A solar sign with a charge management module

Abstract

This utility model discloses a solar sign with a charging management module, comprising: a main body, on which a control box and a solar panel are mounted; the control box houses the charging management module, which includes: a controller; input terminals; a P-channel MOSFET; a protection diode; an MPPT sampling network; a power inductor connected to the drive output terminal of the controller; a freewheeling diode forming a step-down conversion circuit with the power inductor; an absorption network including a clamping diode and an absorption capacitor for suppressing switching noise; a current sampling resistor employing a four-terminal Kelvin connection structure; a temperature detection element connected to the temperature detection pin of the controller for detecting battery temperature; an output terminal for connecting to a battery; and a status indicator for displaying the charging status. This solar sign with a charging management module features high energy conversion efficiency, wide temperature adaptability, and good electromagnetic compatibility.

Description

Technical Field

[0001] This utility model relates to a solar sign with a charging management module. Background Technology

[0002] With the widespread application of solar energy technology in transportation infrastructure, speed limit, warning, and directional signs on highways are increasingly adopting solar-powered systems to address power supply issues in areas far from the power grid, reducing wiring costs and environmental impact. These signage systems typically include solar panels, charge controllers, batteries, and LED displays.

[0003] In these systems, the charging management module is a critical component, responsible for efficiently converting and storing the energy generated by the solar panels into batteries, while protecting the batteries from overcharging, over-discharging, and extreme temperature conditions. However, existing solar road sign charging management modules suffer from several major problems:

[0004] First, the energy conversion efficiency is low. Traditional charging controllers typically use a simple PWM (pulse width modulation) control method, which cannot enable the solar panels to operate at their maximum power point, resulting in low energy capture efficiency, especially under low light conditions. In addition, commonly used anti-backflow diodes generate a voltage drop of 0.5-0.7V, causing a 6-8% energy loss at a system voltage of 7-15V, significantly reducing the overall system efficiency.

[0005] Secondly, they have poor temperature adaptability. The temperature range along highways is large, potentially spanning from -20°C to 60°C in the dead of winter. Existing charging modules generally lack effective temperature monitoring and management functions, continuing to charge according to standard parameters even under extreme temperature conditions. This leads to a significant reduction in battery life, increased maintenance frequency, and the generation of electronic waste.

[0006] Third, there are electromagnetic compatibility (EMC) issues. Highway environments contain numerous wireless communication devices and Intelligent Transportation Systems (ITS), and the electromagnetic interference generated by switch-mode chargers can affect the normal operation of these devices. Traditional charging modules do not adequately address EMI suppression, easily leading to mutual interference problems.

[0007] Fourth, maintenance is difficult. The signage equipment along the highway is numerous and scattered, making it difficult for maintenance personnel to obtain timely information about the equipment status. This often requires unnecessary on-site inspections, increasing maintenance costs and carbon emissions.

[0008] Therefore, there is an urgent need to develop a solar charging management module optimized for highway signage applications, which can improve energy utilization efficiency, extend battery life, and reduce electromagnetic interference, thereby reducing overall operating costs and environmental impact. Utility Model Content

[0009] The purpose of this invention is to provide a solar sign with a charging management module. This solar sign with a charging management module features high energy conversion efficiency, wide temperature adaptability, and good electromagnetic compatibility.

[0010] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0011] A solar-powered sign with a charging management module includes: a main body, on which a control box and a solar panel are mounted; the control box houses the charging management module, which includes: a controller with MPPT and temperature detection functions; an input terminal for connecting to the solar panel; a P-channel MOSFET whose source is connected to the positive terminal of the input terminal to prevent backflow of battery power into the solar panel at night; a protection diode connected in parallel between the input terminal and the P-channel MOSFET to provide transient protection; an MPPT sampling network including a high-resistance resistor and a filter capacitor, connected to the MPPT pin of the controller; a power inductor connected to the drive output terminal of the controller; a freewheeling diode forming a step-down converter circuit with the power inductor; an absorption network including a clamping diode and an absorption capacitor to suppress switching noise; a current sampling resistor with a four-terminal Kelvin connection; a temperature detection element connected to the temperature detection pin of the controller to detect battery temperature; an output terminal for connecting to a battery; and a status indicator for displaying the charging status.

[0012] The present invention is further configured such that the P-channel MOSFET forms an ideal diode structure with a forward voltage drop of less than 0.1V, thereby reducing energy loss and preventing nighttime backflow current.

[0013] The present invention is further configured such that: the high-resistance resistor in the MPPT sampling network is 1MΩ and the filter capacitor is 470pF, forming a low-pass filter structure, which is used to smooth the solar panel voltage sampling signal and improve the MPPT tracking accuracy.

[0014] The present invention is further configured such that: the current sampling resistor is a 30mΩ constantan wire resistor, which has multiple heat dissipation holes below it and is connected by a ≥50mil wide trace to form a heat dissipation structure.

[0015] The present invention is further configured such that the temperature detection element is a 10kΩ NTC thermistor, which can automatically adjust the charging parameters or stop charging under low temperature conditions (<0℃) and high temperature conditions (>45℃).

[0016] The present invention is further configured such that: the status indicator is a dual-color LED, including a red indicator and a green indicator, which are respectively connected to the CHRG# pin and the DONE# pin of the controller, and are used to indicate the charging status and the charging completed status.

[0017] The present invention is further configured to include a loop compensation network, comprising resistors, capacitors, and capacitors connected to the FB pin of the controller to form a Type-II / III compensation structure, thereby improving system stability.

[0018] The present invention is further configured such that the clamping diodes and absorption capacitors in the absorption network are arranged close to the switching node to form a local EMI suppression structure, thereby reducing high-frequency switching noise.

[0019] The present invention is further configured such that: the controller is located at the center of the circuit board, so that the signal path is minimized, and the power conversion area, input protection area, control monitoring area and output interface area are clearly divided in space.

[0020] The present invention is further configured such that the power inductor, freewheeling diode and current sampling resistor form a layout structure with minimum loop area, thereby reducing switching losses and electromagnetic interference.

[0021] In summary, this utility model has the following beneficial effects:

[0022] High-efficiency energy conversion structure: This invention employs a P-channel MOSFET to form an ideal diode structure, reducing the forward voltage drop from 0.5-0.7V in traditional diodes to 0.05-0.1V, thus reducing energy loss. Simultaneously, the controller's MPPT function, combined with a specially designed sampling network (a low-pass filter structure consisting of a 1MΩ resistor and a 470pF capacitor), continuously tracks the maximum power point of the solar panel, maintaining high energy capture efficiency even under low-light conditions, a significant improvement over traditional PWM controllers. This high-efficiency design allows a solar panel of the same area to provide more energy for a sign, or, while meeting the same power supply requirements, reduces the solar panel area, lowering costs and material consumption.

[0023] High-precision current control system: This invention employs a four-terminal Kelvin connection structure for the current sampling resistor (30mΩ constantan wire), eliminating the influence of connection resistance and contact resistance on sampling accuracy. This structure significantly improves the accuracy of charging current control compared to traditional two-terminal sampling. Current control ensures that the battery charging process follows safe parameters, avoiding overcharging and undercharging, and extending battery life. Simultaneously, the use of ≥50mil wide traces and multiple heat dissipation holes creates an effective heat dissipation structure, preventing localized overheating caused by high charging current.

[0024] Wide-temperature-range safe charging mechanism: This invention achieves precise temperature monitoring by connecting a 10kΩ NTC thermistor to the temperature detection pin of the controller. Under low-temperature conditions (<0℃), the system automatically disables or reduces the charging current to prevent lithium metal deposition problems that occur during low-temperature charging. Under high-temperature conditions (>45℃), the system reduces the charging current or completely stops charging until the temperature drops back to a safe range. This intelligent temperature-controlled charging extends the average battery life in outdoor environments from the traditional 2-3 years to 3-4.5 years, reducing battery replacement frequency and significantly lowering maintenance costs and electronic waste generation.

[0025] Electromagnetic Compatibility Optimization: This invention incorporates an absorption network consisting of clamping diodes and absorption capacitors at the power switching node. These components are arranged close to the switching node, forming a localized EMI suppression structure. Actual measurements show that this configuration reduces the peak voltage of switching noise by 40-60% and EMI radiation by approximately 15-20 dB. Simultaneously, the loop compensation network of the Type-II / III compensation structure optimizes the frequency response of the control loop, enabling the system to quickly recover to a stable state under sudden changes in illumination or load, reducing output voltage fluctuations. This EMI control configuration allows the module to operate stably in the complex electromagnetic environment of highways, without interfering with surrounding intelligent transportation system equipment or other devices. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of this utility model;

[0027] Figure 2 This is a circuit diagram of the charging management module of this utility model.

[0028] Reference numerals: 1. Main body; 2. Solar panel; 3. Control box. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, a solar sign with a charging management module includes a main body 1, a solar panel 2 on the top of the main body 1, a control box 3 on one side of the main body, and a charging management module inside the control box.

[0031] like Figure 2As shown, the charging management module includes a controller (U1), an input terminal (P2), a P-channel MOSFET (Q1), a protection diode (D2), an MPPT sampling network (R5, C4), a power inductor (L1), a freewheeling diode (D3), a snubber network (D4, C7), a current sampling resistor (R8), a temperature detection element (P1), an output terminal (P3), and a status indicator (LED1).

[0032] The charging management module has a linear layout and is functionally divided into four main physical areas: an input protection zone, a buck power conversion zone, a control and monitoring zone, and an output interface zone. This layout conforms to the energy flow path, ensures the sequential nature of signal processing, and creates clear functional zoning in space.

[0033] The P-channel MOSFET (Q1) forms an ideal diode structure, with its source connected to the positive terminal of the input (P2) and its drain connected to the subsequent circuitry. This structure utilizes the low on-resistance characteristic of the MOSFET to control the forward voltage drop below 0.1V, significantly reducing energy loss compared to the 0.5-0.7V of a traditional diode. Under nighttime conditions without sunlight, the MOSFET is turned off, and its high source-drain impedance ensures a return current of less than 1μA, effectively preventing backflow from the battery to the solar panel.

[0034] A protection diode (D2) is connected in parallel between the input terminal (P2) and the P-channel MOSFET (Q1) to provide transient protection. In the event of a sudden reverse power connection or induced voltage caused by a low-resistance power failure, the protection diode provides a clamping and discharging path to protect downstream circuitry from damage.

[0035] The MPPT sampling network consists of a high-resistance resistor (R5) and a filter capacitor (C4), connected to the MPPT pin of the controller (U1). The high-resistance resistor (R5) is 1MΩ, and the filter capacitor (C4) is 470pF, together forming a low-pass filter structure with a time constant of approximately 470μs. This setup smooths out instantaneous fluctuations in solar panel voltage, avoiding MPPT tracking errors caused by short-term fluctuations, while maintaining responsiveness to real changes in illumination, thus improving the stability and accuracy of MPPT tracking.

[0036] The controller (U1) features MPPT and temperature detection functions, uses a CN3722 chip, and is located in the center of the circuit board. This layout balances the length of each signal path, shortens the transmission distance of control signals, and reduces signal attenuation and interference.

[0037] The power inductor (L1) is connected to the drive output terminal of the controller (U1). It is a 10μH / 10A inductor with a shielded winding structure to reduce electromagnetic radiation. The inductor is positioned close to the controller's drive output pin, forming the shortest drive path and reducing switching losses. A large copper area and an array of heat dissipation holes are located beneath the inductor, creating an effective heat conduction path.

[0038] The freewheeling diode (D3) and the power inductor (L1) form a buck converter circuit. The freewheeling diode adopts a Schottky structure, which has fast switching characteristics and low forward voltage drop, reducing energy loss during freewheeling. The freewheeling diode is placed close to the power inductor, minimizing the current loop area and reducing parasitic inductance and electromagnetic radiation.

[0039] The absorption network, comprising a clamping diode (D4) and an absorption capacitor (C7), is used to suppress switching noise. The clamping diode and absorption capacitor are positioned close to the switching node, forming a localized EMI suppression structure. The clamping diode clamps voltage spikes generated during switching, preventing overvoltage damage to power devices; the absorption capacitor absorbs high-frequency switching noise, reducing electromagnetic interference. The absorption network lowers the peak voltage of switching noise, effectively improving the system's electromagnetic compatibility.

[0040] The current sampling resistor (R8) employs a four-terminal Kelvin connection structure, is a 30mΩ constantan wire resistor, and has a physical size of 1.0×10mm. In this structure, the two ends are high-current paths, and the two middle points are voltage sampling points, effectively eliminating the influence of connection resistance and contact resistance on sampling accuracy. Multiple heat dissipation holes are located below the current sampling resistor, connected by traces ≥50mil wide, forming a heat dissipation structure to prevent localized overheating caused by high current. This high-precision current sampling structure improves the accuracy of charging current control, ensuring the safety and efficiency of the battery charging process.

[0041] The temperature sensing element (P1) is a 10kΩ NTC thermistor, connected to the temperature sensing pin of the controller (U1) to detect the battery temperature. The temperature sensing element is physically positioned close to the battery to ensure accurate monitoring of the actual battery temperature. Under low-temperature conditions (<0°C), the controller automatically reduces the charging current or disables charging based on the temperature reading, preventing lithium metal deposition caused by charging at low temperatures. Under high-temperature conditions (>45°C), the controller reduces the charging current or completely stops charging to avoid overheating and accelerated aging of the battery. This temperature-sensing charging strategy significantly extends battery life, increasing it from 2-3 years to 3-4.5 years in outdoor environments.

[0042] The output terminal (P3) is used to connect the battery and uses HB9500 screw terminals for easy field wiring and maintenance. An output filter capacitor is located near the output terminal to reduce output ripple and provide a stable charging current. The output area is spatially separated from the input area to avoid signal coupling and interference.

[0043] The status indicator (LED1) is a dual-color LED, including a red indicator and a green indicator, which are connected to the CHRG# and DONE# pins of the controller (U1), respectively. When the system is charging, the CHRG# pin is pulled low, illuminating the red indicator; when charging is complete or the system enters trickle charging mode, the DONE# pin is pulled low, illuminating the green indicator. The status indicator is located at the edge of the circuit board for easy visual inspection, allowing maintenance personnel to intuitively determine the system's operating status and reducing diagnostic time.

[0044] This invention also includes a loop compensation network comprising resistors (R7), (R6), capacitors (C5), (C6), and (C8), connected to the FB pin of the controller (U1) to form a Type-II / III compensation structure, improving system stability. Resistor (R7) is 100kΩ, resistor (R6) is 120Ω, capacitor (C5) is 220nF, capacitor (C6) is 100nF, and capacitor (C8) is 4.7pF. This compensation network optimizes the frequency response of the control loop. Capacitors (C5) and (C6) provide low-frequency zero-point phase margin enhancement, while capacitor (C8) provides high-frequency pole-point noise suppression. The loop compensation components are closely arranged around the FB pin of the controller, shortening the signal path and reducing interference.

[0045] The power inductor (L1), freewheeling diode (D3), and current sampling resistor (R8) form a layout with minimal loop area, reducing switching losses and electromagnetic interference. This minimizes parasitic inductance and resistance, improving conversion efficiency and electromagnetic compatibility. Maintaining an appropriate distance between the power conversion area and the control area reduces the impact of electromagnetic interference on the control signal.

[0046] In actual operation, when the solar panel receives sunlight, the generated electrical energy first enters the module through the input terminal (P2). The P-channel MOSFET (Q1) automatically turns on, transferring the electrical energy to the subsequent circuit. At the same time, the MPPT sampling network (R5, C4) samples and filters the solar panel voltage and transmits it to the controller (U1). The controller adjusts the duty cycle of the drive signal according to the existing MPPT algorithm, so that the solar panel operates near the maximum power point, maximizing the energy capture efficiency.

[0047] Electrical energy is converted into a suitable voltage and current for battery charging via a step-down converter circuit (composed of controller U1, power inductor L1, and freewheeling diode D3). After the current passes through the current sampling resistor (R8), its voltage drop is sampled by the controller, forming a closed-loop control to ensure the charging current is precisely controlled within the set value. Simultaneously, the temperature detection element (P1) continuously monitors the battery temperature, and the controller adjusts the charging parameters based on the temperature readings to ensure safe charging under various temperature conditions.

[0048] When the battery voltage approaches the set float charge voltage, the system switches from constant current mode to constant voltage mode, and the charging current gradually decreases. When the charging current drops to the set threshold, the controller determines that the battery is fully charged, pulls the DONE# pin low, and illuminates the green indicator light to indicate that charging is complete.

[0049] The absorption network (D4, C7) works continuously throughout the charging process to suppress voltage spikes and electromagnetic interference during switching, ensuring stable and reliable system operation.

[0050] This invention achieves high-efficiency energy conversion, precise current control, intelligent temperature management, good electromagnetic compatibility, and convenient maintenance through reasonable structural design and spatial layout. It is particularly suitable for applications such as highway signs, which require long-term reliable operation and low maintenance frequency.

[0051] The technical effectiveness of the solar sign with a charging management module was evaluated through the following experiments.

[0052] 1. The test employed a comparative experimental method, comparing the module of this utility model with three traditional charging controllers (PWM controller, conventional MPPT controller, and simple temperature-controlled charger). The test environment included two scenarios: standard conditions (constant temperature of 25℃, standard illumination) and simulated outdoor conditions (temperature cycling from -20℃ to 60℃, changes in light intensity, and electromagnetic interference sources). Precision measuring equipment was used to record key performance parameters. Each test was repeated five times, and the average value was taken to ensure data reliability.

[0053] 2. Technical Effect Comparison Table

[0054]

[0055] 3. Verification Methods and Results

[0056] Energy conversion efficiency test: Using a simulated solar array with different light intensities (1000W / m²) 2 500W / m 2 200W / m 2 100W / m 2 ), measure the input and output power of each controller. (At 100W / m) 2Under low-light conditions, this module still maintains an energy conversion efficiency of 78.6%, while the PWM controller only achieves 48.2%. Actual field tests show that this module can capture an additional 2-3 hours of low-light energy per day, and the solar panel area can be reduced by 25% while meeting the same power supply requirements.

[0057] Charging current accuracy test: Under different battery states (20%, 50%, and 80% charging), the deviation between the set current of each controller and the actual charging current was compared. The deviation of this utility model module is ±1.5%, which is better than the ±4.2%~±5.5% of traditional controllers. High-precision charging current control significantly reduces the risk of overcharging and undercharging. In long-term use tests, the battery capacity degradation rate was reduced by 35%.

[0058] Temperature adaptability test: Temperature changes from -20℃ to 60℃ were simulated in a temperature cycling chamber, and the charging behavior of each controller was observed. Under temperatures below 0℃ and above 45℃, the module of this invention can automatically adjust the charging current or stop charging, while the traditional controller continues to charge at unsafe parameters. Long-term comparative testing (18 months) shows that the battery capacity retention rate protected by the module of this invention is 92%, while the battery capacity retention rate protected by the traditional controller is only 62-78%.

[0059] EMI Compatibility Testing: Conducted and radiated interference tests were conducted according to GB / T 17626 standard. The radiated level of this module in the 150kHz frequency band was 52dBμV, lower than the standard limit of 28dB, while traditional controllers were only 5-15dB below the limit. In coexistence tests with ITS equipment in a highway environment, this module did not exhibit any interference events, while other controllers generated an average of 2-5 interference events per week.

[0060] Experimental verification shows that solar signs with charging management modules have the following beneficial effects: energy conversion efficiency improved by 21-89% under low light conditions, charging current accuracy improved by 64-73%, battery life extended by 50-100% in outdoor environments, and EMI radiation levels reduced by 23-42%. Comprehensive testing proves that this module is suitable for applications such as highway signs, which require long-term reliable operation and low maintenance frequency. Its structural design and technical characteristics effectively address the shortcomings of traditional charging modules in terms of energy efficiency, safety, and compatibility, and it has broad application prospects.

Claims

1. A solar-powered signboard with a charging management module, characterized in that, include: The main body includes a control box and a solar panel. The control box contains a charging management module, which includes: The controller (U1) has MPPT and temperature detection functions; Input terminal (P2) is used to connect the solar panel; The P-channel MOSFET (Q1), whose source is connected to the positive terminal of the input terminal (P2), is used to prevent the battery from backflowing into the solar panel at night. A protection diode (D2) is connected in parallel between the input terminal (P2) and the P-channel MOSFET (Q1) to provide transient protection; The MPPT sampling network, including a high-resistance resistor (R5) and a filter capacitor (C4), is connected to the MPPT pin of the controller (U1); A power inductor (L1) is connected to the drive output terminal of the controller (U1); The freewheeling diode (D3) and the power inductor (L1) form a step-down converter circuit; An absorption network, including a clamping diode (D4) and an absorption capacitor (C7), is used to suppress switching noise; The current sampling resistor (R8) adopts a four-terminal Kelvin connection structure; A temperature sensing element (P1) is connected to the temperature sensing pin of the controller (U1) for detecting battery temperature; Output terminal (P3) is used to connect to the battery; Status indicator (LED1) is used to display the charging status.

2. The solar sign with a charging management module according to claim 1, characterized in that, The P-channel MOSFET (Q1) forms an ideal diode structure with a forward voltage drop below 0.1V, reducing energy loss and preventing nighttime backflow current.

3. The solar sign with a charging management module according to claim 1, characterized in that, The high-resistance resistor (R5) in the MPPT sampling network is 1MΩ, and the filter capacitor (C4) is 470pF, forming a low-pass filter structure to smooth the solar panel voltage sampling signal and improve MPPT tracking accuracy.

4. The solar sign with a charging management module according to claim 1, characterized in that, The current sampling resistor (R8) is a 30mΩ constantan wire resistor, with multiple heat dissipation holes below it, and is connected by traces ≥50mil wide to form a heat dissipation structure.

5. The solar sign with a charging management module according to claim 1, characterized in that, The temperature sensing element (P1) is a 10kΩ NTC thermistor, which can automatically adjust the charging parameters or stop charging under low temperature conditions (<0℃) and high temperature conditions (>45℃).

6. The solar sign with a charging management module according to claim 1, characterized in that, The status indicator (LED1) is a dual-color LED, including a red indicator and a green indicator, which are respectively connected to the CHRG# pin and DONE# pin of the controller (U1) to indicate the charging status and the charging completed status.

7. The solar sign with a charging management module according to claim 1, characterized in that, It also includes a loop compensation network, consisting of resistors (R7), (R6), capacitors (C5), (C6), and (C8), connected to the FB pin of the controller (U1) to form a Type-II / III compensation structure, thereby improving system stability.

8. The solar sign with a charging management module according to claim 1, characterized in that, The clamping diode (D4) and absorption capacitor (C7) in the absorption network are arranged close to the switching node to form a local EMI suppression structure, reducing high-frequency switching noise.

9. The solar sign with a charging management module according to claim 1, characterized in that, The controller (U1) is located at the center of the circuit board, which minimizes the signal path, and the power conversion area, input protection area, control monitoring area and output interface area are clearly divided in space.

10. The solar sign with a charging management module according to claim 1, characterized in that, The power inductor (L1), freewheeling diode (D3), and current sampling resistor (R8) form a layout structure with minimal loop area, reducing switching losses and electromagnetic interference.

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