A magnetoelectric vibration energy harvesting system capable of tracking the maximum power point

Abstract

The present invention discloses a magnetoelectric vibration energy harvesting system capable of tracking the maximum power point, comprising a magnetoelectric vibration energy harvester, an electric energy conversion circuit, a control circuit and a cold start circuit. The control circuit first calculates the internal impedance module of the magnetoelectric vibration energy harvester based on the open-circuit voltage and short-circuit current of the magnetoelectric vibration energy harvester, then adjusts the electric energy conversion circuit based on the internal impedance module of the magnetoelectric vibration energy harvester to achieve impedance module matching, and uses the perturbation observation method to adjust the maximum output power of the electric energy conversion circuit, thereby achieving maximum power point tracking. The system has the advantage that perturbing a single parameter can achieve rapid and accurate tracking of the maximum power point, the energy conversion efficiency is high, and the overall circuit structure is simple.

Description

Technical Field

[0001] The present invention relates to a magnetoelectric vibration energy harvesting system, in particular to a magnetoelectric vibration energy harvesting system capable of tracking a maximum power point. Background Art

[0002] With the rapid development of the Internet of Things (IoT), the deep integration of various sensing technologies, wireless communication technologies, and AI technologies has promoted collaborative perception and intelligent control among wireless sensor network nodes, and has broad application prospects in smart cities, smart homes, industrial IoT, smart wearable devices, and other fields. Currently, wireless sensor network nodes are mainly powered by rechargeable chemical batteries. When the number of devices is large and the locations are remote, the cost and difficulty of charging and maintenance are high. Therefore, research on self-powered technology to power low-power microelectronic devices such as wireless sensor network nodes is a key link in promoting their intelligent development. Magnetoelectric vibration energy harvesting technology has the advantages of no need for external power supply, high output power, and high reliability, and has received widespread attention in recent years.

[0003] To achieve maximum power transmission, impedance matching is usually performed between the magnetoelectric vibration energy harvester and the magnetoelectric energy harvesting interface circuit. However, the existing magnetoelectric energy harvesting interface circuit only achieves impedance matching at the resonant frequency point. However, the actual environmental vibration frequency varies. Once it deviates from the resonant frequency, the energy harvesting efficiency of the magnetoelectric energy harvesting interface circuit will drop significantly. In addition, the existing magnetoelectric energy harvesting interface circuit requires the electromechanical parameters of the magnetoelectric vibration energy harvester to be obtained in advance. However, the structural characteristics and parameters of each magnetoelectric vibration energy harvester vary, resulting in the magnetoelectric energy harvesting interface circuit being unable to use a unified program to adapt to them, which limits the scope of use of the magnetoelectric energy harvesting interface circuit. In order to solve the impedance matching problem of the magnetoelectric vibration energy harvester at the non-resonant frequency and the matching problem between different magnetoelectric vibration energy harvesters and the magnetoelectric energy harvesting interface circuit, and to improve the energy harvesting efficiency, researchers proposed an adaptive maximum power point tracking scheme based on the perturbation observation method.

[0004] Chinese invention patent application number CN202311019592.7 discloses a maximum power tracking method and application for energy harvesters. This method determines the perturbation direction based on the phase and amplitude relationship between the load voltage and the open-circuit voltage in the interface circuit. When applied to a magnetoelectric vibration energy harvesting system, this method can maintain a conjugate match between the load impedance and the equivalent internal impedance of the magnetoelectric energy harvester, accurately tracking the maximum power of the magnetoelectric energy harvester in a non-resonant state, and the overall circuit structure of the magnetoelectric vibration energy harvesting system is relatively simple. However, this method requires the simultaneous perturbation of both phase and amplitude parameters, and the objective function gradient calculation is complex, requiring reliance on a high-performance microcontroller. This increases energy loss and reduces the energy conversion efficiency of the magnetoelectric vibration energy harvesting system.

[0005] For example, Xiao et al. published a magnetoelectric vibration energy harvesting system in their paper “Xiao H, Peng H, et al. Automatic impedance matching with dual timescale P&O in fully self-poweredelectromagnetic vibration energy harvesting[J]. IEEE Transactions on Power Electronics, 2024, 39(3): 3377-3390.” in 2024. This magnetoelectric vibration energy harvesting system determines the internal impedance of the magnetoelectric vibration energy harvester based on the perturbation observation method by using the diameter and central angle of the perturbation circle, thereby achieving maximum power point tracking. This magnetoelectric vibration energy harvesting system can achieve fast and accurate maximum power point tracking in a non-resonant state, and has high energy conversion efficiency. However, it requires simultaneous perturbation observation of the two parameters, diameter and central angle. However, the circuit structure for mapping these two parameters is relatively complex, resulting in a relatively complex overall circuit structure. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a magnetoelectric vibration energy harvesting system with high energy conversion efficiency, simple overall circuit structure, and the ability to quickly and accurately track the maximum power point by perturbing a single parameter.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a magnetoelectric vibration energy harvesting system capable of tracking the maximum power point, including a magnetoelectric vibration energy harvester, an electric energy conversion circuit, a control circuit and a cold start circuit, wherein the magnetoelectric vibration energy harvester is used to convert vibration energy into AC voltage. V E Output, the power conversion circuit is used to convert the AC voltage V E Convert to supply voltage V CC output, the control circuit is used to supply voltage V CC When the internal working voltage is reached, the system enters the working state and controls the power conversion circuit to convert the AC voltage V E Perform maximum power point tracking, the cold start circuit is used to V CC When the internal working voltage of the control circuit is not reached, the power supply voltage is turned on and the working state is entered. V CCIncrease to reach the internal working voltage of the control circuit, the specific method in which the control circuit controls the electric energy conversion circuit to perform maximum power point tracking is: the control circuit first calculates the internal impedance model of the magnetoelectric vibration energy harvester according to the open-circuit voltage and short-circuit current of the magnetoelectric vibration energy harvester, and then adjusts the input internal resistance of the electric energy conversion circuit according to the internal impedance model of the magnetoelectric vibration energy harvester to achieve impedance model matching, and uses the perturbation observation method to perturb the boost rectifier voltage inside the electric energy conversion circuit to adjust the electric energy conversion circuit to output the maximum power, thereby achieving maximum power point tracking.

[0008] Compared with the prior art, the present invention has the advantage of calculating the internal impedance modulus of the magnetoelectric vibration energy harvester based on the open-circuit voltage and short-circuit current of the magnetoelectric vibration energy harvester through a control circuit. This allows for rapid determination of the internal impedance modulus of the magnetoelectric vibration energy harvester, dynamic adjustment of the input internal resistance within the power conversion circuit, impedance modulus matching, and preliminary maximum power point tracking. To reduce errors introduced by the estimated values and sampling accuracy used in the calculation, a perturbation-and-observation method is utilized to further fine-tune and optimize the maximum power output of the power conversion circuit, more accurately tracking the maximum power point and achieving high-speed and accurate maximum power point tracking. Furthermore, in the non-resonant state of the magnetoelectric vibration energy harvester, the control circuit can autonomously measure the internal impedance modulus of the magnetoelectric vibration energy harvester and adaptively perform impedance modulus matching. Consequently, the present invention utilizes the control circuit to perform maximum power point tracking, which is sequentially performed in the short-circuit, open-circuit, and energy harvesting phases. The power conversion circuit achieves maximum power transmission. Perturbing a single parameter (i.e., the boost rectifier voltage within the power conversion circuit) enables rapid and accurate maximum power point tracking, resulting in high energy conversion efficiency and a simple overall circuit structure.

[0009] Furthermore, the magnetoelectric vibration energy harvester has a positive output terminal and a negative output terminal, and the positive output terminal and the negative output terminal of the magnetoelectric vibration energy harvester are used to output the AC voltage. V E, the electric energy conversion circuit has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, a fifth input terminal, an input / output terminal, a first output terminal and a second output terminal, the control circuit has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, a power supply terminal, a first output terminal, a second output terminal and a third output terminal, the cold start circuit has a first input terminal, a second input terminal, a control terminal and an output terminal; the positive output terminal of the magnetoelectric vibration energy harvester is respectively connected to the first input terminal of the electric energy conversion circuit, the first input terminal of the control circuit and the first input terminal of the cold start circuit, and the negative output terminal of the magnetoelectric vibration energy harvester is respectively connected to the second input terminal of the electric energy conversion circuit, the The second input end of the control circuit is connected to the second input end of the cold start circuit, the third input end of the power conversion circuit is connected to the first output end of the control circuit, the fourth input end of the power conversion circuit is connected to the second output end of the control circuit, the fifth input end of the power conversion circuit is connected to the third output end of the control circuit, the input and output ends of the power conversion circuit are respectively connected to the output end of the cold start circuit and the third input end of the control circuit, the first output end of the power conversion circuit is connected to the fourth input end of the control circuit, and the second output end of the power conversion circuit serves as the output end of the magnetoelectric vibration energy capture system for outputting the supply voltage V CC The power supply end of the control circuit is connected to the second output end of the power conversion circuit.

[0010] Furthermore, the electric energy conversion circuit includes an electric energy storage device, a boost rectifier circuit, a power management circuit, a first analog switch and a second analog switch. The boost rectifier circuit has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, a first output terminal and a second output terminal. The power management circuit has an input terminal, an energy storage terminal and an output terminal. The electric energy storage device has a positive terminal and a negative terminal. The first analog switch has a first input terminal, a second input terminal, a control terminal, a first output terminal and a second output terminal. The second analog switch has an input terminal, a control terminal and an output terminal. The first input terminal of the first analog switch is the first input terminal of the electric energy conversion circuit, the second input terminal of the first analog switch is the second input terminal of the electric energy conversion circuit, the first output terminal of the first analog switch is connected to the first input terminal of the boost rectifier circuit, and the second output terminal of the first analog switch is connected to the boost rectifier circuit. The second input end of the circuit is connected, the first output end of the boost rectifier circuit is the first output end of the power conversion circuit, the third input end of the boost rectifier circuit is the third input end of the power conversion circuit, the fourth input end of the boost rectifier circuit is the fourth input end of the power conversion circuit, the second output end of the boost rectifier circuit is connected to the input end of the second analog switch, and its connection end is the input and output end of the power conversion circuit, the control end of the second analog switch is the fifth input end of the power conversion circuit, the output end of the second analog switch is connected to the input end of the power management circuit, the energy storage end of the power management circuit is connected to the positive end of the power storage device, the negative end of the power storage device is grounded, the output end of the power management circuit is the second output end of the power conversion circuit, and the control end of the first analog switch is connected to the output end of the power management circuit.

[0011] Furthermore, the boost rectifier circuit includes a first diode, a second diode, a first NMOS transistor, a second NMOS transistor, a first capacitor and a first resistor, the first capacitor is an electrolytic capacitor, the anode of the first diode is connected to the drain of the first NMOS transistor, and its connection end is the first input end of the boost rectifier circuit, the anode of the second diode is connected to the drain of the second NMOS transistor, and its connection end is the second input end of the boost rectifier circuit, the cathode of the first diode, the cathode of the second diode, and the positive end of the first capacitor are connected, and their connection end is the second output end of the boost rectifier circuit, the source of the first NMOS transistor is connected to one end of the first resistor, and their connection end is the first output end of the boost rectifier circuit, the source of the second NMOS transistor, the negative end of the first capacitor and the other end of the first resistor are all grounded, the gate of the first NMOS transistor is the third input end of the boost rectifier circuit, and the gate of the second NMOS transistor is the fourth input end of the boost rectifier circuit.

[0012] Furthermore, the control circuit includes a polarity detection circuit, a timing control circuit, a microcontroller and a current detection circuit. The polarity detection circuit has a first input terminal, a second input terminal and an output terminal. The timing control circuit has a first input terminal, a second input terminal, a third input terminal, a first output terminal and a second output terminal. The microcontroller has a PWM output terminal, a first output terminal, a second output terminal, a first input terminal, a second input terminal and a power supply terminal. The PWM output terminal of the microcontroller is used to output a PWM signal. The current detection circuit has a power supply terminal, an input terminal and an output terminal. The first input terminal of the polarity detection circuit is the first input terminal of the control circuit, the second input terminal of the polarity detection circuit is the second input terminal of the control circuit, and the output terminal of the polarity detection circuit is connected to the first input terminal of the timing control circuit. The second input end of the timing control circuit is connected to the PWM output end of the microcontroller, the third input end of the timing control circuit is connected to the first output end of the microcontroller, the first output end of the timing control circuit is the first output end of the control circuit, the second output end of the timing control circuit is the second output end of the control circuit, the second output end of the microcontroller is the third output end of the control circuit, the first input end of the microcontroller is the third input end of the control circuit, the second input end of the microcontroller is connected to the output end of the current detection circuit, the input end of the current detection circuit is the fourth input end of the control circuit, the power supply end of the microcontroller is connected to the power supply end of the current detection circuit, and its connection end is the power supply end of the control circuit.

[0013] Furthermore, the polarity detection circuit includes a second resistor, a second capacitor, a third resistor, a third capacitor and a first comparator, the first comparator has a non-inverting input terminal, an inverting input terminal and an output terminal, one end of the second resistor is the first input terminal of the polarity detection circuit, one end of the third resistor is the second input terminal of the polarity detection circuit, the other end of the second resistor, one end of the second capacitor and the non-inverting input terminal of the first comparator are connected, the other end of the third resistor, one end of the third capacitor and the inverting input terminal of the first comparator are connected, the other end of the second capacitor and the other end of the third capacitor are both grounded, and the output terminal of the first comparator is the output terminal of the polarity detection circuit.

[0014] Furthermore, the timing control circuit includes a first NOT gate, a first OR gate, a second OR gate, a first AND gate and a second AND gate. The first NOT gate has an input and an output. The first OR gate, the second OR gate, the first AND gate and the second AND gate all have a first input, a second input and an output. The input of the first NOT gate is connected to the second input of the second OR gate, and its connection end is the first input of the timing control circuit. The output of the first NOT gate is connected to the first input of the first OR gate. The second input of the first OR gate is connected to the first input of the second OR gate, and its connection end is the second input of the timing control circuit. The output of the first OR gate is connected to the first input of the first AND gate. The output of the second OR gate is connected to the second input of the second AND gate. The second input of the first AND gate is connected to the first input of the second AND gate, and its connection end is the third input of the timing control circuit. The output of the first AND gate is the first output of the timing control circuit, and the output of the second AND gate is the second output of the timing control circuit.

[0015] Furthermore, the current detection circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a first op amp, a second op amp, a third op amp, a fourth op amp, a third diode, a fourth diode and a fourth capacitor; the fourth resistor, the fifth resistor, the sixth resistor, the seventh resistor, the eighth resistor, the ninth resistor, the first op amp and the second op amp constitute a differential amplifier circuit, the tenth resistor, the third op amp, the fourth op amp, the third diode, the fourth diode and the fourth capacitor constitute a peak detection circuit, the first op amp, the second op amp, the third op amp and the fourth op amp all have a non-inverting input terminal, an inverting input terminal and an output terminal; one end of the fourth resistor, one end of the sixth resistor and the inverting input terminal of the first op amp are connected, the other end of the fourth resistor is the input terminal of the current detection circuit, the other end of the sixth resistor, the output terminal of the first op amp and the output terminal of the third op amp The non-inverting input terminal is connected, one end of the fifth resistor, one end of the seventh resistor and the non-inverting input terminal of the first operational amplifier are connected, the other end of the seventh resistor, the inverting input terminal of the second operational amplifier and the output terminal of the second operational amplifier are connected, one end of the eighth resistor, one end of the ninth resistor and the non-inverting input terminal of the second operational amplifier are connected, the positive electrode of the third diode, one end of the tenth resistor and the inverting input terminal of the third operational amplifier are connected, the other end of the tenth resistor, the inverting input terminal of the fourth operational amplifier and the output terminal of the fourth operational amplifier are connected, and their connection ends are the output terminal of the current detection circuit, the cathode of the third diode, the positive electrode of the fourth diode and the output terminal of the third operational amplifier are connected, the cathode of the fourth diode, one end of the fourth capacitor and the non-inverting input terminal of the fourth operational amplifier are connected, the other end of the ninth resistor is the power supply terminal of the current detection circuit, and the other end of the fifth resistor, the other end of the eighth resistor and the other end of the fourth capacitor are all grounded.

[0016] Furthermore, the cold start circuit includes a voltage doubler rectifier circuit and a third analog switch, the voltage doubler rectifier circuit has a first input end, a second input end and an output end, and the third analog switch has a first input end, a second input end, a control end, a first output end and a second output end; the first input end of the third analog switch is the first input end of the cold start circuit, the second input end of the third analog switch is the second input end of the cold start circuit, the control end of the third analog switch is the control end of the cold start circuit, the first output end of the third analog switch is connected to the first input end of the voltage doubler rectifier circuit, the second output end of the third analog switch is connected to the second input end of the voltage doubler rectifier circuit, and the output end of the voltage doubler rectifier circuit is the output end of the cold start circuit.

[0017] Furthermore, the specific process of the control circuit performing maximum power point tracking is as follows:

[0018] Step S1: The microcontroller calculates the internal impedance model of the magnetoelectric vibration energy harvester according to formula (1). R opt :

[0019] (1)

[0020] in, V EOC is the open circuit voltage of the magnetoelectric vibration energy harvester, I ESC is the short-circuit current of the magnetoelectric vibration energy harvester, R 1 is the resistance value of the first resistor, V DC is the boost rectified voltage outputted from the second output terminal of the boost rectifier circuit, V ESC is the short-circuit AC voltage outputted by the first output terminal of the boost rectifier circuit, V D is the voltage drop of the first diode or the second diode;

[0021] Step S2: Calculate the input resistance of the boost rectifier circuit according to formula (2). R in :

[0022] (2)

[0023] Where * is the multiplication operator. L C is the internal coil inductance of the magnetoelectric vibration energy harvester, with a typical value of 10mH. d represents the duty cycle,d = 50%, T S is the period of the PWM signal output by the PWM output terminal of the microcontroller;

[0024] Step S3: R in and R opt Matching and adjusting the period of the PWM signal outputted by the PWM output terminal of the microcontroller T S , the specific matching method is:

[0025] S3.1. Obtain the DC voltage outputted by the second output terminal of the boost rectifier circuit. V DC , the DC voltage outputted from the second output terminal of the current boost rectifier circuit V DC Assign to V PO1 ;

[0026] S3.2, the period of the PWM signal outputted by the PWM output terminal of the microcontroller T S Reduce Δ T , where Δ T Equal to 5~10% T S , detecting the DC voltage outputted by the second output terminal of the current boost rectifier circuit V DC And assign it to V PO2 ;

[0027] S3.3, determine the voltage V PO1 and V PO2 The size of , and determine whether to continue the disturbance based on the judgment result:

[0028] if V PO1 and V PO2 Approximately equal, that is V PO1 and V PO2 If the difference between the two is less than 0.1V, it is considered that the energy output by the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point has reached its peak value, the output power of the electric energy conversion circuit has reached its maximum, the maximum power point tracking has been achieved, and no further disturbance is required. The period of the PWM signal output by the PWM output terminal of the microcontroller is maintained. TS constant;

[0029] if V PO1 and V PO2 Not approximately equal, that is V PO1 and V PO2 If the difference between them is not less than 0.1V, it is determined that the disturbance needs to be continued and the process goes to step S3.4;

[0030] S3.4, if the voltage V PO2 Greater than V PO1 , it is considered that the disturbance direction of the boost rectifier voltage is correct, and the period of the PWM signal output by the PWM output terminal of the current microcontroller is T S It is indeed larger than the true value, then continue to reduce the cycle of the PWM signal output by the PWM output terminal of the microcontroller T S , each time the Δ T , and each time it decreases, the DC voltage output from the second output terminal of the current boost rectifier circuit is detected. V DC And assign it to V PO2 , and determine the voltage V PO2 and V PO1 Are they approximately equal until the voltage V PO2 and V PO1 When the two are approximately equal, the disturbance observation is stopped. At this time, the energy output by the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point has reached a peak value, and the output power of the electric energy conversion circuit has reached a maximum, thus achieving maximum power point tracking.

[0031] If the voltage V PO2 Less than V PO1 , it means that the disturbance direction of the boost rectifier voltage is wrong, and it is believed that the period of the PWM signal output by the PWM output terminal of the current microcontroller is T S It is indeed smaller than the true value. At this time, the period of the PWM signal output from the PWM output terminal of the microcontroller is T S Increase, each time increase Δ T, and each time it increases, the DC voltage output from the second output terminal of the current boost rectifier circuit is detected. V DC And assign it to V PO2 , and determine the voltage V PO2 and V PO1 Are they approximately equal until the voltage V PO2 and V PO1 When the values are approximately equal, the disturbance observation is stopped. At this time, the energy output by the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point has reached a peak value, and the output power of the electric energy conversion circuit has reached a maximum, thus achieving maximum power point tracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a framework diagram of the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point of the present invention;

[0033] Figure 2 A boost rectifier circuit diagram of the magnetoelectric vibration energy capture system capable of tracking the maximum power point of the present invention;

[0034] Figure 3 A polarity detection circuit and a timing control circuit diagram of the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point of the present invention;

[0035] Figure 4 A current detection circuit diagram of the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point of the present invention;

[0036] Figure 5 The alternating current of the magnetoelectric vibration energy harvester of the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point of the present invention I E and the control signal working waveform of the boost rectifier circuit;

[0037] Figure 6 This is a flow chart of energy capture disturbance and observation of the magnetoelectric vibration energy capture system capable of tracking the maximum power point of the present invention;

[0038] Figure 7 The AC voltage output by the magnetoelectric vibration energy harvester of the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point of the present invention is V E And the experimental waveform diagram of the boost rectifier voltage outputted from the second output terminal of the boost rectifier circuit. DETAILED DESCRIPTION

[0039] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0040] Example 1: Figure 1 As shown, a magnetoelectric vibration energy harvesting system capable of tracking the maximum power point includes a magnetoelectric vibration energy harvester 1, an electric energy conversion circuit 2, a control circuit 3 and a cold start circuit 4. The magnetoelectric vibration energy harvester 1 is used to convert vibration energy into AC voltage. V E Output, the power conversion circuit 2 is used to convert the AC voltage V E Convert to supply voltage V CC Output, control circuit 3 is used to supply voltage V CC When the voltage is greater than or equal to its internal working voltage, it enters the working state and controls the power conversion circuit 2 to the AC voltage V E Perform maximum power point tracking, cold start circuit 4 is used to V CC When the voltage inside the control circuit 3 is less than the internal working voltage, it enters the working state, making the power supply voltage V CC Increase to be greater than or equal to the internal working voltage of the control circuit 3, the specific way in which the control circuit 3 controls the electric energy conversion circuit 2 to perform maximum power point tracking is: the control circuit 3 first calculates the internal impedance mode of the magnetoelectric vibration energy harvester 1, and then adjusts the input internal resistance of the electric energy conversion circuit 2 according to the internal impedance mode of the magnetoelectric vibration energy harvester 1 to achieve impedance mode matching, and uses the perturbation observation method to perturb the boost rectifier voltage inside the electric energy conversion circuit 2 to adjust the electric energy conversion circuit 2 to output the maximum power, thereby achieving maximum power point tracking.

[0041] In this embodiment, the control circuit 3 first calculates the internal impedance modulus of the magnetoelectric vibration energy harvester based on the open-circuit voltage and short-circuit current of the magnetoelectric vibration energy harvester 1, and can quickly obtain the internal impedance modulus of the magnetoelectric vibration energy harvester 1. The control circuit 3 dynamically adjusts the input internal resistance of the power conversion circuit 2 to make it equal to the internal impedance modulus of the magnetoelectric vibration energy harvester 1, thereby achieving impedance modulus matching and preliminary maximum power point tracking. In order to reduce the errors caused by the estimated values and sampling accuracy used in the calculation, the perturbation observation method is used to further finely adjust and optimize the output maximum power of the power conversion circuit 2, more accurately track the maximum power point, and thus achieve high-speed and accurate maximum power point tracking. In addition, in the non-resonant state of the magnetoelectric vibration energy harvester 1, the control circuit 3 can autonomously measure the internal impedance modulus of the magnetoelectric vibration energy harvester 1 and adaptively perform impedance modulus matching.

[0042] Example 2: This example is basically the same as Example 1, except that: in this example, the magnetoelectric vibration energy harvester 1 has a positive output terminal and a negative output terminal, and the positive output terminal and the negative output terminal of the magnetoelectric vibration energy harvester 1 are used to output an AC voltage.V E The electric energy conversion circuit 2 has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, a fifth input terminal, an input / output terminal, a first output terminal and a second output terminal. The control circuit 3 has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, a power supply terminal, a first output terminal, a second output terminal and a third output terminal. The cold start circuit 4 has a first input terminal, a second input terminal, a control terminal and an output terminal. The positive output terminal of the magnetoelectric vibration energy harvester 1 is respectively connected to the first input terminal of the electric energy conversion circuit 2, the first input terminal of the control circuit 3 and the first input terminal of the cold start circuit 4, and the negative output terminal of the magnetoelectric vibration energy harvester 1 is respectively connected to the The second input terminal, the second input terminal of the control circuit 3 and the second input terminal of the cold start circuit 4 are connected, the third input terminal of the power conversion circuit 2 is connected to the first output terminal of the control circuit 3, the fourth input terminal of the power conversion circuit 2 is connected to the second output terminal of the control circuit 3, the fifth input terminal of the power conversion circuit 2 is connected to the third output terminal of the control circuit 3, the input and output terminals of the power conversion circuit 2 are respectively connected to the output terminal of the cold start circuit 4 and the third input terminal of the control circuit 3, the first output terminal of the power conversion circuit 2 is connected to the fourth input terminal of the control circuit 3, and the second output terminal of the power conversion circuit 2 serves as the output terminal of the magnetoelectric vibration energy capture system for outputting the supply voltage V CC , the power supply end of the control circuit 3 is connected to the second output end of the power conversion circuit 2.

[0043] In this embodiment, the electric energy conversion circuit 2 includes an electric energy storage BAT, a boost rectifier circuit, a power management circuit, a first analog switch S1 and a second analog switch S2. The boost rectifier circuit has a first input terminal, a second input terminal, a third input terminal, a fourth input terminal, a first output terminal and a second output terminal. The power management circuit has an input terminal, an energy storage terminal and an output terminal. The electric energy storage BAT has a positive terminal and a negative terminal. The first analog switch S1 has a first input terminal, a second input terminal, a control terminal, a first output terminal and a second output terminal. The second analog switch S2 has an input terminal, a control terminal and an output terminal. The first input terminal of the first analog switch S1 is the first input terminal of the electric energy conversion circuit 2, the second input terminal of the first analog switch S1 is the second input terminal of the electric energy conversion circuit 2, the first output terminal of the first analog switch S1 is connected to the first input terminal of the boost rectifier circuit, and the first output terminal of the first analog switch S1 is connected to the first input terminal of the boost rectifier circuit. The second output end is connected to the second input end of the boost rectifier circuit, the first output end of the boost rectifier circuit is the first output end of the power conversion circuit 2, the third input end of the boost rectifier circuit is the third input end of the power conversion circuit 2, the fourth input end of the boost rectifier circuit is the fourth input end of the power conversion circuit 2, the second output end of the boost rectifier circuit is connected to the input end of the second analog switch S2, and its connection end is the input and output end of the power conversion circuit 2, the control end of the second analog switch S2 is the fifth input end of the power conversion circuit 2, the output end of the second analog switch S2 is connected to the input end of the power management circuit, the energy storage end of the power management circuit is connected to the positive end of the power storage device BAT, the negative end of the power storage device BAT is grounded, the output end of the power management circuit is the second output end of the power conversion circuit 2, and the control end of the first analog switch S1 is connected to the output end of the power management circuit.

[0044] In this embodiment, the control circuit 3 includes a polarity detection circuit, a timing control circuit 3, a microcontroller and a current detection circuit. The polarity detection circuit has a first input terminal, a second input terminal and an output terminal. The timing control circuit 3 has a first input terminal, a second input terminal, a third input terminal, a first output terminal and a second output terminal. The microcontroller has a PWM output terminal, a first output terminal, a second output terminal, a first input terminal, a second input terminal and a power supply terminal. The PWM output terminal of the microcontroller is used to output a PWM signal. The current detection circuit has a power supply terminal, an input terminal and an output terminal. The first input terminal of the polarity detection circuit is the first input terminal of the control circuit 3, the second input terminal of the polarity detection circuit is the second input terminal of the control circuit 3, and the output terminal of the polarity detection circuit is connected to the timing control circuit. The first input end of the circuit 3 is connected, the second input end of the timing control circuit 3 is connected to the PWM output end of the microcontroller, the third input end of the timing control circuit 3 is connected to the first output end of the microcontroller, the first output end of the timing control circuit 3 is the first output end of the control circuit 3, the second output end of the timing control circuit 3 is the second output end of the control circuit 3, the second output end of the microcontroller is the third output end of the control circuit 3, the first input end of the microcontroller is the third input end of the control circuit 3, the second input end of the microcontroller is connected to the output end of the current detection circuit, the input end of the current detection circuit is the fourth input end of the control circuit 3, the power supply end of the microcontroller is connected to the power supply end of the current detection circuit, and its connection end is the power supply end of the control circuit 3.

[0045] In this embodiment, the cold start circuit 4 includes a voltage doubler rectifier circuit and a third analog switch S3. The voltage doubler rectifier circuit has a first input end, a second input end and an output end. The third analog switch S3 has a first input end, a second input end, a control end, a first output end and a second output end. The first input end of the third analog switch S3 is the first input end of the cold start circuit 4, the second input end of the third analog switch S3 is the second input end of the cold start circuit 4, the control end of the third analog switch S3 is the control end of the cold start circuit 4, the first output end of the third analog switch S3 is connected to the first input end of the voltage doubler rectifier circuit, the second output end of the third analog switch S3 is connected to the second input end of the voltage doubler rectifier circuit, and the output end of the voltage doubler rectifier circuit is the output end of the cold start circuit 4.

[0046] In this embodiment, the first analog switch S1 is connected to a power supply voltage at its control terminal. V CC When the internal operating voltage is reached, the power supply voltage V CC When the internal operating voltage is not reached, the second analog switch S2 is turned off and the control signal connected to its control terminal is V CTRL2 When high, it is on and controls the signal V CTRL2When it is low level, it is turned off and there is no control signal. V CTRL2 The third analog switch S3 is automatically turned on at the control terminal, and the power supply voltage is connected to the control terminal. V CC When the internal operating voltage is reached, the supply voltage is turned off and V CC It turns on when its internal operating voltage is not reached.

[0047] Example 3: This example is basically the same as Example 2, except that: in this example, Figure 2 As shown, the boost rectifier circuit includes a first diode D1, a second diode D2, a first NMOS transistor NM1, a second NMOS transistor NM2, a first capacitor C1 and a first resistor R1. The first capacitor C1 is an electrolytic capacitor. The anode of the first diode D1 is connected to the drain of the first NMOS transistor NM1, and the connection end thereof is the first input end of the boost rectifier circuit. The anode of the second diode D2 is connected to the drain of the second NMOS transistor NM2, and the connection end thereof is the second input end of the boost rectifier circuit. The cathode of the first diode D1, The cathode of the second diode D2 and the positive end of the first capacitor C1 are connected, and the connection end thereof is the second output end of the boost rectifier circuit. The source of the first NMOS transistor NM1 and one end of the first resistor R1 are connected, and the connection end thereof is the first output end of the boost rectifier circuit. The source of the second NMOS transistor NM2, the negative end of the first capacitor C1, and the other end of the first resistor R1 are all grounded. The gate of the first NMOS transistor NM1 is the third input end of the boost rectifier circuit, and the gate of the second NMOS transistor NM2 is the fourth input end of the boost rectifier circuit.

[0048] In this embodiment, Figure 3 As shown, the polarity detection circuit includes a second resistor R2, a second capacitor C2, a third resistor R3, a third capacitor C3 and a first comparator CM1. The first comparator CM1 has a non-inverting input terminal, an inverting input terminal and an output terminal. One end of the second resistor R2 is the first input terminal of the polarity detection circuit, one end of the third resistor R3 is the second input terminal of the polarity detection circuit, the other end of the second resistor R2 and one end of the second capacitor C2 are connected to the non-inverting input terminal of the first comparator CM1, the other end of the third resistor R3 and one end of the third capacitor C3 are connected to the inverting input terminal of the first comparator CM1, the other end of the second capacitor C2 and the other end of the third capacitor C3 are both grounded, and the output terminal of the first comparator CM1 is the output terminal of the polarity detection circuit.

[0049] In the polarity detection circuit, the second resistor R2 and the second capacitor C2 form a first RC filter circuit, the third resistor R3 and the third capacitor C3 form a second RC filter circuit, and the AC voltage V EFirst, it passes through two RC filter circuits and is input into the first comparator CM1. The first comparator CM1 outputs a square wave reference signal. V ref , where the square wave reference signal V ref The high level corresponds to the AC voltage V E In the positive half cycle, the low level corresponds to the AC voltage V E negative half cycle;

[0050] In this embodiment, Figure 3 As shown, the timing control circuit 3 includes a first NOT gate NOT, a first OR gate OR1, a second OR gate OR2, a first AND gate AND1 and a second AND gate AND2. The first NOT gate NOT has an input terminal and an output terminal. The first OR gate OR1, the second OR gate OR2, the first AND gate AND1 and the second AND gate AND2 all have a first input terminal, a second input terminal and an output terminal. The input terminal of the first NOT gate NOT is connected to the second input terminal of the second OR gate OR2, and the connection terminal thereof is the first input terminal of the timing control circuit 3. The output terminal of the first NOT gate NOT is connected to the first input terminal of the first OR gate OR1. The first OR gate OR1 The second input terminal of is connected to the first input terminal of the second OR gate OR2, and the connection terminal thereof is the second input terminal of the timing control circuit 3. The output terminal of the first OR gate OR1 is connected to the first input terminal of the first AND gate AND1, the output terminal of the second OR gate OR2 is connected to the second input terminal of the second AND gate AND2, the second input terminal of the first AND gate AND1 is connected to the first input terminal of the second AND gate AND2, and the connection terminal thereof is the third input terminal of the timing control circuit 3. The output terminal of the first AND gate AND1 is the first output terminal of the timing control circuit 3, and the output terminal of the second AND gate AND2 is the second output terminal of the timing control circuit 3.

[0051] In the timing control circuit 3, the square wave reference signal V ref The output is input to the second input terminal of the second OR gate OR2, and its negative signal is input to the first input terminal of the first OR gate OR1. The second input terminal of the first OR gate OR1 and the first input terminal of the second OR gate OR2 are both connected to the PWM signal output by the microcontroller. The first OR gate OR1 performs an OR operation on the signals input to its two input terminals, and the obtained OR operation result is output to the first input terminal of the first AND gate AND1. The second OR gate OR2 performs an OR operation on the signals input to its two input terminals, and the obtained OR operation result is output to the second input terminal of the second AND gate AND1. The second input terminal of the first AND gate AND1 and the first input terminal of the second AND gate AND1 are both connected to the control signal output from the first output terminal of the microcontroller. V CTRL1The first AND gate AND1 performs an AND operation on the signals input to its two input terminals and obtains the AND operation result as the first control signal V PWM1 Output, the second AND gate AND2 performs an AND operation on the signals connected to its two input terminals, and obtains the AND operation result as the second control signal V PWM2 Output, whereby the square wave reference signal provided by the polarity detection circuit V ref , so that the PWM signal provided by the microcontroller controls the signal V CTRL1 Under the action of the timing control circuit, two control signals are output V PWM1 and V PWM2 , controlling the gates of the two NMOS tubes in the boost rectifier circuit, so that the boost rectifier circuit operates in the short-circuit stage, open-circuit stage, and energy capture stage.

[0052] In this embodiment, Figure 4 As shown, the current detection circuit includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a first operational amplifier OP1, a second operational amplifier OP2, a third operational amplifier OP3, a fourth operational amplifier OP4, a third diode D3, a fourth diode D4 and a fourth capacitor C4; the first operational amplifier OP1, the second operational amplifier OP2, the third operational amplifier OP3 and the fourth operational amplifier OP4 all have a non-inverting input terminal, an inverting input terminal and an output terminal; one end of the fourth resistor R4 and one end of the sixth resistor R6 are connected to the inverting input terminal of the first operational amplifier OP1, the other end of the fourth resistor R4 is the input terminal of the current detection circuit, the other end of the sixth resistor R6 and the output terminal of the first operational amplifier OP1 are connected to the non-inverting input terminal of the third operational amplifier OP3, one end of the fifth resistor R5 and one end of the seventh resistor R7 are connected to the non-inverting input terminal of the first operational amplifier OP1, and the The other end of the seventh resistor R7, the inverting input terminal of the second op amp OP2 and the output terminal of the second op amp OP2 are connected, one end of the eighth resistor R8, one end of the ninth resistor R9 are connected to the non-inverting input terminal of the second op amp OP2, the positive electrode of the third diode D3, one end of the tenth resistor R10 and the inverting input terminal of the third op amp OP3 are connected, the other end of the tenth resistor R10, the inverting input terminal of the fourth op amp OP4 and the output terminal of the fourth op amp OP4 are connected, and their connection end is the output terminal of the current detection circuit, the cathode of the third diode D3, the positive electrode of the fourth diode D4 and the output terminal of the third op amp OP3 are connected, the cathode of the fourth diode D4, one end of the fourth capacitor C4 and the non-inverting input terminal of the fourth op amp OP4 are connected, the other end of the ninth resistor R9 is the power supply terminal of the current detection circuit, and the other end of the fifth resistor R5, the other end of the eighth resistor R8 and the other end of the fourth capacitor C4 are all grounded.

[0053] In the current detection circuit, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the first operational amplifier OP1 and the second operational amplifier OP2 form a differential amplifier circuit for converting the short-circuit AC voltage outputted from the first output terminal of the boost rectifier circuit to V ESC The peak value is amplified to a range that can be directly sampled by the microcontroller, and the tenth resistor R10, the third operational amplifier OP3, the fourth operational amplifier OP4, the third diode D3, the fourth diode D4 and the fourth capacitor C4 form a peak detection circuit for amplifying the short-circuit AC voltage V ESC Performs peak tracking and outputs a DC voltage that can be directly sampled by a microcontroller V ADC .

[0054] In this embodiment, when the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point is working, the magnetoelectric vibration energy harvester 1 converts the vibration energy into an AC voltage. V E The AC current outputted between the first output terminal and the second output terminal of the magnetoelectric vibration energy harvester 1 is recorded as I E , an AC voltage is connected between the first input terminal and the second input terminal of the first analog switch S1 V E and AC current I E , an AC voltage is connected between the first input terminal and the second input terminal of the third analog switch S3 V E and AC current I E , connect AC voltage between the first input terminal and the second input terminal of the polarity detection circuit V E and AC current I E At this time, if the power in the energy storage BAT is insufficient, the power supply voltage output by the output terminal of the power management circuit V CC The voltage is too small to reach the operating voltage of the microcontroller and the current detection circuit. The microcontroller and the current detection circuit cannot work. The first analog switch S1 is turned off, the second analog switch S2 and the third analog switch S3 are turned on, the cold start circuit 4 and part of the power conversion circuit work, the control circuit does not work, and the AC voltage connected between the first input terminal and the second input terminal of the first analog switch S1 is too low. V E The voltage is output to the voltage doubler rectifier circuit through the first output terminal and the second output terminal of the first analog switch S1. The voltage doubler rectifier circuit converts the AC voltage VE The DC voltage is outputted at its output terminal through the second analog switch S2, and the DC voltage is outputted to the input terminal of the power management circuit. The power management circuit converts the voltage at its input terminal into a supply voltage. V CC Output through its output terminal until the output supply voltage V CC Reach the operating voltage of the microcontroller and the current detection circuit; if there is enough energy in the energy storage BAT, the power management circuit converts the energy in the energy storage BAT and outputs it at its output end. At this time, the power supply voltage output by the output end of the power management circuit is V CC Stable, reaching the operating voltage of the microcontroller and the current detection circuit, the microcontroller and the current detection circuit work, the third analog switch S3 is turned off, the cold start circuit 4 does not work, the first analog switch S1 and the second analog switch S2 are turned on, and an AC voltage is connected between the first input terminal and the second input terminal of the first analog switch S1 V E The first output terminal and the second output terminal of the first analog switch S1 are output to the boost rectifier circuit, which converts the AC voltage V E Rectify to get DC voltage V DC (i.e. boost rectified voltage) is output at its second output terminal, the DC voltage V DC The second analog switch S2 outputs the signal to the input of the power management circuit. The power management circuit receives the DC voltage at its input. V DC Convert to supply voltage V CC Output through its output terminal, on the other hand, it uses the DC voltage connected to its input terminal V DC The electric energy storage device BAT is charged and stored.

[0055] In this embodiment, the specific process of the control circuit 3 to achieve maximum power point tracking is as follows: First, the polarity detection circuit of the control circuit 3 detects the AC voltage V E The positive and negative half cycles of the square wave reference signal are output at the output end. V ref , provides reference signal for timing control circuit, boost rectifier circuit works on AC current I E Sampling is performed and a short-circuit AC voltage is output at the first output terminal. V ESC , due to the short-circuit AC voltage V ESCUsually it is at the mV level. At this time, the current detection circuit first short-circuit the AC voltage V ESC Amplify it to a range that can be directly sampled by the microcontroller, and then amplify the short-circuit AC voltage V ESC Performs peak tracking and outputs a DC voltage that can be directly sampled by a microcontroller V ADC To the first input terminal of the microcontroller, the microcontroller receives a DC voltage according to the DC voltage input to the first input terminal. V ADC , outputs the corresponding PWM signal at its PWM output terminal to control the timing control circuit, so that the first output terminal of the timing control circuit outputs the corresponding control signal V PWM1 At the same time, the microcontroller receives a DC voltage from its first input terminal. V ADC , outputs the corresponding control signal at its first output terminal V CTRL1 The second output terminal of the control timing control circuit outputs the corresponding control signal V PWM2 , control signal V PWM1 and control signals V PWM2 The boost rectifier circuit is made to work in the short-circuit stage, the open-circuit stage and the energy-capturing stage in sequence.

[0056] The working waveform of the boost rectifier circuit is as follows: Figure 5 As shown, due to the alternating current I E It can more intuitively show the working waveform changes of the boost rectifier circuit. Figure 5 The AC current output by the magnetoelectric vibration energy harvester is also presented. I E The waveform diagram of . Figure 5 It can be seen that when the control signal V PWM1 and control signals V PWM2 When both are high level, the boost rectifier circuit works in the short circuit stage. At this time, the microcontroller detects the short circuit current of the magnetoelectric vibration energy harvester 1 through the current detection circuit. The first NMOS tube NM1 and the second NMOS tube NM2 work in the on state. The AC voltage V E The first NMOS transistor NM1, the first resistor R1 and the second NMOS transistor NM2 form a closed loop, the boost rectifier circuit is in a short-circuit state, and the boost rectifier circuit receives the AC current through the first resistor R1. I E Sampling is performed and the corresponding short-circuit AC voltage is output at its first output terminalV ESC ; When the control signal V PWM1 and control signals V PWM2 When both are at low level, the boost rectifier circuit works in the open circuit stage. At this time, the microcontroller detects the open circuit voltage of the magnetoelectric vibration energy harvester 1 when it works. The first NMOS tube NM1 and the second NMOS tube NM2 work in the off state and generate parasitic diodes. The first diode D1, the second diode D2, the first NMOS tube NM1, the second NMOS tube NM2 and the second capacitor C2 form a full-bridge rectifier circuit. The boost rectifier circuit is in the open circuit state, and the DC voltage output by its second output terminal is V DC Add the voltage drop of the first diode D1 or the second diode D2 V D Approximately AC voltage V E Peak open circuit voltage V EOC When AC voltage V E In the positive half cycle, the control signal V PWM1 The PWM signal output from the PWM output terminal of the microcontroller, the control signal V PWM2 is high, and when the AC voltage V E In the negative half cycle, the control signal V PWM1 High level, control signal V PWM2 When the PWM signal is output from the PWM output terminal of the microcontroller, the boost rectifier circuit works in the energy capture stage; when the AC voltage V E In the positive half cycle, if the PWM signal output by the PWM output terminal of the microcontroller is at a low level, the first NMOS tube NM1 is in the off state and the second NMOS tube NM2 is in the on state, the AC voltage V E Together with the first diode D1, the first capacitor C1 and the second NMOS tube NM2, a closed loop is formed. The boost rectifier circuit is in the positive half cycle charging stage. V E In the negative half cycle, if the PWM signal output by the PWM output terminal of the microcontroller is at a low level, the first NMOS tube NM1 is in the on state and the second NMOS tube NM2 is in the off state, the AC voltage V ETogether with the second diode D2, the first capacitor C1 and the first NMOS tube NM1, a closed loop is formed. The boost rectifier circuit is in the negative half-cycle charging stage. When charging and short-circuiting discharge are carried out quickly in sequence, the boost rectifier circuit has a negative half-cycle charging stage. V E Rectification and boosting are performed simultaneously.

[0057] Example 4: This example is basically the same as Example 3, except that: in this example, Figure 6 As shown in FIG, when the boost rectifier circuit operates in the energy capture stage, the specific process of the control circuit 3 performing maximum power point tracking is as follows:

[0058] Step S1: The microcontroller calculates the internal impedance model of the magnetoelectric vibration energy harvester 1 according to formula (1). R opt :

[0059] (1)

[0060] in, V EOC is the open circuit voltage of the magnetoelectric vibration energy harvester 1, I ESC is the short-circuit current of the magnetoelectric vibration energy harvester 1, R 1 is the resistance of the first resistor R1, V DC is the boost rectified voltage outputted from the second output terminal of the boost rectifier circuit, V ESC is the short-circuit AC voltage outputted from the first output terminal of the boost rectifier circuit, V D is the voltage drop of the first diode D1 or the second diode D2;

[0061] Step S2: Calculate the input resistance of the boost rectifier circuit according to formula (2): R in :

[0062] (2)

[0063] Where * is the multiplication operator. L C is the inductance of the internal coil of the magnetoelectric vibration energy harvester 1, with a typical value of 10mH. d represents the duty cycle, d = 50%, T S is the period of the PWM signal output from the PWM output terminal of the microcontroller;

[0064] Step S3: R in andR opt Match and adjust the period of the PWM signal output from the PWM output of the microcontroller T S , the specific matching method is:

[0065] S3.1. Obtain the DC voltage outputted by the second output terminal of the current boost rectifier circuit V DC , the DC voltage output from the second output terminal of the current boost rectifier circuit V DC Assign to V PO1 ,

[0066] S3.2, the period of the PWM signal output from the PWM output terminal of the microcontroller T S Reduce Δ T , where Δ T Equal to 5~10% T S , detect the DC voltage output by the second output terminal of the current boost rectifier circuit V DC And assign it to V PO2 ;

[0067] S3.3, determine the voltage V PO1 and V PO2 The size of , and determine whether to continue the disturbance based on the judgment result:

[0068] if V PO1 and V PO2 Approximately equal, that is V PO1 and V PO2 If the difference between them is less than 0.1V, it is considered that the energy output by the magnetoelectric vibration energy harvesting system that can track the maximum power point has reached its peak value, the output power of the electric energy conversion circuit has reached its maximum, and the maximum power point tracking has been achieved. There is no need to continue to disturb and maintain the period of the PWM signal output by the PWM output terminal of the microcontroller. T S constant;

[0069] if V PO1 and V PO2 Not approximately equal, that is V PO1 and V PO2If the difference between them is not less than 0.1V, it is determined that the disturbance needs to be continued and the process goes to step S3.4;

[0070] S3.4, if the voltage V PO2 Greater than V PO1 , according to the energy storage formula of capacitor, C 1 is the capacitance of the first capacitor C1, W is the amount of electricity stored in the first capacitor C1, indicating that the energy storage of the first capacitor C1 increases, the disturbance direction of the boost rectifier voltage is correct, and the period of the PWM signal output by the current microcontroller PWM output terminal is T S It is indeed larger than the true value. At this time, continue to reduce the period of the PWM signal output by the PWM output terminal of the microcontroller. T S , each time the Δ T , and every time it decreases, the DC voltage output by the second output terminal of the current boost rectifier circuit is detected V DC And assign it to V PO2 , and determine the voltage V PO2 and V PO1 Are they approximately equal until the voltage V PO2 and V PO1 When the two are approximately equal, the disturbance observation is stopped. At this time, the energy output by the magnetoelectric vibration energy harvesting system that can track the maximum power point has reached its peak value, and the output power of the electric energy conversion circuit has reached its maximum, thus achieving maximum power point tracking.

[0071] If the voltage V PO2 Less than V PO1 , it means that the disturbance direction of the boost rectifier voltage is wrong, and it is believed that the period of the PWM signal output by the current microcontroller PWM output terminal is T S It is indeed smaller than the true value. At this time, the period of the PWM signal output from the PWM output terminal of the microcontroller is T S Increase, each time increase Δ T , and each time it increases, the DC voltage output from the second output terminal of the current boost rectifier circuit is detected. V DC And assign it to V PO2 , and determine the voltage V PO2 and V PO1Are they approximately equal until the voltage V PO2 and V PO1 When the two are approximately equal, the disturbance observation is stopped. At this time, the energy output by the magnetoelectric vibration energy harvesting system that can track the maximum power point has reached its peak value, and the output power of the electric energy conversion circuit has reached its maximum, thus realizing maximum power point tracking.

[0072] In this embodiment, by adjusting the period of the PWM signal outputted by the PWM output terminal of the microcontroller T S During the process of observing the boost rectifier voltage during the disturbance, the AC voltage V E In the positive half cycle, the first output terminal of the microcontroller outputs the control signal V PWM1 The PWM signal output by the PWM output terminal of the microcontroller and the control signal output by the second output terminal of the microcontroller V PWM2 is high level, at this time the control signal output by the first output terminal of the microcontroller V PWM1 Synchronous adjustment, in the AC voltage V E In the negative half cycle, the first output terminal of the microcontroller outputs the control signal V PWM1 The second output terminal of the microcontroller outputs a control signal of high level. V PWM2 The PWM signal output by the PWM output terminal of the microcontroller is the control signal output by the second output terminal of the microcontroller. V PWM2 Synchronous adjustment.

[0073] In the current industry, the open circuit voltage is usually obtained by Laplace transform simplification based on the motion differential equation and electrical equation of the magnetoelectric vibration energy harvester 1. V EOC and short-circuit current I ESC formula:

[0074] (3)

[0075] (4)

[0076] (5)

[0077] According to formulas (4) and (5), the internal impedance model of the magnetoelectric vibration energy harvester 1 is obtained. R opt , as shown in formula (6):

[0078] (6)

[0079] In formulas (3), (4), (5) and (6), A is the vibration acceleration of the magnetoelectric vibration energy harvester 1, ω is the vibration angular frequency of the magnetoelectric vibration energy harvester 1; M, K, D, β, R C 、L C They are the equivalent mass, equivalent stiffness, equivalent damping, electromagnetic conversion coefficient, coil resistance and coil inductance of the magnetoelectric vibration energy harvester 1 , and these parameters need to be determined by performing mechanical and electrical tests on the magnetoelectric vibration energy harvester 1 in advance.

[0080] In this embodiment, the internal impedance mode of the magnetoelectric vibration energy harvester 1 is derived based on the equivalent circuit of the magnetoelectric vibration energy harvester 1 using the impedance mode matching principle. R opt By measuring the open circuit voltage V EOC and short-circuit current I ESC The internal impedance modulus of the magnetoelectric vibration energy harvester 1 is equal, so it can be directly calculated according to formula (1) R opt Therefore, the present invention can skip the measurement of the magnetoelectric vibration energy harvester 1 M, K, D, β, R C 、L C These parameters are used to obtain the internal impedance model of the magnetoelectric vibration energy harvester 1, shortening the measurement path and time.

[0081] In order to verify the implementation process of the maximum power point tracking in this embodiment, a circuit experiment was conducted on the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point, wherein the AC voltage of the magnetoelectric vibration energy harvester 1 is V E and the boost rectifier voltage outputted from the second output terminal of the boost rectifier circuit V DC The experimental waveform is as follows Figure 7 As shown. The parameters of the magnetoelectric vibration energy harvester 1 are: M =68.61g, K = 15664.73N / m, D = 0.6155Ns / m, β = 10.04N / A, R C = 23.8Ω, L C = 14.92mH. Analysis Figure 7It can be seen that the magnetoelectric vibration energy harvester 1 works at a resonance frequency of 76.05 Hz and a vibration acceleration of 1.5 m / s. 2 Under the condition of , the theoretical maximum output power is 1.88mW, the open circuit voltage V EOC is 1.68V, short circuit current I ESC The optimal load (internal impedance mode) is 8.94 mA. R opt ) is 188Ω, and the test is carried out in the short circuit stage. V ESC The voltage is 8.28mV, the resistance of the first resistor R1 is 1Ω, and the test is performed in the open circuit stage. V DC is 1.24V, the diode voltage drop V D is 0.35V, so we can calculate R opt The initial period of the PWM signal output from the PWM output terminal of the microcontroller during the energy capture phase is 192Ω. T S For 416ms, the input resistance of the boost rectifier circuit R in Adjust to equal R opt To achieve impedance matching, due to the calculation of the boost rectifier circuit R in hour L C Used estimates and calculations R opt After the error is stable for 1s, disturbance and observation are performed. T S The DC voltage output from the second output terminal of the boost rectifier circuit is reduced by 10%. V DC Increase by 0.18V and continue to T S Reduce by 10% and observe the DC voltage output from the second output terminal of the boost rectifier circuit. V DC Increase by 0.12V and continue to T S Reduce by 10% and observe the DC voltage output from the second output terminal of the boost rectifier circuit. V DC The voltage increases by 0.03V and the fluctuation is less than 0.1V. At this time, the output power is 1.85mW, the perturbation and observation are completed, and the maximum power point is tracked. The maximum power point matching efficiency can reach 98.4%, and the maximum power point is found within 4s.

[0082] When operating at a constant resonant frequency and vibration acceleration, the reference patent (application number CN202311019592.7) achieves a maximum power point matching efficiency of 97.9% within 4 seconds, and the reference document "Xiao H, Peng H, et al. Automatic impedance matching with dual timescale P&O in fully self-powered electromagnetic vibration energy harvesting[J]. IEEE Transactions on Power Electronics, 2024, 39(3): 3377-3390." achieves a maximum power point matching efficiency of 96.7% within 15 seconds. It can be seen that the present invention has obvious advantages over the reference patents and documents.

[0083] In summary, the magnetoelectric vibration energy harvesting system of the present invention has high energy conversion efficiency, simple overall circuit structure, and can quickly and accurately track the maximum power point by perturbing a single parameter, and has broad application prospects.

Claims

1. A magnetoelectric vibration energy harvesting system capable of tracking the maximum power point, comprising a magnetoelectric vibration energy harvester, an electric energy conversion circuit, a control circuit, and a cold start circuit. The magnetoelectric vibration energy harvester is used to convert vibration energy into AC voltage. V E Output, the power conversion circuit is used to convert the AC voltage V E Convert to supply voltage V CC output, the control circuit is used to supply voltage V CC When the internal working voltage is reached, the system enters the working state and controls the power conversion circuit to convert the AC voltage V E Perform maximum power point tracking, the cold start circuit is used to V CC When the internal working voltage of the control circuit is not reached, the power supply voltage is turned on and the working state is entered. V CC Increased to reach the internal working voltage of the control circuit, characterized in that The specific manner in which the control circuit controls the electric energy conversion circuit to perform maximum power point tracking is as follows: the control circuit first calculates the internal impedance modulus of the magnetoelectric vibration energy harvester based on the open-circuit voltage and short-circuit current of the magnetoelectric vibration energy harvester, then adjusts the input internal resistance of the electric energy conversion circuit based on the internal impedance modulus of the magnetoelectric vibration energy harvester to achieve impedance modulus matching, and uses the perturbation-observation method to perturb the boost rectifier voltage within the electric energy conversion circuit to adjust the electric energy conversion circuit to output maximum power, thereby achieving maximum power point tracking; The magnetoelectric vibration energy harvester has a positive output terminal and a negative output terminal, the power conversion circuit has five input terminals, an input / output terminal and two output terminals, the control circuit has five input terminals, a power supply terminal and three output terminals, and the cold start circuit has two input terminals, a control terminal and an output terminal; the positive output terminal of the magnetoelectric vibration energy harvester is respectively connected to the first input terminal of the power conversion circuit, the first input terminal of the control circuit and the first input terminal of the cold start circuit, and the negative output terminal of the magnetoelectric vibration energy harvester is respectively connected to the second input terminal of the power conversion circuit, the second input terminal of the control circuit and the second input terminal of the cold start circuit. The third input terminal of the electric energy conversion circuit is connected to the first output terminal of the control circuit, the fourth input terminal of the electric energy conversion circuit is connected to the second output terminal of the control circuit, the fifth input terminal of the electric energy conversion circuit is connected to the third output terminal of the control circuit, the input and output terminals of the electric energy conversion circuit are respectively connected to the output terminal of the cold start circuit and the third input terminal of the control circuit, the first output terminal of the electric energy conversion circuit is connected to the fourth input terminal of the control circuit, the second output terminal of the electric energy conversion circuit serves as the output terminal of the magnetoelectric vibration energy capture system, and the power supply terminal of the control circuit is connected to the second output terminal of the electric energy conversion circuit; The electric energy conversion circuit includes an electric energy storage device, a boost rectifier circuit, a power management circuit, and two analog switches. The boost rectifier circuit has four input terminals and two output terminals. The power management circuit has an input terminal, an energy storage terminal, and an output terminal. The electric energy storage device has a positive terminal and a negative terminal. The first analog switch has two input terminals, a control terminal, and two output terminals. The second analog switch has an input terminal, a control terminal, and an output terminal. The two input ends of the first analog switch are the two input ends of the electric energy conversion circuit, the two output ends of the first analog switch are connected to the first input end and the second input end of the boost rectifier circuit, the first output end of the boost rectifier circuit is the first output end of the electric energy conversion circuit, the third input end of the boost rectifier circuit is the third input end of the electric energy conversion circuit, the fourth input end of the boost rectifier circuit is the fourth input end of the electric energy conversion circuit, the second output end of the boost rectifier circuit is connected to the input end of the second analog switch, and the connection end thereof is the input and output end of the electric energy conversion circuit, the control end of the second analog switch is the fifth input end of the electric energy conversion circuit, the output end of the second analog switch is connected to the input end of the power management circuit, the energy storage end of the power management circuit is connected to the positive end of the electric energy storage device, the negative end of the electric energy storage device is grounded, the output end of the power management circuit is the second output end of the electric energy conversion circuit, and the control end of the first analog switch is connected to the output end of the power management circuit; The boost rectifier circuit includes a first diode, a second diode, a first NMOS transistor, a second NMOS transistor, a first capacitor and a first resistor. The first capacitor is an electrolytic capacitor. The anode of the first diode is connected to the drain of the first NMOS transistor, and the connection end thereof is the first input end of the boost rectifier circuit. The anode of the second diode is connected to the drain of the second NMOS transistor, and the connection end thereof is the second input end of the boost rectifier circuit. The cathode of the first diode, the cathode of the second diode, and the positive end of the first capacitor are connected, and the connection end thereof is the second output end of the boost rectifier circuit. The source of the first NMOS transistor is connected to one end of the first resistor, and the connection end thereof is the first output end of the boost rectifier circuit. The source of the second NMOS transistor, the negative end of the first capacitor, and the other end of the first resistor are all grounded. The gate of the first NMOS transistor is the third input end of the boost rectifier circuit, and the gate of the second NMOS transistor is the fourth input end of the boost rectifier circuit. The control circuit includes a polarity detection circuit, a timing control circuit, a microcontroller and a current detection circuit. The polarity detection circuit has two input terminals and an output terminal, the timing control circuit has three input terminals and two output terminals, the microcontroller has a PWM output terminal, two output terminals, two input terminals and a power supply terminal, and the current detection circuit has a power supply terminal, an input terminal and an output terminal. The first input end of the polarity detection circuit is the first input end of the control circuit, the second input end of the polarity detection circuit is the second input end of the control circuit, the output end of the polarity detection circuit is connected to the first input end of the timing control circuit, the second input end of the timing control circuit is connected to the PWM output end of the microcontroller, the third input end of the timing control circuit is connected to the first output end of the microcontroller, the first output end of the timing control circuit is the first output end of the control circuit, the second output end of the timing control circuit is the second output end of the control circuit, the second output end of the microcontroller is the third output end of the control circuit, the first input end of the microcontroller is the third input end of the controlled circuit, the second input end of the microcontroller is connected to the output end of the current detection circuit, the input end of the current detection circuit is the fourth input end of the control circuit, the power supply end of the microcontroller is connected to the power supply end of the current detection circuit, and the connection end thereof is the power supply end of the control circuit; The specific process of the control circuit performing maximum power point tracking is as follows: Step S1: The microcontroller calculates the internal impedance model of the magnetoelectric vibration energy harvester according to formula (1). R opt : (1) in, V EOC is the open circuit voltage of the magnetoelectric vibration energy harvester, I ESC is the short-circuit current of the magnetoelectric vibration energy harvester, R 1 is the resistance value of the first resistor, V DC is the boost rectified voltage outputted from the second output terminal of the boost rectifier circuit, V ESC is the short-circuit AC voltage outputted by the first output terminal of the boost rectifier circuit, V D is the voltage drop of the first diode or the second diode; Step S2: Calculate the input resistance of the boost rectifier circuit according to formula (2). R in : （2） Where * is the multiplication operator. L C is the internal coil inductance of the magnetoelectric vibration energy harvester, with a typical value of 10mH. d represents the duty cycle, d = 50%, T S is the period of the PWM signal output by the PWM output terminal of the microcontroller; Step S3: R in and R opt Matching and adjusting the period of the PWM signal outputted by the PWM output terminal of the microcontroller T S , the specific matching method is: S3.

1. Obtain the DC voltage outputted by the second output terminal of the boost rectifier circuit. V DC , the DC voltage outputted from the second output terminal of the current boost rectifier circuit V DC Assign to V PO1 ; S3.2, the period of the PWM signal outputted by the PWM output terminal of the microcontroller T S Reduce Δ T , where Δ T Equal to 5~10% T S , detecting the DC voltage outputted by the second output terminal of the current boost rectifier circuit V DC And assign it to V PO2 ; S3.3, determine the voltage V PO1 and V PO2 The size of , and determine whether to continue the disturbance based on the judgment result: if V PO1 and V PO2 Approximately equal, that is V PO1 and V PO2 If the difference between the two is less than 0.1V, it is considered that the energy output by the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point has reached its peak value, the output power of the electric energy conversion circuit has reached its maximum, the maximum power point tracking has been achieved, and no further disturbance is required. The period of the PWM signal output by the PWM output terminal of the microcontroller is maintained. T S constant; if V PO1 and V PO2 Not approximately equal, that is V PO1 and V PO2 If the difference between them is not less than 0.1V, it is determined that the disturbance needs to be continued and the process goes to step S3.4; S3.4, if the voltage V PO2 Greater than V PO1 , it is considered that the disturbance direction of the boost rectifier voltage is correct, and the period of the PWM signal output by the PWM output terminal of the current microcontroller is T S It is indeed larger than the true value, then continue to reduce the cycle of the PWM signal output by the PWM output terminal of the microcontroller T S , each time the Δ T , and each time it decreases, the DC voltage output from the second output terminal of the current boost rectifier circuit is detected. V DC And assign it to V PO2 , and determine the voltage V PO2 and V PO1 Are they approximately equal until the voltage V PO2 and V PO1 When the voltage is approximately equal, the disturbance observation is stopped. At this time, the energy output by the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point has reached its peak value, and the output power of the power conversion circuit has reached its maximum, thus achieving maximum power point tracking. If the voltage V PO2 Less than V PO1 , it means that the disturbance direction of the boost rectifier voltage is wrong, and it is believed that the period of the PWM signal output by the PWM output terminal of the current microcontroller is T S It is indeed smaller than the true value. At this time, the period of the PWM signal output from the PWM output terminal of the microcontroller is T S Increase, each time increase Δ T , and each time it increases, the DC voltage output from the second output terminal of the current boost rectifier circuit is detected. V DC And assign it to V PO2 , and determine the voltage V PO2 and V PO1 Are they approximately equal until the voltage V PO2 and V PO1 When the values are approximately equal, the disturbance observation is stopped. At this time, the energy output by the magnetoelectric vibration energy harvesting system capable of tracking the maximum power point has reached a peak value, and the output power of the electric energy conversion circuit has reached a maximum, thus achieving maximum power point tracking.

2. The magnetoelectric vibration energy harvesting system capable of tracking the maximum power point according to claim 1, characterized in that The polarity detection circuit includes a second resistor, a second capacitor, a third resistor, a third capacitor and a first comparator. The first comparator has a non-inverting input terminal, an inverting input terminal and an output terminal. One end of the second resistor is the first input terminal of the polarity detection circuit, one end of the third resistor is the second input terminal of the polarity detection circuit, the other end of the second resistor and one end of the second capacitor are connected to the non-inverting input terminal of the first comparator, the other end of the third resistor and one end of the third capacitor are connected to the inverting input terminal of the first comparator, the other end of the second capacitor and the other end of the third capacitor are both grounded, and the output terminal of the first comparator is the output terminal of the polarity detection circuit.

3. The magnetoelectric vibration energy harvesting system capable of tracking the maximum power point according to claim 1, characterized in that The timing control circuit includes a first NOT gate, a first OR gate, a second OR gate, a first AND gate, and a second AND gate. The first NOT gate has an input and an output. The first OR gate, the second OR gate, the first AND gate, and the second AND gate all have a first input, a second input, and an output. The input of the first NOT gate is connected to the second input of the second OR gate, and its connection end is the first input of the timing control circuit. The output of the first NOT gate is connected to the first input of the first OR gate. The second input of the first OR gate is connected to the first input of the second OR gate, and its connection end is the second input of the timing control circuit. The output of the first OR gate is connected to the first input of the first AND gate. The output of the second OR gate is connected to the second input of the second AND gate. The second input of the first AND gate is connected to the first input of the second AND gate, and its connection end is the third input of the timing control circuit. The output of the first AND gate is the first output of the timing control circuit, and the output of the second AND gate is the second output of the timing control circuit.

4. The magnetoelectric vibration energy harvesting system capable of tracking the maximum power point according to claim 1, characterized in that The current detection circuit includes a fourth resistor to a tenth resistor, four operational amplifiers, a third diode, a fourth diode and a fourth capacitor; one end of the fourth resistor, one end of the sixth resistor and the inverting input terminal of the first operational amplifier are connected, the other end of the fourth resistor is the input terminal of the current detection circuit, the other end of the sixth resistor, the output terminal of the first operational amplifier and the non-inverting input terminal of the third operational amplifier are connected, one end of the fifth resistor, one end of the seventh resistor and the non-inverting input terminal of the first operational amplifier are connected, the other end of the seventh resistor, the inverting input terminal of the second operational amplifier and the output terminal of the second operational amplifier are connected, one end of the eighth resistor, one end of the ninth resistor and the The non-inverting input terminal of the second operational amplifier is connected, the positive electrode of the third diode, one end of the tenth resistor and the inverting input terminal of the third operational amplifier are connected, the other end of the tenth resistor, the inverting input terminal of the fourth operational amplifier and the output terminal of the fourth operational amplifier are connected, and the connection end thereof is the output terminal of the current detection circuit, the negative electrode of the third diode, the positive electrode of the fourth diode and the output terminal of the third operational amplifier are connected, the negative electrode of the fourth diode, one end of the fourth capacitor and the non-inverting input terminal of the fourth operational amplifier are connected, the other end of the ninth resistor is the power supply terminal of the current detection circuit, and the other end of the fifth resistor, the other end of the eighth resistor and the other end of the fourth capacitor are all grounded.

5. The magnetoelectric vibration energy harvesting system capable of tracking the maximum power point according to claim 4, characterized in that The cold start circuit includes a voltage doubler rectifier circuit and a third analog switch. The voltage doubler rectifier circuit has a first input end, a second input end and an output end. The third analog switch has a first input end, a second input end, a control end, a first output end and a second output end. The first input end of the third analog switch is the first input end of the cold start circuit, the second input end of the third analog switch is the second input end of the cold start circuit, the control end of the third analog switch is the control end of the cold start circuit, the first output end of the third analog switch is connected to the first input end of the voltage doubler rectifier circuit, the second output end of the third analog switch is connected to the second input end of the voltage doubler rectifier circuit, and the output end of the voltage doubler rectifier circuit is the output end of the cold start circuit.

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