Adaptive Maximum Power Tracking Parallel Synchronous Flipping Interface Circuit

Abstract

The adaptive maximum power point tracking (MPPT) parallel synchronous flipping interface circuit provided by this invention utilizes a parallel synchronous switching inductor module, a maximum power point tracking (MPPT) module, and a DC-DC load voltage adjustment module. This circuit efficiently converts the AC signal generated by the piezoelectric transducer into a DC signal and performs voltage regulation, thereby achieving efficient and stable energy harvesting and load independence, improving the overall energy conversion efficiency of the system. Furthermore, the MPPT module can determine the flipping coefficient in real time, ensuring that the optimal power output point is achieved under different loads, thereby improving system stability and energy utilization.

Description

Technical Field

[0001] The present invention relates to the technical field of power management, and in particular to an adaptive maximum power tracking parallel synchronous flipping interface circuit. Background Art

[0002] With the continuous development of the Internet of Things (IoT), applications relying on wireless sensor networks (WSNs) are rapidly gaining popularity in a wide range of fields, including health monitoring, smart buildings, and environmental monitoring. These wireless sensor nodes consume energy during operation and require long operating life and a compact size to facilitate deployment in various environments. However, traditional batteries, due to their low energy density and large size, struggle to meet these requirements.

[0003] Energy harvesting (EH) technology has emerged as an ideal alternative. Currently, piezoelectric energy harvesting interface circuits utilize several typical topologies. While full-bridge rectifier circuits offer simplicity, they also suffer from energy waste. The P-SSHI interface, on the other hand, utilizes resonance technology to effectively reduce losses in parasitic capacitance, improving energy extraction efficiency. However, the output power of the interface circuit still varies with load, resulting in unstable power output under suboptimal load conditions.

[0004] In summary, the problems existing in the prior art need to be solved urgently. Summary of the Invention

[0005] The present invention provides an adaptive maximum power tracking parallel synchronous flip interface circuit to solve the defects in the prior art and realize maximum power point tracking.

[0006] The present invention provides an adaptive maximum power tracking parallel synchronous flip interface circuit, comprising: a parallel synchronous switch inductor module, a maximum power point tracking module and a DC-DC load voltage adjustment module;

[0007] The parallel synchronous switching inductor module is used to convert the AC signal generated by the piezoelectric transducer into a DC signal;

[0008] The maximum power point tracking module is used to determine the maximum power point according to the open circuit voltage and the rollover coefficient;

[0009] The DC-DC load voltage adjustment module is used to adjust the DC signal to a target voltage according to the maximum power point.

[0010] According to an adaptive maximum power tracking parallel synchronous flip interface circuit provided by the present invention, it is characterized in that the parallel type synchronous switch inductor module includes: a negative level converter;

[0011] The negative level converter is connected to the energy storage capacitor through a switch, and the negative level converter is used for performing energy conversion and resonance to reverse the voltage across the piezoelectric piece.

[0012] According to an adaptive maximum power point tracking parallel synchronous flip interface circuit provided by the present invention, the maximum power point tracking module includes: an open circuit timing control unit, a flip coefficient judgment unit and an open circuit voltage sampling unit;

[0013] The open circuit timing control unit is used to control the opening and closing of the switch to control the open circuit time;

[0014] The open circuit voltage sampling unit is used to collect the open circuit voltage of the piezoelectric transducer in real time and feed it back to the flip coefficient judgment unit;

[0015] The rollover coefficient judgment unit is used to calculate the rollover coefficient in real time according to the open circuit voltage.

[0016] According to an adaptive maximum power tracking parallel synchronous flip interface circuit provided by the present invention, the DC-DC load voltage adjustment module includes a four-switch Buck-Boost unit and a control unit;

[0017] The control unit is configured to adjust the DC signal to a target voltage through the four-switch Buck-Boost unit according to the maximum power point.

[0018] According to an adaptive maximum power tracking parallel synchronous flip interface circuit provided by the present invention, the flip coefficient judgment unit includes: a comparator;

[0019] The comparator is used to compare the voltage after the piezoelectric transducer is flipped with a preset voltage division value to determine the range of the flip coefficient.

[0020] According to an adaptive maximum power tracking parallel synchronous flip interface circuit provided by the present invention, the open circuit voltage sampling circuit includes: a first capacitor and a second capacitor;

[0021] The first capacitor is used to sample the flip voltage;

[0022] The second capacitor is used to sample the maximum voltage;

[0023] The open circuit voltage is determined by determining the difference between the flip voltage and the maximum voltage.

[0024] According to an adaptive maximum power tracking parallel synchronous flip interface circuit provided by the present invention, the step of determining the open circuit voltage by determining the difference between the flip voltage and the maximum voltage specifically includes:

[0025] After the first capacitor samples the flip voltage, when the second capacitor samples the maximum voltage, the bottom plate of the first capacitor is connected to the top plate of the second capacitor to form a parallel circuit, and the accurate value of the open circuit voltage is obtained by charge redistribution.

[0026] According to an adaptive maximum power tracking parallel synchronous flip interface circuit provided by the present invention, the open circuit voltage is:

[0027]

[0028] Among them, V M is the maximum voltage, V r is the reversal voltage.

[0029] The adaptive maximum power point tracking (MPPT) parallel synchronous flipping interface circuit provided by the present invention utilizes a parallel synchronous switching inductor module, a maximum power point tracking (MPPT) module, and a DC-DC load voltage adjustment module. This circuit efficiently converts the AC signal generated by the piezoelectric transducer into a DC signal and performs voltage regulation, thereby achieving efficient and stable energy collection and load independence, improving the overall energy conversion efficiency of the system. Furthermore, the MPPT module can determine the flipping coefficient in real time, ensuring that the optimal power output point can be achieved under different loads, thereby improving system stability and energy utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is a module schematic diagram of the adaptive maximum power tracking parallel synchronous flip interface circuit provided by the present invention;

[0032] Figure 2 This is a working principle diagram of the parallel synchronous switching inductor module provided by the present invention;

[0033] Figure 3 This is the open circuit signal enabling waveform diagram provided by the present invention;

[0034] Figure 4 This is a circuit diagram of a flip coefficient discrimination circuit provided by the present invention;

[0035] Figure 5 is a circuit diagram of an open circuit voltage sampling circuit provided by the present invention;

[0036] Figure 6This is a circuit diagram of the DC-DC load voltage adjustment module provided by the present invention. DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0038] Currently, piezoelectric energy harvesting interface circuits employ several topologies. First, the traditional full-bridge rectifier circuit is widely used as an interface circuit in piezoelectric energy harvesting systems due to its simplicity and stability. However, when a full-bridge rectifier circuit operates, a large amount of charge is lost in parasitic capacitance and cannot be effectively collected, resulting in energy waste.

[0039] To improve the energy extraction efficiency of piezoelectric energy harvesting interface circuits, a piezoelectric energy harvesting interface technology based on a parallel synchronous switched inductor (P-SSHI), also known as bias-flip technology, has been proposed. This technology reduces parasitic capacitance losses through inductor-capacitor resonance, improving efficiency. However, the output power of both full-bridge and PSSHI interface circuits varies with the load, causing it to further decrease under suboptimal load conditions. Therefore, achieving load independence—that is, maintaining constant output power regardless of load size—is a key issue in piezoelectric energy interface circuit design.

[0040] Maximum power point tracking (MPPT) technology is a common solution to achieve the output power of the interface circuit to be independent of the load. Common algorithms for implementing maximum power tracking technology include open-circuit voltage algorithm, hill climbing algorithm, etc. By tracking the maximum power point of the piezoelectric interface, the independence of the output power from the load is achieved. Liao Wu et al. from Hunan University proposed a self-powered low-power piezoelectric energy harvesting circuit system, including an SSHI circuit and a maximum power point tracking circuit based on the open-circuit voltage method. The FoM of the interface circuit reached 170.4%. This method of directly opening the circuit to achieve the MPPT function requires a long time for detection, resulting in a large amount of charge waste and easily causing device overvoltage problems. In 2021, B. et al. not only used a multi-step flipping technique to reduce energy loss during LC resonance but also exploited the circuit's unique characteristics to achieve MPPT. However, a significant drawback is that the flipping coefficient acquisition requires off-chip calculation. Therefore, when the inductance or parasitic capacitance changes, the optimal load value also changes, requiring recalibration. Its adaptability and practicality need to be improved.

[0041] In order to solve the problems in the prior art, the present invention proposes an adaptive maximum power tracking parallel synchronous flip interface circuit to achieve maximum power point tracking. The adaptive maximum power tracking parallel synchronous flip interface circuit is described below. Figure 1 As shown, including but not limited to the following modules: a parallel synchronous switching inductor module, a maximum power point tracking module and a DC-DC load voltage adjustment module;

[0042] The parallel synchronous switching inductor module is used to convert the AC signal generated by the piezoelectric transducer into a DC signal.

[0043] A parallel synchronous switching inductor module is connected to the piezoelectric transducer to convert the AC signal generated by the piezoelectric transducer into a DC signal. This module includes a negative level converter and an energy storage capacitor. The resonance between the negative level converter and the energy storage capacitor enables voltage reversal across the piezoelectric disc, reducing losses in parasitic capacitance and improving energy conversion efficiency. The module operates by utilizing the resonant properties of the inductor and capacitor. Upon input of an AC signal, the inductor and capacitor undergo synchronous reversal to achieve energy conversion, and then output a DC signal through storage in the energy storage capacitor.

[0044] The maximum power point tracking module is used to determine the maximum power point according to the open circuit voltage and the rollover coefficient.

[0045] The maximum power point tracking module is used to determine the maximum power point based on the open circuit voltage and the rollover coefficient, ensuring that the system can maintain optimal power output under different loads. The module includes an open circuit timing control unit, a rollover coefficient judgment unit, and an open circuit voltage sampling unit. The open circuit timing control unit controls the opening and closing of the switch to maintain the open circuit state within a specific time, so that the circuit can accurately collect the open circuit voltage. The open circuit voltage sampling unit is used to collect the open circuit voltage of the piezoelectric transducer and feed it back to the rollover coefficient judgment unit in real time. The rollover coefficient judgment unit calculates the rollover coefficient based on the collected open circuit voltage to determine the maximum power point under the current load conditions, and outputs it to the subsequent DC-DC load voltage adjustment module for voltage adjustment.

[0046] The DC-DC load voltage adjustment module is used to adjust the DC signal to a target voltage according to the maximum power point.

[0047] The DC-DC load voltage adjustment module is used to adjust the DC signal generated by the parallel synchronous switching inductor module to the target voltage to meet the voltage requirements of different loads. This module uses a four-switch Buck-Boost circuit structure and receives maximum power point information from the maximum power point tracking module through a control unit. Based on this maximum power point, the four-switch Buck-Boost unit is controlled to stably adjust the DC signal to the target voltage, thereby ensuring the stability of the system output voltage, improving energy utilization efficiency, and meeting the stable voltage requirements of wireless sensor nodes.

[0048] As a further optional embodiment, the parallel synchronous switching inductor module includes: a negative level converter;

[0049] The negative level converter is connected to the energy storage capacitor through a switch, and the negative level converter is used for performing energy conversion and resonance to reverse the voltage across the piezoelectric piece.

[0050] In this embodiment, the parallel synchronous switching inductor module further includes a negative level converter, which is connected to the energy storage capacitor through a switch and is used to convert and resonate energy to achieve the reversal of the voltage across the piezoelectric plate, thereby improving the energy collection efficiency.

[0051] The working principle of the negative level converter can be found in the attached Figure 2 and attached Figure 3 , its simplified working state and waveform are shown in the figure. The interface circuit contains six working states during operation, and state 2 can be ignored and skipped according to the control signal, thereby realizing the adaptive open circuit voltage sampling function. P 、C P , I P are the equivalent resistance, parasitic capacitance and equivalent current source of the piezoelectric transducer respectively. S is the output capacitor, and a negative level shifter is used to convert V P 、V N The high voltage terminal in the circuit is connected to the output capacitor and controls the current direction so that the current always flows from C S The upper plate of the circuit flows to ground. When the circuit is operating, if open-circuit voltage sampling is not performed, the interface circuit's operating sequence is State 1 - State 2 - State 3 - State 4 - State 5 - State 6 (Phase VI) - State 1, then the next cycle is entered. If open-circuit voltage sampling is performed, the circuit's operating sequence is State 1 - State 3 - State 4 - State 5 - State 6 - State 1, then the next cycle is entered.

[0052] The working process of the interface circuit includes the following states:

[0053] Phase I: Piezoelectric plate parasitic capacitance C PThe voltage across the capacitor is lower than the voltage of the energy storage capacitor, and the equivalent current source I P The parasitic capacitance is charged while the negative level shifter is off.

[0054] Phase II: When the parasitic capacitor voltage is equal to the energy storage capacitor voltage, the equivalent current source starts to supply power to the load and supplies power to the capacitor C through the negative level converter. S When the AC signal generated by the vibration passes through zero, the flip switch S is closed, causing the parasitic capacitance and inductance to form an RLC resonant circuit, generating high-frequency resonance.

[0055] Phase III: Capacitor energy is converted into inductor current through the RLC circuit, and then converted back into parasitic capacitor energy. At this time, the polarity of the parasitic capacitor voltage is reversed, and this process lasts for half a resonant cycle. The presence of the current limiting diode prevents the current from reversing, forming an equivalent disconnection state. RLC resonance reduces the voltage V across the parasitic capacitor. PN By V S Flip to -V r The voltage after flipping is slightly lower than the voltage before flipping. This process uses the flipped charge to reduce charge loss in subsequent reverse charging and improve energy collection efficiency.

[0056] Phase IV: Entering the negative half cycle of vibration, the equivalent current source I P In reverse, the parasitic capacitance C P Reverse charging causes the piezoelectric chip voltage to change from -V r Charge to -V S , enter state five.

[0057] Phase V: The equivalent current source continues to charge the energy storage capacitor through the negative voltage converter until the current crosses zero again, triggering high-frequency RLC resonance in the opposite direction. The voltage across the piezoelectric plate is reversed again, and the parasitic capacitance V PN From -V S Flip to V r , return to state 1 and continue charging.

[0058] When skipping state 2, the switch between the negative voltage converter and the energy storage capacitor is disconnected by opening the V enable signal OC, and the circuit is always in state 1. At this time, the equivalent current source is continuously the parasitic capacitor C P Charging. The voltage of the parasitic capacitor can be higher than the voltage of the energy storage capacitor until the current crosses zero again and the circuit enters state three. This design of skipping state two allows the parasitic capacitor to charge freely and obtains the important parameter of the piezoelectric transducer - open circuit voltage V OC , thereby calculating the maximum power point of the P-SSHI circuit and achieving efficient energy harvesting and adaptive voltage regulation.

[0059] As a further optional embodiment, the maximum power point tracking module includes: an open circuit timing control unit, a flip coefficient judgment unit and an open circuit voltage sampling unit;

[0060] The open circuit timing control unit is used to control the opening and closing of the switch to control the open circuit time;

[0061] The open circuit voltage sampling unit is used to collect the open circuit voltage of the piezoelectric transducer in real time and feed it back to the flip coefficient judgment unit;

[0062] The rollover coefficient judgment unit is used to calculate the rollover coefficient in real time according to the open circuit voltage.

[0063] In this embodiment, the maximum power point tracking module includes an open-circuit timing control unit, a flip coefficient judgment unit and an open-circuit voltage sampling unit, which are used to realize open-circuit voltage sampling and real-time calculation of the flip coefficient of the piezoelectric transducer, thereby determining the maximum power point and improving energy collection efficiency.

[0064] Open-circuit timing control unit: This controls the on and off switching of the switches, thereby precisely controlling the open-circuit duration. During maximum power point tracking, the timing of the switches is adjusted to keep the circuit open for a specific period of time, thereby obtaining accurate open-circuit voltage data.

[0065] The open-circuit voltage sampling unit is used to collect the open-circuit voltage of the piezoelectric transducer in real time and feed the collected open-circuit voltage data back to the rollover coefficient determination unit. This sampling unit monitors the open-circuit voltage of the piezoelectric transducer in real time during the open-circuit state, ensuring the accuracy of voltage sampling and providing a reliable voltage reference for subsequent rollover coefficient calculations.

[0066] Flip coefficient determination unit: This unit calculates the flip coefficient in real time based on the open-circuit voltage data. The flip coefficient is determined based on the collected open-circuit voltage and the voltage difference before and after the circuit flips. By accurately calculating the flip coefficient, the flip coefficient determination unit enables the circuit to maintain stable maximum power output under different load conditions, thereby improving the piezoelectric energy conversion efficiency and the adaptability of the interface circuit.

[0067] Through the above structural design, the maximum power point tracking module can effectively track the maximum power point of the piezoelectric transducer, ensuring that the interface circuit can maintain optimal energy collection efficiency under different environmental conditions and loads.

[0068] The principle of maximum power point tracking method is as follows:

[0069] The direct relationship between output power and load size can be expressed by the following formula:

[0070]

[0071] If and only if When the maximum power

[0072] Among them, P OUT : Interface circuit output power

[0073] V RECT : Interface circuit output voltage

[0074] R L : Load resistance size

[0075] f P : Vibration frequency

[0076] Q NET : Net output charge of the piezoelectric transducer within half a cycle

[0077] λ: flip coefficient size, which is defined as V BF =V RECT *λ,V BF is the parasitic capacitance voltage after flipping.

[0078] Based on the above formula, determining the maximum power point depends on determining the rollover coefficient and open-circuit voltage. This invention proposes an MPPT method that can achieve adaptive tracking of the maximum power point. This method for obtaining the rollover coefficient λ does not rely on external adjustment and can achieve adaptive tracking during the chip's operation. The following briefly describes the principle of achieving adaptive tracking. According to the formula:

[0079] V BF =V RECT *λ

[0080] Assume that we have an output voltage V RECT Perform a series of voltage divisions, assuming the voltage division coefficients are k1, k2, k3... That is:

[0081]

[0082] Record pressure coefficient k n The corresponding voltage divider is V div [n], we can BF and V div By comparing the values of [n], it is not difficult to derive the following relationship:

[0083]

[0084] The same logic applies

[0085]

[0086] Therefore, only the comparison voltage V BF and Vdiv [n] can indirectly compare the relative magnitudes of the rollover coefficient λ and the voltage divider coefficients k1, k2, k3, etc., thereby determining the range in which the rollover coefficient lies. This method allows for adaptive determination of the rollover coefficient range without the need for external manual adjustment.

[0087] In circuit implementation, each comparison relies on a comparator. Therefore, accurately determining the rollover coefficient requires significant hardware overhead and consumes significant power. Therefore, it's necessary to weigh the pros and cons and select the appropriate voltage divider coefficient and number of comparators to strike a balance between accuracy and power consumption. Because this method can't accurately determine the rollover coefficient, it inevitably introduces a certain degree of error in tracking the maximum power point. This design uses four comparators for comparison. The voltage divider coefficients used and the corresponding rollover coefficients are shown in the following table:

[0088]

[0089] As a further optional embodiment, the flip coefficient determination unit includes: a comparator;

[0090] The comparator is used to compare the voltage after the piezoelectric transducer is flipped with a preset voltage division value to determine the range of the flip coefficient.

[0091] In this embodiment, the flip coefficient determination unit further includes a comparator for enhancing the accuracy and efficiency of flip coefficient determination. The comparator determines the flip coefficient range by comparing the voltage of the piezoelectric transducer after flipping with a preset voltage divider value, thereby optimizing the maximum power point tracking performance.

[0092] Comparator: After the piezoelectric transducer completes its flip, it compares its output voltage with a preset voltage divider. This comparison determines whether the post-flip voltage is within the target range, thereby deriving the specific range of the flip coefficient. If the post-flip voltage is higher or lower than the preset voltage divider, the circuit automatically adjusts the flip coefficient based on the comparison result to ensure voltage regulation near the maximum power point.

[0093] The flip coefficient determination circuit is as shown in the attached Figure 4 As shown, the energy storage capacitor of the front stage is connected to the output of the interface circuit, and its voltage is V rec In this embodiment, multiple comparators are used to determine the reversal coefficient. Several resistors divide the output voltage according to the voltage division method designed in the table above. Outputs OUT1-4 constitute the output result of our reversal coefficient determination, thereby obtaining the maximum power point.

[0094] As a further optional embodiment, the open circuit voltage sampling circuit includes: a first capacitor and a second capacitor;

[0095] The first capacitor is used to sample the flip voltage;

[0096] The second capacitor is used to sample the maximum voltage;

[0097] The open circuit voltage is determined by determining the difference between the flip voltage and the maximum voltage.

[0098] In this embodiment, the open circuit voltage sampling circuit includes two sampling capacitors: a first capacitor and a second capacitor, which are used to accurately measure the flip voltage and the maximum voltage of the piezoelectric transducer, thereby determining the open circuit voltage.

[0099] The first capacitor is used to sample when the piezoelectric transducer generates a flip voltage, record the flip voltage value, and provide a basis for the subsequent calculation of the open circuit voltage.

[0100] The second capacitor is used to sample the piezoelectric transducer when it reaches its maximum voltage and record the maximum voltage value. This sampling process ensures that the flip voltage and maximum voltage are fully preserved, making the calculation of the open circuit voltage highly accurate.

[0101] The open circuit voltage sampling circuit is as shown in the attached Figure 5 As shown in Figure 1, the sampling is divided into three steps, and the open circuit voltage is obtained by using the principle of charge redistribution. After the open circuit signal is given to the parallel synchronous switch inductor module, the parallel synchronous switch inductor module skips the attached Figure 2 In state 2, the parasitic capacitance C P The attached Figure 3 The peak voltage V in the second half cycle M , half the difference between this peak value and the voltage at the completion of the flip It is the open circuit voltage in the maximum power point calculation formula. The open circuit voltage is sampled to this value through three working steps. In state one, capacitor C1 samples the reversal voltage Vr for the first time, where the red plate is the upper plate of capacitor C1. In state two, capacitor C2 samples the maximum voltage VM. In phase three, the bottom plate of capacitor C1 with a voltage of Vr is connected to the top plate of capacitor C2 with a voltage of VM. According to the principle of charge redistribution, the capacitor voltage after the parallel connection is completed is exactly the open circuit voltage.

[0102] As a further optional embodiment, the step of determining the open circuit voltage by determining the difference between the flip voltage and the maximum voltage specifically includes:

[0103] After the first capacitor samples the flip voltage, when the second capacitor samples the maximum voltage, the bottom plate of the first capacitor is connected to the top plate of the second capacitor to form a parallel circuit, and the accurate value of the open circuit voltage is obtained by charge redistribution.

[0104] In this embodiment, the open circuit voltage is determined by calculating the difference between the flip voltage and the maximum voltage. The specific operation is as follows:

[0105] After the first capacitor samples the flipped voltage, the second capacitor then samples the maximum voltage. During this process, the bottom plate of the first capacitor is connected to the top plate of the second capacitor, forming a parallel circuit. This parallel structure allows the two capacitors to achieve voltage balance through charge redistribution.

[0106] During the charge redistribution process, the system automatically balances the voltage value based on the conservation laws of capacitor voltage and charge, accurately reflecting the actual open-circuit voltage. This design avoids the accumulation of voltage measurement errors through physical charge redistribution, effectively improving the accuracy of open-circuit voltage measurement and providing high-precision data input for the subsequent maximum power point tracking module.

[0107] As a further optional embodiment, the DC-DC load voltage adjustment module includes a four-switch Buck-Boost unit and a control unit;

[0108] The control unit is configured to adjust the DC signal to a target voltage through the four-switch Buck-Boost unit according to the maximum power point.

[0109] In this embodiment, the DC-DC load voltage adjustment module includes a four-switch Buck-Boost unit and a control unit.

[0110] Specifically, the control unit precisely adjusts the operating state of the four-switch Buck-Boost unit based on the maximum power point requirements. By switching the four switches on and off, the Buck-Boost unit can step up or down the input voltage, thereby adjusting the DC input signal to the target voltage. This design ensures that the system can stably output the target voltage under various load conditions, enabling the energy collected by the piezoelectric transducer to be efficiently transferred to the subsequent load, while also optimizing the overall power efficiency of the system.

[0111] During application, by real-time control of the operating mode of the four-switch Buck-Boost unit, it can adapt to fluctuations in the input voltage and maintain the stability of the output voltage to achieve precise control of the load supply voltage, thereby further improving energy utilization efficiency and extending the service life of the system.

[0112] In order to adjust the voltage of the interface circuit to the voltage corresponding to the maximum power point, a DC-DC load voltage adjustment module is designed as shown in the attached figure. Figure 6 As shown, it consists of a four-switch Buck-Boost circuit and a control module. The energy storage capacitor of the front stage is connected to the output of the interface circuit, and its voltage is V RECThe latter stage is connected to the output capacitor and the load. Its function is to calculate the maximum power point voltage based on the open circuit voltage Voc and the rollover coefficient λ sampled by the above circuit, and adjust V REC To the maximum power point voltage to achieve maximum power point tracking. Its working principle is as follows:

[0113] (i) According to the flip coefficient, the circuit output OUT1-OUT4 is judged, and V REC Perform corresponding voltage division so that the voltage division value is (1-λ)V REC

[0114] (ii) A hysteresis comparator is used to compare the Voc sampled by the open circuit voltage sampling module with the voltage divider value. When Voc < (1-λ) V_REC, SW5 is high and SW6 is low, so that the Buck-Boost switches SW1 and SW3 are turned on, and SW2 and SW4 are turned off. The inductor current increases, and energy is transferred from V REC Transferred to the inductor, at this time V REC Decrease. When Voc<(1-λ)V REC When the switches SW1 and SW3 are closed, and SW2 and SW4 are opened, the energy is transferred from the inductor to the output capacitor. REC charging, so V REC Rising. Through the hysteresis window of the hysteresis comparator, (1-λ)V REC Equal to Voc, maintain V REC voltage at the maximum power point.

[0115] As a further optional embodiment, the open circuit voltage is:

[0116]

[0117] Among them, V M is the maximum voltage, V r is the reversal voltage.

[0118] In this embodiment, the open circuit voltage sampling circuit can obtain the open circuit voltage by the following calculation formula:

[0119]

[0120] Among them, V M is the maximum voltage obtained by sampling, V r is the flip voltage. Through this formula, the system can accurately calculate the open circuit voltage after collecting the flip voltage and maximum voltage.

[0121] This method utilizes the voltage changes generated by the piezoelectric transducer during its flipping process, allowing the system to obtain the piezoelectric transducer's open-circuit voltage in real time under different environments. This allows for more accurate determination and tracking of the maximum power point, improving energy conversion efficiency. Furthermore, by implementing this calculation formula within the control unit, the precise open-circuit voltage can be obtained without the need for additional complex circuitry, simplifying circuit design and enhancing the system's reliability and applicability.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An adaptive maximum power tracking parallel synchronous flip interface circuit, characterized in that: include: Parallel synchronous switching inductor module, maximum power point tracking module and DC-DC load voltage adjustment module; The parallel synchronous switching inductor module is used to convert the AC signal generated by the piezoelectric transducer into a DC signal; The maximum power point tracking module is used to determine the maximum power point according to the open circuit voltage and the rollover coefficient; The DC-DC load voltage adjustment module is used to adjust the DC signal to a target voltage according to the maximum power point; The maximum power point tracking module includes: an open circuit timing control unit, a flip coefficient judgment unit and an open circuit voltage sampling unit; The open circuit timing control unit is used to control the opening and closing of the switch to control the open circuit time; The open circuit voltage sampling unit is used to collect the open circuit voltage of the piezoelectric transducer in real time and feed it back to the flip coefficient judgment unit; The flip coefficient judgment unit is used to calculate the flip coefficient in real time based on the voltage after the piezoelectric transducer is flipped and a preset voltage division value; The flip coefficient judgment unit includes: a comparator; The comparator is used to compare the voltage after the piezoelectric transducer is flipped with a preset voltage division value to determine the range of the flip coefficient.

2. The adaptive maximum power tracking parallel synchronous flip interface circuit according to claim 1, characterized in that: The parallel synchronous switch inductor module includes: a negative level converter; The negative level converter is connected to the energy storage capacitor through a switch, and the negative level converter is used for performing energy conversion and resonance to reverse the voltage across the piezoelectric piece.

3. The adaptive maximum power tracking parallel synchronous flip interface circuit according to claim 1, characterized in that: The open circuit voltage sampling unit includes: a first capacitor and a second capacitor; The first capacitor is used to sample the flip voltage; The second capacitor is used to sample the maximum voltage; The open circuit voltage is determined by determining the difference between the flip voltage and the maximum voltage.

4. The adaptive maximum power tracking parallel synchronous flip interface circuit according to claim 3, characterized in that: The step of determining the open circuit voltage by determining the difference between the flip voltage and the maximum voltage specifically includes: After the first capacitor samples the flip voltage, when the second capacitor samples the maximum voltage, the bottom plate of the first capacitor is connected to the top plate of the second capacitor to form a parallel circuit, and the accurate value of the open circuit voltage is obtained by charge redistribution.

5. The adaptive maximum power tracking parallel synchronous flip interface circuit according to claim 1, characterized in that: The DC-DC load voltage adjustment module includes a four-switch Buck-Boost unit and a control unit; The control unit is configured to adjust the DC signal to a target voltage through the four-switch Buck-Boost unit according to the maximum power point.

6. The adaptive maximum power tracking parallel synchronous flip interface circuit according to claim 1, characterized in that: The open circuit voltage is: in, is the maximum voltage, is the reversal voltage.

Images