Low Voltage Energy Harvesting Circuit with Maximum Power Point Tracking

Abstract

The present invention discloses a low-voltage energy collection circuit with maximum power tracking. It includes an input module, a voltage and current detection module, an MCU control module, a boost circuit module, a DC-DC energy management module, an energy storage module, and an output module; the input end of the boost circuit module is connected to the input end of the input module, and the output end is connected to the input end of the DC-DC energy management module; the input end of the voltage and current detection module is connected to the current and voltage collection part of the input module, and the output end is connected to the input end of the MCU control module; the MCU control module controls the on and off of two MOS tubes in the boost circuit module; the energy storage interface pin of the DC-DC energy management module is connected to the input / output end of the energy storage module, and the output end is connected to the input end of the output module. The present invention is specifically used for low-voltage weak energy collection, can realize impedance matching by maximum power tracking, execute different management strategies according to the size of the acquired energy value, and minimize the power consumption of the collection circuit.

Description

Technical Field

[0001] The present invention relates to the technical field of energy harvesting, and in particular to a low-voltage energy harvesting circuit with maximum power tracking. Background Art

[0002] In recent years, the emergence of wireless sensor devices has changed the traditional data collection and monitoring methods, and is widely used in environmental monitoring, power plant temperature and pressure monitoring, factory gas monitoring and other fields. The above-mentioned communication modules and sensor modules are usually very small in size, with low communication power consumption and sensor working power consumption, and the required power is also very small. For wired networking modules, the traditional power supply method is direct wire power supply, while for wireless networking modules, the traditional power supply method is battery power supply.

[0003] However, these IoT devices have different operating environments and are huge in number. With the increasing number of communication modules and sensor modules, the complexity and maintenance difficulty of direct wire power supply have increased significantly, and wiring is difficult in complex environments, and wiring is prone to loosening in high-frequency vibration environments. Chemical battery power supply has limited power and requires regular manual maintenance and battery replacement. As the number of devices increases, labor costs will also increase significantly. In addition, the large-scale use of chemical batteries will eventually cause pollution and damage to the environment, which runs counter to the concept of green development.

[0004] Therefore, people began to use energy such as light, wind, heat, and vibration in the environment to replace batteries as the power source for wireless sensor devices to achieve efficient self-powered systems. Compared with traditional battery power supply methods, energy harvesting technology reduces the maintenance and processing costs associated with battery-powered systems, as well as the infrastructure costs required to implement AC power supply; compared with traditional power supply equipment, energy harvesting technology also requires additional energy management technology and corresponding low-voltage energy harvesting circuits. For these low-power, low-voltage energy sources, subsequent energy management circuits are particularly important, not only to convert the obtained energy into usable electrical energy, but also to ensure efficiency, that is, to obtain maximum power.

[0005] The prior art has a corresponding energy harvesting circuit, but it has the following disadvantages: first, it is impossible to harvest energy with very low voltage because the starting voltage is relatively high; second, the energy harvesting circuit system is loaded, so that the energy loss of the harvesting circuit itself is relatively large; third, the load impedance in the circuit system is always mismatched with the internal resistance of the energy collector, resulting in a relatively large energy loss of the energy collector itself; fourth, the harvested energy is not efficiently managed, resulting in unnecessary energy loss. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a low-voltage energy harvesting circuit with maximum power tracking, which is specially used for low-voltage weak energy harvesting and has a low starting voltage. Regardless of whether the load internal resistance in the circuit system changes or the internal resistance of the energy harvester changes due to environmental reasons, the circuit can achieve impedance matching through maximum power tracking, thereby improving the efficiency of energy collection of the entire harvesting circuit. At the same time, an ultra-low power consumption, highly integrated energy management chip is adopted to execute different management strategies according to the size of the acquired energy value, thereby minimizing the power consumption of the harvesting circuit, which not only improves the energy utilization of the entire system, but also ensures the normal operation of the load.

[0007] To achieve the above-mentioned purpose, the low-voltage energy harvesting circuit with maximum power tracking of the present invention is characterized in that it includes: an input module, a voltage and current detection module, an MCU control module, a boost circuit module, a DC-DC energy management module, an energy storage module, and an output module;

[0008] The input end of the input module is connected to the low-voltage energy collector to obtain energy obtained by the low-voltage energy collector from the environment;

[0009] The input end of the voltage and current detection module is connected to the voltage and current collection part of the input module, and is used to collect the voltage and current signals of the input module and transmit the collected voltage and current signals;

[0010] The input end of the MCU control module is connected to the output end of the voltage and current detection module, and is used to receive and read the voltage and current values ​​in the voltage and current detection module, and change the duty cycle of the output PWM wave as the voltage and current change, so as to always keep the output power at the maximum;

[0011] The boost circuit module input end is connected to the input module output end, and is used to amplify the input module voltage value. The boost circuit module includes two MOS tubes, which are respectively connected to the output end of the MCU control module. The MCU control module is used to control the on and off of the two MOS tubes, and the duty cycle of the MOS tubes is changed as the voltage and current change. The on and off times of the two MOS tubes are always opposite, that is, the sum of the duty cycles of the two MOS tubes is 1, so that the characteristic impedance of the low-voltage energy collection circuit is always matched with the internal resistance of the energy collector, so as to achieve maximum power tracking;

[0012] The input end of the DC-DC energy management module is connected to the output end of the boost circuit module, and includes a fourth energy management chip with a higher starting voltage and a third energy management chip with a lower starting voltage, which is used to extract energy from the DC signal output by the boost circuit, and execute different management strategies according to the obtained input voltage value, output the set specific voltage and current value, and ensure the normal operation of the load;

[0013] The management strategy is specifically:

[0014] When the input voltage value is within the set threshold, the fourth energy management chip cannot work normally, and the third energy management chip is started to work until the input voltage reaches the set threshold. The fourth energy management chip supplies power to the load and stores excess energy in the energy storage module;

[0015] When the input voltage value is higher than the set threshold, the fourth energy management chip works normally, generates a high level to cut off the third energy management chip, and reduces power consumption; at the same time, it supplies power to the load and stores excess energy in the energy storage module;

[0016] When the input voltage value is lower than the set threshold, the third energy management chip works normally, and the fourth energy management chip cannot work and cannot provide energy to the load. A part of the energy stored in the energy storage module is converted into a specific voltage value together with the energy collected by the circuit to ensure the normal operation of the load;

[0017] The input / output end of the energy storage module is connected to the energy storage interface pin of the DC-DC energy management module, and is used to store the excess energy collected by the circuit in the energy storage element when the circuit collects sufficient energy; when the circuit collects insufficient energy, the stored energy in the energy storage element is provided to the DC-DC energy management module;

[0018] The input end of the output module is connected to the output end of the DC-DC energy management module, and is used to stably provide the specific voltage and current signals output by the DC-DC energy management module to the load.

[0019] Further, the DC-DC energy management module includes a third energy management chip U3, a multifunctional fourth energy management chip U4, a first transformer T1, a first diode D1, a third MOS tube Q3, a second inductor L2, a third inductor L3, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, an eleventh capacitor C11, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13;

[0020] One end of the first transformer T1 and one end of the sixth capacitor C6 are respectively connected to one end of the second inductor L2 as the input end of the DC-DC energy management module and the output end of the boost circuit module; one end of the third capacitor C3 and one end of the fourth capacitor C4 are respectively connected to four ends of the first transformer T1; three ends of the first transformer T1 are grounded; two ends of the first transformer T1 are connected to pin 15 of the third energy management chip U3 to cause oscillation so that the first transformer T1 can work normally; pin 13 of the third energy management chip U3 is connected to two ends of the fourth capacitor C4; two ends of the third capacitor C3 and one end of the first diode D1 are respectively connected to pin 14 of the third energy management chip U3;

[0021] The 2 ends of the first diode D1 are connected to the D end of the third MOS transistor Q3; the 2 ends of the sixth resistor R6 and the S end of the third MOS transistor Q3 are grounded respectively; the G end of the third MOS transistor Q3 and the 1 end of the sixth resistor R6 are connected to the pin 13 of the fourth energy management chip U4 respectively;

[0022] End 1 of the fifth capacitor C5, pin 2 and pin 3 of the third energy management chip U3 are respectively connected to pin 10 of the third energy management chip U3; pin 1, pin 8, pin 9, pin 16 of the third energy management chip U3, and end 2 of the fifth capacitor C5 are all grounded; pin 4 of the third energy management chip U3, end 2 of the eighth capacitor C8, end 2 of the ninth capacitor C9, end 1 of the eleventh capacitor C11, and pin 3 and pin 6 of the fourth energy management chip U4 are respectively connected to pin 19 of the fourth energy management chip U4;

[0023] The 2 ends of the sixth capacitor C6 and the 2 ends of the seventh capacitor C7 are respectively connected to the 5 pins of the fourth energy management chip U4 and grounded; the 1 end of the seventh capacitor C5 is connected to the 4 pins of the fourth energy management chip U4;

[0024] One end of the eighth resistor R8, one end of the eleventh resistor R11, and one end of the thirteenth resistor R13 are respectively connected to the 8th pin of the fourth energy management chip U4; one end of the seventh resistor R7 and two ends of the eighth resistor R8 are respectively connected to the pin 7 of the fourth energy management chip U4; one end of the tenth resistor R10 and two ends of the eleventh resistor R11 are respectively connected to the 10th pin of the energy management chip U4; two ends of the tenth resistor R10 and one end of the ninth resistor R9 are respectively connected to the 11th pin of the fourth energy management chip U4; one end of the twelfth resistor R12 and two ends of the thirteenth resistor R13 are respectively connected to the 12th pin of the fourth energy management chip U4; two ends of the seventh resistor R7, two ends of the ninth resistor R9, and two ends of the twelfth resistor R12 are respectively grounded;

[0025] Pin 20 of the fourth energy management chip U4 is connected to the two ends of the second inductor L2; Pin 18 of the fourth energy management chip U4 is connected to the input / output end of the energy storage module 6 as the excess energy output of the DC-DC energy management module;

[0026] End 1 of the third inductor L3 is connected to pin 16 of the fourth energy management chip U4; end 2 of the third inductor L3 and pin 14 of the fourth energy management chip U4 are connected to the input / output end of the energy storage module as excess energy output of the DC-DC energy management module.

[0027] Furthermore, the voltage and current detection module includes a first amplifier U1, a second amplifier U2, a first resistor R1 and a second resistor R2, wherein the 3rd pin of the first amplifier U1, the 1st pin and the 8th pin of the second amplifier U2 are respectively connected to the output end of the input module as the input end of the voltage and current detection module; the 1st end of the first resistor R1 and the 2nd end of the second resistor R2 are respectively connected to the 4th pin of the first amplifier U1; the 5th pin of the first amplifier U1 and the 5th pin of the second amplifier U2 are respectively connected to a 5V voltage source as the power supply of the voltage and current detection module 2; the 1st end of the second resistor R2 is connected to the 1st pin of the first amplifier U1, and together with the 4th pin of the second amplifier U2, it serves as the output end of the voltage and current detection module and is connected to the input end of the MCU control module; the 7th pin of the second amplifier U2 is connected to a -5V voltage source; the 2nd pin and the 3rd pin of the second amplifier U2 are respectively connected to a 5V voltage source to adjust the amplification factor to 100 times; the 2nd pin of the first amplifier U1, the 2nd end of the first resistor R1, and the 6th pin of the second amplifier U2 are all grounded.

[0028] Furthermore, the MCU control module includes an ultra-low power main control chip, wherein pins 2 and 4 of the main control chip are respectively connected to the voltage value and current value measured by the voltage and current detection module as input ends, pins 9 and 12 of the main control chip are respectively connected to two controlled MOS tubes of the boost circuit module as output ends, pin 1 of the main control chip is connected to the output end of the DC-DC energy management module as the power supply of the MCU control module, and pin 20 of the main control chip is grounded.

[0029] Furthermore, the boost circuit module includes a first inductor L1, a fourth resistor R4, a fifth resistor R5, a second capacitor C2, a first MOS transistor Q1, and a second MOS transistor Q2, wherein the first end of the first inductor L1 is connected to the output end of the input module as the input end of the boost circuit module; the D end of the first MOS transistor Q1 and the D end of the second MOS transistor Q2 are respectively connected to the second end of the first inductor L1; the first end of the fourth resistor R4 is connected to the G end of the second MOS transistor Q2, and the first end of the fifth resistor R5 is connected to the G end of the first MOS transistor Q1, while the first MOS transistor Q1 and the second MOS transistor Q2 are respectively connected to the output end of the MCU control module as controlled elements; the S end of the second MOS transistor Q2 and the second ends of the fourth resistor R4 are both connected to the second ends of the second capacitor C2 and grounded; the S end of the first MOS transistor Q1 and the second ends of the fifth resistor R5 are respectively connected to the first end of the second capacitor C2 and the connection ends are used as the output end of the boost circuit module.

[0030] Furthermore, the input module includes a third resistor R3, a first capacitor C1 and an input terminal IN, and one end of the third resistor R3 and one end of the first capacitor C1 are respectively connected to one end of the output terminal IN as a source of voltage detection and a first end source of current detection; two ends of the third resistor R3 serve as a second end source of current detection and are connected to the input end of the boost circuit module as the output end of the input module; two ends of the first capacitor C1 and two ends of the input terminal IN are respectively grounded for suppressing interference signals.

[0031] Furthermore, the first capacitor C1 is a high-frequency, low-loss capacitor; the first amplifier U1 and the second amplifier U2 are both highly integrated, low-power, high-quality amplifiers; the main control chip of the MCU control module is MSP430G2553, the power supply voltage of MSP430G2553 is as low as 1.8V, and the current in the running mode and the standby mode is as low as 230μA and 0.5μA respectively; the first MOS tube Q1 and the second MOS tube Q2 are both SI2302A, and the SI2302A is a low-power, high-frequency, high-performance N-channel MOS tube; the third MOS tube Q3 is 2SK3615; the third energy management chip is LTC3108, and the fourth energy management chip is BQ25570.

[0032] Furthermore, the energy storage module includes an energy storage element BAT, end 1 of the energy storage element BAT is connected to pin 1 8 of the fourth energy management chip U4 and the connection end serves as the input / output end of the energy storage module; end 2 of the energy storage element BAT is grounded.

[0033] Furthermore, the energy storage element BAT is one of a thin film battery, a supercapacitor, and a rechargeable lithium battery.

[0034] Furthermore, the output module includes a tenth capacitor C10 and an output interface terminal road, end 1 of the tenth capacitor C10 is connected to ends 1 and 2 of the output interface terminal road and the connecting end is connected to the output end of the DC-DC energy management module as the input end of the output module, end 2 of the tenth capacitor C10 is grounded, and ends 3 and 4 of the output interface terminal road are grounded.

[0035] The advantages of the present invention are:

[0036] 1. The present invention is specially used for low-voltage weak energy collection, has a low starting voltage, can continuously collect and manage a variety of environmental energies, and power low-power small electronic devices;

[0037] 2. The present invention controls the impedance of the entire collection circuit to match the internal resistance of the energy harvester through the front-end circuit, that is, the maximum power tracking technology. Regardless of whether the load internal resistance in the circuit system changes or the internal resistance of the energy harvester changes due to environmental reasons, the circuit can achieve impedance matching through maximum power tracking, thereby improving the efficiency of energy collection of the entire collection circuit;

[0038] 3. In order to reduce the energy loss of each electronic device in this application, the present invention adopts an ultra-low power consumption, highly integrated energy management chip, which switches between two energy management chips with higher starting voltage and lower starting voltage according to the energy value obtained, so as to better reduce the power consumption of the collection circuit, and not only store the excess energy in the energy storage module, but also convert part of the energy stored in the energy storage module and the energy collected by the circuit into a specific voltage value to ensure the normal operation of the load;

[0039] 4. The diodes and capacitors selected in the present invention have ultra-low loss characteristics, and a high-frequency inductor with minimum parasitic inductance characteristics is used in the package, which reduces the power consumption of the original circuit to the maximum extent and improves the energy utilization of the entire system;

[0040] The low-voltage energy harvesting circuit with maximum power tracking of the present invention is specially used for low-voltage weak energy harvesting and has a low starting voltage. Regardless of whether the load internal resistance in the circuit system changes or the internal resistance of the energy harvester changes due to environmental reasons, the circuit can achieve impedance matching through maximum power tracking, thereby improving the efficiency of energy collection of the entire harvesting circuit. At the same time, an ultra-low power consumption, highly integrated energy management chip is adopted to execute different management strategies according to the size of the acquired energy value, thereby minimizing the power consumption of the harvesting circuit, thereby not only improving the energy utilization rate of the entire system, but also ensuring the normal operation of the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A block diagram of a low voltage energy harvesting circuit with maximum power point tracking according to the present invention;

[0042] Figure 2 The working principle of the low-voltage energy harvesting circuit with maximum power tracking of the present invention;

[0043] Figure 3 is a circuit diagram of the input module in the present invention;

[0044] Figure 4 is a circuit diagram of the voltage and current detection module in the present invention;

[0045] Figure 5 A circuit diagram of the MCU control module in the present invention;

[0046] Figure 6 is a circuit diagram of the boost circuit module in the present invention;

[0047] Figure 7 is a circuit diagram of a DC-DC energy management module in the present invention;

[0048] Figure 8 is a circuit diagram of the energy storage module in the present invention;

[0049] Fig. 9 is a circuit diagram of the output module in the present invention;

[0050] In the figure: input module 1, voltage and current detection module 2, MCU control module 3, boost circuit module 4, DC-DC energy management module 5, energy storage module 6, and output module 7. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0052] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the 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 a limitation on the invention.

[0053] like Figure 1 As shown, the low-voltage energy harvesting circuit with maximum power tracking of the present invention includes: an input module 1, a voltage and current detection module 2, an MCU control module 3, a boost circuit module 4, a DC-DC energy management module 5, an energy storage module 6, and an output module 7.

[0054] The input end of the boost circuit module 4 is connected to the input end of the input module 1, and the output end of the boost circuit module 4 is connected to the input end of the DC-DC energy management module 5. The input end of the voltage and current detection module 2 is connected to the current and voltage collection point of the input module 1, and the output end of the voltage and current detection module 2 is connected to the input end of the MCU control module 3. The output end of the MCU control module 3 is connected to the two MOS tubes of the boost circuit module 4 to control the on and off of the MOS tube. The energy storage interface pin of the DC-DC energy management module 5 is connected to the input / output end of the energy storage module 6. The output end of the DC-DC energy management module 5 is connected to the input end of the output module 7.

[0055] The present invention is specially used for low-voltage weak energy collection, has a low starting voltage, and can continuously collect and manage a variety of environmental energies to power low-power small electronic devices.

[0056] The input end of the input module 1 is connected to the low-voltage energy collector to obtain energy obtained by the low-voltage energy collector from the environment.

[0057] Specifically, Figure 3As shown, the input module 1 includes a third resistor R3, a first capacitor C1 and an input terminal IN. One end of the third resistor R3 and one end of the first capacitor C1 are respectively connected to one end of the output terminal IN as a source of voltage detection and a first end source of current detection; two ends of the third resistor R3 are used as a second end source of current detection and as an output end of the input module 1 to connect to the input end of the boost circuit module 4; two ends of the first capacitor C1 and two ends of the input terminal IN are respectively grounded to suppress interference signals. The resistance value of the third resistor R3 is 50 milliohms, and its function is to detect the magnitude of the input current.

[0058] Preferably, the first capacitor C1 is a high-frequency, low-loss capacitor.

[0059] The input end of the voltage and current detection module 2 is connected to the voltage and current collection part of the input module 1, and is used to collect the voltage and current signals of the input module 1 and transmit the collected voltage and current signals.

[0060] Specifically, Figure 4 As shown, the voltage and current detection module 2 includes a first amplifier U1, a second amplifier U2, a first resistor R1 and a second resistor R2. Pin 3 of the first amplifier U1, pin 1 and pin 8 of the second amplifier U2 are respectively used as the input end of the voltage and current detection module 2 and connected to the output end of the input module 1; end 1 of the first resistor R1 and end 2 of the second resistor R2 are respectively connected to pin 4 of the first amplifier U1; pin 5 of the first amplifier U1 and pin 5 of the second amplifier U2 are respectively connected to a 5V voltage source as the power supply of the voltage and current detection module 2; end 1 of the second resistor R2 is connected to pin 1 of the first amplifier U1, and together with pin 4 of the second amplifier U2, it serves as the output end of the voltage and current detection module 2 and is connected to the input end of the MCU control module 3; pin 7 of the second amplifier U2 is connected to a -5V voltage source; pins 2 and 3 of the second amplifier U2 are respectively connected to a 5V voltage source to adjust the amplification factor to 100 times; pin 2 of the first amplifier U1, end 2 of the first resistor R1, and pin 6 of the second amplifier U2 are all grounded.

[0061] The resistance values ​​of the first resistor R1 and the second resistor R2 determine that the multiple of the first amplifier is 4. The accuracy of the two amplifiers is very high, so the measurement circuit can well provide input information to the MCU control module 3. The selected first amplifier U1 and the second amplifier U2 are both highly integrated, low-power, high-quality amplifiers, so the loss of this part is relatively low.

[0062] The input end of the MCU control module 3 is connected to the output end of the voltage and current detection module 2, and is used to receive and read the voltage and current values ​​in the voltage and current detection module 2, and change the duty cycle of the output PWM wave as the voltage and current change, so as to always keep the output power at the maximum.

[0063] Specifically, Figure 5 As shown, the MCU control module 3 includes an ultra-low power main control chip, pins 2 and 4 of the main control chip are respectively connected to the voltage value and current value measured by the voltage and current detection module 2 as input ends, pins 9 and 12 of the main control chip are respectively connected to the two controlled MOS tubes of the boost circuit module 4 as output ends, pin 1 of the main control chip is connected to the output end of the DC-DC energy management module 5 as the power supply of the MCU control module 3, and pin 20 of the main control chip is grounded.

[0064] Preferably, the main control chip of the MCU control module 3 is MSP430G2553, the power supply voltage of MSP430G2553 is as low as 1.8V, and the current in the running mode and the standby mode are respectively as low as 230μA and 0.5μA. Therefore, the main controller has ultra-low power consumption, and its 10-bit AD digital-to-analog converter can well meet the acquisition and measurement functions, so it is very suitable for meeting the special needs of ultra-low power consumption and high precision applications.

[0065] The input end of the boost circuit module 4 is connected to the output end of the input module 1, and is used to amplify the voltage value of the input module 1. The boost circuit module 4 includes two MOS tubes, which are respectively connected to the output ends of the MCU control module 3. The MCU control module 3 is used to control the on and off of the two MOS tubes, and the duty cycle of the MOS tubes is changed as the voltage and current change. The on and off times of the two MOS tubes are always opposite, that is, the sum of the duty cycles of the two MOS tubes is 1, so that the characteristic impedance of the low-voltage energy collection circuit is always matched with the internal resistance of the energy collector, thereby realizing maximum power tracking.

[0066] Specifically, Figure 6As shown, the boost circuit module 4 includes a first inductor L1, a fourth resistor R4, a fifth resistor R5, a second capacitor C2, a first MOS transistor Q1, and a second MOS transistor Q2. The first end of the first inductor L1 is connected to the output end of the input module 1 as the input end of the boost circuit module 4; the D end of the first MOS transistor Q1 and the D end of the second MOS transistor Q2 are respectively connected to the second end of the first inductor L1; the first end of the fourth resistor R4 is connected to the G end of the second MOS transistor Q2, and the first end of the fifth resistor R5 is connected to the G end of the first MOS transistor Q1. At the same time, the first MOS transistor Q1 and the second MOS transistor Q2 are respectively connected to the output end of the MCU control module 3 as controlled elements; the S end of the second MOS transistor Q2 and the second ends of the fourth resistor R4 are both connected to the second ends of the second capacitor C2 and grounded; the S end of the first MOS transistor Q1 and the second ends of the fifth resistor R5 are respectively connected to the first end of the second capacitor C2 and the connection ends are used as the output end of the boost circuit module 4.

[0067] The first MOS tube Q1 and the second MOS tube Q2 are both low-power, high-frequency, high-performance N-channel MOS tubes of model SI2302A. At the same time, the on and off times of the two MOS tubes are always opposite, that is, the sum of the duty cycles is 1, to ensure the normal operation of the circuit. The duty cycles of the two MOS tubes are controlled by the MCU control module 3, so that the impedance of the overall circuit matches the internal resistance of the energy collector, that is, the algorithm is used to achieve maximum power tracking and maximize the collected power.

[0068] like Figure 2 As shown, the algorithm principle of the maximum power tracking technology of the circuit of the present invention will be explained below: first, the initial duty cycle D, step size ΔD, power allowable error Δ, and the initial power are set to zero. The main control chip obtains the collected input voltage and current, calculates the input power at this time, and compares it with the input power calculated last time. If the absolute value of the difference between the two calculated powers is within the set range Δ, the duty cycle will not be changed; if the absolute value of the difference between the two calculated powers is not within the set range Δ, compare the power this time with the power of the previous time. If the power obtained this time is greater than the power of the previous time, the duty cycle increases by a step size ΔD, otherwise, it decreases by a step size ΔD. This cycle is repeated to always maintain the maximum output power and change the duty cycle to achieve impedance matching.

[0069] The present invention controls the impedance of the entire collection circuit to match the internal resistance of the energy harvester through a front-end circuit, that is, the maximum power tracking technology. Regardless of whether the load internal resistance in the circuit system changes or the internal resistance of the energy harvester changes due to environmental reasons, the circuit can achieve impedance matching through maximum power tracking, thereby improving the efficiency of the entire collection circuit in collecting energy.

[0070] The input end of the DC-DC energy management module 5 is connected to the output end of the boost circuit module 4, and includes a fourth energy management chip with a higher starting voltage and a third energy management chip with a lower starting voltage, which are used to extract energy from the DC signal output by the boost circuit, and execute different management strategies according to the obtained input voltage value, output the set specific voltage and current values, and ensure the normal operation of the load.

[0071] Specifically, Figure 7 As shown, the DC-DC energy management module 5 includes a third energy management chip U3, a multifunctional fourth energy management chip U4, a first transformer T1, a first diode D1, a third MOS tube Q3, a second inductor L2, a third inductor L3, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, an eleventh capacitor C11, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13;

[0072] One end of the first transformer T1 and one end of the sixth capacitor C6 are respectively connected to one end of the second inductor L2 as the input end of the DC-DC energy management module 5 and connected to the output end of the boost circuit module 4; one end of the third capacitor C3 and one end of the fourth capacitor C4 are respectively connected to four ends of the first transformer T1; three ends of the first transformer T1 are grounded; two ends of the first transformer T1 are connected to pin 15 of the third energy management chip U3 to cause oscillation so that the first transformer T1 can work normally; pin 13 of the third energy management chip U3 is connected to two ends of the fourth capacitor C4; two ends of the third capacitor C3 and one end of the first diode D1 are respectively connected to pin 14 of the third energy management chip U3;

[0073] The 2 ends of the first diode D1 are connected to the D end of the third MOS transistor Q3; the 2 ends of the sixth resistor R6 and the S end of the third MOS transistor Q3 are grounded respectively; the G end of the third MOS transistor Q3 and the 1 end of the sixth resistor R6 are connected to the pin 13 of the fourth energy management chip U4 respectively;

[0074] End 1 of the fifth capacitor C5, pin 2 and pin 3 of the third energy management chip U3 are respectively connected to pin 10 of the third energy management chip U3; pin 1, pin 8, pin 9, pin 16 of the third energy management chip U3, and end 2 of the fifth capacitor C5 are all grounded; pin 4 of the third energy management chip U3, end 2 of the eighth capacitor C8, end 2 of the ninth capacitor C9, end 1 of the eleventh capacitor C11, and pin 3 and pin 6 of the fourth energy management chip U4 are respectively connected to pin 19 of the fourth energy management chip U4;

[0075] The 2 ends of the sixth capacitor C6 and the 2 ends of the seventh capacitor C7 are respectively connected to the 5 pins of the fourth energy management chip U4 and grounded; the 1 end of the seventh capacitor C5 is connected to the 4 pins of the fourth energy management chip U4;

[0076] One end of the eighth resistor R8, one end of the eleventh resistor R11, and one end of the thirteenth resistor R13 are respectively connected to the 8th pin of the fourth energy management chip U4; one end of the seventh resistor R7 and two ends of the eighth resistor R8 are respectively connected to the pin 7 of the fourth energy management chip U4; one end of the tenth resistor R10 and two ends of the eleventh resistor R11 are respectively connected to the 10th pin of the energy management chip U4; two ends of the tenth resistor R10 and one end of the ninth resistor R9 are respectively connected to the 11th pin of the fourth energy management chip U4; one end of the twelfth resistor R12 and two ends of the thirteenth resistor R13 are respectively connected to the 12th pin of the fourth energy management chip U4; two ends of the seventh resistor R7, two ends of the ninth resistor R9, and two ends of the twelfth resistor R12 are respectively grounded;

[0077] Pin 20 of the fourth energy management chip U4 is connected to the two ends of the second inductor L2; Pin 18 of the fourth energy management chip U4 is connected to the input / output end of the energy storage module 6 as the excess energy output of the DC-DC energy management module 5;

[0078] End 1 of the third inductor L3 is connected to pin 16 of the fourth energy management chip U4; end 2 of the third inductor L3 and pin 14 of the fourth energy management chip U4 are connected to the input / output end of the energy storage module 6 as the excess energy output of the DC-DC energy management module 5.

[0079] Preferably, the third energy management chip model is LTC3108, and the fourth energy management chip model is BQ25570. The use of LTC3108 reduces the startup voltage of the entire circuit, and the use of the BQ25570 chip improves the anti-interference ability of the circuit. At the same time, when the collected energy is sufficient, the BQ25570 works stably, and the third MOS tube Q3 is used to cut off the LTC3108 chip, thereby reducing the power consumption of the entire circuit.

[0080] Preferably, the model of the third MOS tube Q3 is 2SK3615.

[0081] The management strategy is specifically:

[0082] When the input voltage value is within the set threshold, the fourth energy management chip U4 cannot work normally, and the third energy management chip U3 is started to work until the input voltage reaches the set threshold. The fourth energy management chip U4 supplies power to the load and stores the excess energy in the energy storage module 6;

[0083] When the input voltage value is higher than the set threshold, the fourth energy management chip U4 works normally, generates a high level to cut off the third energy management chip U3, and reduces power consumption; at the same time, it supplies power to the load and stores excess energy in the energy storage module 6;

[0084] When the input voltage value is lower than the set threshold, the third energy management chip U3 works normally, and the fourth energy management chip U4 cannot work and cannot provide energy to the load. A part of the energy stored in the energy storage module 6 is converted into a specific voltage value together with the energy collected by the circuit to ensure the normal operation of the load.

[0085] Specifically, the set threshold of the input voltage value is 100-300 millivolts.

[0086] In order to reduce the energy loss of each electronic device in this application, the present invention adopts an ultra-low power consumption, highly integrated energy management chip, which switches between two energy management chips with a higher starting voltage and a lower starting voltage according to the size of the acquired energy value, thereby better reducing the power consumption of the collection circuit. Not only can the excess energy be stored in the energy storage module, but also a part of the energy stored in the energy storage module and the energy collected by the circuit can be converted into a specific voltage value to ensure the normal operation of the load.

[0087] The input / output end of the energy storage module 6 is connected to the energy storage interface pin of the DC-DC energy management module 5, and is used to store the excess energy collected by the circuit in the energy storage element when the circuit collects sufficient energy; when the circuit collects insufficient energy, the stored energy in the energy storage element is provided to the DC-DC energy management module 5.

[0088] Specifically, Figure 8 As shown, the energy storage module 6 includes an energy storage element BAT, end 1 of the energy storage element BAT is connected to pin 1 of the fourth energy management chip U4 and the connection end serves as the input / output end of the energy storage module 6; end 2 of the energy storage element BAT is grounded.

[0089] Preferably, the energy storage element BAT is one of a thin film battery, a super capacitor, and a rechargeable lithium battery. The energy storage element BAT stores the excess energy collected by the system to improve the overall energy utilization of the system.

[0090] The input end of the output module 7 is connected to the output end of the DC-DC energy management module 5, and is used to stably provide the specific voltage and current signals output by the DC-DC energy management module 5 to the load.

[0091] Specifically, Fig. 9 As shown, the output module 7 includes a No. 10 capacitor C10 and an output interface terminal road, a terminal 1 of the No. 10 capacitor C10 is connected to the terminals 1 and 2 of the output interface terminal road, and the connection terminal is connected to the output terminal of the DC-DC energy management module 5 as the input terminal of the output module 7, a terminal 2 of the No. 10 capacitor C10 is grounded, and terminals 3 and 4 of the output interface terminal road are grounded. This module has a simple circuit structure and low loss.

[0092] The low-voltage energy harvesting circuit with maximum power tracking of the present invention is specially used for low-voltage weak energy harvesting, and has a low starting voltage. No matter whether the load internal resistance in the circuit system changes or the internal resistance of the energy harvester changes due to environmental reasons, the circuit can achieve impedance matching through maximum power tracking, thereby improving the efficiency of energy collection of the entire harvesting circuit; at the same time, an ultra-low power consumption, highly integrated energy management chip is adopted, and different management strategies are executed according to the size of the acquired energy value, thereby minimizing the power consumption of the harvesting circuit, which not only improves the energy utilization rate of the entire system, but also ensures the normal operation of the load; in addition, the diodes and capacitors selected by the present invention have the characteristics of ultra-low loss, and a high-frequency inductor with a minimum parasitic inductance characteristic is adopted in the package, thereby minimizing the power consumption of the original circuit and improving the energy utilization rate of the entire system.

[0093] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A low voltage energy harvesting circuit with maximum power tracking, characterized in that: include: An input module (1), a voltage and current detection module (2), an MCU control module (3), a boost circuit module (4), a DC-DC energy management module (5), an energy storage module (6), and an output module (7); The input end of the input module (1) is connected to the low-voltage energy collector and is used to obtain energy obtained by the low-voltage energy collector from the environment; The input end of the voltage and current detection module (2) is connected to the voltage and current collection part of the input module (1), and is used to collect the voltage and current signals of the input module (1), and transmit the collected voltage and current signals; The input end of the MCU control module (3) is connected to the output end of the voltage and current detection module (2), and is used to receive and read the voltage and current values ​​in the voltage and current detection module (2), and to change the duty cycle of the PWM wave at the output end as the voltage and current change, so as to always keep the output power at a maximum; The boost circuit module (4) has an input end connected to the output end of the input module (1) and is used to amplify the voltage value of the input module (1). The boost circuit module (4) comprises two MOS tubes, which are respectively connected to the output end of the MCU control module (3). The MCU control module (3) is used to control the on and off of the two MOS tubes, and the duty cycle of the MOS tubes is changed as the voltage and current change. The on and off times of the two MOS tubes are always opposite, that is, the sum of the duty cycles of the two MOS tubes is 1, so that the characteristic impedance of the low-voltage energy collection circuit is always matched with the internal resistance of the energy collector, thereby realizing maximum power tracking; The input end of the DC-DC energy management module (5) is connected to the output end of the boost circuit module (4), and includes a fourth energy management chip with a higher starting voltage and a third energy management chip with a lower starting voltage, and is used to extract energy from the DC signal output by the boost circuit, and execute different management strategies according to the acquired input voltage value, and output a set specific voltage and current value to ensure the normal operation of the load; The management strategy is specifically: When the input voltage value is within the set threshold, the fourth energy management chip cannot work normally, and the third energy management chip is started to work until the input voltage reaches the set threshold. The fourth energy management chip supplies power to the load and stores excess energy in the energy storage module (6); When the input voltage value is higher than the set threshold, the fourth energy management chip works normally, generates a high level to cut off the third energy management chip, and reduces power consumption; at the same time, it supplies power to the load and stores excess energy in the energy storage module (6); When the input voltage value is lower than the set threshold, the third energy management chip works normally, the fourth energy management chip cannot work and cannot provide energy to the load, and a part of the energy stored in the energy storage module (6) is converted into a specific voltage value together with the energy collected by the circuit to ensure the normal operation of the load; The input / output end of the energy storage module (6) is connected to the energy storage interface pin of the DC-DC energy management module (5) and is used to store the excess energy collected by the circuit in the energy storage element when the circuit collects sufficient energy; When the circuit collects insufficient energy, the stored energy in the energy storage element is provided to the DC-DC energy management module (5); The input end of the output module (7) is connected to the output end of the DC-DC energy management module (5) and is used to stably provide the specific voltage and current signals output by the DC-DC energy management module (5) to the load.

2. The low voltage energy harvesting circuit with maximum power point tracking according to claim 1, characterized in that: The DC-DC energy management module (5) comprises a third energy management chip U3, a multifunctional fourth energy management chip U4, a first transformer T1, a first diode D1, a third MOS tube Q3, a second inductor L2, a third inductor L3, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, an eighth capacitor C8, a ninth capacitor C9, an eleventh capacitor C11, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13; End 1 of the first transformer T1 and end 1 of the sixth capacitor C6 are respectively connected to end 1 of the second inductor L2 as the input end of the DC-DC energy management module (5) and connected to the output end of the boost circuit module (4); End 1 of the third capacitor C3 and end 1 of the fourth capacitor C4 are respectively connected to end 4 of the first transformer T1; End 3 of the first transformer T1 is grounded; End 2 of the first transformer T1 is connected to pin 15 of the third energy management chip U3 to induce oscillation so that the first transformer T1 can work normally; Pin 13 of the third energy management chip U3 is connected to end 2 of the fourth capacitor C4; End 2 of the third capacitor C3 and end 1 of the first diode D1 are respectively connected to pin 14 of the third energy management chip U3; The 2 ends of the first diode D1 are connected to the D end of the third MOS transistor Q3; the 2 ends of the sixth resistor R6 and the S end of the third MOS transistor Q3 are grounded respectively; the G end of the third MOS transistor Q3 and the 1 end of the sixth resistor R6 are connected to the pin 13 of the fourth energy management chip U4 respectively; End 1 of the fifth capacitor C5, pin 2 and pin 3 of the third energy management chip U3 are respectively connected to pin 10 of the third energy management chip U3; pin 1, pin 8, pin 9, pin 16 of the third energy management chip U3, and end 2 of the fifth capacitor C5 are all grounded; pin 4 of the third energy management chip U3, end 2 of the eighth capacitor C8, end 2 of the ninth capacitor C9, end 1 of the eleventh capacitor C11, and pin 3 and pin 6 of the fourth energy management chip U4 are respectively connected to pin 19 of the fourth energy management chip U4; The 2 ends of the sixth capacitor C6 and the 2 ends of the seventh capacitor C7 are respectively connected to the 5 pins of the fourth energy management chip U4 and grounded; the 1 end of the seventh capacitor C7 is connected to the 4 pins of the fourth energy management chip U4; One end of the eighth resistor R8, one end of the eleventh resistor R11, and one end of the thirteenth resistor R13 are respectively connected to the 8th pin of the fourth energy management chip U4; one end of the seventh resistor R7 and two ends of the eighth resistor R8 are respectively connected to the pin 7 of the fourth energy management chip U4; one end of the tenth resistor R10 and two ends of the eleventh resistor R11 are respectively connected to the 10th pin of the energy management chip U4; two ends of the tenth resistor R10 and one end of the ninth resistor R9 are respectively connected to the 11th pin of the fourth energy management chip U4; one end of the twelfth resistor R12 and two ends of the thirteenth resistor R13 are respectively connected to the 12th pin of the fourth energy management chip U4; two ends of the seventh resistor R7, two ends of the ninth resistor R9, and two ends of the twelfth resistor R12 are respectively grounded; Pin 20 of the fourth energy management chip U4 is connected to the two ends of the second inductor L2; pin 18 of the fourth energy management chip U4 is connected to the input / output end of the energy storage module (6) as the excess energy output of the DC-DC energy management module (5); End 1 of the third inductor L3 is connected to pin 16 of the fourth energy management chip U4; end 2 of the third inductor L3 and pin 14 of the fourth energy management chip U4 are connected to the input / output end of the energy storage module (6) as excess energy output of the DC-DC energy management module (5).

3. The low voltage energy harvesting circuit with maximum power point tracking according to claim 2, characterized in that: The voltage and current detection module (2) comprises a first amplifier U1, a second amplifier U2, a first resistor R1 and a second resistor R2; the 3rd pin of the first amplifier U1 and the 1st and 8th pins of the second amplifier U2 are respectively connected to the output end of the input module (1) as the input end of the voltage and current detection module (2); the 1st end of the first resistor R1 and the 2nd end of the second resistor R2 are respectively connected to the 4th pin of the first amplifier U1; the 5th pin of the first amplifier U1 and the 5th pin of the second amplifier U2 are respectively connected to a 5V voltage source as the voltage and current detection module (2); The power supply of the current detection module (2); the 1 end of the second resistor R2 is connected to the 1 pin of the first amplifier U1, and together with the 4 pin of the second amplifier U2, serves as the output end of the voltage and current detection module (2) and is connected to the input end of the MCU control module (3); the 7 pin of the second amplifier U2 is connected to a -5V voltage source; the 2 pins and the 3 pins of the second amplifier U2 are respectively connected to a 5V voltage source to adjust the amplification factor to 100 times; the 2 pin of the first amplifier U1, the 2 end of the first resistor R1, and the 6 pin of the second amplifier U2 are all grounded.

4. The low voltage energy harvesting circuit with maximum power point tracking according to claim 3, characterized in that: The MCU control module (3) comprises an ultra-low power consumption main control chip, wherein pins 2 and 4 of the main control chip are respectively connected to the voltage value and current value measured by the voltage and current detection module (2) as input ends, pins 9 and 12 of the main control chip are respectively connected to two controlled MOS tubes of the boost circuit module (4) as output ends, pin 1 of the main control chip is connected to the output end of the DC-DC energy management module (5) as the power supply of the MCU control module (3), and pin 20 of the main control chip is grounded.

5. The low voltage energy harvesting circuit with maximum power point tracking according to claim 4, characterized in that: The boost circuit module (4) comprises a first inductor L1, a fourth resistor R4, a fifth resistor R5, a second capacitor C2, a first MOS transistor Q1, and a second MOS transistor Q2; an end 1 of the first inductor L1 is connected to the output end of the input module (1) as the input end of the boost circuit module (4); a D end of the first MOS transistor Q1 and a D end of the second MOS transistor Q2 are respectively connected to ends 2 of the first inductor L1; an end 1 of the fourth resistor R4 is connected to ends 3 of the second MOS transistor Q2; and an end 2 of the fourth resistor R4 is connected to ends 4 of the second MOS transistor Q2. G end, the 1 end of the fifth resistor R5 is connected to the G end of the first MOS transistor Q1, and the first MOS transistor Q1 and the second MOS transistor Q2 are respectively connected to the output end of the MCU control module (3) as controlled elements; the S end of the second MOS transistor Q2 and the 2 ends of the fourth resistor R4 are both connected to the 2 ends of the second capacitor C2 and grounded; the S end of the first MOS transistor Q1 and the 2 ends of the fifth resistor R5 are respectively connected to the 1 end of the second capacitor C2 and the connected ends serve as the output end of the boost circuit module (4).

6. The low voltage energy harvesting circuit with maximum power point tracking according to claim 5, characterized in that: The input module (1) comprises a third resistor R3, a first capacitor C1 and an input terminal IN; one end of the third resistor R3 and one end of the first capacitor C1 are respectively connected to one end of the output terminal IN as a source of voltage detection and a first end source of current detection; two ends of the third resistor R3 are used as a second end source of current detection and as an output end of the input module (1) connected to an input end of a boost circuit module (4); two ends of the first capacitor C1 and two ends of the input terminal IN are respectively grounded for suppressing interference signals.

7. The low voltage energy harvesting circuit with maximum power point tracking according to claim 6, characterized in that: The first capacitor C1 is a high-frequency, low-loss capacitor; the first amplifier U1 and the second amplifier U2 are both highly integrated, low-power, high-quality amplifiers; the main control chip of the MCU control module (3) is MSP430G2553, the power supply voltage of MSP430G2553 is as low as 1.8V, and the current in the running mode and the standby mode are respectively as low as 230μA and 0.5μA; the first MOS tube Q1 and the second MOS tube Q2 are both SI2302A, and the SI2302A is a low-power, high-frequency, high-performance N-channel MOS tube; the third MOS tube Q3 is 2SK3615; the third energy management chip is LTC3108, and the fourth energy management chip is BQ25570.

8. The low voltage energy harvesting circuit with maximum power point tracking according to claim 1, characterized in that: The energy storage module (6) comprises an energy storage element BAT, one end of the energy storage element BAT is connected to the 8th pin of the fourth energy management chip U4 and the connection end serves as the input / output end of the energy storage module (6); the second end of the energy storage element BAT is grounded.

9. The low voltage energy harvesting circuit with maximum power point tracking according to claim 8, characterized in that: The energy storage element BAT is one of a thin film battery, a super capacitor, and a rechargeable lithium battery.

10. The low voltage energy harvesting circuit with maximum power point tracking according to claim 1, characterized in that: The output module (7) comprises a tenth capacitor C10 and an output interface terminal road, end 1 of the tenth capacitor C10 is connected to ends 1 and 2 of the output interface terminal road, and the connection end is connected to the output end of the DC-DC energy management module (5) as the input end of the output module (7), end 2 of the tenth capacitor C10 is grounded, and ends 3 and 4 of the output interface terminal road are grounded.

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