and the eighth capacitor _C8 are both supercapacitors. Supercapacitors have fast charging and discharging speeds, long cycle life, stable working characteristics, and simple charging and discharging circuits.

The working process of the energy storage unit 202 is as follows: when the voltage across the seventh capacitor _C7 reaches the upper limit voltage of charging, the charging stops, and the seventh capacitor _C7 starts to discharge. During the discharge of the seventh capacitor _C7 , the eighth capacitor _C8 starts to charge. When the voltage across the seventh capacitor _C7 drops to the lower limit voltage of discharge, the discharge stops and charging starts again, and the charging and discharging are repeated until both the seventh capacitor _C7 and the eighth capacitor _C8 reach the upper limit voltage of charging.

When the voltage drop across the eighth capacitor _C8 is greater than the voltage drop across the seventh capacitor _C7 , the eighth capacitor _C8 charges the seventh capacitor _C7 , and the second diode _D2 is used to prevent current backflow during charging.

The pin VOUT1 of the second chip IC2 is connected to the first output terminal Port4 of the energy storage unit, the pin VOUT2 of the second chip IC2 is connected to the second output terminal Port5 of the energy storage unit, and the pin VOUT-LDO of the second chip IC2 is connected to the output terminal Port6 of the low voltage difference linear regulator.

The energy storage unit first output terminal Port4 , the energy storage unit second output terminal Port5 , and the low voltage drop linear regulator output terminal Port6 constitute the energy output unit 203 .

During the light energy collection process, continuous charging may cause chip overvoltage, or undervoltage may occur due to a sudden drop in ambient light energy. In order to enhance the stability of the energy collection circuit, it is necessary to design a voltage threshold to protect the chip and the photoelectric conversion device. In this embodiment, the first threshold setting unit 204 and the second threshold setting unit 205 are both used to set the voltage threshold.

Preferably, the first threshold setting unit 204 includes a third resistor R ₃ , a fourth resistor R ₄ and a fifth resistor R ₅ , wherein the positive electrode of the third resistor R ₃ is connected to the pin SET-VOUTTL of the second chip IC2, and the negative electrode is grounded. The positive electrode of the fourth resistor R ₄ is connected to the pin SET-VOUTH of the second chip IC2, and the negative electrode is connected to the positive electrode of the third resistor R ₃ . The positive electrode of the fifth resistor R ₅ is connected to the pin SET-VOUTFB of the second chip IC2, and the negative electrode is connected to the positive electrode of the fourth resistor R ₄ .

The first threshold setting unit 204 can design the thresholds for charging and discharging of the supercapacitors _C7 and _C8 . Since the output voltage values of the first output terminal Port4 of the energy storage unit and the second output terminal Port5 of the energy storage unit are equal to the voltage values across the supercapacitors, the first threshold setting unit 204 can set the upper and lower thresholds for the output voltages of the first output terminal Port4 of the energy storage unit and the second output terminal Port5 of the energy storage unit. The formula for the upper and lower thresholds is:

Wherein, V _VOUTTH is the upper threshold, V _VOUTTL is the lower threshold, R3 is the resistance value of the third resistor _R3 , R4 is the resistance value of the fourth resistor _R4 , and R5 is the resistance value of the fifth resistor _R5 .

The second threshold setting unit 205 includes a sixth resistor R ₆ , a seventh resistor R ₇ and a tenth capacitor C ₁₀ . The sixth resistor R ₆ has a positive electrode connected to the pin VOUT-LDO of the second chip IC2 and a negative electrode connected to the pin FB-DO of the second chip IC2. The tenth capacitor C ₁₀ has a positive electrode connected to the positive electrode of the sixth resistor R ₆ and the output terminal Port6 of the low voltage difference linear regulator and a negative electrode connected to the negative electrode of the sixth resistor R ₆ . The seventh resistor R ₇ has a positive electrode connected to the negative electrode of the tenth capacitor C ₁₀ and a negative electrode of the seventh resistor R ₇ is grounded. The tenth capacitor C ₁₀ is used to filter out ripples. The second threshold setting unit 205 is used to set the output voltage V _LDO of the built-in low voltage difference linear regulator (used to output a stable voltage) of the second chip IC2, that is, to set the output voltage of the output terminal Port6 of the low voltage difference linear regulator. The output voltage satisfies the formula:

Wherein, V _LDO is the output voltage of the low voltage dropout linear regulator built in the second chip IC2 , R6 is the resistance value of the sixth resistor _R6 , and R7 is the resistance value of the seventh resistor _R7 .

In addition, in the energy management circuit 200 , the positive electrode of the eleventh capacitor C ₁₁ is connected to the pin VOUT2 of the second chip IC2 and the pin VIN-LDO of the second chip IC2 , and the negative electrode is grounded. The eleventh capacitor C ₁₁ is used to filter out ripples.

The positive electrode of the ninth capacitor _C9 is connected to the pin VINT of the second chip IC2, and the negative electrode is grounded. When the circuit is just connected, the ninth capacitor _C9 is fully charged first to supply energy to the internal circuit of the second chip IC2, so that the chip starts to work.

The pin AGND of the second chip IC2 is grounded.

The second chip IC2 pins STBY-LDO, ENA-LDO, INT, CIN2 and SW-CNT are connected to the microprocessor, that is, Port7, Port8, Port9, Port10, Port11 are all microprocessor ports. When the microprocessor outputs a high-level signal to the pin STBY-LDO, the pin VOUT1 outputs electrical energy; when the microprocessor outputs a low-level signal to the pin STBY-LDO, the pin VOUT1 is turned off;

When the microprocessor outputs a high level signal to the ENA-LDO pin, the VOUT2 pin outputs electrical energy. When the microprocessor outputs a low level signal to the ENA-LDO pin, the VOUT2 pin is turned off.

If the pin CIN2 is grounded, the timer function of the second chip IC2 will be turned on, and the sixth capacitor _C6 will control the output of the pin VOUT2;

If the microprocessor outputs a low level signal to any one or both of the STBY-LDO and ENA-LDO pins of the second chip IC2, the pin VOUT-LDO is turned off;

If the microprocessor outputs high level signals to both the STBY-LDO and ENA-LDO pins of the second chip IC2, the pin VOUT-LDO outputs electrical energy.

Preferably, the second chip IC2 is Infineon's S6AE102A, which is a chip for indoor light energy collection and has the characteristics of ultra-low power consumption, a static current of only 280nA, and a startup power of 1.2μW. It can manage the electric energy output by the boost circuit 100, including storage element charge and discharge threshold setting, backup battery management, and multi-channel output selection.

The preferred capacitance of the fifth capacitor _C5 is 10μF, the preferred resistance of the third resistor _R3 is 9.1MΩ, the preferred resistance of the fourth resistor _R4 is 1.93MΩ, the preferred resistance of the fifth resistor _R5 is 3.25MΩ, the preferred capacitance of the sixth capacitor _C6 is 1nF, the preferred capacitance of the ninth capacitor _C9 is 1μF, the preferred capacitance of the tenth capacitor _C10 is 1μF, the preferred capacitance of the eleventh capacitor _C11 is 1μF, the preferred resistance of the sixth resistor _R6 is 2.4MΩ, the preferred resistance of the seventh resistor _R7 is 4MΩ, the value of the seventh capacitor _C7 is determined according to the energy consumption of the next-level signal processing circuit connected subsequently, the value of the eighth capacitor _C8 is determined according to the value of the seventh capacitor _C7 , and the capacitance of the eighth capacitor _C8 should be greater than the capacitance of the seventh capacitor _C7 .

The specific process of the signal processing circuit energy consumption test is as follows: a voltage regulator is used to power the active devices in the signal processing circuit, a signal generator is used to output a small signal into the signal processing circuit, and the output signal of the signal processing circuit is observed through an oscilloscope while adjusting the parameters in the signal processing circuit until the peak value of the output signal reaches 3.3V (3.3V can meet the level standard of the subsequent microprocessor), and the reading of the voltage regulator is observed, and the power consumption P of the signal processing circuit is read as 202.5μW.

Then the value of the seventh capacitor _C7 is calculated according to the following formula:

Wherein, W is the energy consumption of the signal processing circuit (also the energy stored in the process of the voltage across the seventh capacitor _C7 rising from 0V to the voltage upper limit threshold), T is the working cycle of the signal processing circuit, C is the capacitance of the seventh capacitor _C7 , and U is the set upper voltage threshold.

In this embodiment, the value of the seventh capacitor _C7 is 10 mF, and the value of the eighth capacitor _C8 is 500 mF.

Since the output voltage of the first output terminal Port4 of the energy storage unit and the second output terminal Port5 of the energy management circuit 200 is equal to the voltage across the seventh capacitor _C7 and the eighth capacitor _C8 , the output voltage will increase and decrease with the charging and discharging of the capacitor. In order to provide a stable voltage for the subsequent load, it is necessary to add a voltage stabilizing circuit 300 after the first output terminal Port4 of the energy storage unit and the second output terminal Port5 of the energy storage unit.

Specifically, as shown in FIG3 , the voltage stabilizing circuit 300 includes a third chip IC3, a twelfth capacitor _C12 , and a thirteenth capacitor _C13 . The positive electrode of the twelfth capacitor _C12 is connected to the input terminal Port12 of the voltage stabilizing circuit, the pin VIN and the pin EN of the third chip IC3, and the negative electrode is grounded. The positive electrode of the thirteenth capacitor _C13 is connected to the output terminal Port13 of the voltage stabilizing circuit and the pin VOUT of the third chip IC3, and the negative electrode is grounded. The pin GND of the third chip IC3 is grounded. The output terminal Port13 of the voltage stabilizing circuit can be used to power the active devices in the next level circuit. The twelfth capacitor _C12 and the thirteenth capacitor _C13 are used for energy storage and filtering.

Preferably, the third chip IC3 is a low voltage drop linear voltage regulator chip ADP160 produced by ADI. The preferred capacitance values of the twelfth capacitor C12 and the thirteenth capacitor C13 are both 1 μF.

In summary, the beneficial effects of the energy harvesting circuit of the present invention are:

1. The boost circuit 100 can realize the function of maximum power point regulation. The voltage at the maximum power point can be adjusted by adjusting the resistance values of the first resistor _R1 and the second resistor _R2 , so as to facilitate adjustment according to the requirements of the maximum power point voltage of different photoelectric conversion devices, so that they all work at the maximum power, thereby maintaining a higher energy collection power of the system;

2. The boost circuit 100 can achieve stable output of the current of the photoelectric conversion device, which is convenient for the subsequent distribution and regulation of the current;

3. The energy management circuit 200 can realize the storage and management of electric energy, including the setting of storage element charge and discharge thresholds, backup battery management and multi-channel output selection;

4. The voltage stabilizing circuit 300 can provide stable power supply to subsequent loads.

Example 2

Referring to Figures 1 to 15, the second embodiment of the present invention is based on the previous embodiment. This embodiment provides a visible light information and energy transmission system. The energy collection circuit in the system adopts the energy collection circuit described in Example 1.

Specifically, as shown in Figure 4, the system also includes a transmitting end 400, which includes a first microprocessor 401, an LED driving circuit 402, and an LED module 403. The output end of the first microprocessor 401 is connected to the input end of the LED driving circuit 402, and the output end of the LED driving circuit 402 is connected to the input end of the LED module 403.

The first microprocessor 401 of the transmitting end 400 is used for signal modulation and encoding. The function of the LED driving circuit 402 is to input a current of appropriate magnitude to both ends of the LED module 403 so that the light intensity of the LED module 403 changes rapidly to transmit information.

The receiving end 500 includes a photoelectric conversion device 501 , an information and energy decoupling circuit 502 , the energy collection circuit described in Embodiment 1, a signal processing circuit 503 and a second microprocessor 504 .

First of all, it should be noted that the information and energy decoupling circuit 502 includes three branches, as shown in Figure 5, namely, an energy collection branch 502a, a current control branch 502b and an information transmission branch 502c. The output end of the energy collection branch 502a is connected to the input end of the energy collection circuit of Example 1.

The energy collection branch 502a includes a first switch _S1 and an eighth resistor _R8 , wherein the eighth resistor _R8 is a variable resistor, and its cathode is connected to the energy collection branch output terminal Port14. The energy collection branch 502 is used to collect electrical energy.

The current control branch 502 b includes a second switch S ₂ and a ninth resistor R ₉ . The ninth resistor R ₉ is a variable resistance resistor, and a negative electrode thereof is grounded.

The information transmission branch 502c includes a third switch _S3 , a fourteenth capacitor _C14 and a tenth resistor _R10 , wherein the tenth resistor _R10 is a variable resistor, and its negative electrode is grounded. A node is taken at the wire connecting the fourteenth capacitor _C14 and the tenth resistor _R10 , and the node is connected to the output unit 502d. The output unit 502d includes a first branch and a second branch connected in parallel, wherein the first branch includes a fourth switch _S4 and a fifteenth output terminal Port15, and the second branch includes a fifth switch _S5 and a sixteenth output terminal Port16.

The energy collection branch 502a, the current control branch 502b and the information transmission branch 502c are respectively connected to the seventeenth input terminal Port17. The seventeenth input terminal Port17 is connected to the output terminal of the photoelectric conversion device 501. The photoelectric conversion device 501 outputs an alternating current defined as I _AC and a direct current defined as I _DC . The direct current I _DC represents electrical energy and the alternating current I _AC represents an electrical signal. Both are input into the decoupling circuit through the seventeenth input port Port17, and then divided into three branches. The current flowing through the energy collection branch 502a is defined as the energy collection branch AC current I _AC1 and the DC current I _DC1 , the current flowing through the current control branch 502b is defined as the current control branch AC current I _AC2 and the DC current I _DC2 , and the current flowing through the information transmission branch 502c is defined as the information transmission branch AC current I _AC3 and the DC current I _DC3 . The signal output through the eighth resistor R ₈ in the energy collection branch 502a is called the photoelectric conversion device output voltage U _DC1 , that is, the photoelectric conversion device output voltage U _DC1 in Example 1. The signal output through the fourteenth capacitor C ₁₄ in the information transmission branch 502c is called the fourteenth capacitor C ₁₄ output voltage U _C. The current control branch 502b is used to control the AC current I _AC3 flowing into the information transmission branch 502c, and the information transmission branch 300 is used to transmit electrical signals.

The first switch S ₁ , the second switch S ₂ , and the third switch S ₃ are used to control the on and off of the three branches. The fourth switch S ₄ and the fifth switch S ₅ are used to control the flow direction of the output signal at the output end of the fourteenth capacitor C ₁₄ in the information transmission branch 502 c. The eighth resistor R ₈ , the ninth resistor R ₉ , the tenth resistor R ₁₀ and the fourteenth capacitor C ₁₄ are used to separate and regulate the output alternating current I _AC and the direct current I _DC of the photoelectric conversion device 501.

By controlling the five switches in the decoupling circuit, the entire circuit can exhibit three working modes with different functions, namely energy harvesting mode, information transmission mode and information and energy transmission mode.

Specifically, as shown in FIG6 , when the first switch _S1 is closed, and the second switch _S2 and the third switch _S3 are opened, the receiving end 500 operates in the energy collection mode, and the electric energy output by the photoelectric conversion device 501 can be fully input into the energy collection circuit in Embodiment 1 by adjusting the resistance value of the eighth resistor _R8 to the minimum;

As shown in FIG7 , when the first switch _S1 and the fifth switch _S5 are disconnected, and the second switch _S2 , the third switch _S3 and the fourth switch _S4 are closed, the receiving end 500 works in the information transmission mode, and the distribution of the _AC current IAC output by the photoelectric conversion device 501 between the current control branch 502b and the information transmission branch 502c can be adjusted by adjusting the ninth resistor _R9 and the tenth resistor _R10 , so that the AC current _IAC3 of the information transmission branch 502c is maximized;

As shown in FIG8 , when the second switch S ₂ and the fourth switch S ₄ are disconnected, and the first switch S ₁ , the third switch S ₃ and the fifth switch S ₅ are closed, the receiving end 500 operates in the information and energy transmission mode, and the fourteenth capacitor C ₁₄ has the characteristics of blocking direct current and passing alternating current, and can suppress the direct current I _DC output by the photoelectric conversion device 501 from being input into the information transmission branch 502c, so that most of the electric energy flows into the energy collection branch 502a. In addition, by adjusting the resistance values of the eighth resistor R ₈ and the tenth resistor R ₁₀ , the distribution of the alternating current I _AC output by the photoelectric conversion device 501 between the energy collection branch 502a and the information transmission branch 502c can be adjusted, so that the alternating current I _AC3 of the information transmission branch 502c is maximized.

It should be noted that the proportion of the AC current I _AC distribution can be expressed by the following formula:

Wherein, ω is the angular frequency of the optical signal output by the transmitting end 400, j is an imaginary number, R9 is the resistance value of the ninth resistor _R9 , R10 is the resistance value of the tenth resistor _R10 , and C14 is the capacitance value of the fourteenth capacitor _C14 .

This embodiment mainly studies the energy collection mode. In order to better verify the technical effect of the present invention, test data is used to illustrate it. It should be noted that the following test results are based on the visible light information and energy transmission system using the energy collection circuit described in Example 1:

As shown in Figures 9 to 12, they are the test results of the information and energy transmission system in the energy collection mode (the eighth resistor _R8 in the energy collection branch is set to 0Ω), and Figures 13 to 15 are the test results of the information and energy transmission system in the information and energy transmission mode.

FIG9 shows the output voltage (U _DC1 )-current (I _DC1 ) characteristics of the photoelectric conversion device as a function of the transmission distance (d). The test method is as follows: the transmission distance between the LED module 403 and the photoelectric converter 501 (photovoltaic cell) is changed, and the output voltage U _DC1 and the output current I _DC1 of the photoelectric converter 501 are measured using a multimeter.

FIG10 shows the output voltage (U _DC1 )-power (P _DC1 ) characteristics of the photoelectric conversion device as a function of the transmission distance (d). The output power of the photoelectric conversion device is the product of the output voltage and the output current, so the curve can be drawn based on FIG9 .

It can be seen from the test results that the output current of the photoelectric conversion device gradually decreases as the output voltage increases, and the output power increases first and then decreases as the output voltage increases. Therefore, when the lighting conditions are constant, the maximum power point of the photoelectric conversion device 501 is related to the output voltage. When the lighting conditions change, that is, when the distance between the LED module 403 and the photoelectric conversion device 501 increases, the output voltage corresponding to the maximum power point gradually shifts to the left. Therefore, when we increase the transmission distance, we need to adjust the boost circuit to increase the output voltage U _DC1 of the photoelectric conversion device, so that the photoelectric conversion device 501 works at the maximum power point.

After determining the change position of the maximum power point of the photoelectric conversion device 501, in order to make the energy harvesting circuit store electrical energy to meet the power supply requirements of subsequent loads, it is necessary to perform more detailed tests on the relevant parameters involved in the capacitor energy storage process.

First, the upper voltage threshold of the energy management circuit 200 is set to 4V, and the lower voltage threshold is set to 3.3V. Then, the relationship between the charging performance parameters of a 10mF capacitor and the distance is tested. The test results are shown in Table 2.

Table 2 compares the data of 10mF energy storage capacitor at different distances.

Transmission distance (cm) 5 10 15 20 25 Charging time(s) 71 112 216 365 570 Storable energy (mJ) 101.8 101.8 101.8 101.8 101.8 Charging power (mW) 1.434 0.910 0.471 0.279 0.179

The charging time of capacitors with different capacitance values was repeatedly tested with a fixed transmission distance of 5 cm. The test results are shown in Table 3.

Table 3 The charging time required for energy storage capacitors with different capacitance values when the transmission distance is 5cm.

Capacitance(mF) 10 100 470 First charging time(s) 71.6 549.5 2569.7 Second charging time(s) 70.4 553.3 2571.1 The third charging time (s) 72.3 548.7 2563.3 Average charging time(s) 71.4 550.5 2567.4

The performance parameters and test results of capacitors with different capacitance values are shown in Table 4.

Table 4 Performance parameters of capacitors with different capacitance values.

Performance 10mF 100mF 470mF Storable energy (mJ) 101.800 800.000 3760.000 Average charging time(s) 71.400 550.500 2567.400 Average charging power (mW) 1.426 1.453 1.465

In this process, after measuring a set of data, a resistor needs to be connected at both ends of the capacitor to release the electrical energy stored in the capacitor. And after completing a capacitor energy storage test, the next set of experiments should be conducted 5 minutes apart to reserve time for the circuit to cool down. For each capacitor value, three sets of repetitive experiments are conducted to reduce the impact of random errors.

It can be seen from the test data that as the transmission distance (the distance between the LED module 403 and the photoelectric conversion device 501) increases, the charging time gradually increases and the charging power gradually decreases;

As the size of the storage capacitor increases, the charging time gradually increases, the storable energy gradually increases, and the charging power gradually increases.

FIG11 is a curve showing the relationship between the second resistor _R2 and the output voltage U _DC1 of the photoelectric conversion device. The test method is as follows: the distance between the LED module 403 and the photoelectric conversion device 501 is fixed at 5 cm, the value of the second resistor _R2 is changed, and the value of the output voltage U _DC1 of the photoelectric conversion device is measured with a multimeter. It can be seen that as the second resistor _R2 increases, the output voltage U _DC1 of the photoelectric conversion device decreases. Therefore, the output voltage U _DC1 of the photoelectric conversion device can be adjusted by adjusting the value of the second resistor _R2 , so that the photoelectric conversion device 501 works at the maximum power point.

FIG12 is a curve showing the relationship between the output voltage U _DC1 of the photoelectric conversion device and the charging time of the seventh capacitor C ₇ when the value is 10 mF. The test method is as follows: the upper voltage threshold of the energy management circuit 200 is set to 4V, the lower voltage threshold is set to 3.3V, the distance between the LED module 403 and the photoelectric conversion device 501 is fixed to 5 cm, the value of the second resistor R ₂ is changed, thereby changing the value of the output voltage U _DC1 of the photoelectric conversion device, and the voltage value across the seventh capacitor C ₇ is measured with a multimeter, and the time for the voltage to rise from 0V to the set maximum voltage threshold is recorded. In this process, after measuring a set of data, a resistor needs to be connected across the capacitor to release the electrical energy stored in the capacitor.

It can be seen from the test results that as the output voltage U _DC1 of the photoelectric conversion device increases, the charging time of the supercapacitor first decreases and then increases. It can be seen that there is an output voltage of the photoelectric conversion device that maximizes the output power of the photoelectric conversion device 501, thereby minimizing the charging time of the supercapacitor.

FIG13 is a schematic diagram showing the effect of the boost circuit 100 on the output current of the photoelectric conversion device, U _STORE is the voltage value across the seventh capacitor C ₇ , the second resistor R ₂ is 560 kΩ, the eighth resistor R ₈ in the energy collection branch 502a is 0Ω, and the tenth resistor R ₁₀ in the information transmission branch 502c is 2 kΩ. The test method is: the distance between the LED module 403 and the photoelectric conversion device 501 is fixed to 10 cm, and a multimeter is used to test the changes of the DC current I _DC1 of the energy collection branch 502a and the AC current I _AC3 of the information transmission branch 502c with the voltage across the seventh capacitor C ₇ in the presence and absence of the boost circuit 100 (the energy management circuit 200 and the voltage stabilizing circuit 300 are still present).

It can be seen from the test results that before using the boost circuit 100, as the voltage U _STORE across the seventh capacitor C ₇ increases, I _DC1 and I _AC3 will change. The change of I _DC1 indicates that the output power of the photoelectric conversion device has been changing and cannot be maintained at the maximum power collection point. The change of I _AC3 indicates that the output signal U _C of the fourteenth capacitor C ₁₄ (i.e., the output signal of the information transmission branch 502c) has been changing, which is not conducive to subsequent signal processing. In addition, it is also impossible to prove that adjusting the circuit parameters of the receiving end 400 can regulate the output current distribution of the photoelectric conversion device. After using the boost circuit 100, I _DC1 and I _AC3 remain basically unchanged, indicating that the photoelectric conversion device can be maintained at the maximum power collection point by adjusting the circuit parameters, and the output signal of the information transmission branch 502c is more stable, which is convenient for subsequent signal processing.

The test conditions of FIG. 14 and FIG. 15 are as follows: the distance between the LED module 403 and the photoelectric conversion device 501 is 10 cm, the eighth resistor _R8 in the energy collection branch 502a is 5.6 kΩ, and the tenth resistor _R10 in the information transmission branch 502c is 2 kΩ.

FIG14 is a schematic diagram showing the influence of the output voltage U _DC1 of the photoelectric conversion device on the currents of each branch. It can be seen that as the output voltage U _DC1 of the photoelectric conversion device increases, the currents of each branch gradually decrease.

FIG15 is a schematic diagram showing the effect of the output voltage U _DC1 of the photoelectric conversion device on the power and the signal-to-interference ratio SIR. The test results show that as the output voltage U _DC1 of the photoelectric conversion device increases, the output power P _DC1 of the photoelectric conversion device increases first and then decreases, the power of the eighth resistor R ₈ in the energy collection branch 502a gradually decreases, and the signal-to-interference ratio SIR gradually decreases, that is, the effect of the interference signal on the actual transmission signal becomes smaller and smaller. Adjusting the eighth resistor R ₈ and the second resistor R ₂ in the energy collection branch 502a can adjust the distribution of the current, thereby adjusting the intensity of the interference signal and the actual transmission signal, so as to adjust the SIR of the information transmission branch, and the SIR will affect the communication rate that the system can achieve. However, the eighth resistor R ₈ in the energy collection branch 502a will consume part of the power P _R8 , so that the energy collection power P _DC1 is reduced. It can be seen that the eighth resistor R ₈ and the second resistor R ₂ in the energy collection branch 502a affect the balance between energy collection and information transmission.

In summary, the beneficial effects of the present invention are:

1. The visible light information and energy transmission system of the present invention realizes controllable separation of electrical signals and electrical energy by applying a decoupling circuit, thereby enabling the system to switch between three working modes: energy collection, information transmission, and information and energy transmission.

2. The boost circuit 100 can realize the function of maximum power point regulation. The voltage at the maximum power point can be adjusted by adjusting the resistance values of the first resistor _R1 and the second resistor _R2 , so as to facilitate adjustment according to the maximum power point voltage requirements of different photoelectric conversion devices, so that they all work at maximum power, thereby maintaining a higher energy collection power of the system.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims (10)

1. An energy harvesting circuit, characterized in that: it includes: A boost circuit (100) comprising a maximum power point adjustment unit (101), an output control unit (102) and an output unit (103) all connected to a first chip (IC1), wherein the maximum power point adjustment unit (101) is used to adjust the voltage at an input end (Port1) of the boost circuit to be at a maximum power collection point; An energy management circuit (200) comprises an energy input unit (201), an energy storage unit (202), an energy output unit (203), a first threshold setting unit (204) and a second threshold setting unit (205), all of which are connected to a second chip (IC2); the energy input unit (201) is also connected to the output unit (103); the first threshold setting unit (204) is used to adjust the charge and discharge thresholds of the energy storage unit (202) and the output voltage of the energy output unit (203). 2. The energy harvesting circuit according to claim 1, characterized in that: the maximum power point adjustment unit (101) comprises a first capacitor ( _C1 ), a first resistor ( _R1 ) and a second resistor ( _R2 ), the positive electrode of the first capacitor ( _C1 ) is connected to the boost circuit input terminal (Port1) and the positive electrode of the first resistor ( _R1 ), the negative electrode of the first capacitor ( _C1 ) is grounded, the positive electrode of the first resistor ( _R1 ) and the boost circuit input terminal (Port1) are also connected to the first chip (IC1), the negative electrode of the first resistor ( _R1 ) is connected to the positive electrode of the second resistor ( _R2 ), and the negative electrode of the second resistor ( _R2 ) is grounded. 3. The energy harvesting circuit according to claim 2, characterized in that: the output control unit (102) comprises a second capacitor (C ₂ ) and a control module (102a), the second capacitor (C ₂ ) is used to filter out ripples, and the control module (102a) is used to control the output voltage of the output unit (103). 4. The energy harvesting circuit according to claim 3, characterized in that: the output unit (103) comprises a boost circuit output end (Port2) and a fourth capacitor (C ₄ ), a positive electrode of the fourth capacitor (C ₄ ) is connected to the boost circuit output end (Port2) and the first chip (IC1), and a negative electrode of the fourth capacitor (C ₄ ) is grounded. 5. The energy harvesting circuit according to claim 4, characterized in that: the energy input unit (201) comprises a backup power supply module (201a), an energy management circuit input terminal (Port3), a first diode ( _D1 ) and a fifth capacitor ( _C5 ), the backup power supply module (201a) is connected to the second chip (IC2), the anode of the first diode ( _D1 ) is connected to the energy management circuit input terminal (Port3), the cathode of the first diode ( _D1 ) is connected to the second chip (IC2), the positive electrode of the fifth capacitor ( _C5 ) is connected to the cathode of the first diode ( _D1 ), and the negative electrode of the fifth capacitor ( _C5 ) is grounded. 6. The energy harvesting circuit according to claim 5, characterized in that: the energy storage unit (202) comprises a seventh capacitor ( _C7 ) and an eighth capacitor ( _C8 ) connected in parallel, the positive electrodes of the seventh capacitor ( _C7 ) and the eighth capacitor ( _C8 ) are both connected to the second chip (IC2), the negative electrode of the seventh capacitor ( _C7 ) is connected to the cathode of the second diode (D2), the negative electrode of the eighth capacitor ( _C8 ) is connected to the anode of the second diode (D2), and the anode and cathode of the second diode (D2) are both grounded. 7. The energy harvesting circuit according to claim 6, characterized in that: the first threshold setting unit (204) comprises a third resistor (R ₃ ), a fourth resistor (R ₄ ) and a fifth resistor (R ₅ ), the positive electrodes of the third resistor (R ₃ ), the fourth resistor (R ₄ ) and the fifth resistor (R ₅ ) are all connected to the second chip (IC2), the negative electrode of the third resistor (R ₃ ) is grounded, the negative electrode of the fourth resistor (R ₄ ) is connected to the positive electrode of the third resistor (R ₃ ), and the negative electrode of the fifth resistor (R ₅ ) is connected to the positive electrode of the fourth resistor (R ₄ ); The second threshold setting unit (205) comprises a sixth resistor ( _R6 ), a seventh resistor ( _R7 ) and a tenth capacitor ( _C10 ), the sixth resistor ( _R6 ) and the tenth capacitor ( _C10 ) are connected in parallel and both positive and negative electrodes are connected to the second chip (IC2), the positive electrode of the seventh resistor ( _R7 ) is connected to both the sixth resistor ( _R6 ) and the negative electrode of the tenth capacitor ( _C10 ), and the negative electrode of the seventh resistor ( _R7 ) is grounded. 8. The energy harvesting circuit according to claim 7, characterized in that: the energy output unit (203) includes a first output terminal (Port4) and a second output terminal (Port5) of the energy storage unit connected to the energy storage unit (202) through the second chip (IC2), and an output terminal (Port6) of a low voltage difference linear regulator directly connected to the second chip (IC2). 9. A visible light information and energy transmission system, characterized in that it includes: A transmitting end (400), comprising a first microprocessor (401), an LED driving circuit (402), and an LED module (403), wherein the output end of the first microprocessor (401) is connected to the input end of the LED driving circuit (402), and the output end of the LED driving circuit (402) is connected to the input end of the LED module (403); A receiving end (500), comprising a photoelectric conversion device (501), an information and energy decoupling circuit (502), an energy collection circuit as claimed in any one of claims 1 to 7, a signal processing circuit (503) and a second microprocessor (504), wherein the input end of the photoelectric conversion device (501) receives visible light from the LED module (403), and the output end of the photoelectric conversion device (501) is connected to the input end of the information and energy decoupling circuit (502). 10. The visible light information and energy co-transmission system according to claim 8, characterized in that: the information and energy decoupling circuit (502) comprises: An energy collection branch (502a), used for collecting electric energy, comprising an eighth resistor ( _R8 ); a current control branch (502b), comprising a ninth resistor ( _R9 ); An information transmission branch (502c), used for transmitting electrical signals, comprising a fourteenth capacitor (C ₁₄ ) and a tenth resistor (R ₁₀ ) connected in series, and an output unit (502d) connected in parallel with the tenth resistor (R ₁₀ ); The current control branch (502b) is used to control the current flowing into the information transmission branch (502c); The output end of the energy collection branch (502a) is connected to the input end of the energy collection circuit, and the energy collection circuit supplies power to the signal processing circuit (503).