A magnetoelectric vibration energy harvesting system capable of power optimization

Abstract

This invention discloses a magnetoelectric vibration energy harvesting system capable of power optimization, comprising a magnetoelectric vibration energy harvester and a magnetoelectric vibration energy harvesting circuit. The magnetoelectric vibration energy harvesting circuit includes an energy harvesting module, an accelerometer, and a microcontroller module. The energy harvesting module converts AC voltage into DC voltage and a square wave signal, respectively, and uses the DC voltage to power the microcontroller module and the accelerometer. The accelerometer senses environmental vibration and generates a corresponding acceleration signal. The microcontroller module first determines the open-circuit voltage of the magnetoelectric vibration energy harvester based on the angular frequency of the square wave signal and the amplitude of the acceleration signal, and then uses a fractional-order open-circuit voltage method to control the output power of the energy harvesting module to achieve maximum power transmission. The advantages are that the fractional-order open-circuit voltage method is used to achieve maximum power transmission without interrupting the energy transmission process, and it also has fast dynamic response characteristics and high energy harvesting effect.

Description

Technical Field

[0001] This invention relates to magnetoelectric vibration energy harvesting systems, and more particularly to a magnetoelectric vibration energy harvesting system capable of power optimization. Background Technology

[0002] With the rapid development of IoT technology, wireless sensor network nodes, as a core component, are deeply integrated with 5G, AI, and edge computing technologies, showing broad application prospects in smart cities, smart agriculture, wearable medical and health devices, and other fields. Currently, wireless network sensor nodes are primarily powered by chemical batteries, which presents challenges in complex deployment environments and large node numbers, leading to high charging and maintenance costs and difficulties. Therefore, researching self-powered technologies, such as environmental energy harvesting, to provide sustainable energy support for wireless network sensor nodes is a breakthrough towards achieving unlimited power endurance. Magnetoelectric vibration energy harvesting technology, with its advantages of small device size and high output power, has received widespread attention in recent years.

[0003] To achieve maximum power transfer, existing magnetoelectric vibration energy harvesting systems typically employ two classical power optimization methods: the fractional-order open-circuit voltage method and the perturbation-observation method. Chinese invention patent application CN118041124A discloses a spring-pendulum type piezoelectric hybrid energy harvesting device. This device uses the conventional fractional-order open-circuit voltage method as the maximum power transfer strategy for the magnetoelectric vibration energy harvesting circuit, exhibiting fast dynamic response characteristics. However, this device requires periodically disconnecting the magnetoelectric vibration energy harvester and the magnetoelectric vibration energy harvesting circuit to measure the open-circuit voltage of the magnetoelectric vibration energy harvester. This periodically interrupts the energy transfer between the magnetoelectric vibration energy harvester and the circuit, resulting in suboptimal energy harvesting performance. For example, Chinese invention patent application CN117492506A discloses a resistive damping intelligent adjustment circuit and method. This method uses a microcontroller module to collect the voltage and current of the energy storage capacitor in real time to calculate the output power over a certain period of time, and uses the perturbation-observation method to adjust the duty cycle parameter of the pulse width modulation signal controlling the on / off state of the electronic switch, thereby adjusting the system's resistive damping and achieving maximum power transfer of the magnetoelectric vibration energy harvesting circuit. Although this method does not require interrupting the energy transfer process, the perturbation-observation method requires multiple "perturbation-observation" cycles to adjust to near the maximum power operating point, resulting in a slow response to rapidly changing vibration signals and thus poor energy harvesting effect. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a magnetoelectric vibration energy harvesting system that can optimize power transmission, achieves maximum power transmission using the fractional open-circuit voltage method without interrupting the energy transmission process, and has both fast dynamic response characteristics and high energy harvesting effect.

[0005] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a magnetoelectric vibration energy harvesting system capable of power optimization, comprising a magnetoelectric vibration energy harvester and a magnetoelectric vibration energy harvesting circuit. The magnetoelectric vibration energy harvester is used to sense environmental vibrations and generate corresponding AC voltage outputs. The magnetoelectric vibration energy harvesting circuit includes an energy harvesting module, an accelerometer, and a microcontroller module. The energy harvesting module is used to convert the AC voltage into a DC voltage VCC and a square wave signal V, respectively. fre The microcontroller module and the accelerometer are powered by the DC voltage VCC, and the square wave signal V is used to power the microcontroller module and the accelerometer. fre The square wave signal V is output to the microcontroller module. fre The accelerometer has the same frequency as the AC voltage and is used to sense environmental vibrations and generate a corresponding acceleration signal V. acc The output is sent to the microcontroller module; the microcontroller module is used to first output the square wave signal V. fre The angular frequency and the acceleration signal V acc The amplitude is used to determine the open-circuit voltage V of the magnetoelectric vibration energy trap. EOC Then, the output power of the energy capture module is controlled by the fractional open-circuit voltage method to achieve maximum power transmission.

[0006] Compared with existing technologies, the advantages of this invention lie in that it constructs a magnetoelectric vibration energy harvesting circuit using an energy harvesting module, an accelerometer, and a microcontroller module. The energy harvesting module converts the AC voltage output from the magnetoelectric vibration energy harvester into a DC voltage VCC and a square wave signal V. fre It also outputs the DC voltage VCC to the microcontroller module and accelerometer to power them, and outputs the square wave signal V. fre The square wave signal V is output to the microcontroller module. fre The accelerometer senses environmental vibrations and generates a corresponding acceleration signal V, with the frequency of the AC voltage output by the magnetoelectric vibration energy harvester being the same. acc The output is sent to the microcontroller module, which first determines the output based on the square wave signal V. fre angular frequency and acceleration signal V acc The amplitude is used to determine the open-circuit voltage V of the magnetoelectric vibration energy trap. EOC Then, the fractional-order open-circuit voltage method is used to control the output power of the energy harvesting module to achieve maximum power transmission. Therefore, when using the fractional-order open-circuit voltage method to achieve maximum power transmission, this invention utilizes the acceleration signal output by the accelerometer to provide a reference signal for power optimization of the magnetoelectric vibration energy harvesting system, based on the square wave signal V... fre angular frequency and acceleration signal V accThe open-circuit voltage can be obtained by measuring the amplitude, thus eliminating the need to periodically disconnect the magnetoelectric vibration energy harvester and the magnetoelectric vibration energy harvesting circuit to measure the open-circuit voltage. This does not require interrupting the energy transfer process, ensuring the continuity of the energy harvesting process, and combining fast dynamic response characteristics with high energy harvesting effect.

[0007] Furthermore, the magnetoelectric vibration energy harvester is implemented using a moving iron structure, and the microcontroller module uses formula (1) to determine the open-circuit voltage V of the magnetoelectric vibration energy harvester. EOC :

[0008] (1)

[0009] The magnetoelectric vibration energy harvester can be equivalently represented as a single-degree-of-freedom linear vibration system comprising a spring, a mass block, damping, and an electromagnetic transducer. M The mass of the mass block of the equivalent linear vibration system of the magnetoelectric vibration energy harvester. K Let be the stiffness of the spring in the equivalent linear vibration system of the magnetoelectric vibration energy harvester. D The damping of the equivalent linear vibration system of the magnetoelectric vibration energy harvester. Let be the electromechanical coupling coefficient of the electromagnetic transducer component in the equivalent linear vibration system of the magnetoelectric vibration trap. A The acceleration signal V acc amplitude, The square wave signal V fre angular frequency.

[0010] Furthermore, the energy harvesting module includes a full-bridge rectifier, a DC-DC converter, a lithium battery, a linear regulator, a shaping circuit, a multipath voltage divider circuit, a reference voltage circuit, and a hysteresis comparator circuit. The full-bridge rectifier rectifies the AC voltage into a DC voltage Vdc, which is then output to the DC-DC converter and the multipath voltage divider circuit. The shaping circuit converts the AC voltage into a square wave signal V. fre The DC-DC converter circuit converts the DC voltage Vdc into a charging DC voltage to charge the lithium battery; the linear regulator converts this charging DC voltage into a DC voltage VCC; the multi-path voltage divider circuit includes multiple selectable voltage divider paths with different voltage division coefficients; and the microcontroller module pre-stores possible open-circuit voltages V. EOC The values ​​of V and the table of reference for each voltage divider path; when the microcontroller module determines the open-circuit voltage V EOCThen, the corresponding voltage divider path is found in the lookup table, and the multi-path voltage divider circuit is controlled to select this path to divide the DC voltage Vdc, generating the corresponding divided voltage Vdc,div, which is output to the hysteresis comparator circuit. The reference voltage circuit is used to connect the DC voltage VCC and generates the upper threshold voltage VH and the lower threshold voltage VL, which are output to the hysteresis comparator circuit. The hysteresis comparator circuit performs a hysteresis comparison on the divided voltage Vdc,div based on the upper threshold voltage VH and the lower threshold voltage VL, and outputs a control signal VEN to control the opening and closing of the DC-DC converter circuit, changing the magnitude of the DC voltage Vdc, limiting the divided voltage Vdc,div between the upper threshold voltage VH and the lower threshold voltage VL, and making the DC voltage Vdc hysteresis at the current open circuit voltage V. EOC Maximum power transfer is achieved at approximately half of the maximum power.

[0011] Furthermore, the magnetoelectric vibration energy harvester has a first output terminal and a second output terminal; the energy harvesting module has a first AC input terminal, a second AC input terminal, a control signal input terminal, a square wave signal output terminal, and a power output terminal; the accelerometer has an acceleration signal output terminal and a power input terminal; and the microcontroller module has a digital signal input terminal, an analog signal input terminal, a power input terminal, and a control signal output terminal. The first and second output terminals of the magnetoelectric vibration energy harvester are used to output AC voltage. The first output terminal of the magnetoelectric vibration energy harvester is connected to the first AC input terminal of the energy harvesting module, and the second output terminal of the magnetoelectric vibration energy harvester is connected to the first AC input terminal of the energy harvesting module. The second AC input terminal of the energy capture module is connected; the control signal input terminal of the energy capture module is connected to the control signal output terminal of the microcontroller module. The microcontroller module outputs a control signal to the control signal input terminal of the energy capture module through its control signal output terminal to control the output power of the energy capture module; the power output terminal of the energy capture module is used to output DC voltage VCC, and the power output terminal of the energy capture module is connected to the power input terminal of the microcontroller module and the power input terminal of the accelerometer respectively; the square wave signal output terminal of the energy capture module is connected to the digital signal input terminal of the microcontroller module to output a square wave signal V. fre The accelerometer's acceleration signal output terminal is connected to the microcontroller module's analog signal input terminal to output the acceleration signal V. acc To the microcontroller module.

[0012] Furthermore, the full-bridge rectifier has a first input terminal, a second input terminal, and an output terminal; the DC-DC converter has an input terminal, an output terminal, and a control terminal; the lithium battery has a positive terminal and a negative terminal; the linear regulator has an input terminal, an output terminal, and a ground terminal; the shaping circuit has a first input terminal, a second input terminal, and an output terminal; the multi-path voltage divider circuit has an input terminal, a control terminal, and an output terminal; the reference voltage circuit has an input terminal, a first output terminal, and a second output terminal; the hysteresis comparator circuit has a first input terminal, a second input terminal, a third input terminal, and an output terminal; the first input terminal of the full-bridge rectifier is connected to the first input terminal of the shaping circuit, and its connection terminal is the first AC input terminal of the energy harvesting module; the second input terminal of the full-bridge rectifier is connected to the second input terminal of the shaping circuit, and its connection terminal is the second AC input terminal of the energy harvesting module; the output terminal of the shaping circuit is the energy harvesting module's... The square wave signal output terminal of the energy harvesting module is connected to the input terminal of the DC-DC converter and the input terminal of the multi-path voltage divider circuit, respectively. The control terminal of the multi-path voltage divider circuit is the control signal input terminal of the energy harvesting module. The positive terminal of the lithium battery and the input terminal of the linear regulator are connected to the output terminal of the DC-DC converter, respectively. The output terminal of the linear regulator is the power output terminal of the energy harvesting module. The negative terminal of the lithium battery and the ground terminal of the linear regulator are both grounded. The input terminal of the reference voltage circuit is connected to the output terminal of the linear regulator. The first input terminal of the hysteresis comparator circuit is connected to the output terminal of the multi-path voltage divider circuit, the second input terminal of the hysteresis comparator circuit is connected to the first output terminal of the reference voltage circuit, the third input terminal of the hysteresis comparator circuit is connected to the second output terminal of the reference voltage circuit, and the output terminal of the hysteresis comparator circuit is connected to the control terminal of the DC-DC converter.

[0013] Furthermore, the full-bridge rectifier includes a first diode, a second diode, a third diode, a fourth diode, and a first capacitor. The anode of the first diode and the cathode of the third diode are connected, and their connection point is the first input terminal of the full-bridge rectifier. The anode of the second diode and the cathode of the fourth diode are connected, and their connection point is the second input terminal of the full-bridge rectifier. The cathodes of the first diode, the cathodes of the second diode, and one end of the first capacitor are connected, and their connection point is the output terminal of the full-bridge rectifier. The anodes of the third diode, the anodes of the fourth diode, and the other end of the first capacitor are all grounded. The shaping circuit includes a first operational amplifier, which has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the first operational amplifier is the first input terminal of the shaping circuit, the inverting input terminal of the first operational amplifier is the second input terminal of the shaping circuit, and the output terminal of the first operational amplifier is the output terminal of the shaping circuit.

[0014] Furthermore, the multipath voltage divider circuit includes a first resistor voltage divider module and a multiplexer; the first resistor voltage divider module has an input terminal, 16 output terminals, and a ground terminal; the input terminal of the first resistor voltage divider module is the input terminal of the multipath voltage divider circuit; the ground terminal of the first resistor voltage divider module is grounded; the multiplexer has 16 input terminals, 4 control input terminals, and an output terminal. The 4 control input terminals of the multiplexer constitute the control terminals of the multipath voltage divider circuit, used to receive 4-bit binary data as control signals. Under the control of the 4-bit binary data, one of its input terminals and one of its output terminals are turned on; the 16 output terminals of the first resistor voltage divider module are connected one-to-one with the 16 input terminals of the multiplexer; the output terminal of the multiplexer is the output terminal of the multipath voltage divider circuit.

[0015] Furthermore, the first resistor voltage divider module includes 16 resistors, numbered 1 to 16. One end of the first resistor serves as both the input and output terminal of the resistor voltage divider module. The other end of the k-th resistor is connected to one end of the (k+1)-th resistor, and this connection point becomes the (k+1)-th output terminal of the resistor voltage divider module, where k = 1, 2, ..., 15. The other end of the 16th resistor is the ground terminal of the resistor voltage divider module. The reference voltage circuit includes a second, a third, and a fourth resistor voltage divider module. The second, third, and fourth resistor voltage divider modules... Both the three-resistor voltage divider module and the fourth-resistor voltage divider module have input and output terminals. The input terminal of the second-resistor voltage divider module is the input terminal of the reference voltage circuit, used to connect to the DC voltage VCC. The output terminal of the second-resistor voltage divider module is connected to the input terminal of the third-resistor voltage divider module, and its connection terminal is the first output terminal of the reference voltage circuit, used to output the upper limit threshold voltage VH. The output terminal of the third-resistor voltage divider module is connected to the input terminal of the fourth-resistor voltage divider module, and its connection terminal is the second output terminal of the reference voltage circuit, used to output the lower limit threshold voltage VL. The output terminal of the fourth-resistor voltage divider module is grounded.

[0016] Furthermore, the hysteresis comparator circuit includes a second operational amplifier, a third operational amplifier, a first NAND gate, and a second NAND gate. Both the second and third operational amplifiers have a non-inverting input, an inverting input, and an output. Both the first and second NAND gates have a first input, a second input, and an output. The inverting input of the second operational amplifier and the non-inverting input of the third operational amplifier are connected, and this connection point serves as the first input of the hysteresis comparator circuit. The non-inverting input of the second operational amplifier serves as the second input of the hysteresis comparator circuit, and the inverting input of the third operational amplifier serves as the third input of the hysteresis comparator circuit. The output of the second operational amplifier is connected to the first input of the first NAND gate, and the output of the third operational amplifier is connected to... The second input terminal of the second NAND gate is connected, the second input terminal of the first NAND gate and the output terminal of the second NAND gate are connected, the first input terminal of the second NAND gate and the output terminal of the first NAND gate are connected, and their connection terminal is the output terminal of the hysteresis comparator circuit; the DC-DC converter circuit includes a DC-DC converter and a first inductor. The DC-DC converter has an input terminal, an inductor connection terminal, a control input terminal, an output terminal and a ground terminal. The input terminal of the DC-DC converter is connected to one end of the first inductor, and its connection terminal is the input terminal of the DC-DC converter circuit. The inductor connection terminal of the DC-DC converter is connected to the other end of the first inductor. The output terminal of the DC-DC converter is the output terminal of the DC-DC converter circuit. The control input terminal of the DC-DC converter is the control input terminal of the DC-DC converter circuit. The ground terminal of the DC-DC converter is grounded.

[0017] Furthermore, the specific process by which the microcontroller module uses the fractional-order open-circuit voltage method to control the output power of the energy harvesting module is as follows:

[0018] Step S1: After power-on, the microcontroller module operates according to the preset default open-circuit voltage V. EOC The multi-path voltage divider circuit is controlled to select the corresponding voltage divider path to divide the DC voltage Vdc, generating the corresponding divided voltage Vdc,div output;

[0019] Step S2: According to the preset control cycle, periodically control the multi-path voltage divider circuit, and record the current cycle number as T. The control process of the Tth cycle is as follows:

[0020] Step S2.1: Acquire acceleration signal V acc and square wave signal V fre And acquire the acceleration signal V acc The amplitude A and the square wave signal V fre angular frequency The open-circuit voltage V is calculated using formula (1). EOC ;

[0021] Step S2.2: If T=1, then determine the currently obtained open-circuit voltage V. EOC Compared to the default open-circuit voltage VEOC Has it changed? If it has changed, then obtain the open-circuit voltage V from the lookup table and compare it with the currently calculated voltage. EOC The corresponding voltage divider path is selected, and the multi-path voltage divider circuit is switched to that voltage divider path. The next cycle count starts from 1 again. If there is no change, the control of the multi-path voltage divider circuit remains unchanged, and the microcontroller module waits for the preset wake-up time t before entering the next cycle.

[0022] If T=2 or T=3, then determine the currently obtained open-circuit voltage V. EOC Compared to the open-circuit voltage V of the previous cycle EOC Has it changed? If it has changed, then obtain the open-circuit voltage V from the lookup table and compare it with the currently calculated voltage. EOC The corresponding voltage divider path is selected, and the multi-path voltage divider circuit is switched to that voltage divider path. The next cycle count starts from 1 again. If there is no change, the control of the multi-path voltage divider circuit remains unchanged, and the microcontroller module waits for the preset wake-up time t before entering the next cycle.

[0023] If T≥4, then determine the currently obtained open-circuit voltage V. EOC The open-circuit voltage V relative to the (T-1)th cycle EOC If there is no change, the control of the multipath voltage divider circuit remains unchanged, and the microcontroller module waits for a preset wake-up time t' before entering the next cycle, where t' is greater than t. If there is a change, the open-circuit voltage V calculated at the time of calculation is obtained from the lookup table. EOC The corresponding voltage divider path controls the multi-path voltage divider circuit to switch to that voltage divider path. The microcontroller module waits for the preset wake-up time t before entering the next cycle, and the next cycle count starts from 1 again. Attached Figure Description

[0024] Figure 1 This is a structural block diagram of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention;

[0025] Figure 2 This is a structural block diagram of the energy harvesting module of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention;

[0026] Figure 3 The circuit diagram shows the full-bridge rectifier and shaping circuit of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention.

[0027] Figure 4 The circuit diagram shows the multipath voltage divider circuit of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention.

[0028] Figure 5The circuit diagram shows the reference voltage circuit and hysteresis comparator circuit of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention.

[0029] Figure 6 The circuit diagram shows the DC-DC converter circuit of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention.

[0030] Figure 7 The waveform diagram of the power optimization theory of the magnetoelectric vibration energy harvesting system of the present invention is shown below.

[0031] Figure 8 The experimental waveforms of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention are shown at fixed vibration acceleration frequencies and amplitudes.

[0032] Figure 9 The experimental waveforms of the magnetoelectric vibration energy harvesting system capable of power optimization according to the present invention are shown under fixed vibration acceleration frequency and variable acceleration amplitude. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0034] Example 1: As Figure 1 As shown, a magnetoelectric vibration energy harvesting system capable of power optimization includes a magnetoelectric vibration energy harvester 1 and a magnetoelectric vibration energy harvesting circuit. The magnetoelectric vibration energy harvester 1 is used to sense environmental vibrations and generate corresponding AC voltage outputs. The magnetoelectric vibration energy harvesting circuit includes an energy harvesting module 2, an accelerometer 3, and a microcontroller module 4. The energy harvesting module 2 is used to convert the AC voltage into a DC voltage VCC and a square wave signal V, respectively. fre The microcontroller module 4 and accelerometer 3 are powered by a DC voltage VCC, and the square wave signal V is converted into a DC voltage VCC. fre Output to microcontroller module 4; square wave signal V fre The frequency is the same as that of the AC voltage; the accelerometer 3 is used to sense environmental vibrations and generate the corresponding acceleration signal V. acc The output is sent to microcontroller module 4; microcontroller module 4 is used to first output the square wave signal V. fre angular frequency and acceleration signal V acc The amplitude is used to determine the open-circuit voltage V of the magnetoelectric vibration energy harvester 1. EOC Then, the output power of the energy harvesting module 2 is controlled by the fractional open-circuit voltage method to achieve maximum power transmission.

[0035] In this embodiment, when the magnetoelectric vibration energy harvester 1 senses the AC voltage output by the environmental vibration, the energy harvesting module 2 converts the AC voltage into a DC voltage VCC and a square wave signal V, respectively. freIt also outputs the DC voltage VCC to the microcontroller module 4 and the accelerometer 3 to power the microcontroller module 4 and the accelerometer 3, and outputs the square wave signal V. fre The square wave signal V is output to microcontroller module 4. fre The accelerometer 3 operates and outputs a square wave signal V, with the frequency of the AC voltage output by the magnetoelectric vibration energy harvester 1 being the same. fre The signal is transferred to microcontroller module 4. Microcontroller module 4 first determines the signal based on the square wave signal V. fre angular frequency and acceleration signal V acc The amplitude is used to determine the open-circuit voltage V of the magnetoelectric vibration energy harvester 1. EOC Then, the fractional-order open-circuit voltage method is used to control the output power of the energy harvesting module 2 to achieve maximum power transmission. Therefore, in this embodiment, when using the fractional-order open-circuit voltage method to achieve maximum power transmission, the acceleration signal output by the accelerometer 3 provides a reference signal for power optimization of the magnetoelectric vibration energy harvesting system, based on the square wave signal V... fre angular frequency and acceleration signal V acc The open-circuit voltage can be obtained by measuring the amplitude, thus eliminating the need to periodically disconnect the magnetoelectric vibration energy harvester 1 and the magnetoelectric vibration energy harvesting circuit to measure the open-circuit voltage. This eliminates the need to interrupt the energy transfer process, ensuring the continuity of the energy harvesting process, and combining fast dynamic response characteristics with high energy harvesting effect.

[0036] Example 2: This example is basically the same as Example 1, except that: in this example, the magnetoelectric vibration energy harvester 1 is implemented using a moving iron structure. The magnetoelectric vibration energy harvester 1 can be equivalent to a single-degree-of-freedom linear vibration system containing a spring, a mass block, damping, and an electromagnetic transducer component. M The mass of the mass block of the equivalent linear vibration system. K The stiffness of the spring in the equivalent linear vibration system. D For the damping of the equivalent linear vibration system, is the electromechanical coupling coefficient of the electromagnetic transducer component of the equivalent linear vibration system.

[0037] In this embodiment, based on Newton's second law of motion and Kirchhoff's voltage law, the differential equation of motion and the electrical equation of the magnetoelectric vibration energy harvester can be expressed as follows:

[0038] (1)

[0039] (2)

[0040] In formulas (1) and (2), a This indicates the fundamental acceleration excitation experienced by the magnetoelectric vibration energy harvester. u This represents the relative displacement response of the mass block in an equivalent linear vibration system. The relative velocity response of the mass block in the equivalent linear vibration system. The relative acceleration response of the mass block in the equivalent linear vibration system. a = Asin ( t ), A Basic acceleration excitation a amplitude, Basic acceleration excitation a angular frequency, t This indicates a specific moment. After connecting the magnetoelectric vibration energy harvester to the magnetoelectric vibration energy harvesting circuit, the magnetoelectric vibration energy harvesting circuit can be considered equivalent to a load resistor. V E This represents the output voltage of the magnetoelectric vibration energy harvester at a certain moment; the voltage across the magnetoelectric vibration energy harvester circuit is equal to the output voltage of the magnetoelectric vibration energy harvester. V E , I E This represents the current flowing through the magnetoelectric vibration energy harvesting circuit at a certain moment. R C The resistance of the electromagnetic transducer component in the equivalent linear vibration system. L C The inductance is the electromagnetic transducer component of the equivalent linear vibration system.

[0041] make I E =0, substituting it into formulas (1) and (2) and solving them simultaneously, we obtain the output voltage of the magnetoelectric vibration energy harvester in the open-circuit state at a certain moment. V E The instantaneous value. This output voltage is extracted. V E The steady-state amplitude is used to obtain the open-circuit voltage V of the magnetoelectric vibration energy trap. EOC The expression for is shown in equation (3):

[0042] (3)

[0043] Since the magnetoelectric vibration energy harvester and the accelerometer are in the same vibration environment, they are both subjected to the same basic acceleration excitation. A It can also be represented as the acceleration signal V sensed by the accelerometer at a certain moment. acc amplitude, Corresponding to square wave signal V fre The angular frequency, which is the acceleration signal V acc The angular frequency. Therefore, based on the magnetoelectric vibration energy harvester 1, the angular frequency is determined. M , K , D and After obtaining these design parameters, all that is needed is to acquire the acceleration signal V. acc and square wave signal V fre Then the acceleration signal V can be obtained. acc The amplitude and square wave signal V fre Given the angular frequency, the microcontroller module 4 can use formula (3) to calculate the open-circuit voltage V of the magnetoelectric vibration energy trap 1 at any given time. EOC .

[0044] Example 3: This example is basically the same as Example 2, except that: in this example, as Figure 2 As shown, in this embodiment, the energy harvesting module 2 includes a full-bridge rectifier, a DC-DC converter, a lithium battery BAT1, a linear regulator, a shaping circuit, a multi-path voltage divider circuit, a reference voltage circuit, and a hysteresis comparator circuit. The full-bridge rectifier is used to rectify the AC voltage into a DC voltage Vdc, which is then output to the DC-DC converter and the multi-path voltage divider circuit, respectively. The shaping circuit is used to convert the AC voltage into a square wave signal V. fre The DC-DC converter circuit converts the DC voltage Vdc into a charging DC voltage to charge the lithium battery BAT1; the linear regulator converts this charging DC voltage into a DC voltage VCC; the multi-path voltage divider circuit includes multiple selectable voltage divider paths with different voltage division coefficients; the microcontroller module has four pre-stored locations containing possible open-circuit voltages V. EOC The values ​​of V and the comparison table of each voltage divider path; when the microcontroller module 4 determines the open circuit voltage V EOC Then, the corresponding voltage divider path is found in the lookup table, and the multi-path voltage divider circuit is controlled to select this path to divide the DC voltage Vdc, generating the corresponding divided voltage Vdc,div, which is output to the hysteresis comparator circuit. The reference voltage circuit is used to connect the DC voltage VCC and generates the upper threshold voltage VH and the lower threshold voltage VL, which are output to the hysteresis comparator circuit. The hysteresis comparator circuit performs a hysteresis comparison on the divided voltage Vdc,div based on the upper threshold voltage VH and the lower threshold voltage VL, and outputs a control signal VEN to control the opening and closing of the DC-DC converter circuit, changing the magnitude of the DC voltage Vdc, limiting the divided voltage Vdc,div between the upper threshold voltage VH and the lower threshold voltage VL, and making the DC voltage Vdc hysteresis at the current open circuit voltage V. EOC Maximum power transfer is achieved at approximately half of the maximum power.

[0045] In this embodiment, the magnetoelectric vibration energy harvester 1 has a first output terminal and a second output terminal; the energy harvesting module 2 has a first AC input terminal, a second AC input terminal, a control signal input terminal, a square wave signal output terminal, and a power output terminal; the accelerometer 3 has an acceleration signal output terminal and a power input terminal; and the microcontroller module 4 has a digital signal input terminal, an analog signal input terminal, a power input terminal, and a control signal output terminal. The first and second output terminals of the magnetoelectric vibration energy harvester 1 are used to output AC voltage. The first output terminal of the magnetoelectric vibration energy harvester 1 is connected to the first AC input terminal of the energy harvesting module 2, and the second output terminal of the magnetoelectric vibration energy harvester 1 is connected to the energy harvesting module 2. The second AC input terminal of the energy harvesting module 2 is connected; the control signal input terminal of the energy harvesting module 2 is connected to the control signal output terminal of the microcontroller module 4, and the microcontroller module 4 outputs a control signal to the control signal input terminal of the energy harvesting module 2 through its control signal output terminal to control the output power of the energy harvesting module 2; the power output terminal of the energy harvesting module 2 is used to output DC voltage VCC, and the power output terminal of the energy harvesting module 2 is connected to the power input terminal of the microcontroller module 4 and the power input terminal of the accelerometer 3 respectively; the square wave signal output terminal of the energy harvesting module 2 is connected to the digital signal input terminal of the microcontroller module 4 to output square wave signal V. fre The acceleration signal output terminal of the accelerometer 3 is connected to the analog signal input terminal of the microcontroller module 4, for outputting the acceleration signal V. acc To microcontroller module 4.

[0046] In this embodiment, the full-bridge rectifier has a first input terminal, a second input terminal, and an output terminal; the DC-DC converter has an input terminal, an output terminal, and a control terminal; the lithium battery BAT1 has a positive terminal and a negative terminal; the linear regulator has an input terminal, an output terminal, and a ground terminal; the shaping circuit has a first input terminal, a second input terminal, and an output terminal; the multi-path voltage divider circuit has an input terminal, a control terminal, and an output terminal; the reference voltage circuit has an input terminal, a first output terminal, and a second output terminal; the hysteresis comparator circuit has a first input terminal, a second input terminal, a third input terminal, and an output terminal; the first input terminal of the full-bridge rectifier is connected to the first input terminal of the shaping circuit, and its connection terminal is the first AC input terminal of the energy harvesting module 2; the second input terminal of the full-bridge rectifier is connected to the second input terminal of the shaping circuit, and its connection terminal is the second AC input terminal of the energy harvesting module 2; the output terminal of the shaping circuit is the first AC input terminal of the energy harvesting module 2. The square wave signal output terminal of block 2; the input terminal of the DC-DC converter circuit and the input terminal of the multi-path voltage divider circuit are respectively connected to the output terminal of the full-bridge rectifier; the control terminal of the multi-path voltage divider circuit is the control signal input terminal of the energy harvesting module 2; the positive terminal of the lithium battery BAT1 and the input terminal of the linear regulator are respectively connected to the output terminal of the DC-DC converter circuit; the output terminal of the linear regulator is the power output terminal of the energy harvesting module 2; the negative terminal of the lithium battery BAT1 and the ground terminal of the linear regulator are both grounded; the input terminal of the reference voltage circuit is connected to the output terminal of the linear regulator; the first input terminal of the hysteresis comparator circuit is connected to the output terminal of the multi-path voltage divider circuit, the second input terminal of the hysteresis comparator circuit is connected to the first output terminal of the reference voltage circuit, the third input terminal of the hysteresis comparator circuit is connected to the second output terminal of the reference voltage circuit, and the output terminal of the hysteresis comparator circuit is connected to the control terminal of the DC-DC converter circuit.

[0047] Example 4: This example is basically the same as Example 2, except that: in this example, as Figure 3 As shown, the full-bridge rectifier includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, and a first capacitor C1. The anode of the first diode D1 and the cathode of the third diode D3 are connected, and their connection point is the first input terminal of the full-bridge rectifier. The anode of the second diode D2 and the cathode of the fourth diode D4 are connected, and their connection point is the second input terminal of the full-bridge rectifier. The cathodes of the first diode D1 and the second diode D2 are connected to one end of the first capacitor C1, and their connection point is the output terminal of the full-bridge rectifier. The anodes of the third diode D3 and the fourth diode D4, and the other end of the first capacitor C1 are all grounded. The shaping circuit includes a first operational amplifier U1, which has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the first operational amplifier U1 is the first input terminal of the shaping circuit, the inverting input terminal of the first operational amplifier U1 is the second input terminal of the shaping circuit, and the output terminal of the first operational amplifier U1 is the output terminal of the shaping circuit.

[0048] In this embodiment, as Figure 4 As shown, the multipath voltage divider circuit includes a first resistor voltage divider module RR1 and a multiplexer MUX1. The first resistor voltage divider module RR1 has an input terminal, 16 output terminals, and a ground terminal. The input terminal of the first resistor voltage divider module RR1 is the input terminal of the multipath voltage divider circuit. The ground terminal of the first resistor voltage divider module RR1 is grounded. The multiplexer MUX1 has 16 input terminals, 4 control input terminals, and an output terminal. The 4 control input terminals of the multiplexer MUX1 constitute the control terminals of the multipath voltage divider circuit, used to input the 4-bit binary data Vctrl as the control signal. A0 V A1 V A2 V A3 In the 4-bit binary data V A0 V A1 V A2 V A3 Under control, one input and one output terminal are connected; the 16 output terminals of the first resistor voltage divider module RR1 are connected one-to-one with the 16 input terminals of the multiplexer MUX1; the output terminal of the multiplexer MUX1 is the output terminal of the multipath voltage divider circuit. The first resistor voltage divider module RR1 includes 16 resistors, namely the first resistor R1 to the 16th resistor R16; one end of the first resistor R1 is both the input terminal and the first output terminal of the resistor voltage divider module; the other end of the kth resistor Rk is connected to one end of the (k+1)th resistor R(k+1), and its connection terminal is the (k+1)th output terminal of the resistor voltage divider module, k=1, 2, ..., 15; the other end of the 16th resistor R16 is the ground terminal of the resistor voltage divider module; the reference voltage circuit includes the second resistor voltage divider module RR2, the third resistor voltage divider module RR3, and the fourth resistor voltage divider module RR4; the second resistor voltage divider module RR2 Both the third resistor voltage divider module RR3 and the fourth resistor voltage divider module RR4 have input and output terminals. The input terminal of the second resistor voltage divider module RR2 is the input terminal of the reference voltage circuit, used to connect to the DC voltage VCC. The output terminal of the second resistor voltage divider module RR2 is connected to the input terminal of the third resistor voltage divider module RR3, and its connection terminal is the first output terminal of the reference voltage circuit, used to output the upper limit threshold voltage VH. The output terminal of the third resistor voltage divider module RR3 is connected to the input terminal of the fourth resistor voltage divider module RR4, and its connection terminal is the second output terminal of the reference voltage circuit, used to output the lower limit threshold voltage VL. The output terminal of the fourth resistor voltage divider module RR4 is grounded.

[0049] In this embodiment, as Figure 5As shown, the hysteresis comparator circuit includes a second operational amplifier U2, a third operational amplifier U3, a first NAND gate NAND1, and a second NAND gate NAND2. Both the second operational amplifier U2 and the third operational amplifier U3 have a non-inverting input, an inverting input, and an output. Both the first NAND gate NAND1 and the second NAND gate NAND2 have a first input, a second input, and an output. The inverting input of the second operational amplifier U2 and the non-inverting input of the third operational amplifier U3 are connected, and this connection point is the first input of the hysteresis comparator circuit. The non-inverting input of the second operational amplifier U2... The input terminal is the second input terminal of the hysteresis comparator circuit. The inverting input terminal of the third operational amplifier U3 is the third input terminal of the hysteresis comparator circuit. The output terminal of the second operational amplifier U2 is connected to the first input terminal of the first NAND gate NAND1. The output terminal of the third operational amplifier U3 is connected to the second input terminal of the second NAND gate NAND2. The second input terminal of the first NAND gate NAND1 is connected to the output terminal of the second NAND gate NAND2. The first input terminal of the second NAND gate NAND2 is connected to the output terminal of the first NAND gate NAND1, and its connection terminal is the output terminal of the hysteresis comparator circuit. Figure 6 As shown, the DC-DC converter circuit includes a DC-DC converter U4 and a first inductor L1. The DC-DC converter U4 has an input terminal, an inductor connection terminal, a control input terminal, an output terminal, and a ground terminal. The input terminal of the DC-DC converter U4 is connected to one end of the first inductor L1, and its connection terminal is the input terminal of the DC-DC converter circuit. The inductor connection terminal of the DC-DC converter U4 is connected to the other end of the first inductor L1. The output terminal of the DC-DC converter U4 is the output terminal of the DC-DC converter circuit. The control input terminal of the DC-DC converter U4 is the control input terminal of the DC-DC converter circuit. The ground terminal of the DC-DC converter U4 is grounded.

[0050] In this embodiment, based on the design parameters of the second resistor voltage divider module RR2, the third resistor voltage divider module RR3, and the fourth resistor voltage divider module RR4, and the DC voltage VCC, the upper threshold voltage VH and the lower threshold voltage VL can be obtained. The sum of the upper threshold voltage VH and the lower threshold voltage VL is calculated, and the sum of the two is used as the target reference value for voltage division. Then, based on experiments, the open-circuit voltage V of the magnetoelectric vibration energy harvester, which varies within a certain range, can be measured. EOC The range of values ​​for is within the open-circuit voltage V. EOC Within the range of values, 16 discrete open-circuit voltage points are selected at equal intervals, and the i-th discrete open-circuit voltage point is denoted as V. EOC,i For i = 1, 2, ..., 16, calculate the ratio of the target voltage divider value to each discrete open-circuit voltage point, and then compare the target voltage divider value with the i-th discrete open-circuit voltage point V. EOC,i The ratio is denoted as ki, and this ratio ki is the voltage value at the i-th discrete open-circuit voltage point V. EOC,iThe ideal voltage division coefficient is obtained by calculating the ideal voltage division coefficient for each discrete open-circuit voltage point. Since the voltage division paths of the first resistor voltage divider module RR1 are finite and discrete, this embodiment adopts the nearest matching principle, selecting the voltage division path in the first resistor voltage divider module RR1 that is closest to the ideal voltage division coefficient to establish the discrete open-circuit voltage point V. EOC,i A table showing the comparison of each voltage divider path; in practical applications, the open-circuit voltage V calculated by microprocessor module 4... EOC If it does not exist in the lookup table, then select the one in the lookup table that matches the open-circuit voltage V. EOC The discrete open-circuit voltage point with the smallest absolute difference (if two exist, either one is selected) is used, and its corresponding voltage divider path is invoked. Theoretically, the more detailed the voltage divider path design of the first resistor voltage divider module RR1, the higher the approximation of the ideal voltage divider coefficient, and the more accurate the voltage divider result. Therefore, the microcontroller module 4 calculates the open-circuit voltage V... EOC Then, the corresponding voltage divider path can be determined from the lookup table using the nearest matching principle, and then the input terminal of the multiplexer MUX1 can be connected to its output terminal to connect the corresponding voltage divider path to the circuit.

[0051] In this embodiment, the magnetoelectric vibration energy harvester 1 generates an AC voltage after sensing environmental vibration. The AC voltage is output between its first and second output terminals to a full-bridge rectifier and a shaping circuit. The full-bridge rectifier converts the AC voltage into a DC voltage Vdc, which is then output to a DC-DC converter circuit and a multi-path voltage divider circuit, respectively. The shaping circuit converts the AC voltage into a square wave signal V. fre The output is sent to microcontroller module 4. The DC-DC converter circuit converts the DC voltage Vdc into a charging DC voltage to charge the lithium battery BAT1. The linear regulator converts this charging DC voltage into a DC voltage VCC, which is then output to microcontroller module 4, accelerometer 3, and reference voltage circuit. This provides power to microcontroller module 4 and accelerometer 3, and a reference voltage to the reference voltage circuit. Accelerometer 3 senses environmental vibrations and generates a corresponding acceleration signal V. acc The output is given to microcontroller module 4; microcontroller module 4 outputs the acceleration signal V to it. acc and square wave signal V fre The open-circuit voltage V of its magnetoelectric vibration energy trap 1 is calculated using formula (3). EOCThe voltage is determined by finding the corresponding voltage divider path in the lookup table. Then, the corresponding input and output terminals of the multiplexer MUX1 are connected. The corresponding voltage divider path is selected to divide the DC voltage Vdc, generating a corresponding divided voltage Vdc,div, which is output to the hysteresis comparator circuit. After the reference voltage circuit is connected to the DC voltage VCC, the DC voltage VCC is divided by the second resistor voltage divider module RR2, the third resistor voltage divider module RR3, and the fourth resistor voltage divider module RR4, generating two divided voltages, namely the upper threshold voltage VH and the lower threshold voltage VL, which are output to the hysteresis comparator circuit. The hysteresis comparator circuit performs a hysteresis comparison on the divided voltage Vdc,div according to the upper threshold voltage VH and the lower threshold voltage VL, and outputs a control signal VEN to control the opening and closing of the DC-DC converter circuit. The voltage divider voltage Vdc,div has rising and falling phases. During the rising phase, the initial value of the voltage divider voltage Vdc,div is less than the lower threshold voltage VL, the control signal VEN is low, the DC-DC converter is off, and the voltage divider voltage Vdc,div gradually rises. As the voltage divider voltage Vdc,div rises, the control signal VEN remains low. When the voltage divider voltage Vdc,div rises to the upper threshold voltage VH or higher, the control signal VEN becomes high. During the falling phase, the initial value of the voltage divider voltage Vdc,div is greater than the upper threshold voltage VH, the control signal VEN is high, the DC-DC converter is on, and the DC-DC converter... The DC voltage Vdc is input to the lithium battery BAT1 through the DC-DC converter circuit for discharge. The DC voltage Vdc and the voltage divider voltage Vdc,div gradually decrease. As the voltage divider voltage Vdc,div decreases, the control signal VEN remains high. When the voltage divider voltage Vdc,div drops to the lower threshold voltage VL or lower, the control signal VEN goes low. This allows the voltage divider voltage Vdc,div to hysteresis between the upper threshold voltage VH and the lower threshold voltage VL, with the relationship: Vdc,div ≈ 0.5 × (VL + VH). Simultaneously, this maintains the DC voltage Vdc at the open-circuit voltage V calculated by the microcontroller module 4. EOC Half of that, thus achieving maximum power transfer.

[0052] The theoretical waveform for power optimization of the magnetoelectric vibration energy harvesting system of the present invention is as follows: Figure 7 As shown. Figure 7 In order to control variables, the frequency of the vibration acceleration (i.e., the acceleration signal output by accelerometer 3) remains constant, and only the amplitude of the vibration acceleration changes. Figure 7The waveform of the control signal VEN is also presented. During the time interval t0 to t1, the vibration acceleration begins to be excited and remains constant. The first resistor divider module RR1 and the multiplexer MUX1 divide the DC voltage Vdc to the minimum voltage division factor, making it as low as possible below the upper threshold voltage VH. At this time, the control signal VEN is low, the DC-DC converter circuit is off, and the entire magnetoelectric vibration energy harvesting system is in an open-circuit state. The DC voltage Vdc charges the first capacitor C1 and tends to saturate. During the time interval t1 to t2, the vibration acceleration excitation remains constant. The microcontroller module 4, based on the input acceleration signal V... acc and square wave signal V fre The open-circuit voltage V is calculated. EOC Size, microcontroller module 4 based on the currently calculated open-circuit voltage V EOC Find the corresponding voltage divider path in the lookup table, control the multiplexer to select the corresponding input terminal, so that the voltage divider voltage Vdc,div hysteresis between the lower threshold voltage VL and the upper threshold voltage VH, while the DC voltage Vdc hysteresis at the open circuit voltage V output of the magnetoelectric vibration energy harvester 1. EOC The calculated value is around half; during the time period from t2 to t3, the vibration acceleration increases, and the microcontroller module 4 recalculates the open-circuit voltage V output by the magnetoelectric vibration energy harvester 1. EOC The magnitude, again based on the open-circuit voltage V EOC The multiplexer MUX1 is selected, causing the voltage divider Vdc,div to hysteresis between the lower threshold voltage VL and the upper threshold voltage VH. At this time, due to the increased vibration energy, the DC voltage Vdc charges the first capacitor C1 faster, thus increasing the hysteresis speed of Vdc. EOC As the vibration acceleration increases, the hysteresis range of the DC voltage Vdc shifts positively; during the time interval t3 to t4, the vibration acceleration decreases, and the hysteresis velocity of the DC voltage Vdc slows down. EOC As the voltage decreases, the DC voltage Vdc hysteresis range experiences a negative level shift.

[0053] Example 5: This example is basically the same as Example 4, except that: In this example, the specific process by which the microcontroller module 4 uses the fractional open-circuit voltage method to control the output power of the energy harvesting module 2 is as follows:

[0054] Step S1: After power-on, the microcontroller module 4 operates according to the preset default open-circuit voltage V. EOC The multi-path voltage divider circuit is controlled to select the corresponding voltage divider path to divide the DC voltage Vdc, generating the corresponding divided voltage Vdc,div output;

[0055] Step S2: According to the preset control cycle, periodically control the multi-path voltage divider circuit, and record the current cycle number as T. The control process of the Tth cycle is as follows:

[0056] Step S2.1: Acquire acceleration signal V acc and square wave signal V fre And acquire the acceleration signal V acc The amplitude A and the square wave signal V fre angular frequency The open-circuit voltage V is calculated using formula (3). EOC ;

[0057] Step S2.2: If T=1, then determine the currently obtained open-circuit voltage V. EOC Compared to the default open-circuit voltage V EOC Has it changed? If it has changed, then obtain the open-circuit voltage V from the lookup table and compare it with the currently calculated voltage. EOC The corresponding voltage divider path is controlled, and the multi-path voltage divider circuit is switched to that voltage divider path. The next cycle count starts from 1 again. If there is no change, the control of the multi-path voltage divider circuit remains unchanged, and the microcontroller module 4 waits for the preset wake-up time t before entering the next cycle.

[0058] If T=2 or T=3, then determine the currently obtained open-circuit voltage V. EOC Compared to the open-circuit voltage V of the previous cycle EOC Has it changed? If it has changed, then obtain the open-circuit voltage V from the lookup table and compare it with the currently calculated voltage. EOC The corresponding voltage divider path is controlled, and the multi-path voltage divider circuit is switched to that voltage divider path. The next cycle count starts from 1 again. If there is no change, the control of the multi-path voltage divider circuit remains unchanged, and the microcontroller module 4 waits for the preset wake-up time t before entering the next cycle.

[0059] If T≥4, then determine the currently obtained open-circuit voltage V. EOC The open-circuit voltage V relative to the (T-1)th cycle EOC If there is no change, the control of the multipath voltage divider circuit remains unchanged, and the microcontroller module 4 waits for a preset wake-up time t' before entering the next cycle, where t' is greater than t; if there is a change, the open-circuit voltage V calculated at the time of calculation is obtained from the lookup table. EOC The corresponding voltage divider path is controlled by the multi-path voltage divider circuit to switch to that voltage divider path. The microcontroller module 4 waits for the preset wake-up time t before entering the next cycle, and the next cycle count starts from 1 again.

[0060] In this embodiment, if the open-circuit voltage V is not detected more than three times... EOC If changes occur, the waiting time of microcontroller module 4 will increase, thereby reducing the power consumption of microcontroller module 4.

[0061] To verify the power optimization process of the magnetoelectric vibration energy harvesting system of the present invention, in M =68.61g D =0.6155 N·s / m K =15664.73N / m β A circuit experiment was conducted under a voltage of 10.04 N / A. The experimental waveforms of the DC voltage Vdc, the voltage divider Vdc,div, and the control signal VEN are shown below. Figure 8 and Figure 9 As shown. Analysis Figure 8 It can be seen that, with a fixed vibration acceleration frequency of 76.0 Hz and an amplitude of 3 m / s², 2 Under the excitation of the magnetoelectric vibration energy harvesting system, the power optimization process includes an initialization phase and a power optimization phase. In the initialization phase, the microcontroller module 4 starts working and initializes, controlling the multiplexer MUX1 to select the DC voltage Vdc to the minimum voltage division factor. At this time, the magnetoelectric vibration energy harvester 1 is in an open-circuit state, the control signal VEN is low, the DC-DC converter is off, and the DC voltage Vdc charges the first capacitor C1 and tends to saturate. From the waveform, the saturation voltage of the DC voltage Vdc is approximately 2.4V, the voltage division factor Vdc,div is approximately 0.5V, and the open-circuit voltage V... EOC The calculated value is approximately 2.8V. During the power optimization phase, microcontroller module 4 uses the acceleration signal V input therein as its basis. acc and square wave signal V fre The open-circuit voltage V of the magnetoelectric vibration energy harvester 1 was calculated. EOC The system controls the multiplexer MUX1 to output a voltage divider voltage Vdc,div approximately 1V. At this point, Vdc,div is higher than the upper threshold voltage VH by 0.6V, and the control signal VEN goes high, turning on the DC-DC converter. The DC voltage Vdc is then converted by the DC-DC converter and input to the lithium battery BAT1 for discharge. When the voltage divider voltage Vdc,div is lower than the lower threshold voltage VL by 0.4V, the control signal VEN goes low, turning off the DC-DC converter. Vdc,div gradually rises, and when it exceeds 0.6V, VEN is pulled high. By repeating this process, the voltage divider voltage Vdc,div is stabilized between 0.4V and 0.6V, and the corresponding DC voltage Vdc is stabilized between 0.4V and 1.2V, thus achieving power optimization of the magnetoelectric vibration energy harvesting system. Calculations based on the capacitor energy storage formula show that the magnetoelectric vibration energy harvesting circuit can harvest 6.4mW of power during the power optimization stage. Compared to the 6.8mW output power of the magnetoelectric vibration energy harvester tested through the optimal load curve experiment, the power optimization efficiency of the magnetoelectric vibration energy harvesting system is 94.1%. Figure 9It can be seen that, with a fixed vibration acceleration frequency of 76.0Hz, changing the amplitude of the vibration acceleration at times t1 and t2 causes the microcontroller module 4 to recalculate the open-circuit voltage V output by the magnetoelectric vibration energy harvester 1. EOC The magnitude depends on the open-circuit voltage V. EOC The lookup table controls the selection of the multiplexer MUX1, causing the voltage divider Vdc,div to hysteresis between the lower threshold voltage VL and the upper threshold voltage VH, while the DC voltage Vdc hysteresis at the open-circuit voltage V. EOC As can be seen from the waveform, as the amplitude of vibration acceleration increases, the hysteresis velocity of DC voltage Vdc increases, and the hysteresis range of DC voltage Vdc shifts to a positive level. Conversely, as the amplitude of vibration acceleration decreases, the hysteresis velocity of DC voltage Vdc decreases, and the hysteresis range of DC voltage Vdc shifts to a negative level.

[0062] In summary, the magnetoelectric vibration energy harvesting system of the present invention utilizes the acceleration signal output by the accelerometer 3 to provide a reference signal for power optimization of the magnetoelectric vibration energy harvesting system, based on the square wave signal V. fre angular frequency and acceleration signal V acc The open-circuit voltage can be obtained by measuring the amplitude, thus eliminating the need to periodically disconnect the magnetoelectric vibration energy harvester 1 and the magnetoelectric vibration energy harvesting circuit to measure the open-circuit voltage. This eliminates the need to interrupt the energy transfer process, ensuring the continuity of the energy harvesting process, and combining fast dynamic response characteristics with high energy harvesting effect.

Claims

1. A magnetoelectric vibration energy harvesting system capable of power optimization, comprising a magnetoelectric vibration energy harvester and a magnetoelectric vibration energy harvesting circuit, wherein the magnetoelectric vibration energy harvester is used to sense environmental vibrations and generate a corresponding AC voltage output, characterized in that, The magnetoelectric vibration energy harvesting circuit includes an energy harvesting module, an accelerometer, and a microcontroller module; the energy harvesting module is used to convert the AC voltage into a DC voltage VCC and a square wave signal V, respectively. fre The microcontroller module and the accelerometer are powered by the DC voltage VCC, and the square wave signal V is used to power the microcontroller module and the accelerometer. fre The square wave signal V is output to the microcontroller module. fre The accelerometer has the same frequency as the AC voltage and is used to sense environmental vibrations and generate a corresponding acceleration signal V. acc The output is sent to the microcontroller module; the microcontroller module is used to first output the square wave signal V. fre The angular frequency and the acceleration signal V acc The amplitude is used to determine the open-circuit voltage V of the magnetoelectric vibration energy trap. EOC The output power of the energy harvesting module is then controlled using a fractional-order open-circuit voltage method to achieve maximum power transfer. The energy harvesting module includes a full-bridge rectifier, a DC-DC converter circuit, a lithium battery, a linear regulator, a shaping circuit, a multi-path voltage divider circuit, a reference voltage circuit, and a hysteresis comparator circuit. The multi-path voltage divider circuit includes multiple voltage divider paths with different voltage division coefficients. The microcontroller module pre-stores possible open-circuit voltages V. EOC The values ​​and a table of reference for each voltage divider path are provided. The full-bridge rectifier is connected to the shaping circuit, the DC-DC converter circuit, and the multi-path voltage divider circuit. The DC-DC converter circuit is connected to the lithium battery and the linear regulator. The linear regulator is connected to the reference voltage circuit. The reference voltage circuit and the multi-path voltage divider circuit are connected to the hysteresis comparator circuit. The hysteresis comparator circuit is connected to the DC-DC converter circuit.

2. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 1, characterized in that, The magnetoelectric vibration energy harvester is implemented using a moving iron structure, and the microcontroller module is based on the mass of the mass block of the equivalent linear vibration system of the magnetoelectric vibration energy harvester. M Spring stiffness K Damping D and the electromechanical coupling coefficient of the electromagnetic transducer component The acceleration signal V acc amplitude A and the square wave signal V fre angular frequency Determine the open-circuit voltage V of the magnetoelectric vibration energy harvester. EOC .

3. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 2, characterized in that, The magnetoelectric vibration energy harvester has two output terminals; the energy harvesting module has two AC input terminals, a control signal input terminal, a square wave signal output terminal, and a power output terminal; the accelerometer has an acceleration signal output terminal and a power input terminal; and the microcontroller module has a digital signal input terminal, an analog signal input terminal, a power input terminal, and a control signal output terminal. The two output terminals of the magnetoelectric vibration energy harvester and the two AC input terminals of the energy harvesting module are connected one-to-one. The control signal input terminal of the energy harvesting module is connected to the control signal output terminal of the microcontroller module. The power output terminal of the energy harvesting module is connected to the power input terminals of both the microcontroller module and the accelerometer. The square wave signal output terminal of the energy harvesting module is connected to the digital signal input terminal of the microcontroller module; the acceleration signal output terminal of the accelerometer is connected to the analog signal input terminal of the microcontroller module.

4. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 3, characterized in that, The full-bridge rectifier and shaping circuit have two input terminals and an output terminal; the DC-DC converter and multi-path voltage divider circuit have an input terminal, an output terminal, and a control terminal; the linear regulator has an input terminal and an output terminal; the reference voltage circuit has an input terminal and two output terminals; the hysteresis comparator circuit has three input terminals and an output terminal; the two input terminals of the full-bridge rectifier and the two input terminals of the shaping circuit are connected one-to-one as the two AC input terminals of the energy harvesting module; the output terminal of the shaping circuit is the square wave signal output terminal of the energy harvesting module; the input terminals of the DC-DC converter and the multi-path voltage divider circuit are connected to the full-bridge rectifier and the multi-path voltage divider circuit. The output terminal of the bridge rectifier is connected; the control terminal of the multipath voltage divider circuit is the control signal input terminal of the energy harvesting module; the positive terminal of the lithium battery and the input terminal of the linear regulator are respectively connected to the output terminal of the DC-DC converter; the output terminal of the linear regulator is the power output terminal of the energy harvesting module; the negative terminal of the lithium battery is grounded; the input terminal of the reference voltage circuit is connected to the output terminal of the linear regulator; the three input terminals of the hysteresis comparator circuit are respectively connected to the output terminal of the multipath voltage divider circuit and the two output terminals of the reference voltage circuit, and the output terminal of the hysteresis comparator circuit is connected to the control terminal of the DC-DC converter.

5. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 4, characterized in that, The full-bridge rectifier includes a first diode, a second diode, a third diode, a fourth diode, and a first capacitor. The anode of the first diode and the cathode of the third diode are connected, and their connection point is the first input terminal of the full-bridge rectifier. The anode of the second diode and the cathode of the fourth diode are connected, and their connection point is the second input terminal of the full-bridge rectifier. The cathodes of the first and second diodes are connected to one end of the first capacitor, and their connection point is the output terminal of the full-bridge rectifier. The anodes of the third and fourth diodes and the other end of the first capacitor are all grounded. The shaping circuit includes a first operational amplifier, which has a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of the first operational amplifier is the first input terminal of the shaping circuit, the inverting input terminal of the first operational amplifier is the second input terminal of the shaping circuit, and the output terminal of the first operational amplifier is the output terminal of the shaping circuit.

6. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 5, characterized in that, The multipath voltage divider circuit includes a first resistor voltage divider module and a multiplexer. The first resistor voltage divider module has an input terminal, 16 output terminals, and a ground terminal. The input terminal of the first resistor voltage divider module is the input terminal of the multipath voltage divider circuit. The ground terminal of the first resistor voltage divider module is grounded. The multiplexer has 16 input terminals, 4 control input terminals, and an output terminal. The 4 control input terminals of the multiplexer constitute the control terminals of the multipath voltage divider circuit, used to receive 4-bit binary data as control signals. Under the control of these 4-bit binary data, one of its input terminals and one of its output terminals are turned on. The 16 output terminals of the first resistor voltage divider module are connected one-to-one with the 16 input terminals of the multiplexer. The output terminal of the multiplexer is the output terminal of the multipath voltage divider circuit.

7. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 6, characterized in that, The first resistor voltage divider module includes Q resistors, where Q is an integer greater than or equal to 2. One end of the first resistor serves as both the input and the first output of the resistor voltage divider module. The other end of the kth resistor and one end of the (k+1)th resistor are connected to form the (k+1)th output of the resistor voltage divider module, where k = 1, 2, ..., Q-1. The other end of the Qth resistor is the ground terminal of the resistor voltage divider module. The reference voltage circuit includes a second, third, and fourth resistor voltage divider module. Each of these modules has an input and an output terminal. The input terminal of the second resistor voltage divider module is the input terminal of the reference voltage circuit. The output terminal of the second resistor voltage divider module is connected to the input terminal of the third resistor voltage divider module, and this connection terminal forms the first output terminal of the reference voltage circuit. The output terminal of the third resistor voltage divider module is connected to the input terminal of the fourth resistor voltage divider module, and this connection terminal forms the second output terminal of the reference voltage circuit. The output terminal of the fourth resistor voltage divider module is grounded.

8. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 7, characterized in that, The hysteresis comparator circuit includes a second operational amplifier, a third operational amplifier, a first NAND gate, and a second NAND gate. The connection between the inverting input of the second operational amplifier and the non-inverting input of the third operational amplifier, as well as the non-inverting input of the second operational amplifier and the inverting input of the third operational amplifier, serve as the three inputs of the hysteresis comparator circuit. The outputs of the second and third operational amplifiers are connected to the first input of the first NAND gate and the second input of the second NAND gate, respectively. The second input of the first NAND gate and the output of the second NAND gate are connected. The first input of the second NAND gate and the output of the first NAND gate are connected as the output of the hysteresis comparator circuit.

9. The magnetoelectric vibration energy harvesting system capable of power optimization according to claim 8, characterized in that, The DC-DC converter circuit includes a DC-DC converter and a first inductor. The DC-DC converter has an input terminal, an inductor connection terminal, a control input terminal, and an output terminal. The input terminal of the DC-DC converter and one end of the first inductor are connected as the input terminal of the DC-DC converter circuit. The inductor connection terminal of the DC-DC converter and the other end of the first inductor are connected. The output terminal of the DC-DC converter is the output terminal of the DC-DC converter circuit. The control input terminal of the DC-DC converter is the control input terminal of the DC-DC converter circuit.

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