Maximum power point tracking (MPPT)-based bridge cable solar power generation system

Abstract

The invention discloses a bridge cable solar power generation system based on MPPT (Maximum Power Point Tracking). The bridge cable solar power generation system comprises a flexible solar panel used for collecting and converting solar energy; the MPPT control unit is electrically connected with the flexible solar panel and is used for tracking and optimizing the output power of the flexible solar panel in real time; the energy storage unit is electrically connected with the MPPT control unit and is used for storing electric energy and supplying power to a load; the charging and discharging controller is electrically connected with the MPPT control unit and the energy storage unit and used for managing the charging and discharging process of the system according to the state of the energy storage unit. And the installation adaptation unit is used for fixedly installing the flexible solar panel on a cable of a bridge. The system has the advantages that the bridge cable space is effectively utilized, the cable bending curvature is adapted, power output is optimized, and the power supply stability is ensured, so that the problems that a traditional solar power generation technology is poor in installation adaptability, low in efficiency and insufficient in reliability in a bridge scene are solved.

Description

Technical Field

[0001] This invention relates to the field of renewable energy utilization technology for bridges, and more specifically, to a bridge cable solar power generation system based on MPPT. Background Technology

[0002] In the field of green energy development, the application of solar power generation technology continues to expand. However, traditional photovoltaic power plants are highly dependent on land resources, which poses a significant development obstacle in space-constrained areas such as cities. Integrating photovoltaic systems into large bridge structures, especially the cable sections of suspension bridges, can effectively utilize undeveloped high-altitude spaces, forming a distributed energy supply solution that does not require additional land resources, and has significant practical value.

[0003] However, existing general-purpose solar power generation technologies are insufficient to meet the specific application requirements of bridge cable-stayed structures. Traditional rigid solar panels, due to material limitations, cannot adapt to the continuous bending curvature of bridge cables, leading to problems such as poor fit, stress concentration, and decreased energy conversion efficiency during installation. Simultaneously, general charge and discharge control strategies lack targeted optimization for the dynamic characteristics of bridge loads and the health status of energy storage units, making it difficult to ensure the long-term reliable operation of energy storage systems while guaranteeing a stable power supply. These technical bottlenecks severely restrict the practical effectiveness and economic feasibility of solar power generation in bridge cable-stayed structures.

[0004] Furthermore, the high-altitude environment in which bridge cables operate faces complex factors such as wind loads, structural vibrations, and temperature variations, further complicating system design and operation. Existing technologies fail to provide a comprehensive solution that balances installation adaptability, power optimization, and environmental adaptability, resulting in insufficient system reliability and increased maintenance costs.

[0005] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0006] In view of this, the present invention provides a bridge cable solar power generation system based on MPPT, which has the advantages of effectively utilizing bridge cable space, adapting to cable curvature, optimizing power output and ensuring power supply stability, thereby solving the problems of poor installation adaptability, low efficiency and insufficient reliability of traditional solar power generation technology in bridge scenarios.

[0007] This invention provides a bridge cable solar power generation system based on MPPT, comprising: Flexible solar panels are used to collect and convert solar energy. The MPPT control unit is electrically connected to the flexible solar panel and is used to track and optimize the output power of the flexible solar panel in real time. An energy storage unit, electrically connected to the MPPT control unit, is used to store electrical energy and supply power to the load; A charge / discharge controller is electrically connected to the MPPT control unit and the energy storage unit, respectively, and is used to manage the charge / discharge process of the energy storage unit according to the state of the energy storage unit. An adapter unit is installed to secure the flexible solar panel to the bridge's cables.

[0008] As can be seen from the above, the bridge cable solar power generation system based on MPPT provided in this application fixes the flexible solar panel to the cable by installing an adapter unit, and optimizes the power by combining the MPPT control unit and the charge and discharge controller to manage the energy storage status. This solves the problems of poor installation adaptability, insufficient power optimization and unstable power supply in the prior art. It has the advantages of effectively utilizing the space of the bridge cable, adapting to the bending curvature of the cable, optimizing the power output and ensuring the stability of the power supply. Attached Figure Description

[0009] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of a bridge cable solar power generation system based on MPPT according to an embodiment of the present invention; Figure 2 A schematic diagram of the structure for installing the adapter unit according to an embodiment of the present invention; Figure 3 This is a circuit diagram of a bridge cable solar power generation system based on MPPT according to an embodiment of the present invention; Figure 4 This is a logic diagram for switching charging modes according to an embodiment of the present invention. Attached image description: 11. Carbon fiber substrate; 12. Clamp assembly; 13. Anti-slip layer; 14. Cable. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] Traditional photovoltaic (PV) power generation systems face deployment difficulties in space-constrained areas such as cities due to their reliance on land resources. Furthermore, existing general-purpose solar power generation technologies encounter challenges when applied to specific environments such as bridge cables, where rigid solar panels cannot adapt to the bending curvature of the cables. In addition, common charge and discharge control strategies fail to adequately consider the bridge's load characteristics and battery health, impacting the sustainability of energy supply and the lifespan of energy storage systems.

[0014] In this regard, such as Figure 1 As shown, this application proposes a bridge cable solar power generation system based on MPPT, comprising: Flexible solar panels are used to collect and convert solar energy. The MPPT control unit is electrically connected to the flexible solar panel and is used to track and optimize the output power of the flexible solar panel in real time. The energy storage unit, electrically connected to the MPPT control unit, is used to store electrical energy and supply power to the load; A charge / discharge controller is electrically connected to the MPPT control unit and the energy storage unit, respectively, and is used to manage the charge / discharge process of the energy storage unit according to the state of the energy storage unit. Install the adapter unit to secure the flexible solar panel to the bridge cable 14.

[0015] Flexible solar panels refer to solar panels that are flexible enough to adapt to the installation requirements of non-planar or curved structures and convert solar energy into electrical energy through the photoelectric effect.

[0016] MPPT (Maximum Power Point Tracking) control unit is a unit that uses specific algorithms and circuits to monitor the output characteristics of solar panels in real time and adjust their operating point to ensure that the solar panels always output maximum power under different light and temperature conditions.

[0017] Energy storage units are devices used to store electrical energy, such as battery packs. They store excess electrical energy when the system generates enough power and release electrical energy when the power generation is insufficient or the load demand increases, in order to maintain the continuity and sustainability of the system's power supply.

[0018] A charge / discharge controller is an electronic device that manages the charging and discharging process of an energy storage unit. It determines the charging or discharging strategy based on the current state of the energy storage unit (such as state of charge, voltage, current, etc.) in order to protect the energy storage unit and extend its service life.

[0019] Mounting adapters are components specifically designed to secure flexible solar panels to a particular structure. They need to provide support and connections while adapting to the geometry of the mounting structure and environmental conditions.

[0020] This embodiment provides a bridge cable solar power generation system based on MPPT. This system integrates functional units to achieve the collection, conversion, storage, and management of solar energy, and is adapted to the specific installation environment of bridge cables.

[0021] Specifically, the system includes flexible solar panels, whose main function is to collect solar energy and convert it into electrical energy. One implementation method is to use amorphous silicon thin-film batteries, which have a certain degree of flexibility and can adapt to bending. For example, the flexible solar panel can be directly pasted or fixed to a supporting surface using adhesives. Another implementation method is to use organic solar cells, which are characterized by their thinness and bending capability, making them suitable for scenarios requiring lightweight and flexible installation.

[0022] The MPPT (Maximum Power Point Tracking) control unit is electrically connected to the flexible solar panel to track and optimize its output power in real time. This control unit can employ a controller based on existing algorithms such as the perturbation-observation method or the incremental conductance method, periodically adjusting the solar panel's operating voltage or current to find and maintain it near the maximum power point. For example, the MPPT control unit could be a DC-DC converter with its input connected to the flexible solar panel and its output connected to an energy storage unit, adjusting the converter's duty cycle to change the solar panel's operating point.

[0023] The energy storage unit is electrically connected to the MPPT control unit to store electrical energy and power the load. This energy storage unit can be composed of lead-acid batteries, which are cost-effective and a well-established technology. For example, multiple lead-acid batteries can be connected in series or parallel to form a battery pack to meet specific voltage and capacity requirements. Alternatively, the energy storage unit can use nickel-metal hydride batteries, which have relatively high energy density and long cycle life.

[0024] The charge / discharge controller is electrically connected to both the MPPT control unit and the energy storage unit, and is used to manage the charging and discharging process of the system based on the state of the energy storage unit. This controller can be a relay control circuit that disconnects the charging circuit when the battery voltage reaches a preset upper limit and disconnects the discharging circuit when the battery voltage falls below a preset lower limit. For example, the controller may include a voltage comparator to monitor the voltage state of the energy storage unit and drive the relay to perform on / off operations.

[0025] The mounting adapter unit is used to secure the flexible solar panel to the cable 14 of the bridge. This mounting adapter unit can consist of a metal bracket and fasteners. The metal bracket is designed to encircle a portion of the cable 14, and the flexible solar panel is secured to the bracket using bolts or other fasteners. For example, the bracket can be made of aluminum alloy, which is lightweight and corrosion-resistant. Alternatively, a clamp made of high-strength plastic or composite material can be used to mechanically clamp the flexible solar panel to the cable 14.

[0026] This system utilizes flexible solar panels, solving the problem of traditional rigid solar panels' inability to adapt to the bending curvature of bridge cables, thus enabling distributed energy deployment without occupying additional land on the bridge cables. The application of the MPPT control unit ensures that the solar panels operate at high efficiency under varying environmental conditions. The collaborative work of the energy storage unit and charge / discharge controller allows for the storage and management of electrical energy, guaranteeing continuous power supply to the bridge load. The introduction of installation adapters ensures the installation of flexible solar panels on the cables, improving system reliability.

[0027] In MPPT-based bridge cable solar power generation systems, flexible solar panels are the core component for energy harvesting, and their performance directly affects the overall efficiency and reliability of the system. However, in the special and harsh application environment of bridge cables, traditional flexible solar panels may face challenges such as excessive weight, insufficient flexibility, poor vibration resistance, and poor stability during long-term outdoor service, making it difficult to ensure the continuous and efficient operation of the system under complex working conditions.

[0028] In this regard, this application further proposes that the flexible solar panel is a flexible CIGS thin-film solar panel with a size of 1200mm×600mm, a rated power range of 15W to 30W, and a unit area weight of no more than 1.2kg / m2.

[0029] Specifically, the flexible CIGS thin-film solar panel is a thin-film solar cell that uses copper indium gallium selenide (CIGS) compounds as light-absorbing materials. Its cell layer is deposited on a flexible substrate, such as a polymer film. Compared to traditional crystalline silicon solar panels, CIGS thin-film solar panels have excellent flexibility, capable of withstanding a certain degree of bending and deformation. This makes them ideal for installation on curved or irregular surfaces such as bridge cables 14, achieving a tight fit and avoiding efficiency loss or structural stress caused by installation gaps. Furthermore, CIGS thin-film cells exhibit excellent power generation performance under low-light conditions, maintaining high energy conversion efficiency even on cloudy days, in the early morning, or at dusk when sunlight is insufficient, effectively extending the system's power generation time. Its performance degradation at high temperatures is also relatively small, helping the system maintain stable output under harsh climatic conditions such as high temperatures in summer.

[0030] The flexible solar panel is designed to measure 1200 mm × 600 mm, a size optimized to balance the power generation of a single module with the installation space constraints of the bridge cable 14. This size ensures sufficient light-receiving area for effective energy harvesting without being too large, which would increase installation difficulty or create excessive wind resistance on the cable 14. Furthermore, this standardized size facilitates modular design, production, and rapid on-site installation.

[0031] The rated power range of the flexible solar panels is 15W to 30W. This power range allows a single flexible solar panel module to provide a stable power output, meeting the input requirements of the MPPT control unit. By selecting this power range, system designers can flexibly configure the number of flexible solar panels connected in parallel according to actual energy needs, thereby expanding the total power while reducing the cost and weight of individual modules and improving the overall flexibility and redundancy of the system.

[0032] The weight per unit area of ​​the flexible solar panel is no more than 1.2 kg / m². 2 This lightweight characteristic is crucial for the application of the bridge cable 14. As a load-bearing structure, the bridge cable 14 is subject to strict limitations on additional loads. The extremely low weight per unit area ensures that the installation of the solar panels will not significantly affect the structural integrity and load-bearing capacity of the cable 14, thereby guaranteeing the long-term safe operation of the bridge. At the same time, lightweighting also greatly simplifies the installation process, reducing construction difficulty and costs.

[0033] The above technical solution utilizes flexible CIGS thin-film solar panels. Their inherent high flexibility allows them to perfectly conform to the curved surface of the bridge cable 14, effectively solving the problem of traditional solar panels being difficult to install on curved surfaces. Furthermore, their lightweight and thin characteristics, especially their weight per unit area not exceeding 1.2 kg / m², further enhance their appeal. 2 This significantly reduced the additional load on cable 14, ensuring the safety of the bridge structure. Furthermore, the excellent power generation performance of the CIGS thin-film solar panels under low-light conditions, combined with their optimized size of 1200 mm × 600 mm and rated power range of 15W to 30W, ensures that the system can stably and efficiently collect solar energy under different light intensities, providing sufficient power to the MPPT control unit. This improves the energy conversion efficiency and long-term operational reliability of the entire MPPT-based bridge cable solar power generation system.

[0034] In some embodiments described above in this application, a bridge cable solar power generation system comprising a flexible solar panel and an MPPT control unit is proposed. However, in practical applications, the environment in which bridge cables are located is complex and variable, with rapid fluctuations in light intensity and ambient temperature. This can cause traditional MPPT control units to suffer from slow response speed and insufficient tracking accuracy when tracking the maximum power point of the solar panel, thereby affecting the overall power generation efficiency and energy capture capability of the system.

[0035] In this regard, this application further proposes that the MPPT control unit is a digital control module, which is equipped with a maximum power point dynamic tracking algorithm based on light intensity and temperature parameters, with a maximum power point tracking response time of less than 0.5s and a power tracking error of no more than 5%.

[0036] Specifically, the MPPT control unit is designed as a digital control module, meaning it uses a microcontroller, digital signal processor, or other programmable logic device as its core control unit. Compared to analog control methods, digital control modules offer higher control precision, stronger anti-interference capabilities, and more flexible algorithm implementation capabilities. Through software programming, complex control strategies and parameter adjustments can be easily implemented to adapt to different operating conditions and optimization objectives. For example, the module may include a high-performance microcontroller with an integrated high-speed analog-to-digital converter (ADC) for accurately acquiring voltage and current signals, and a pulse width modulation (PWM) module for precisely controlling the switching action of the power converter.

[0037] Building upon this, the MPPT control unit is equipped with a dynamic maximum power point tracking (MPPT) algorithm based on illuminance and temperature parameters. This algorithm aims to ensure the flexible solar panel always operates at its maximum power point. Given that the output characteristics of the solar panel are significantly affected by illuminance and temperature, this algorithm predicts or quickly locates the maximum power point under current conditions by monitoring these environmental parameters in real time and combining them with pre-set models or empirical data. For example, the algorithm can employ an improved perturbation observation method or incremental conductance method, and introduce compensation mechanisms for illuminance and temperature. When illuminance or temperature changes, the algorithm can quickly adjust the perturbation step size or search range, thereby achieving dynamic and rapid tracking of the maximum power point and avoiding misjudgments or prolonged deviations from the maximum power point during drastic environmental changes.

[0038] Meanwhile, the maximum power point tracking (MPPT) control unit's response time is less than 0.5 seconds. The maximum power point tracking response time refers to the time required for the MPPT control unit to readjust the flexible solar panel's output power to the new maximum power point after a significant change in environmental conditions (such as light intensity or temperature). A response time of less than 0.5 seconds means the system can quickly adapt to environmental changes, reducing energy loss due to tracking lag. This is typically achieved by optimizing the algorithm's convergence speed, improving the controller's processing power, and employing high-bandwidth power conversion circuits. For example, algorithms based on predictive control or fuzzy logic, combined with high sampling rates and fast computation capabilities, can ensure rapid repositioning of the maximum power point.

[0039] Furthermore, the power point tracking (MPPT) control unit's power point tracking error (PPT) does not exceed 5%. PPT error refers to the deviation between the power actually tracked by the MPPT control unit and the theoretical maximum power point. An error of less than 5% indicates high tracking accuracy, effectively capturing most of the usable energy output from the flexible solar panel. This is typically ensured through precise voltage and current sampling, high-resolution analog-to-digital converters, robust control algorithms, and optimized power converter design. For example, by employing high-precision sensors and multi-point sampling techniques, combined with digital filtering and adaptive control strategies, measurement and control errors can be minimized, ensuring the system always operates close to its maximum power point.

[0040] Through the aforementioned technical solution, the MPPT control unit is designed as a digital control module. Its built-in maximum power point tracking (MPPT) algorithm, based on light intensity and temperature parameters, can sense and respond to environmental changes in real time and with precision. When the light intensity or temperature fluctuates around the bridge cable, the algorithm can quickly adjust the operating point of the flexible solar panel, ensuring it always operates near its maximum power point. A MPPT response time of less than 0.5 seconds allows the system to quickly adapt to rapidly changing environments, effectively avoiding energy capture lag caused by environmental changes. Simultaneously, a power tracking error of no more than 5% ensures the system can continuously capture the maximum output power of the flexible solar panel with high precision. Therefore, the MPPT control unit of this application significantly improves the energy capture efficiency and stability of the system in complex and variable environments, maximizing the utilization of solar energy resources and thus improving the power generation performance of the entire bridge cable solar power generation system.

[0041] In some of the embodiments described above in this application, flexible solar panels are fixedly installed on the cables of a bridge. However, in practical applications, ensuring that the flexible solar panels can stably and firmly conform to the curved surface of the cable, effectively support and fix the flexible solar panels, and at the same time take into account their heat dissipation requirements is a key challenge to achieving long-term reliable operation of the system.

[0042] In this regard, such as Figure 2 As shown, this application further proposes an installation adapter unit, which includes a carbon fiber substrate 11 and a clamp assembly 12.

[0043] The carbon fiber substrate 11 is an arc-shaped plate made of carbon fiber composite material. Its concave surface is designed to precisely fit the outer periphery of the cable 14, allowing the carbon fiber substrate 11 to tightly wrap around and adhere to the outer surface of the cable 14, thus providing a stable and shape-matched support foundation for the flexible solar panel. This arc-shaped design maximizes the contact area, effectively disperses stress, and prevents unnecessary deformation of the flexible solar panel due to the cable curvature. Carbon fiber itself possesses excellent properties such as high strength, lightweight, corrosion resistance, and fatigue resistance, making it ideal for applications like bridge cables that are exposed to complex outdoor environments for extended periods, effectively resisting wind loads, vibrations, and environmental erosion. Its convex surface is fixedly connected to the flexible solar panel via thermally conductive insulating adhesive. This thermally conductive insulating adhesive not only acts as an adhesive for mechanical fixation but, more importantly, also possesses excellent thermal conductivity, effectively conducting the heat generated by the flexible solar panel during operation to the carbon fiber substrate 11, which is then dissipated into the environment, preventing localized overheating that could affect power generation efficiency and lifespan. Simultaneously, its insulating properties ensure electrical safety.

[0044] The clamp assembly 12 is a mechanical connector used to provide radial fastening force. It surrounds and locks around the outer periphery of the contact area between the carbon fiber substrate 11 and the cable 14. The clamp assembly 12 applies uniform radial pressure to the carbon fiber substrate 11 via bolts, clips, or other fastening mechanisms, thereby securely fastening the carbon fiber substrate 11 to the cable 14. The clamp assembly 12 is typically made of corrosion-resistant, high-strength materials such as stainless steel or high-strength alloy steel to meet the harsh requirements of the bridge environment. Its structure can be split or integrated, depending on ease of installation and the required fastening force.

[0045] Through the above technical solution, the arc-shaped design of the carbon fiber substrate 11 allows its concave surface to closely fit the outer contour of the cable 14, thereby achieving stable adhesion and effective load-bearing of the flexible solar panel on the curved surface of the cable 14. Simultaneously, the convex surface is fixedly connected to the flexible solar panel via thermally conductive insulating adhesive, providing not only reliable mechanical fixation but also promoting heat conduction generated during operation, effectively solving the heat dissipation problem and helping to maintain optimal working efficiency and extend service life. The clamp assembly 12 surrounds and locks around the outer periphery of the interface between the carbon fiber substrate 11 and the cable 14, providing strong radial fastening force and ensuring the robustness and vibration resistance of the entire installation structure on the bridge cable. This installation adapter unit design effectively solves the problems of stability, robustness, load-bearing capacity, and heat dissipation when installing flexible solar panels in the special and complex environment of bridge cables, ensuring the long-term efficient operation of the power generation system.

[0046] In some embodiments described above in this application, the mounting adapter unit surrounds and locks the carbon fiber substrate 11 via the clamp assembly 12 to secure the flexible solar panel to the cable 14. However, in practical applications, due to environmental factors such as wind, vibration, or temperature changes that may affect the bridge cable, the contact interface between the clamp assembly 12 and the carbon fiber substrate 11 may have insufficient friction, leading to relative slippage between the two and affecting the stability and reliability of the installation.

[0047] In this regard, such as Figure 2 As shown, this application further proposes that the mounting adapter unit also includes an anti-slip layer 13. The anti-slip layer 13 is a material layer with a high coefficient of friction, whose main function is to increase the friction between the two contact surfaces, thereby effectively resisting or preventing relative sliding. The anti-slip layer 13 can be made of various materials, such as weather-resistant rubber, silicone, polyurethane, or engineering plastic films with special textures or particles on the surface. In specific implementations, the anti-slip layer 13 can be made into a sheet-like pad, pre-attached or molded onto the inner surface of the clamp assembly 12 or the outer surface of the carbon fiber substrate 11, ensuring that it can be firmly clamped between the clamp assembly 12 and the carbon fiber substrate 11 when fastened. Furthermore, the surface of the anti-slip layer 13 can also be designed with raised, grooved, or grid-like textures to further improve its engagement with the contact surfaces and the coefficient of friction. The thickness of the anti-slip layer 13 should be optimized to provide sufficient friction without significantly affecting the fastening effect of the clamp assembly 12 or increasing the overall installation complexity.

[0048] Through the above technical solution, the anti-slip layer 13 is cleverly positioned at the contact interface between the clamp assembly 12 and the carbon fiber substrate 11. This anti-slip layer 13 significantly increases the friction between these two components, effectively suppressing or eliminating relative slippage caused by external factors such as bridge vibration, wind load, or temperature changes. This ensures a more stable and reliable installation of the flexible solar panel on the cable 14, avoiding the risks of loosening, component wear, or even detachment due to slippage. It greatly improves the long-term operational stability and safety of the entire solar power generation system in a bridge environment, reduces maintenance costs, and extends the system's service life.

[0049] In some embodiments described above in this application, a bridge cable solar power generation system based on MPPT is proposed, wherein a charge / discharge controller is responsible for managing the charging and discharging process of the energy storage unit. However, in practical applications, if the charge / discharge controller only adopts a single charging strategy or simple switching control, it may not be able to fully adapt to the charging needs of the energy storage unit under different states of charge, thereby affecting the lifespan of the energy storage unit, charging efficiency, and the effective utilization rate of solar energy.

[0050] In this regard, such as Figure 4 As shown, this application further proposes that the charge / discharge controller be configured to automatically switch the charging mode according to the state of charge of the energy storage unit, specifically including: when the state of charge is below 50%, a constant current charging mode is adopted, with a current value range of 1.2~1.8A; when the state of charge is between 50% and 80%, a constant voltage charging mode is adopted, with a voltage value range of 13~15V; when the state of charge is above 80%, charging of the energy storage unit is stopped, and the system switches to a mode in which the flexible solar panel directly supplies power to the load through the MPPT control unit.

[0051] Specifically, the charge / discharge controller is the core of the system's power management. It is configured to intelligently select and execute different charging strategies based on the real-time state of charge (SOC) of the energy storage unit. This automatic switching function is typically implemented through a built-in microcontroller (MCU), which continuously monitors key parameters such as voltage, current, and temperature of the energy storage unit and dynamically adjusts the operating mode of the charging circuit based on preset SOC thresholds and charging algorithms. The aim is to optimize the charging process, ensuring that the energy storage unit receives the most suitable charging conditions at different charge levels, thereby extending its lifespan and improving charging efficiency. When the SOC of the energy storage unit is low, i.e., below 50%, the system will initiate a constant current charging mode. In this mode, the charge / discharge controller precisely controls the charging current, maintaining it within a preset range of 1.2A to 1.8A. This charging method ensures that when the energy storage unit's charge is insufficient, it can quickly replenish the charge with a stable and relatively large current, thus shortening the charging time. In practice, the charge / discharge controller adjusts the output of its internal power conversion module (e.g., a DC-DC converter) and uses a current sensor for real-time feedback to precisely stabilize the charging current at the target value. As the state of charge (SBC) of the energy storage unit increases, reaching 50% to 80%, the charge / discharge controller automatically switches to constant voltage charging mode. In this mode, the charging voltage is precisely controlled within the range of 13V to 15V. The purpose of constant voltage charging is to gradually reduce the charging current as the energy storage unit approaches full charge to prevent overcharging, thereby protecting the energy storage unit and avoiding performance degradation or shortened lifespan due to overvoltage charging. The charge / discharge controller monitors the voltage of the energy storage unit and adjusts the output voltage of the power conversion module accordingly to maintain a constant voltage output. When the SBC of the energy storage unit further increases, exceeding 80%, the charge / discharge controller stops charging the energy storage unit. At this time, to maximize the utilization efficiency of solar energy, the system intelligently switches the operating mode, directly supplying the load with the electrical energy collected by the flexible solar panels and optimized by the MPPT control unit. This mode not only effectively avoids overcharging of the energy storage unit, further extending its lifespan, but also ensures that when the energy storage unit has sufficient charge, solar energy can prioritize and efficiently power the load, reducing energy loss within the energy storage unit. In practice, the charge and discharge controller disconnects the charging path by controlling internal switches or relays, while simultaneously establishing a direct power supply path between the flexible solar panel, the MPPT control unit, and the load.

[0052] Through the above technical solution, the charge and discharge controller can intelligently switch between constant current charging, constant voltage charging, and direct power supply modes based on the state of charge of the energy storage unit. This multi-stage, adaptive charging management strategy effectively solves the problems of low charging efficiency, shortened lifespan of the energy storage unit, and low solar energy utilization that may exist in a single charging mode. Specifically, when the energy storage unit has a low charge, the constant current charging mode can quickly replenish the charge; when the charge is high, the constant voltage charging mode can effectively prevent overcharging and protect the energy storage unit; and when the energy storage unit has a sufficient charge, the system switches to direct power supply to the load through the flexible solar panel via the MPPT control unit, which maximizes the immediate utilization of solar energy and reduces energy loss during the charging and discharging process of the energy storage unit. Overall, this solution significantly improves the system's charging efficiency, extends the lifespan of the energy storage unit, and optimizes the utilization efficiency of solar energy, ensuring the stable and efficient operation of the bridge cable solar power generation system under different operating conditions.

[0053] The aforementioned MPPT-based bridge cable solar power generation system requires its MPPT control unit to track and optimize the output power of the flexible solar panels in real time, manage the charging and discharging process according to the state of charge of the energy storage unit, and even directly supply power to the load under certain conditions. However, in practical applications, especially in outdoor environments such as bridge cables, the system faces risks of complex electromagnetic interference, transient voltage surges, and misoperation (such as reverse power connection). These factors may lead to unstable operation, decreased efficiency, or even damage to the MPPT control unit, thereby affecting the reliability and power generation efficiency of the entire system.

[0054] In this regard, such as Figure 3 As shown, this application further proposes the specific structure of the MPPT control unit, which includes an MCU controller, a TVS diode, a reverse polarity protection diode, a power conversion module, and a drive circuit.

[0055] The MCU controller, as the core of the MPPT control unit, typically employs a high-performance microcontroller, such as one based on the ARM Cortex-M series or PIC series. It incorporates a maximum power point tracking (MPPT) algorithm based on light intensity and temperature parameters. This algorithm can detect the temperature of the flexible solar panel and the surrounding light intensity in real time, and accurately calculate the voltage or current reference value corresponding to the maximum power point of the flexible solar panel under the current environment. Subsequently, the MCU controller generates a corresponding PWM control signal based on the calculated reference value and transmits the PWM control signal to the power conversion module through the drive circuit to adjust the operating state of the power conversion module, ensuring that the flexible solar panel always operates near its maximum power point, thus achieving MPPT tracking control. Furthermore, the MCU controller is also responsible for system status monitoring, fault diagnosis, and communication with the charge / discharge controller to ensure stable system operation.

[0056] A TVS diode (transient voltage suppressor diode) is connected to the input terminal of a flexible solar panel. Its function is to clamp the voltage across the input terminal to a preset safe level at an extremely fast speed (typically on the picosecond scale) when a transient high-energy pulse occurs in the circuit. This absorbs transient overvoltages and prevents voltage spikes from damaging sensitive circuits inside the MPPT control unit (such as power conversion modules and MCU controllers). Its working principle is that when the transient voltage exceeds its breakdown voltage, the TVS diode quickly conducts, providing a low-impedance path to discharge the overcurrent to ground, protecting subsequent circuits.

[0057] The anode of the reverse polarity protection diode is connected to the TVS diode, and the cathode is connected to the first terminal of the power conversion module. Reverse polarity protection diodes are typically Schottky diodes or ordinary rectifier diodes. Their main function is to prevent the power supply (i.e., the flexible solar panel) from being connected with reverse polarity, which would cause current to flow in the opposite direction and potentially cause irreversible damage to the power conversion module and subsequent circuits such as the energy storage unit and charge / discharge controller. When the power supply polarity is correct, the diode conducts in the forward direction, allowing current to flow normally; when the power supply polarity is reversed, the diode blocks current flow, thus providing protection.

[0058] The power conversion module is a key component for implementing the MPPT (Maximum Power Point) function, typically employing a DC-DC converter such as a Buck, Boost, or Buck-Boost topology. In this application, driven by the PWM signal of the MCU controller, this module performs voltage and current conversion on the electrical energy output from the flexible solar panel to ensure that the flexible solar panel always operates at its maximum power point. For example, when the output voltage of the flexible solar panel is higher than the voltage required by the energy storage unit, a Buck converter can be used to step down the voltage; when the output voltage is lower than the required voltage, a Boost converter can be used to step up the voltage. Its efficiency and stability directly affect the overall power generation efficiency of the system.

[0059] The drive circuit is located between the MCU controller and the power conversion module. Its main function is to receive the low-power PWM control signal output from the MCU controller and amplify it into a strong current or high voltage signal sufficient to drive the power switching devices (such as MOSFETs or IGBTs) in the power conversion module. The drive circuit typically includes functions such as level conversion, current amplification, and isolation protection to ensure that the power switching devices can be turned on and off quickly and reliably, thereby enabling the power conversion module to operate efficiently and protecting the MCU controller from interference from the power stage circuitry.

[0060] Through the refined design of the MPPT control unit, the MCU controller, TVS diode, reverse polarity protection diode, power conversion module, and drive circuit are organically integrated, significantly improving the system's robustness and efficiency. The TVS diode effectively suppresses transient voltage spikes, protecting the internal circuitry from overvoltage damage caused by lightning strikes or switching operations, ensuring the system's electrical safety in harsh environments. The reverse polarity protection diode provides basic polarity protection, preventing equipment damage due to misoperation and enhancing system reliability. The MCU controller's built-in dynamic tracking algorithm can accurately capture the maximum power point of the flexible solar panel in real time and precisely control the power conversion module through the drive circuit, maximizing the energy conversion efficiency of the flexible solar panel. Especially when the charge / discharge controller switches to the mode where the flexible solar panel directly supplies power to the load via the MPPT control unit, the MPPT control unit can continuously and stably provide optimized power output, ensuring the load receives efficient and stable power supply, thereby comprehensively improving the overall performance and lifespan of the MPPT-based bridge cable solar power generation system.

[0061] In some of the embodiments described above in this application, a scheme for automatically switching charging modes based on the state of charge of the energy storage unit is proposed. However, in its implementation, if there is a lack of real-time and accurate monitoring and control of key parameters of the charging process, it is difficult to effectively execute the preset charging strategy, which may lead to problems such as low charging efficiency, overcharging or undercharging, thereby affecting the service life of the energy storage unit and the overall performance of the system.

[0062] In this regard, such as Figure 3 As shown, this application further proposes a specific implementation of the charge and discharge controller, which includes a charging voltage sampling circuit, a charging current sampling circuit, a voltage divider circuit, an OLED screen, an ADC, an MCU controller, and a sampling resistor.

[0063] The sampling resistor is connected in series between the power conversion module and the energy storage unit. Its main function is to provide a measurable voltage drop, which is proportional to the charging current flowing through the energy storage unit. By accurately measuring the voltage difference across the sampling resistor, the current charging current can be calculated indirectly and accurately. Typically, a low-resistance, high-precision resistor is chosen for the sampling resistor to reduce its own power consumption and ensure measurement accuracy.

[0064] The charging voltage sampling circuit is used to acquire the charging voltage value output by the power conversion module to the energy storage unit in real time. This circuit is typically composed of a high-impedance resistor divider network or a voltage follower to avoid significant impact on the main circuit. The acquired voltage value is transmitted to the OLED screen for display and also to the MCU controller for monitoring and control, serving as an important basis for judging the charging status of the energy storage unit and adjusting the charging strategy.

[0065] A charging current sampling circuit is connected in parallel across the sampling resistor to accurately measure the voltage drop across it. This circuit typically includes a differential amplifier or current sense amplifier, which amplifies the small voltage difference across the sampling resistor and converts it into a voltage signal that the ADC can acquire. According to Ohm's law, the MCU controller can use this voltage signal and the known resistance of the sampling resistor to calculate the current charging current value. This current value is also transmitted to the OLED screen for display and further transmitted to the MCU controller for monitoring and control.

[0066] A voltage divider circuit is connected in parallel to the input / output terminals of the flexible solar panel, and also connects to the energy storage unit, MCU controller, ADC, and OLED screen. Its main function is to divide the voltage output from the flexible solar panel and the voltage of the energy storage unit, converting the high-voltage signal into a voltage range that can be safely processed and measured by the low-voltage digital circuits of the MCU controller, ADC, and OLED screen. Furthermore, this circuit also monitors the voltage of the energy storage unit. When the state of charge of the energy storage unit exceeds 80%, the MCU controller can use the voltage information provided by the voltage divider circuit to instruct the MCU to stop charging the energy storage unit, thereby achieving overcharge protection.

[0067] As part of the user interface, the OLED screen connects to the MCU controller via an ADC to receive and display parameter information such as voltage and current transmitted from the charging voltage sampling circuit, charging current sampling circuit, and voltage divider circuit. OLED screens offer advantages such as self-illumination, high contrast, and wide viewing angles, enabling users to intuitively view the system's operating status, including key data such as the current charging voltage, charging current, and the state of charge of the energy storage unit, allowing users to easily understand the system's operation in real time.

[0068] An ADC (Analog-to-Digital Converter) is a key component connecting the OLED screen and the MCU controller. It is responsible for converting the analog voltage signals output from the charging voltage sampling circuit, charging current sampling circuit, and voltage divider circuit into digital signals that the MCU controller can recognize and process. The conversion accuracy and speed of the ADC directly affect the accuracy and real-time performance of the system's voltage and current measurements, and thus the accuracy of the MCU controller's charging strategy judgment and control.

[0069] The MCU controller is the core intelligent unit of the charge / discharge controller. It receives digitized voltage and current information from the charging voltage sampling circuit, the charging current sampling circuit, and the voltage divider circuit. Based on this real-time data, the MCU controller can accurately calculate the state of charge of the energy storage unit and intelligently control the charging and discharging process of the energy storage unit according to the preset charging strategy (such as the constant current and constant voltage charging mode switching mentioned above). Simultaneously, the MCU controller is also responsible for sending control commands to the OLED screen according to display requirements, updating the displayed content, and ensuring the accuracy and timeliness of the user interface information.

[0070] Through the above technical solution, this application enables refined management and real-time monitoring of the energy storage unit's charging process. The sampling resistor, charging voltage sampling circuit, and charging current sampling circuit work together to provide the MCU controller with accurate charging voltage and current data, allowing the MCU controller to accurately determine the energy storage unit's state of charge. The voltage divider circuit not only ensures the compatibility of the voltage signal with components such as the MCU controller but also provides crucial voltage monitoring information for the energy storage unit's overcharge protection. With this real-time and accurate data, the MCU controller can intelligently execute the aforementioned dynamic charging mode switching strategy. For example, it uses a constant current charging mode when the state of charge is below 50%, a constant voltage charging mode between 50% and 80%, and stops charging and switches to direct power supply mode when the state of charge is above 80%. This intelligent control avoids overcharging or undercharging, significantly extends the lifespan of the energy storage unit, and improves charging efficiency and safety. Meanwhile, the OLED screen is connected to the MCU controller via ADC, which intuitively displays the system's operating status, charging voltage, current and energy storage unit's state of charge to the user, greatly improving the system's availability and user experience, and making the entire MPPT-based bridge cable solar power generation system more stable and reliable.

[0071] In some embodiments described above, flexible solar panels are installed on bridge cables 14 to generate solar power. However, in practical applications, since bridge cables 14 are typically located in open outdoor environments, key components such as the flexible solar panels and MPPT control units are exposed to harsh environmental factors such as strong ultraviolet radiation, humidity, dust, and temperature fluctuations for extended periods. These factors can lead to performance degradation of the flexible solar panels, aging of the encapsulation materials, and moisture, corrosion, or overheating of the electronic components inside the MPPT control unit, thereby severely affecting the long-term stable operation, power generation efficiency, and service life of the system. Without adequate protection, the long-term stability of the system on the bridge cables 14 is difficult to guarantee.

[0072] In response, this application further proposes an environmental protection unit. This unit aims to provide comprehensive environmental adaptability protection for the MPPT-based bridge cable-stayed solar power generation system, ensuring stable and efficient operation under various harsh outdoor conditions. Specifically, the environmental protection unit includes an UV-resistant PET film adhered to the surface of the flexible solar panel 2. This UV-resistant PET film is a polyethylene terephthalate film that effectively blocks and absorbs the ultraviolet (UV) portion of the solar spectrum by adding UV absorbers or using a special surface coating. The film is tightly bonded to the light-receiving surface of the flexible solar panel 2 in a full-surface lamination manner, forming a transparent protective layer. Its function is to prevent UV radiation from causing photoaging, yellowing, and cracking of the encapsulation material of the flexible solar panel 2, as well as performance degradation of the internal solar cells, thereby extending the service life of the flexible solar panel 2 and maintaining its long-term power generation efficiency.

[0073] In addition, the environmental protection unit includes an aluminum alloy housing located outside the MPPT control unit. This housing is made of high-strength, corrosion-resistant aluminum alloy, and its structural design completely encapsulates the MPPT control unit. Aluminum alloy possesses excellent mechanical strength, effectively resisting external physical impacts; simultaneously, its good corrosion resistance allows it to adapt to outdoor humid and salt spray environments. More importantly, aluminum alloy has good thermal conductivity, helping to quickly dissipate the heat generated by the MPPT control unit during operation to the external environment, preventing excessive internal temperature and ensuring stable operation of the MPPT control unit within a suitable temperature range. Furthermore, the aluminum alloy housing incorporates a moisture-proof and breathable valve. This valve is typically composed of a microporous membrane material with hydrophobic and breathable properties, such as an ePTFE membrane. It is integrated into the aluminum alloy housing, allowing free exchange of air molecules between the inside and outside of the housing, thereby balancing the air pressure difference and effectively preventing condensation inside the housing caused by drastic changes in ambient temperature. Meanwhile, the microporous structure of the vent valve can effectively prevent external contaminants such as liquid water, dust, and sand from entering the housing, keeping the internal environment of the MPPT control unit dry and clean. This significantly reduces the risk of electronic components getting damp, corroded, or short-circuited, further improving the reliability and service life of the MPPT control unit.

[0074] Through the above technical solutions, the environmental protection unit proposed in this application provides comprehensive and multi-layered protection for the MPPT-based bridge cable solar power generation system. The UV-resistant PET film adhered to the surface of the flexible solar panel 2 effectively blocks UV damage to the flexible solar panel 2, significantly delaying its photoaging process and ensuring that the flexible solar panel 2 maintains high power generation efficiency and a long service life during long-term outdoor use. Simultaneously, the aluminum alloy casing located outside the MPPT control unit not only provides robust physical protection, effectively resisting external impacts and dust intrusion, but its excellent thermal conductivity also helps dissipate heat from the MPPT control unit, preventing overheating. More importantly, the moisture-proof and breathable valve built into the aluminum alloy casing cleverly solves the condensation problem caused by temperature differences in the enclosed space of the electronic equipment, while also blocking the entry of moisture and particulate matter, ensuring a dry and clean internal environment for the MPPT control unit. The synergistic effect of these protective measures greatly enhances the environmental adaptability, reliability, and durability of the entire system in the harsh outdoor environment of the bridge cable 14, thereby ensuring the long-term stable operation and efficient output of the power generation system.

[0075] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A bridge cable solar power system based on MPPT, characterized in that, The utility model relates to a kind of solar energy power generation system for bridge, including: Flexible solar panel for collecting and converting solar energy; MPPT control unit, electrically connected with the flexible solar panel, for real-time tracking and optimizing the output power of the flexible solar panel; Energy storage unit, electrically connected with the MPPT control unit, for storing electrical energy and powering the load; Charge and discharge controller, electrically connected with the MPPT control unit and the energy storage unit respectively, for managing the charge and discharge process of the system according to the state of the energy storage unit; Mounting adapter unit for fixing the flexible solar panel on the cable (14) of the bridge.

2. The system of claim 1, wherein, The flexible solar panel is a flexible CIGS thin-film solar panel, with a size of 1200 mm x 600 mm, a rated power range of 15 W to 30 W, and a unit area weight of not more than 1.2 kg / m 2 .

3. The system of claim 1, wherein, The MPPT control unit is a digital control type module, which is configured with a maximum power point dynamic tracking algorithm based on illumination intensity and temperature parameters. The maximum power point tracking response time is less than 0.5s, and the power tracking error is not more than 5%.

4. The system of claim 1, wherein, The mounting adapter unit includes a carbon fiber substrate (11) and a hoop assembly (12). The carbon fiber substrate (11) is an arc-shaped plate body, and its inner concave surface is adapted to the outer peripheral contour of the cable (14) to wrap and fit the outer peripheral surface of the cable (14). Its outer convex surface is fixedly connected with the flexible solar panel through heat-conducting insulating glue to carry and fix the flexible solar panel. The hoop assembly (12) surrounds and locks the fitting place of the carbon fiber substrate (11) and the cable (14) to provide radial fastening force to fasten the carbon fiber substrate (11) on the cable (14).

5. The system of claim 4, wherein, The mounting adapter unit further includes an anti-slip layer (13). The anti-slip layer (13) is arranged at the contact interface of the hoop assembly (12) and the carbon fiber substrate (11) to increase friction and prevent relative sliding.

6. The system of claim 1, wherein, The charge and discharge controller is configured to automatically switch the charging mode according to the state of charge of the energy storage unit, specifically including: When the state of charge is below 50%, use constant current charging mode, and the current value range is 1.2~1.8A; When the state of charge is between 50% and 80%, use constant voltage charging mode, and the voltage value range is 13~15V; When the state of charge is higher than 80%, stop charging the energy storage unit, and switch to the mode of directly supplying power to the load from the flexible solar panel through the MPPT control unit.

7. The system of claim 6, wherein, The MPPT control unit includes an MCU controller, a TVS tube, an anti-reverse diode, a power conversion module, and a driving circuit. The TVS tube is connected with the input end of the flexible solar panel to perform transient voltage suppression protection on the voltage output by the flexible solar panel, preventing voltage spikes from damaging subsequent circuits. The anode of the anti-reverse diode is connected with the TVS tube, and the cathode is connected with the first end of the power conversion module to prevent damage to the power conversion module and subsequent circuits when the power supply is connected in reverse. The second end of the power conversion module is connected with the MCU controller through the driving circuit to perform power conversion processing on the input electrical energy under the control of the MCU controller. The MCU controller is internally provided with a maximum power point dynamic tracking algorithm based on illumination intensity and temperature parameters, is used for real-time detection of the temperature of the flexible solar panel and the illumination intensity where the flexible solar panel is located, and is used for calculating the voltage or current reference value corresponding to the maximum power point of the flexible solar panel under the current environment according to the illumination intensity and the temperature and the maximum power point dynamic tracking algorithm; then, the corresponding PWM control signal is generated according to the calculated reference value, and the PWM control signal is transmitted to the power conversion module through the driving circuit to adjust the working state of the power conversion module, so that the flexible solar panel always works near the maximum power point, and the maximum power point tracking control is realized.

8. The system of claim 6, wherein, The charge-discharge controller comprises a charging voltage sampling circuit, a charging current sampling circuit, a voltage dividing circuit, an OLED screen, an ADC, an MCU controller and a sampling resistor; The sampling resistor is connected in series between the power conversion module and the energy storage unit. The charging voltage sampling circuit is connected with the power conversion module and the OLED screen respectively, is used for collecting the charging voltage value output by the power conversion module to the energy storage unit in real time, and is used for transmitting the charging voltage value to the OLED screen for display and further transmitting the charging voltage value to the MCU controller for monitoring and control. The charging current sampling circuit is connected in parallel at both ends of the sampling circuit and is connected with the OLED screen, is used for collecting the voltage drop at both ends of the sampling resistor, is used for converting the charging current value according to Ohm's law, and is used for transmitting the current value to the OLED screen for display and further transmitting the current value to the MCU controller for monitoring and control. The voltage dividing circuit is connected in parallel at the input / output end of the flexible solar panel, is connected with the energy storage unit, the MCU controller, the ADC and the OLED screen, is used for dividing the voltage output by the flexible solar panel, so that the voltage value is adapted to the power supply demand of the MCU controller, the ADC and the OLED screen, and is used for stopping charging the energy storage unit when the state of charge of the energy storage unit is higher than 80%; The OLED screen is connected with the MCU controller through the ADC, is used for receiving and displaying the voltage, current and other parameter information transmitted from the charging voltage sampling circuit, the charging current sampling circuit and the voltage dividing circuit, and is used for displaying the working state of the system to the user through an intuitive interface; The MCU controller is used for controlling the charging and discharging process of the energy storage unit according to the received charging voltage and charging current information, and is used for sending control instructions to the OLED screen according to the display demand and updating the display content.

9. The system of claim 1, wherein, The system further comprises an environmental protection unit. The environmental protection unit comprises an ultraviolet-proof PET film attached to the surface of the flexible solar panel and an aluminum alloy shell arranged outside the MPPT control unit; the aluminum alloy shell is internally provided with a moisture-proof and air-permeable valve.

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