A tracking and locking maximum power point tracking circuit and its implementation method
By combining rectifier and control circuits, adaptive tracking of the maximum power point can be achieved without current and voltage sampling, solving the problems of high power consumption and slow tracking speed of traditional circuits, improving tracking accuracy and speed, and adapting to different energy sources and interface circuits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUN YAT SEN UNIV
- Filing Date
- 2026-02-05
- Publication Date
- 2026-06-05
AI Technical Summary
Traditional maximum power point tracking circuits require continuous sampling of current and voltage, resulting in high power consumption, slow tracking speed, and inability to adapt to different loads and input conditions, which limits their application in low-power scenarios and modular designs.
By employing a rectifier circuit, a control circuit, and a buck-boost converter control circuit, the inductor current zero-crossing point is indirectly detected, the inductor demagnetization time is adjusted, and a switching timing control signal is generated to achieve maximum power point tracking, thereby reducing sampling requirements and improving tracking speed and accuracy.
It achieves adaptive locking of the maximum power point under different vibration frequencies and open-circuit voltages without repeated perturbations, improving tracking accuracy and speed, reducing power consumption, and adapting to different energy sources and interface circuits.
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Figure CN122159679A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of integrated circuit technology, and in particular to a tracking-locked maximum power point tracking circuit and its implementation method. Background Technology
[0002] In the external environment, the amplitude and frequency of the vibration source change with variations in the environment. After being converted into electrical energy by a piezoelectric transducer, it manifests as an open-circuit voltage (V). OC ) and vibration frequency (f PT The output power of the energy harvesting interface circuit changes with load conditions. To ensure stable maximum power output under varying load conditions, a maximum power point tracking (MPPT) circuit is required. The MPPT circuit maximizes the output power of the energy harvesting interface circuit under different input and load conditions. However, obtaining power information requires high-precision current and voltage sampling, which consumes significant power and reduces the output power of the energy harvesting interface circuit. Furthermore, the MPPT circuit adapts to changes in input; traditional solutions require continuous sampling and tracking of the maximum power point, which slows down the tracking and reduces accuracy. Continuous sampling also leads to substantial power consumption. Summary of the Invention
[0003] To address the aforementioned technical problems, the purpose of this application is to provide a tracking-locked maximum power point tracking circuit and its implementation method, which enables adaptive and automatic tracking of the maximum power point under different input conditions without the need for current and voltage sampling, and improves the tracking speed of the circuit when the input changes.
[0004] To achieve the above objectives, one aspect of this application provides a tracking-locked maximum power point tracking circuit, comprising: A rectifier circuit is used to convert input AC power into DC power and output a drive signal. A control circuit, connected to the rectifier circuit, is used to determine the length of the current inductor demagnetization time, and then adjust the current inductor demagnetization time according to the determination result, thereby realizing the indirect detection of the zero-crossing point of the inductor current and generating a switching timing control signal. A buck-boost converter control circuit, connected to the rectifier circuit and the control circuit, is used to generate a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal; A buck-boost converter, connected to the rectifier circuit, the control circuit, and the buck-boost converter control circuit, is used to adjust the input impedance according to the first switch drive signal and the second switch drive signal to achieve maximum power point tracking.
[0005] In some embodiments, the rectifier circuit includes: A negative level converter is used to convert a negative input level to a positive level. An active diode, connected to the negative level converter, is used to rectify the positive level to obtain the DC power. The bias switching circuit, connected to the AC current source, the negative level converter, and the active diode, is used to control the direction of the inductor current flow when the AC current source crosses zero, so as to achieve the switching of the bias state.
[0006] In some embodiments, the bias switching circuit includes: A first switch, a second switch, and an inductor are provided. One end of the first switch is connected to one end of the AC current source, and the other end of the first switch is connected to one end of the inductor. The other end of the inductor is connected to one end of the second switch, and the other end of the second switch is connected to the other end of the AC current source. Pulse generation circuit, used to generate pulse signals; A reverse current detection circuit is used to detect the inductor current and generate a detection signal; A switch control circuit, connected to the pulse generation circuit and the reverse current detection circuit, is used to control the first switch and the second switch to close or open according to the pulse signal and the detection signal, so as to control the direction of the inductor current.
[0007] In some embodiments, the control circuit includes: A zero-current detection circuit, connected to the rectifier circuit and the buck-boost converter, is used to detect the zero-crossing point of the inductor current based on the first switch drive signal and generate a first output signal. The tracking module, connected to the zero-current detection circuit, is used to reuse the first output signal, determine the length of the current inductor demagnetization time based on the first output signal, and then adjust the current inductor demagnetization time based on the determination result to generate a second output signal; A locking module, connected to the zero-current detection circuit, is used to adjust the current inductor demagnetization time according to the first output signal and generate a third output signal; A multiplexer, connected to the tracking module, the locking module, and the buck-boost converter control circuit, is used to generate the switching timing control signal based on the second output signal and the third output signal.
[0008] In some embodiments, the zero-current detection circuit includes: A dynamic comparator is used to compare the voltage at the turn-off node with the voltage at ground based on the drive signal of the first switch transistor, and obtain the comparison result. A latching circuit, connected to the dynamic comparator, is used to generate the first output signal based on the comparison result.
[0009] In some embodiments, the tracking module includes: A successive approximation control circuit is connected to the zero current detection circuit and is used to adjust the second output signal based on the successive approximation algorithm according to the first output signal. The first register, connected to the successive approximation control circuit, is used to store the current convergence result after successive approximation. The second register, connected to the successive approximation control circuit and the first register, is used to store historical convergence results; A digital comparator, connected to the first register and the second register, is used to compare the current convergence result with the historical convergence result.
[0010] In some embodiments, the buck-boost converter control circuit includes: A switching pulse signal generation circuit, connected to the control circuit, is used to generate switching pulse signals according to the switching timing control signal; A switching timing control circuit, connected to the rectifier circuit, the switching pulse signal generation circuit, and the buck-boost converter, is used to generate the first switching transistor drive signal and the second switching transistor drive signal according to the switching pulse signal and the drive signal.
[0011] In some embodiments, the switching pulse signal generating circuit includes a constant current source, a switch array, a capacitor array, a first transistor, and a second transistor.
[0012] In some embodiments, the switching timing control circuit includes a first timing control circuit and a second timing control circuit. The first timing control circuit includes a multiplexer, two AND gates, two 4-bit counters, a digital comparator, a frequency divider, and a D flip-flop. The second timing control circuit includes a multiplexer, two 2-bit counters, two AND gates, OR gates, NOT gates, and two D flip-flops.
[0013] To achieve the above objectives, another aspect of this application proposes a method for implementing a tracking-locked maximum power point tracking circuit, comprising the following steps: The rectifier circuit converts the input AC power into DC power and outputs a drive signal. The control circuit determines the length of the current inductor demagnetization time and adjusts the current inductor demagnetization time based on the determination result, thereby achieving indirect detection of the zero-crossing point of the inductor current and generating a switching timing control signal. The buck-boost converter control circuit generates a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal. By using a buck-boost converter, the input impedance is adjusted according to the first and second switch drive signals to achieve maximum power point tracking.
[0014] The beneficial effects of this application are as follows: This application provides a tracking-locked maximum power point tracking circuit and its implementation method, including a rectifier circuit, a control circuit, a buck-boost converter control circuit, and a buck-boost converter. The rectifier circuit is used to convert the input AC power into DC power and output a drive signal. The control circuit is used to determine the length of the current inductor demagnetization time, and then adjust the current inductor demagnetization time according to the determination result to achieve indirect detection of the zero-crossing point of the inductor current and generate a switching timing control signal. The buck-boost converter control circuit is used to generate a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal. The buck-boost converter is used to adjust the input impedance according to the first switch drive signal and the second switch drive signal to achieve maximum power point tracking. This application adjusts the input impedance of the buck-boost converter by adjusting the inductor demagnetization time. At the same time, by correlating the operating frequency of the buck-boost converter with the frequency of the vibration energy input, it achieves adaptive locking of the maximum power point under different vibration frequencies and different open-circuit voltages, realizing real-time tracking without repeated disturbances. This improves both tracking accuracy and the tracking speed of the circuit when the input changes. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments of this application are described below. It should be understood that the drawings described below are only for the purpose of clearly illustrating some embodiments of the technical solutions in this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0016] Figure 1 This is a structural block diagram of a tracking-locking maximum power point tracking circuit provided in one embodiment of this application; Figure 2 A circuit schematic diagram of a tracking-locking maximum power point tracking circuit provided in one embodiment of this application; Figure 3 This is a flowchart illustrating a tracking-locking algorithm provided in one embodiment of this application; Figure 4 A circuit schematic diagram of a zero-current detection circuit provided in one embodiment of this application; Figure 5A circuit diagram of a switching pulse signal generation circuit provided in one embodiment of this application; Figure 6 This is a structural block diagram of a switching timing control circuit provided in one embodiment of this application; Figure 7 This is a timing diagram of a switching timing control circuit provided in one embodiment of this application; Figure 8 This is a schematic diagram of a tracking-locking process provided in one embodiment of this application; Figure 9 This is a schematic diagram illustrating the steps of an implementation method for a tracking-locked maximum power point tracking circuit according to an embodiment of this application. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit it. In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those of this application; they are merely examples of apparatuses and methods consistent with some aspects of the embodiments of this application as detailed in the appended claims.
[0018] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various concepts, but unless otherwise stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words “if,” “when,” or “in response to a determination” as used herein may be interpreted as “when…” or “when…” or “in response to a determination.”
[0019] As used in this application, the terms "at least one", "multiple", "each", "any", etc., "at least one" includes one, two or more, "multiple" includes two or more, "each" refers to each of the corresponding multiples, and "any" refers to any one of the multiples.
[0020] In the external environment, the amplitude and frequency of the vibration source change with variations in the environment. After being converted into electrical energy by a piezoelectric transducer, it manifests as an open-circuit voltage (V). OC ) and vibration frequency (f PTThe output power of the energy harvesting interface circuit changes with load conditions. To ensure stable maximum power output under varying load conditions, a maximum power point tracking (MPPT) circuit is required. The MPPT circuit maximizes the output power of the energy harvesting interface circuit under different input and load conditions. However, obtaining power information requires high-precision current and voltage sampling, which consumes significant power and reduces the output power of the energy harvesting interface circuit. Furthermore, the MPPT circuit adapts to changes in input; traditional solutions require continuous sampling and tracking of the maximum power point, which slows down the tracking and reduces accuracy. Continuous sampling also leads to substantial power consumption.
[0021] In summary, traditional maximum power point tracking circuits have the following shortcomings: I. In order to obtain power information P=V I requires current and voltage sampling, which incurs significant power consumption overhead, contradicting the application scenarios of energy harvesting and limiting the application of maximum power point tracking technology in low-power scenarios.
[0022] Second, designing only for a single type of interface circuit cannot adapt to different interface circuit structures. The bundled relationship between the interface circuit and the maximum power point tracking circuit reduces the system design freedom and makes modular design impossible.
[0023] Third, when the input changes, the maximum power point will also change. At this time, the maximum power point tracking circuit needs to dynamically adjust its input impedance to track the new maximum power point. Traditional solutions require continuous sampling and tracking of the maximum power point, which will reduce the tracking accuracy of the circuit. At the same time, continuous sampling will lead to a large power consumption.
[0024] In view of this, embodiments of this application propose a tracking-locked maximum power point tracking circuit, including a rectifier circuit, a control circuit, a buck-boost converter control circuit, and a buck-boost converter. The rectifier circuit is used to convert the input AC power into DC power and output a drive signal. The control circuit is used to determine the length of the current inductor demagnetization time, and then adjust the current inductor demagnetization time according to the determination result to achieve indirect detection of the zero-crossing point of the inductor current and generate a switching timing control signal. The buck-boost converter control circuit is used to generate a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal. The buck-boost converter is used to adjust the input impedance according to the first switch drive signal and the second switch drive signal to achieve maximum power point tracking. This application adjusts the input impedance of the buck-boost converter by adjusting the inductor demagnetization time. At the same time, by correlating the operating frequency of the buck-boost converter with the frequency of the vibration energy input, it achieves adaptive locking of the maximum power point under different vibration frequencies and different open-circuit voltages, realizing real-time tracking without repeated disturbances. This improves both tracking accuracy and the tracking speed of the circuit when the input changes.
[0025] Reference Figure 1 , Figure 1 This is a structural block diagram of a tracking-locked maximum power point tracking circuit according to an embodiment of this application. The embodiment of this application proposes a tracking-locked maximum power point tracking circuit, including: A rectifier circuit is used to convert input AC power into DC power and output a drive signal. The control circuit, connected to the rectifier circuit, is used to determine the length of the current inductor demagnetization time, and then adjust the current inductor demagnetization time according to the determination result, thereby realizing the indirect detection of the zero-crossing point of the inductor current and generating a switching timing control signal. The buck-boost converter control circuit, connected to the rectifier circuit and the control circuit, is used to generate a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal; A buck-boost converter, connected to a rectifier circuit, a control circuit, and a buck-boost converter control circuit, is used to adjust the input impedance according to the first switch drive signal and the second switch drive signal to achieve maximum power point tracking.
[0026] Specifically, the circuit architecture of this application embodiment includes a rectifier circuit (P-SSHI rectifier circuit) and a maximum power point tracking circuit; the maximum power point tracking circuit includes a buck-boost converter, a control circuit (MPPT control circuit), and a buck-boost converter control circuit.
[0027] Reference Figure 2 , Figure 2The circuit schematic of a tracking-locked maximum power point tracking circuit provided in one embodiment of this application is shown. Further, as an optional implementation, the rectifier circuit includes: A negative level converter is used to convert a negative input level to a positive level. An active diode, connected to a negative level converter, is used to rectify a positive level to obtain DC power; The bias switching circuit, connected to an AC current source, a negative level converter, and an active diode, is used to control the direction of inductor current flow when the AC current source crosses zero, thereby switching the bias state.
[0028] Specifically, such as Figure 2 As shown, the rectifier circuit includes a negative voltage converter (NVC), an active diode (AD), and a bias flip circuit (BFC) to convert the input AC power into DC power and store it in capacitor C. R superior.
[0029] The negative level converter transforms the input negative voltage level into a positive voltage level. The active diode has the same unidirectional conductivity as a regular diode, but with a lower voltage drop. After passing through the negative level converter and the active diode, the input AC power is converted into DC power. When the input sinusoidal AC current source I... P When the circuit crosses zero, the bias switching circuit starts working, controlling the direction of the inductor current to switch the bias state.
[0030] Reference Figure 2 As a further optional implementation, the bias switching circuit includes: A first switch, a second switch, and an inductor are provided. One end of the first switch is connected to one end of an AC current source, and the other end of the first switch is connected to one end of an inductor. The other end of the inductor is connected to one end of the second switch, and the other end of the second switch is connected to the other end of an AC current source. Pulse generation circuit, used to generate pulse signals; The reverse current detection circuit is used to detect the inductor current and generate a detection signal; The switch control circuit, connected to the pulse generation circuit and the reverse current detection circuit, is used to control the first switch and the second switch to close or open according to the pulse signal and the detection signal, so as to control the direction of the inductor current.
[0031] Specifically, when the input sinusoidal alternating current source I P When the signal crosses zero, the pulse generation circuit first generates a pulse signal, which, after passing through the switch control circuit, causes the first switch S to... F Second switch S FClose the circuit; then, the reverse current detection circuit detects the inductor current. When the inductor current reverses, the reverse current detection circuit outputs a detection signal to the switch control circuit, controlling the first switch S. F Second switch S F The bias switching process is completed by disconnecting the circuit. Compared to a full-bridge rectifier circuit, the bias switching technology in this embodiment can effectively improve energy harvesting efficiency.
[0032] It should be noted that the buck-boost converter and the rectifier circuit in this embodiment share an inductor L to reduce the number of off-chip components.
[0033] Reference Figure 2 As a further optional implementation, the control circuit includes: The zero-current detection circuit, connected to the rectifier circuit and the buck-boost converter, is used to detect the zero-crossing point of the inductor current based on the first switch drive signal and generate the first output signal. The tracking module, connected to the zero-current detection circuit, is used to reuse the first output signal, determine the length of the current inductor demagnetization time based on the first output signal, and then adjust the current inductor demagnetization time according to the determination result to generate the second output signal; A locking module, connected to a zero-current detection circuit, is used to adjust the current inductor demagnetization time based on the first output signal and generate a third output signal. The multiplexer, connected to the tracking module, the locking module, and the buck-boost converter control circuit, is used to generate switching timing control signals based on the second and third output signals.
[0034] Reference Figure 2 As an optional implementation, the tracking module includes: A successive approximation control circuit is connected to a zero-current detection circuit and is used to adjust the second output signal based on the successive approximation algorithm according to the first output signal. The first register is connected to the successive approximation control circuit and is used to store the current convergence result after successive approximation. The second register, connected to the successive approximation control circuit and the first register, is used to store historical convergence results; A digital comparator, connected to the first and second registers, is used to compare the current convergence result with historical convergence results.
[0035] Specifically, such as Figure 2 As shown, the control circuit includes a zero-current detector (ZCD), a track module, and a lock module. The zero-current detector is used to detect the zero-crossing point of the inductor current, thereby obtaining the inductor demagnetization time T. LThe tracking module includes a successive approximation control circuit, a first register REG1, a second register REG2, and a digital comparator.
[0036] Among them, the successive approximation control circuit is based on the first output signal Q CMP The second output signal Q is adjusted bit by bit using the binary search method. SAR[7:0] After successive approximations are completed, the current convergence result (Q) is stored in the first register REG1. NOW The second register, REG2, receives the value of the first register, REG1, which is the previous convergence result (historical convergence result Q). LAST The result Q of comparing two registers using a digital comparator. NOW and Q LAST When Q LAST Q NOW Its output signal EN L Set to 1. The locking module includes an integral control circuit, which is implemented as an increment / decrement counter. After tracking is complete and the system enters a steady state, it is set according to the first output signal Q. CMP The integral control circuit will affect Q T[7:0] It performs an increment or decrement operation. The multiplexer MUX is used to select different inputs based on control signals S1 and S0, and then outputs a switching timing control signal Q. CAP[7:0] The switching pulse signal generation circuit controls the power switching of the buck-boost converter.
[0037] It should be noted that traditional inductor current detection schemes require high-precision zero-current detection circuits to accurately detect the zero-crossing point, thereby increasing circuit complexity and power consumption. However, the zero-current detection circuit in this embodiment does not require precise detection at the zero-crossing point of the inductor current; instead, it first provides an inductor demagnetization time T. L Then, the switch M in the buck-boost converter is tested. N1 Disconnecting the node voltage V SW The voltage is used to determine the current inductor demagnetization time T. L Whether it is too long or too short, the current inductor demagnetization time T is dynamically adjusted. L The length of the circuit is determined to achieve indirect detection of the zero-crossing point of the inductor current. This scheme reduces the accuracy requirements of the zero-current detection circuit, thereby reducing circuit complexity and power consumption. Simultaneously, the first output signal Q of the zero-current detection circuit... CMP The tracked module is multiplexed, and the output switching timing control signal Q is used. CAP[7:0] The switching timing is controlled to adjust the input impedance of the buck-boost converter, thereby achieving maximum power point tracking.
[0038] In some alternative embodiments, such as Figure 3The diagram shown is a flowchart of the tracking-lock algorithm. The flowchart contains two loop processes; the main loop is used to adjust the inductor magnetization time T. H The sub-loop on the right is used to adjust the inductor demagnetization time T. L Q NOW and Q LAST These are the inductor demagnetization times T stored in the register. L The length of the numeric code.
[0039] In the main loop, the inductor magnetization time T is first initialized. H Then, the corresponding inductor demagnetization time T is searched through a sub-loop. L And stored in Q NOW In the middle. During initialization, both are assigned the value 0, therefore Q is in the first main loop. NOW Q LAST If the condition is met, shorten the inductor magnetization time T. H , continue the loop. In subsequent loops, if Q NOW Q LAST This indicates that the output power is increasing and the cycle continues; conversely, it indicates that the output power is decreasing, at which point the EN flag is locked. L =1, end the loop, enter the locked state, inductor magnetization time T H Increase the value back to the previous value and lock it.
[0040] The purpose of the sub-loop is to search for the magnetization time T of a certain inductor. H The corresponding optimal inductor demagnetization time T L Q SAR[7:0] It is the inductor demagnetization time T stored in the register. L The length of the numeric code, Q CMP This is the first output signal from the zero-current detection circuit. The sub-loop first initializes Q. SAR[7:0] The intermediate value is 10000000, based on the first output signal Q. CMP Determine the current Q SAR[7:0] The inductor demagnetization time T represents L Whether it is too long or too short, the second output signal Q is adjusted using the Successive Approximation Register (SAR) algorithm. SAR[7:0] The value of the second output signal Q is obtained after 8 sub-loops. SAR[7:0] Converging to the optimal value, and storing that value in Q. NOW In the middle, the sub-loop ends and returns to the main loop.
[0041] Reference Figure 4 , Figure 4The circuit diagram shows a zero-current detection circuit according to one embodiment of this application. Further, as an optional implementation, the zero-current detection circuit includes: A dynamic comparator is used to compare the voltage at the off node with the voltage at ground based on the drive signal of the first switching transistor, and obtain the comparison result. The latch circuit, connected to the dynamic comparator, is used to generate a first output signal based on the comparison result.
[0042] Specifically, such as Figure 4 As shown, in the idle state, the first switch drive signal D L For high, through the latching circuit, the first output signal Q CMP Maintain the original state; in the working state, the first switching transistor drive signal D L When the voltage is low, the dynamic comparator operates, comparing the turn-off node voltage V. SW The magnitude of the voltage is compared with the ground voltage, and the result is output to the first output signal Q. CMP .
[0043] It should be noted that this embodiment uses a dynamic comparator instead of a traditional static comparator to achieve zero-crossing detection of the inductor current. The dynamic comparator determines the relationship between the current turn-off time and the optimal turn-off time, and adjusts the turn-off time accordingly. Simultaneously, the results of two consecutive turn-off times are reused to achieve maximum power point tracking, eliminating the need for additional detection circuitry, thus simplifying circuit design and reducing power consumption. When the output voltage V remains stable, this embodiment uses the optimal turn-off time obtained from the dynamic comparator to detect the output current I. From P = V × I, end-to-end maximum power output can be achieved.
[0044] Reference Figure 2 As an optional implementation, the buck-boost converter control circuit includes: A switching pulse signal generation circuit, connected to a control circuit, is used to generate switching pulse signals according to a switching timing control signal. The switching timing control circuit, connected to the rectifier circuit, the switching pulse signal generation circuit, and the buck-boost converter, is used to generate a first switching transistor drive signal and a second switching transistor drive signal based on the switching pulse signal and the drive signal.
[0045] Specifically, the buck-boost converter control circuit includes a switching pulse signal generation circuit (T... H &T L The circuit consists of a generation circuit and a switching timing control circuit. The switching pulse signal generation circuit generates the switching pulse signal T. C The switching timing control circuit is used to generate the switching pulse signal T from the switching pulse signal generation circuit. CThis generates the first switch drive signal D. L Second switch drive signal D H This is used to control the power switching of the buck-boost converter.
[0046] Reference Figure 5 , Figure 5 The circuit diagram of a switching pulse signal generation circuit provided in one embodiment of this application is shown. Further, as an optional implementation, the switching pulse signal generation circuit includes a constant current source, a switch array, a capacitor array, a first transistor, and a second transistor.
[0047] Specifically, such as Figure 5 As shown, the switching pulse signal generation circuit includes a constant current source, a switch array, and a capacitor array. The output signal of the control module controls the switch array, thereby adjusting the capacitor size; the constant current source charges capacitors of different sizes, generating pulses of different widths, which in turn generate the switching control signal for the buck-boost converter.
[0048] Reference Figure 6 , Figure 6 The circuit diagram of the switching timing control circuit provided in one embodiment of this application is shown. Further, as an optional implementation, the switching timing control circuit includes a first timing control circuit and a second timing control circuit. The first timing control circuit includes a multiplexer, two AND gates, two 4-bit counters, a digital comparator, a frequency divider, and a D flip-flop. The second timing control circuit includes a multiplexer, two 2-bit counters, two AND gates, OR gates, NOT gates, and two D flip-flops.
[0049] Specifically, such as Figure 6 and Figure 7 As shown, Figure 7 This is a timing diagram of a switching timing control circuit, D. F The drive signal comes from the pre-rectifier circuit and, after frequency division, serves as the clock input signal for the D flip-flop. In this embodiment, the vibration signal frequency is linked to the operating frequency of the buck-boost converter, thereby achieving adaptive locking of the maximum power point under different vibration frequencies and open-circuit voltages. S1 and S0 are mode control signals because the inductor magnetization time T... H and inductor demagnetization time T L Generate shared modules Figure 5 The capacitor array in the circuit requires mode switching between S1 and S0. The inductor magnetization time T... H The pulse duration is determined by the comparison result of the digital comparator. When the counting results of the two 4-bit counters are equal, the digital comparator outputs a signal to reset the D flip-flop, and the second switching transistor drives the D signal. H Set to low. Inductor demagnetization time T LThe pulse duration is determined by a 2-bit counter. When the 2-bit counter is full, the D flip-flop is reset, and the second switching transistor drives the signal D. L Set high.
[0050] In summary, as Figure 8 The diagram shows the tracking-locking process of a tracking-locking maximum power point tracking circuit. The upper part of the diagram shows the waveforms and digital code transmission relationships of key signals during the tracking-locking process in the main loop; the lower part shows the adjustment of the inductor demagnetization time T based on the first output signal from the zero-current detection circuit in the sub-loop. L The process. Q in the diagram. TH Indicates the inductor magnetization time T H The length of V reflects REC The size of Q. TH The larger the value, the higher the value. REC The higher. Q SAR[7:0] Represents the inductor demagnetization time T L The length of Q. In this embodiment of the application, Q SAR[7:0] Designed as an 8-bit digital code, it maintains accuracy while covering the inductor demagnetization time T under different input conditions. L Range. To accelerate the convergence speed during the tracking phase, embodiments of this application use a successive approximation algorithm to adjust Q. SAR[7:0] The value of this value allows us to obtain the precise inductor demagnetization time T in just 8 cycles. L Value. After each sub-loop ends, each numeric code is determined according to... Figure 3 The transmission is shown. When Q NOW LAST At that time, EN L =1, Inductor magnetization time T H Returning to the point of maximum power, Q LAST Storage inductor demagnetization time T L Passed to Q T[7:0] The system enters a locked state. In the sub-loop, the first output signal Q output by the zero-current detection circuit in this embodiment of the application... CMP Determine the Q of the i-th bit SAR[i] Set to 1 or 0 to adjust the inductor demagnetization time T. L The length. For example Figure 8 As shown in the lower left section, during the tracking phase: if Figure 2 power switch M N1 When disconnected, the inductor current I L <0, V SW The node will be pulled high, and the first output signal Q from the zero-current detection circuit will be generated. CMP =0 indicates that the current inductor demagnetization time T L If the time is too long, the inductor demagnetization time T needs to be shortened. L Therefore, the current position Q is... SAR[i] Set to 0; conversely, if I L >0, V SW The node will drop to a negative voltage, and the first output signal Q of the zero-current detection circuit will be generated. CMP =1 indicates the current inductor demagnetization time T L If the time is too short, the inductor demagnetization time T needs to be extended. L Therefore, the current position Q is... SAR[i] Set to 1. For example... Figure 8 As shown in the lower right section, during the locking phase, the optimal inductor demagnetization time T differs from that during the tracking phase. L Will follow V REC The inductor demagnetization time T changes continuously during this stage. L Under certain input conditions, this is a fixed value. To ensure that the switch of the buck-boost converter precisely opens when the inductor current crosses zero, an integral control method is used to adjust the inductor demagnetization time T. L . When I L When Q < 0, T[7:0] 1. Inductor demagnetization time T L Shorten; when I L When Q > 0, T[7:0] +1, Inductor demagnetization time T L Extend the final inductor demagnetization time T L It stabilizes near the optimal value.
[0051] The structure and working principle of the tracking-locked maximum power point tracking circuit of this application embodiment have been described above. It can be understood that the embodiments of this application have the following advantages compared with the conventional maximum power point tracking circuit: First, an adaptive maximum power point tracking (MPPT) circuit is proposed, which adjusts the input impedance of the buck-boost converter by adjusting the inductor demagnetization time. Simultaneously, by correlating the operating frequency of the buck-boost converter with the frequency of the vibration energy input, adaptive locking of the MPPT is achieved under different vibration frequencies and open-circuit voltages. Real-time tracking can be achieved without repeated perturbations, improving both tracking accuracy and tracking speed when the input changes.
[0052] Second, a sampling-free maximum power point tracking (MPPT) method is proposed. This method uses a dynamic comparator instead of a traditional static comparator to achieve zero-crossing detection of the inductor current. The comparison result of the dynamic comparator is used to determine the relationship between the current turn-off time and the optimal turn-off time, and the turn-off time is adjusted accordingly. Simultaneously, the results of two consecutive turn-off times are reused to achieve MPPT, eliminating the need for additional detection circuitry, thus simplifying circuit design and reducing power consumption.
[0053] Third, a maximum power point tracking (MPPT) method for output power detection is proposed. When the output voltage V remains stable, the optimal turn-off time obtained through a dynamic comparator is used to detect the output current I. By using P=V×I, end-to-end maximum power output can be achieved. This method is independent of the pre-amplifier interface circuit, thus allowing operation with different energy sources (such as vibration energy, thermal energy, solar energy, etc.) and different interface circuits.
[0054] Furthermore, in addition to the circuit structure and method mentioned in the above embodiments, the present application can also make the following modifications: 1. In addition to the buck-boost converter power structure, buck converter, boost converter, and switched capacitor converter structures can also be used; 2. The proposed adaptive locking method is applicable to rectifier circuits based on bias switching, such as parallel synchronous switching inductor rectifier circuits, series synchronous switching inductor rectifier circuits, and synchronous switching capacitor circuits. 3. In addition to using a constant current source to charge the capacitor and generate pulses, an oscillator can also be used to generate adjustable pulses. The key is to generate a pulse signal that can be digitally controlled. 4. Besides using tracking approximation control and integral control methods to achieve tracking and locking, other algorithms can also be used. The core lies in the first output signal Q output by the zero-current detection circuit. CMP Quickly adjust the inductor demagnetization time T L .
[0055] Reference Figure 9 This application provides a method for implementing a tracking-locked maximum power point tracking circuit, which is used to implement the circuit, including the following steps S101 to S104: Step S101: The input AC power is converted into DC power through a rectifier circuit, and a drive signal is output. Step S102: The control circuit determines the length of the current inductor demagnetization time, and then adjusts the current inductor demagnetization time according to the determination result to realize the indirect detection of the zero crossing point of the inductor current and generate a switching timing control signal. Step S103: The buck-boost converter control circuit generates a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal. Step S104: Using a buck-boost converter, the input impedance is adjusted according to the first switch drive signal and the second switch drive signal to achieve maximum power point tracking.
[0056] The contents of the above tracking-locked maximum power point tracking circuit embodiments are all applicable to this implementation method embodiment. The specific functions implemented in this implementation method embodiment are the same as those in the above tracking-locked maximum power point tracking circuit embodiments, and the beneficial effects achieved are also the same as those achieved in the above tracking-locked maximum power point tracking circuit embodiments.
[0057] In the foregoing description of this specification, the references to terms such as "one embodiment," "another embodiment," or "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0058] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.
[0059] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.
Claims
1. A tracking-locking type maximum power point tracking circuit, characterized in that, include: A rectifier circuit is used to convert input AC power into DC power and output a drive signal. A control circuit, connected to the rectifier circuit, is used to determine the length of the current inductor demagnetization time, and then adjust the current inductor demagnetization time according to the determination result, thereby realizing the indirect detection of the zero-crossing point of the inductor current and generating a switching timing control signal. A buck-boost converter control circuit, connected to the rectifier circuit and the control circuit, is used to generate a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal; A buck-boost converter, connected to the rectifier circuit, the control circuit, and the buck-boost converter control circuit, is used to adjust the input impedance according to the first switch drive signal and the second switch drive signal to achieve maximum power point tracking.
2. The circuit according to claim 1, characterized in that, The rectifier circuit includes: A negative level converter is used to convert a negative input level to a positive level. An active diode, connected to the negative level converter, is used to rectify the positive level to obtain the DC power. The bias switching circuit, connected to the AC current source, the negative level converter, and the active diode, is used to control the direction of the inductor current flow when the AC current source crosses zero, so as to achieve the switching of the bias state.
3. The circuit according to claim 2, characterized in that, The bias switching circuit includes: A first switch, a second switch, and an inductor are provided. One end of the first switch is connected to one end of the AC current source, and the other end of the first switch is connected to one end of the inductor. The other end of the inductor is connected to one end of the second switch, and the other end of the second switch is connected to the other end of the AC current source. Pulse generation circuit, used to generate pulse signals; A reverse current detection circuit is used to detect the inductor current and generate a detection signal; A switch control circuit, connected to the pulse generation circuit and the reverse current detection circuit, is used to control the first switch and the second switch to close or open according to the pulse signal and the detection signal, so as to control the direction of the inductor current.
4. The circuit according to claim 1, characterized in that, The control circuit includes: A zero-current detection circuit, connected to the rectifier circuit and the buck-boost converter, is used to detect the zero-crossing point of the inductor current based on the first switch drive signal and generate a first output signal. The tracking module, connected to the zero-current detection circuit, is used to reuse the first output signal, determine the length of the current inductor demagnetization time based on the first output signal, and then adjust the current inductor demagnetization time based on the determination result to generate a second output signal; A locking module, connected to the zero-current detection circuit, is used to adjust the current inductor demagnetization time according to the first output signal and generate a third output signal; A multiplexer, connected to the tracking module, the locking module, and the buck-boost converter control circuit, is used to generate the switching timing control signal based on the second output signal and the third output signal.
5. The circuit according to claim 4, characterized in that, The zero-current detection circuit includes: A dynamic comparator is used to compare the voltage at the turn-off node with the voltage at ground based on the drive signal of the first switch transistor, and obtain the comparison result. A latching circuit, connected to the dynamic comparator, is used to generate the first output signal based on the comparison result.
6. The circuit according to claim 4, characterized in that, The tracking module includes: A successive approximation control circuit is connected to the zero current detection circuit and is used to adjust the second output signal based on the successive approximation algorithm according to the first output signal. The first register, connected to the successive approximation control circuit, is used to store the current convergence result after successive approximation. The second register, connected to the successive approximation control circuit and the first register, is used to store historical convergence results; A digital comparator, connected to the first register and the second register, is used to compare the current convergence result with the historical convergence result.
7. The circuit according to claim 1, characterized in that, The buck-boost converter control circuit includes: A switching pulse signal generation circuit, connected to the control circuit, is used to generate switching pulse signals according to the switching timing control signal; A switching timing control circuit, connected to the rectifier circuit, the switching pulse signal generation circuit, and the buck-boost converter, is used to generate the first switching transistor drive signal and the second switching transistor drive signal according to the switching pulse signal and the drive signal.
8. The circuit according to claim 7, characterized in that, The switching pulse signal generation circuit includes a constant current source, a switch array, a capacitor array, a first transistor, and a second transistor.
9. The circuit according to claim 7, characterized in that, The switching timing control circuit includes a first timing control circuit and a second timing control circuit. The first timing control circuit includes a multiplexer, two AND gates, two 4-bit counters, a digital comparator, a frequency divider, and a D flip-flop. The second timing control circuit includes a multiplexer, two 2-bit counters, two AND gates, OR gates, NOT gates, and two D flip-flops.
10. A method for implementing a tracking-locked maximum power point tracking circuit, used to implement it through any one of claims 1 to 9, characterized in that, Includes the following steps: The rectifier circuit converts the input AC power into DC power and outputs a drive signal. The control circuit determines the length of the current inductor demagnetization time and adjusts the current inductor demagnetization time based on the determination result, thereby achieving indirect detection of the zero-crossing point of the inductor current and generating a switching timing control signal. The buck-boost converter control circuit generates a first switch drive signal and a second switch drive signal according to the switching timing control signal and the drive signal. By using a buck-boost converter, the input impedance is adjusted according to the first and second switch drive signals to achieve maximum power point tracking.