A photovoltaic array maximum power point dynamic tracking system

Abstract

The application discloses a photovoltaic array maximum power point dynamic tracking system, comprising a photovoltaic array, a sensing detection unit, a DC-DC conversion circuit, a load and a microprocessor controller. The sensing detection unit samples output voltage and current in real time, the microprocessor controller executes an improved adaptive step perturbation and observation method MPPT algorithm, according to the comparison result of the current power and the power at the last sampling time, sends a driving signal to the DC-DC conversion circuit to change the duty cycle, adjusts the output voltage to realize dynamic tracking. The system is equipped with an environment monitoring module to collect irradiance and temperature, sets a small value of step length and a preset step perturbation mechanism. The DC-DC conversion circuit adopts a Boost voltage increasing circuit. In addition, the system has a data display and storage unit, an integrated communication interface module, and supports remote monitoring. The system can effectively solve the contradiction of the traditional fixed step method, improve the tracking accuracy and efficiency, accurately adjust the working point, facilitate performance analysis, realize remote monitoring, and efficiently and accurately track the maximum power point.

Description

Technical Field

[0001] This application relates to the field of photovoltaic control technology, and more specifically to a dynamic maximum power point tracking system for a photovoltaic array. Background Technology

[0002] With the increasing global demand for clean energy, solar energy, as an abundant and renewable energy source, has received widespread attention for its development and utilization. Photovoltaic arrays, as key equipment for converting solar energy into electricity, directly affect the utilization effect of solar energy through their conversion efficiency. However, the output power of photovoltaic arrays is significantly affected by environmental factors such as irradiance and temperature, and their maximum power point (MPP) changes dynamically under different environmental conditions.

[0003] Traditional maximum power point tracking (MPPT) technology for photovoltaic arrays has several limitations. Some technologies employ a fixed-step perturbation observation method. When the step size is large, significant steady-state oscillations occur near the maximum power point, leading to power loss. Conversely, when the step size is small, the tracking speed is slow when moving away from the maximum power point, failing to respond promptly to environmental changes. Other technologies lack real-time monitoring and comprehensive consideration of environmental factors, making it impossible to accurately adjust the operating point according to environmental changes. Furthermore, existing systems are inadequate in terms of data storage, display, and remote monitoring, failing to meet the management and maintenance needs of large-scale photovoltaic power generation systems and hindering the full realization of the photovoltaic array's power generation potential. Therefore, the development of an efficient and accurate dynamic maximum power point tracking system for photovoltaic arrays is urgently needed. Summary of the Invention

[0004] The photovoltaic array maximum power point tracking system provided in this application aims to efficiently and accurately track the maximum power point of a photovoltaic array under different environmental conditions, thereby improving the conversion and utilization efficiency of solar energy. Through the coordinated operation of its components, the system monitors the operating status of the photovoltaic array in real time and dynamically adjusts the operating point according to environmental and power changes, ensuring that the photovoltaic array always operates near its maximum power point.

[0005] To overcome the above-mentioned technical deficiencies, this application provides a photovoltaic array maximum power point tracking system, comprising: Photovoltaic arrays are used to convert solar energy into electrical energy; The sensing and detection unit is used to sample the output voltage U(k) and output current I(k) of the photovoltaic array in real time, where k is the current sampling time; A DC-DC converter circuit, whose input terminal is connected to the output terminal of the photovoltaic array, is used to adjust the operating point of the photovoltaic array; The load is connected to the output terminal of the DC-DC conversion circuit. A microprocessor controller is electrically connected to both the sensing unit and the DC-DC conversion circuit. The microprocessor controller is configured to execute instructions stored in memory to implement a Maximum Power Point Tracking (MPPT) algorithm, which periodically calculates the current power. Based on the comparison between the current power and the power P(k-1) at the previous sampling time, a drive signal is sent to the DC-DC conversion circuit to change its duty cycle D, thereby adjusting the output voltage of the photovoltaic array and realizing dynamic tracking of the maximum power point.

[0006] As a preferred embodiment of this application, the sensing and detection unit includes a voltage sensor and a current sensor. The voltage sensor is connected to the ADC interface of the microprocessor controller using a resistor voltage divider circuit, and the current sensor is connected to the ADC interface of the microprocessor controller using a Hall current sensor.

[0007] As a preferred embodiment of this application, the microprocessor controller is further connected to an environmental monitoring module, which includes at least one irradiance sensor and a temperature sensor for collecting the irradiance value G and the ambient temperature value T on the surface of the photovoltaic array panel.

[0008] As a preferred embodiment of this application, the MPPT algorithm executed by the microprocessor controller is an improved adaptive step-size perturbation observation method. Its core is that the perturbation voltage step size ΔU is not a fixed value, but is dynamically adjusted according to the approximate distance between the current operating point and the maximum power point of the photovoltaic array.

[0009] As a preferred embodiment of this application, the formula for calculating the adaptive step size ΔU is as follows:

[0010] Where N is an adjustable coefficient greater than 0, used to control the magnitude of the step size adjustment; dP / dU is the approximate value of the power versus voltage at the current operating point, which is calculated from the voltage and power values ​​of two consecutive sampling periods. The calculation formula is: dP / dU=(P(k)-P(k-1)) / (U(k)-U(k-1)).

[0011] As a preferred embodiment of this application, the microprocessor controller is further configured to, when executing the algorithm, determine that the system is very close to the maximum power point when the calculated dP / dU value is less than a preset very small first threshold ε1, and at this time the step size ΔU is forcibly set to a fixed small value ΔU_min in order to reduce steady-state oscillations near the maximum power point.

[0012] As a preferred embodiment of this application, the microprocessor controller is further configured to: calculate the power change ΔP=P(k)-P(k-1) after each disturbance; if ΔP is less than a preset second threshold ε2, and this state continues for more than M sampling periods, it is determined that the external environment has changed slowly, and the system will automatically execute a larger preset step size disturbance to jump out of the possible misjudgment stagnation point.

[0013] As a preferred embodiment of this application, the DC-DC conversion circuit is a boost converter circuit, including an inductor L, a power MOSFET switch, a freewheeling diode, and an output capacitor C; the PWM drive signal output by the microprocessor controller is connected to the gate of the power MOSFET switch, and the output voltage of the photovoltaic array is linearly controlled by changing the duty cycle D of the PWM drive signal.

[0014] As a preferred embodiment of this application, the microprocessor controller is also connected to a data display and storage unit for real-time display of system operating parameters, including the output voltage, output current, output power, duty cycle, and tracking efficiency of the photovoltaic array, and is capable of storing historical operating data for analysis.

[0015] As a preferred embodiment of this application, the microprocessor controller also integrates a communication interface module. This module adopts RS-485 or CAN bus protocol to upload system status data to a remote monitoring center and can receive instructions from the remote monitoring center to realize remote start / stop, parameter setting, and fault diagnosis functions.

[0016] Compared with existing technologies, the advantages of this application are as follows: The photovoltaic array maximum power point dynamic tracking system of this application has several significant advantages. First, in the MPPT algorithm, an improved adaptive step-size perturbation observation method is adopted. The perturbation voltage step size is dynamically adjusted according to the approximate distance between the current operating point and the maximum power point of the photovoltaic array, which effectively solves the contradiction between the tracking speed and steady-state oscillation of the traditional fixed step-size method, and improves the tracking accuracy and efficiency.

[0017] Secondly, the system is equipped with a comprehensive environmental monitoring module that can collect environmental parameters such as irradiance and temperature in real time, providing accurate data for the algorithm and enabling the system to precisely adjust its operating point according to environmental changes. Furthermore, it incorporates a forced small step size and a preset step size perturbation mechanism to reduce steady-state oscillations when approaching the maximum power point and to avoid misjudgment stagnation points when the environment changes slowly.

[0018] In addition, the system features a data display and storage unit, capable of displaying operating parameters in real time and storing historical data for easy analysis of system performance. It also integrates a communication interface module, supporting remote monitoring centers in acquiring system status data, sending commands, and enabling remote start / stop, parameter setting, and fault diagnosis. These innovative designs enable the system to efficiently and accurately achieve dynamic tracking of the photovoltaic array's maximum power point, improving solar energy conversion and utilization efficiency. Attached Figure Description

[0019] Figure 1 This invention provides a structural diagram of a photovoltaic array maximum power point tracking system. Figure 2 A schematic diagram of the DC-DC conversion circuit (Boost converter topology) of this invention; In the diagram: 101, photovoltaic array; 102, sensing and detection unit; 103, DC-DC conversion circuit; 104, load; 105, microprocessor controller; 106, environmental monitoring module; 107, data display and storage unit. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] When describing positional relationships, unless otherwise specified, when an element is referred to as being "on" another element, it may be directly on the other element or there may be intermediate elements. It is also understood that when an element is referred to as being "between" two elements, it may be the only one between the two elements, or there may be one or more intermediate elements.

[0023] When using the terms “including,” “having,” and “comprising” as described herein, another component may be added unless explicitly qualifying terms such as “only,” “consisting of,” etc. are used. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0024] It should also be understood that, in interpreting an element, although not explicitly described, the element is interpreted as including a range of error, which should be within the acceptable deviation range of a particular value as determined by a person skilled in the art. For example, "approximately," "about," or "substantially" can mean within one or more standard deviations, without limitation herein.

[0025] As attached Figure 1 -Appendix Figure 2 As shown, in order to overcome the above-mentioned technical defects, this application provides a photovoltaic array maximum power point tracking system, comprising: Photovoltaic array 101 is used to convert solar energy into electrical energy; The sensing and detection unit 102 is used to sample the output voltage U(k) and output current I(k) of the photovoltaic array in real time, where k is the current sampling time; DC-DC converter circuit 103, whose input terminal is connected to the output terminal of the photovoltaic array, is used to adjust the operating point of the photovoltaic array; Load 104 is connected to the output terminal of the DC-DC conversion circuit 103; The microprocessor controller 105 is electrically connected to the sensing unit 102 and the DC-DC conversion circuit 103, respectively. The microprocessor controller 105 is configured to execute instructions stored in memory to implement a maximum power point tracking (MPPT) algorithm, which periodically calculates the current power. Based on the comparison between the current power and the power P(k-1) at the previous sampling time, a drive signal is sent to the DC-DC conversion circuit 103 to change its duty cycle D, thereby adjusting the output voltage of the photovoltaic array and realizing dynamic tracking of the maximum power point.

[0026] In one embodiment of this application, the sensing unit 102 includes a voltage sensor and a current sensor. The voltage sensor is connected to the ADC interface of the microprocessor controller 105 using a resistor voltage divider circuit. This resistor voltage divider circuit has the advantages of simple structure and low cost. Specifically, the resistor voltage divider circuit consists of two high-precision resistors connected in series. The output voltage of the photovoltaic array is applied across these two series resistors. According to the voltage division principle of the series circuit, a voltage signal proportional to the output voltage of the photovoltaic array can be obtained at the connection point of the two resistors. After appropriate signal conditioning (such as filtering, amplification, etc.), this signal is input to the ADC interface of the microprocessor controller 105 so that the microprocessor controller 105 can accurately read the output voltage value of the photovoltaic array.

[0027] The current sensor uses a Hall effect current sensor connected to the ADC interface of the microprocessor controller 105. The Hall effect current sensor operates based on the Hall effect principle. When the output current of the photovoltaic array passes through the magnetic core of the Hall effect current sensor, a Hall voltage signal proportional to the current magnitude is generated on the Hall element. This Hall voltage signal is amplified and linearized by internal circuitry, outputting a standard voltage signal. This signal is then conditioned and input to the ADC interface of the microprocessor controller 105, thereby achieving accurate measurement of the photovoltaic array's output current. This Hall effect current sensor has advantages such as isolated measurement, fast response speed, high accuracy, and good linearity, effectively avoiding the influence of current measurement on the photovoltaic array and subsequent circuits.

[0028] The microprocessor controller 105 is also connected to an environmental monitoring module 106, which includes at least one irradiance sensor and a temperature sensor for collecting the irradiance value G and the ambient temperature value T on the surface of the photovoltaic array panel.

[0029] Furthermore, the irradiance sensor employs a high-precision photoelectric sensor, capable of converting received solar radiation energy into an electrical signal. This sensor typically has a wide spectral response range, enabling accurate measurement of solar radiation intensity at different wavelengths. During actual installation, the irradiance sensor should be installed near the surface of the photovoltaic array panel, maintaining the same orientation and tilt angle as the panel to ensure that the measured irradiance value accurately reflects the solar radiation received by the photovoltaic array panel. The electrical signal output from the irradiance sensor is processed by a signal conditioning circuit (such as amplification and filtering) and then input to the corresponding interface of the microprocessor controller 105. The microprocessor controller 105 converts the electrical signal into the actual irradiance value G according to a pre-set calibration curve.

[0030] The temperature sensor employs a high-precision thermistor or a digital temperature sensor. Thermistors are characterized by high sensitivity and low cost; they reflect ambient temperature by measuring the change in resistance as a function of temperature. In practical applications, the thermistor should be tightly attached to the back of the photovoltaic array panel to accurately measure its temperature. The thermistor's resistance value is converted into a voltage signal using a simple voltage divider circuit, and then input to the ADC interface of the microprocessor controller 105. The microprocessor controller 105 converts the voltage signal into the actual temperature value T based on the thermistor's resistance-temperature characteristic curve. Digital temperature sensors, on the other hand, offer advantages such as high integration, high measurement accuracy, and digital output signals. They can be directly connected to the communication interface of the microprocessor controller 105 (such as I2C, SPI, etc.), allowing the microprocessor controller 105 to obtain the ambient temperature value T by reading the digital signal output from the digital temperature sensor.

[0031] The MPPT algorithm executed by the microprocessor controller 105 is an improved adaptive step-size perturbation observation method. Its core is that the perturbation voltage step size ΔU is not a fixed value, but is dynamically adjusted according to the approximate distance between the current operating point and the maximum power point of the photovoltaic array.

[0032] Traditional perturbation-observation methods use a fixed step size for perturbation. When the step size is large, the system can quickly track the vicinity of the maximum power point when far away from it, but significant steady-state oscillations occur when approaching the maximum power point, leading to power loss. When the step size is small, although steady-state oscillations can be reduced, the tracking speed is slow when far from the maximum power point, making it unable to respond promptly to environmental changes. The improved adaptive step-size perturbation-observation method proposed in this application effectively solves the above problems by dynamically adjusting the perturbation voltage step size ΔU.

[0033] The formula for calculating the adaptive step size ΔU is: Here, N is an adjustable coefficient greater than 0, used to control the magnitude of the step size adjustment. The value of N needs to be adjusted according to the actual system performance requirements and environmental changes. Generally speaking, the larger the value of N, the larger the step size adjustment magnitude, and the faster the system tracking speed, but the greater the potential for steady-state oscillation; the smaller the value of N, the smaller the step size adjustment magnitude, and the slower the system tracking speed, but the smaller the steady-state oscillation. In practical applications, a suitable value of N can be determined through experiments and simulations.

[0034] dP / dU is an approximate value of the power-voltage differential at the current operating point. It is calculated using the voltage and power values ​​over two consecutive sampling periods, with the formula: dP / dU = (P(k) - P(k-1)) / (U(k) - U(k-1)). This formula uses data from discrete sampling points to approximate the power-voltage differential. When the sampling period is short enough, this approximation can accurately reflect the power change trend at the current operating point. When the absolute value of dP / dU is large, it indicates that the current operating point is far from the maximum power point. In this case, the perturbation voltage step size ΔU should be increased to accelerate the tracking speed. When the absolute value of dP / dU is small, it indicates that the current operating point is close to the maximum power point. In this case, the perturbation voltage step size ΔU should be decreased to reduce steady-state oscillations.

[0035] In one embodiment of this application, the microprocessor controller 105 is further configured to: when the calculated dP / dU value is less than a preset very small first threshold ε1, determine that the system is very close to the maximum power point, and at this time force the step size ΔU to be set to a fixed small value ΔU_min in order to reduce steady-state oscillations near the maximum power point.

[0036] The first threshold ε1 is a crucial parameter, and its value needs to be determined based on the characteristics of the photovoltaic array and the system's accuracy requirements. If ε1 is too large, the system may set the step size to a small value before truly approaching the maximum power point, thus affecting the tracking speed. If ε1 is too small, the system may fail to set the step size to a small value in time when approaching the maximum power point, resulting in large steady-state oscillations. Generally, the value of ε1 can be determined through experiments and simulations, typically between 0.001 and 0.01.

[0037] When the value of dP / dU is less than ε1, it indicates that the power change at the current operating point is very slow, meaning the system is very close to the maximum power point. In this case, forcing the step size ΔU to a fixed, small value ΔU_min can effectively reduce steady-state oscillations near the maximum power point, improving the system's tracking accuracy and stability. The value of ΔU_min also needs to be adjusted according to the actual situation. Generally, ΔU_min should be small enough to ensure the system maintains a small oscillation amplitude near the maximum power point, but it cannot be too small, otherwise it will affect the system's response speed. Typically, the value of ΔU_min is between 0.01 and 0.1V.

[0038] In one embodiment of this application, the microprocessor controller 105 is further configured to: calculate the power change ΔP=P(k)-P(k-1) after each disturbance; if ΔP is less than a preset second threshold ε2, and this state continues for more than M sampling periods, it is determined that the external environment has changed slowly, and the system will automatically execute a larger preset step size disturbance to jump out of the possible misjudgment stagnation point.

[0039] The second threshold ε2 and the number of sampling periods M are important parameters for determining whether the external environment is undergoing slow changes. The value of ε2 should be determined based on the power variation range of the photovoltaic array and the accuracy requirements of the system. If ε2 is too large, the system may fail to detect slow changes in the external environment in a timely manner; if ε2 is too small, the system may misjudge, treating normal power fluctuations as changes in the external environment. Generally, the value of ε2 can be determined through experiments and simulations, and is usually between 0.1% and 1% of the rated power of the photovoltaic array.

[0040] The value of the sampling period M also needs to be adjusted according to the actual situation. The larger the value of M, the more accurate the system's judgment of changes in the external environment, but the slower the response speed; the smaller the value of M, the faster the system response speed, but false judgments may occur. Generally speaking, the value of M is between 5 and 20.

[0041] When ΔP is less than ε2 and this state persists for more than M sampling periods, it indicates that the system may have entered a false alarm point. This means that due to slow changes in the external environment or sensor measurement errors, the system mistakenly believes it has reached the maximum power point when it has not. In this case, the system automatically performs a larger preset step size perturbation to break this stagnation and allow the system to restart the search for the maximum power point. The size of the preset step size should be determined based on the characteristics of the photovoltaic array and the system's performance requirements. Generally, the preset step size should be larger than the step size during normal tracking to ensure that the system can quickly escape the stagnation point.

[0042] In one embodiment of this application, the DC-DC conversion circuit 103 is a boost converter circuit, including an inductor L, a power MOSFET switch, a freewheeling diode, and an output capacitor C; the PWM drive signal output by the microprocessor controller 105 is connected to the gate of the power MOSFET switch, and the output voltage of the photovoltaic array is linearly controlled by changing the duty cycle D of the PWM drive signal.

[0043] The working principle of the Boost converter circuit is as follows: When the power MOSFET switch is turned on, energy is stored in the inductor L. At this time, the output voltage of the photovoltaic array is applied to the inductor L, and the inductor current increases linearly. Simultaneously, the freewheeling diode is turned off, and the output capacitor C supplies power to the load 104. When the power MOSFET switch is turned off, the energy stored in the inductor L is released through the freewheeling diode to the output capacitor C and the load 104. At this time, the inductor current decreases linearly, and the output voltage increases. By continuously controlling the turn-on and turn-off of the power MOSFET switch, i.e., changing the duty cycle D of the PWM drive signal, the output voltage can be regulated.

[0044] The value of inductor L should be determined based on factors such as the operating frequency, input voltage range, output voltage requirements, and load current of the boost circuit. Generally, a larger value of inductor L results in lower inductor current ripple, but the size and cost of the inductor will also increase accordingly. The power MOSFET switch should be selected with low on-resistance, high switching speed, and sufficient voltage withstand capability to reduce switching losses and improve circuit efficiency. The freewheeling diode should be selected with fast recovery characteristics and low forward voltage drop to reduce energy loss. The value of output capacitor C should be determined based on the output voltage ripple requirements and the dynamic response requirements of the load. Generally, a larger value of output capacitor C results in lower output voltage ripple, but the size and cost of the capacitor will also increase accordingly.

[0045] The relationship between the duty cycle D of the PWM drive signal output by the microprocessor controller 105 and the output voltage can be expressed by the voltage gain formula of the Boost converter circuit: Vout = Vin / (1-D), where Vout is the output voltage, Vin is the input voltage (i.e., the output voltage of the photovoltaic array), and D is the duty cycle of the PWM drive signal. By changing the duty cycle D, linear adjustment of the output voltage can be achieved, thereby controlling the output voltage of the photovoltaic array and making it operate near its maximum power point.

[0046] In one embodiment of this application, the microprocessor controller 105 is further connected to a data display and storage unit 107, which is used to display system operating parameters in real time, including the output voltage, output current, output power, duty cycle and tracking efficiency of the photovoltaic array, and can store historical operating data for analysis.

[0047] The data display and storage unit 107 typically consists of a display device such as a liquid crystal display (LCD) or an organic light-emitting diode display (OLED) and a memory (such as flash memory, SD card, etc.). The display device is used to display the system's operating parameters in real time, allowing operators to intuitively understand the system's working status. The display interface can be a graphical interface or a digital display interface. A graphical interface can more intuitively display the system's operating parameters and trends, while a digital display interface is simpler and clearer.

[0048] The memory is used to store historical operating data, including photovoltaic array output voltage, output current, output power, duty cycle, and tracking efficiency at different points in time. This historical operating data can be used to analyze system performance and stability, evaluate the effectiveness of the maximum power point tracking algorithm, and provide a basis for system optimization and improvement. The memory can use timed storage or event-triggered storage. Timed storage refers to storing system operating parameters at certain time intervals (such as every minute, every hour, etc.); event-triggered storage refers to storing system operating parameters when a specific event occurs in the system (such as a change in the maximum power point, a sudden change in the external environment, etc.).

[0049] In one embodiment of this application, the microprocessor controller 105 also integrates a communication interface module. This module adopts RS-485 or CAN bus protocol to upload system status data to a remote monitoring center and can receive instructions from the remote monitoring center to realize remote start / stop, parameter setting and fault diagnosis functions.

[0050] RS-485 is a commonly used serial communication protocol with advantages such as long communication distance, strong anti-interference capability, and low cost. When using the RS-485 protocol, the microprocessor controller 105 converts TTL level to RS-485 level via an RS-485 converter chip, and then communicates with the remote monitoring center via twisted-pair cable. During communication, appropriate parameters such as baud rate, data bits, stop bits, and parity bits need to be set to ensure the accuracy and reliability of the communication.

[0051] The CAN bus is a high-performance, high-reliability fieldbus protocol with advantages such as multi-master communication, strong real-time performance, and strong anti-interference capabilities. When using the CAN bus protocol, the microprocessor controller 105 connects to the CAN bus through a CAN controller chip to achieve data transmission with a remote monitoring center. The CAN bus protocol defines different frame types, such as data frames, remote frames, and error frames, to implement different communication functions.

[0052] The remote monitoring center can acquire system status data through the communication interface module, such as the output voltage, output current, output power, duty cycle, and tracking efficiency of the photovoltaic array, as well as irradiance and ambient temperature values ​​collected by the environmental monitoring module. Simultaneously, the remote monitoring center can send commands to the microprocessor controller 105 to remotely start / stop the system, set parameters, and diagnose faults. For example, operators can remotely start or stop the system, adjust the parameters of the maximum power point tracking algorithm, and query historical operating data and fault information through the remote monitoring center.

[0053] The above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and are not intended to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope defined by this application.

Claims

1. A photovoltaic array maximum power point tracking system, characterized in that, include: A photovoltaic array (101) is used to convert solar energy into electrical energy; The sensing and detection unit (102) is used to sample the output voltage U(k) and output current I(k) of the photovoltaic array in real time, where k is the current sampling time; DC-DC conversion circuit (103), whose input terminal is connected to the output terminal of the photovoltaic array, is used to adjust the operating point of the photovoltaic array; A load or battery (104) is connected to the output terminal of the DC-DC conversion circuit (103); A microprocessor controller (105) is electrically connected to the sensing unit (102) and the DC-DC converter circuit (103), respectively; the microprocessor controller (105) is configured to execute instructions stored in memory to implement a maximum power point tracking (MPPT) algorithm that periodically calculates the current power. Based on the comparison between the current power and the power P(k-1) at the previous sampling time, a drive signal is sent to the DC-DC conversion circuit (103) to change its duty cycle D, thereby adjusting the output voltage of the photovoltaic array and realizing dynamic tracking of the maximum power point.

2. The photovoltaic array maximum power point tracking system as described in claim 1, characterized in that, The sensing and detection unit (102) includes a voltage sensor and a current sensor. The voltage sensor is connected to the ADC interface of the microprocessor controller (105) using a resistor voltage divider circuit, and the current sensor is connected to the ADC interface of the microprocessor controller (105) using a Hall current sensor.

3. The photovoltaic array maximum power point tracking system as described in claim 1 or 2, characterized in that, The microprocessor controller (105) is also connected to an environmental monitoring module (106), which includes at least one irradiance sensor and a temperature sensor for collecting the irradiance value G and the ambient temperature value T on the surface of the photovoltaic array panel.

4. The photovoltaic array maximum power point tracking system as described in claim 1, characterized in that, The MPPT algorithm executed by the microprocessor controller (105) is an improved adaptive step-size perturbation observation method. Its core is that the perturbation voltage step size ΔU is not a fixed value, but is dynamically adjusted according to the approximate distance between the current operating point and the maximum power point of the photovoltaic array.

5. The photovoltaic array maximum power point tracking system as described in claim 4, characterized in that, The formula for calculating the adaptive step size ΔU is: Where N is an adjustable coefficient greater than 0, used to control the magnitude of the step size adjustment; dP / dU is the approximate value of the power versus voltage at the current operating point, which is calculated from the voltage and power values ​​of two consecutive sampling periods. The calculation formula is: dP / dU = (P(k) - P(k-1)) / (U(k) - U(k-1)).

6. The photovoltaic array maximum power point tracking system as described in claim 5, characterized in that, When executing the algorithm, the microprocessor controller (105) is further configured to: when the calculated value of dP / dU is less than a preset very small first threshold ε1, determine that the system is very close to the maximum power point, and at this time force the step size ΔU to be set to a fixed small value ΔU_min in order to reduce steady-state oscillations near the maximum power point.

7. The photovoltaic array maximum power point tracking system as described in claim 5 or 6, characterized in that, When executing the algorithm, the microprocessor controller (105) is further configured to: calculate the power change ΔP = P(k) - P(k-1) after each disturbance; if ΔP is less than a preset second threshold ε2, and this state continues for more than M sampling periods, it is determined that the external environment has changed slowly, and the system will automatically execute a larger preset step size disturbance to jump out of the possible misjudgment stagnation point.

8. The photovoltaic array maximum power point tracking system as described in claim 1, characterized in that, The DC-DC conversion circuit (103) is a boost circuit, including an inductor L, a power MOSFET switch, a freewheeling diode and an output capacitor C; the PWM drive signal output by the microprocessor controller (105) is connected to the gate of the power MOSFET switch, and the output voltage of the photovoltaic array is linearly controlled by changing the duty cycle D of the PWM drive signal.

9. The photovoltaic array maximum power point tracking system as described in claim 1, characterized in that, The microprocessor controller (105) is also connected to a data display and storage unit (107) for displaying system operating parameters in real time, including the output voltage, output current, output power, duty cycle and tracking efficiency of the photovoltaic array, and is able to store historical operating data for analysis.

10. The photovoltaic array maximum power point tracking system as described in claim 1, characterized in that, The microprocessor controller (105) also integrates a communication interface module, which adopts RS-485 or CAN bus protocol to upload system status data to the remote monitoring center and can receive instructions from the remote monitoring center to realize remote start / stop, parameter setting and fault diagnosis functions.

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