Storage battery and mains supply switching device under solar charging condition

Abstract

The invention provides a storage battery and mains supply switching device under a solar charging condition, and belongs to the technical field of new energy power supply and intelligent power grids. Comprising a power conversion module which comprises a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) power device; the hardware zero-cross detection circuit comprises a first comparator and an optical coupling isolation element and is used for phase detection; a pre-driving chip, wherein the pre-driving chip comprises a second gate driver; the third coulomb metering chip is used for carrying out SOC estimation by combining ampere-hour integration and an open-circuit voltage correction technology; the fourth impedance conversion chip is used for measuring the internal resistance growth rate and calculating the capacity attenuation rate; a fast recovery diode is connected in series in the main loop, and an RCD absorption circuit is configured in the main loop. And the effects of rapid non-impact switching, high-precision SOC estimation, dynamic threshold adjustment and prolonging of the service life of the battery are achieved.

Description

Technical Field

[0001] The present application belongs to the field of new energy power supply and smart grid technology, and specifically relates to a battery and mains power switching device under solar charging conditions. Background Art

[0002] In the field of new energy power supply and smart grid technology, solar hybrid power supply systems are gradually becoming one of the important power supply methods, especially suitable for power supply scenarios such as reservoir safety monitoring equipment, photovoltaic energy storage systems, off-grid and grid-connected microgrids, and communication base station power supply.

[0003] However, traditional solar-to-mains switching solutions face numerous technical bottlenecks, including long switching delays (over 50ms), high SOC estimation errors (over ±15%), fixed thresholds that fail to adapt to over-discharge and capacity waste caused by battery aging, and excessive EMI caused by arcing. These issues not only affect system response speed and switching stability, but also shorten battery life and increase maintenance costs. Summary of the Invention

[0004] In order to solve at least one technical problem existing in the background technology, the present application provides a battery and AC power switching device under solar charging conditions. By adopting high-performance silicon carbide MOSFET, precise hardware zero-crossing detection circuit, high-speed pre-driver chip and intelligent battery management algorithm, it achieves fast and impact-free switching, high-precision SOC estimation and dynamic adjustment of threshold to extend battery life.

[0005] The technical solutions adopted in this application are:

[0006] The embodiment of the present application provides a battery and mains switching device under solar charging conditions, comprising:

[0007] A power conversion module, wherein the power conversion module includes a silicon carbide MOSFET power device, wherein the silicon carbide MOSFET power device has a blocking voltage of 900V and an on-state resistance of 65mΩ;

[0008] A hardware zero-crossing detection circuit, comprising a first comparator and an optocoupler isolation element for phase detection;

[0009] A pre-driver chip, the pre-driver chip including a second gate driver, wherein the pre-driver chip has an isolation withstand voltage of 5kVRms and a transmission delay of 76ns±5ns;

[0010] The third coulomb metering chip is used to combine ampere-hour integration and open-circuit voltage correction technology to estimate SOC. Among them, it automatically enters the static mode for 15 minutes every 24 hours, during which time the SOC-OCV characteristic curve is fitted using the least squares method;

[0011] The fourth impedance conversion chip is used to measure the internal resistance growth rate and calculate the capacity attenuation rate;

[0012] The main circuit includes a fast recovery diode connected in series and an RCD absorption circuit.

[0013] According to the battery and mains switching device under solar charging provided by the embodiment of the present application, efficient, stable and intelligent energy management is achieved by integrating a variety of advanced electronic components and intelligent algorithms. The power conversion module adopts silicon carbide MOSFET power devices, which significantly improves the system's high voltage resistance and efficiency and reduces heat loss with its high blocking voltage of 900V and on-state resistance as low as 65mΩ. The hardware zero-crossing detection circuit uses the first (LM311) comparator combined with the optocoupler isolation element for precise phase detection, ensuring smooth switching in the absence of voltage shock, greatly reducing the potential risk of damage to sensitive equipment. The second (TI ISO5852S-Q1) in the pre-driver chip has an isolation withstand voltage of 5kVRms and a transmission delay of 76ns±5ns, which can quickly respond to control signals and further improve switching speed and stability.

[0014] Furthermore, the third coulomb counter chip (TI BQ34Z100-R1) estimates the battery's state of charge (SOC) by combining ampere-hour integration with open-circuit voltage correction technology. It automatically enters a 15-minute rest mode every 24 hours, during which it uses the least squares method to fit the SOC-OCV characteristic curve. This effectively improves the accuracy of remaining battery charge estimation, maintaining high accuracy across a wide temperature range. The fourth impedance conversion chip (AD5933) measures the internal resistance growth rate and calculates the capacity decay rate, dynamically adjusting the battery's state of health assessment threshold and extending the battery's actual service life. The fast recovery diode connected in series with the RCD snubber circuit in the main circuit not only reduces voltage spikes and spark energy during switching transients, but also significantly reduces electromagnetic interference, ensuring safe and reliable system operation.

[0015] In summary, this device realizes the transition from traditional mechanical switching to high-efficiency semiconductor switching, which not only significantly shortens the switching time and improves the response speed and stability of the system, but also extends the battery life and reduces maintenance costs through precise battery management and effective arc suppression measures.

[0016] According to one embodiment of the present application, two of the silicon carbide MOSFET power devices are connected in parallel to form a bridge arm and are fixed on an AlN ceramic substrate through a silver sintering process, wherein the power terminals of the silicon carbide MOSFET power devices are connected with 4mm thick silver-plated copper busbars and fastened with M5 titanium alloy screws, and the torque is controlled at 2.5N·m±0.2N·m.

[0017] According to one embodiment of the present application, the phase error of the hardware zero-crossing detection circuit is less than 1 degree, so as to perform a smooth switching process without voltage shock.

[0018] According to one embodiment of the present application, the pre-driver chip is configured with an on-resistance of 4.7Ω±1%, an off-resistance of 100Ω±1%, and a Miller clamp tube, wherein the BSS138MOSFET in the Miller clamp tube is connected in series with a 2.2kΩ resistor.

[0019] According to one embodiment of the present application, the switch response time is less than 10 ns.

[0020] According to one embodiment of the present application, the third coulomb metering chip is suitable for performing high-precision estimation over the entire temperature range in combination with a temperature compensation formula, wherein the temperature compensation formula is:

[0021] SOC_corrected=SOC_raw×[1+0.003×(T-25℃)]+0.0015×(T-25℃)2.

[0022] According to one embodiment of the present application, the SOC estimation error is within ±3%.

[0023] According to one embodiment of the present application, the fourth impedance conversion chip communicates with the main control MCU via a high-speed SPI interface.

[0024] According to one embodiment of the present application, the fast recovery diode connected in series in the main circuit is of model C4D10120A, and has a reverse recovery time of 30ns;

[0025] The RCD absorption circuit includes a 10Ω / 5W pulse-resistant carbon film resistor and a 0.1μF / 1kV low ESR film capacitor.

[0026] According to one embodiment of the present application, the battery and mains switching device under the solar charging condition includes a four-layer high-density PCB with a power loop area of ​​2cm 2 Within. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 A schematic diagram of the structure of a battery and mains switching device under solar charging conditions provided in an embodiment of the present application;

[0029] Figure 2 This is a flow chart of the switching control between the battery and the AC power switching device under the solar charging condition provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the overall concept of the present application, a detailed description is given below in an illustrative manner in conjunction with the accompanying drawings.

[0031] The following description sets forth many specific details to facilitate a thorough understanding of the present application. However, the present application may also be implemented in other ways than those described herein, and therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below. It should be noted that the embodiments of the present application and the features of each embodiment may be combined with each other unless there is a conflict.

[0032] In addition, in the description of the present application, it should be understood that the terms "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present application.

[0033] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0034] In this application, unless otherwise expressly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0035] like Figure 1 and Figure 2 As shown, the embodiment of the present application provides a battery and mains switching device under solar charging conditions, comprising:

[0036] A power conversion module, the power conversion module includes a silicon carbide MOSFET power device, wherein the silicon carbide MOSFET power device has a blocking voltage of 900V and an on-state resistance of 65mΩ;

[0037] A hardware zero-crossing detection circuit includes a first comparator and an optocoupler isolation element for phase detection;

[0038] A pre-driver chip, the pre-driver chip includes a second gate driver, wherein the pre-driver chip has an isolation withstand voltage of 5kVRms and a transmission delay of 76ns±5ns;

[0039] The third coulomb metering chip is used to combine ampere-hour integration and open-circuit voltage correction technology to estimate SOC. Among them, it automatically enters the static mode for 15 minutes every 24 hours, during which time the SOC-OCV characteristic curve is fitted using the least squares method;

[0040] The fourth impedance conversion chip is used to measure the internal resistance growth rate and calculate the capacity attenuation rate;

[0041] Main circuit: a fast recovery diode is connected in series in the main circuit and an RCD absorption circuit is configured.

[0042] According to the battery and mains switching device under solar charging provided by the embodiment of the present application, efficient, stable and intelligent energy management is achieved by integrating a variety of advanced electronic components and intelligent algorithms. The power conversion module adopts silicon carbide MOSFET power devices, which significantly improves the system's high voltage resistance and efficiency and reduces heat loss with its high blocking voltage of 900V and on-state resistance as low as 65mΩ. The hardware zero-crossing detection circuit uses the first (LM311) comparator combined with the optocoupler isolation element for precise phase detection, ensuring smooth switching in the absence of voltage shock, greatly reducing the potential risk of damage to sensitive equipment. The second (TI ISO5852S-Q1) in the pre-driver chip has an isolation withstand voltage of 5kVRms and a transmission delay of 76ns±5ns, which can quickly respond to control signals and further improve switching speed and stability.

[0043] Furthermore, the third coulomb counter chip (TI BQ34Z100-R1) estimates the battery's state of charge (SOC) by combining ampere-hour integration with open-circuit voltage correction technology. It automatically enters a 15-minute rest mode every 24 hours, during which it uses the least squares method to fit the SOC-OCV characteristic curve. This effectively improves the accuracy of remaining battery charge estimation, maintaining high accuracy across a wide temperature range. The fourth impedance conversion chip (AD5933) measures the internal resistance growth rate and calculates the capacity decay rate, dynamically adjusting the battery's state of health assessment threshold and extending the battery's actual service life. The fast recovery diode connected in series with the RCD snubber circuit in the main circuit not only reduces voltage spikes and spark energy during switching transients, but also significantly reduces electromagnetic interference, ensuring safe and reliable system operation.

[0044] In summary, this device realizes the transition from traditional mechanical switching to high-efficiency semiconductor switching, which not only significantly shortens the switching time and improves the response speed and stability of the system, but also extends the battery life and reduces maintenance costs through precise battery management and effective arc suppression measures.

[0045] In some embodiments of the present application, two silicon carbide MOSFET power devices are connected in parallel to form a bridge arm and are fixed on an AlN ceramic substrate through a silver sintering process, wherein the power terminals of the silicon carbide MOSFET power devices are connected with 4mm thick silver-plated copper busbars and fastened with M5 titanium alloy screws, and the torque is controlled at 2.5N·m±0.2N·m.

[0046] Specifically, first, parallel design: The primary purpose of using two SiC MOSFETs in parallel is to increase current-carrying capacity. Since a single MOSFET has limited current capacity, parallel connection effectively shares the total current, preventing damage from overloading a single device. Furthermore, parallel design improves system redundancy, ensuring that even if one MOSFET fails, the other can still maintain basic functionality.

[0047] Second, silver sintering: Silver sintering is an advanced connection technology that utilizes the fusion of silver particles under high temperature and high pressure to achieve metal-to-metal connections. Compared to traditional soldering methods, silver sintering offers higher thermal and electrical conductivity while also being able to withstand higher temperatures and mechanical stresses, ensuring a highly reliable and stable connection between the SiC MOSFET and the AlN ceramic substrate.

[0048] Aluminum nitride (AlN) ceramics are known for their excellent thermal conductivity, low dielectric constant, and good mechanical strength. Using AlN as a substrate material not only facilitates rapid heat dissipation and reduces thermal resistance, but also provides better electrical isolation, ensuring safe circuit operation.

[0049] Third, silver-plated copper busbar connections and titanium alloy screw fastening: The power terminals are connected using 4mm thick silver-plated copper busbars. The silver coating increases surface conductivity and reduces contact resistance. M5 titanium alloy screws are used for fastening, ensuring a secure and corrosion-resistant connection. Torque is controlled at 2.5N·m ± 0.2N·m, ensuring that the connection is neither overtightened, causing material damage, nor overly loose, causing poor contact.

[0050] The parallel design allows the system to handle higher currents while maintaining a compact footprint, improving overall efficiency. The silver sintering process combined with the use of an AlN ceramic substrate significantly enhances thermal conductivity, reduces the risk of hotspot formation, and extends device life. This enables the entire module to maintain stable operation even under extreme operating conditions, enhancing the system's long-term reliability. Silver-plated copper busbars and precisely controlled tightening torque ensure minimal contact resistance, further improving electrical performance and reducing energy loss.

[0051] In some embodiments of the present application, the phase error of the hardware zero-crossing detection circuit is less than 1 degree, so as to perform a smooth switching process without voltage shock.

[0052] Zero-crossing detection refers to the circuit's ability to accurately identify when an AC signal crosses zero (i.e., transitions from the positive half-cycle to the negative half-cycle, or vice versa). By precisely capturing this moment, the operation of the switching devices can be synchronized, enabling power switching to occur at the optimal timing. The LM311 comparator compares the input signal with the reference ground potential. Once a zero-crossing is detected, the corresponding logic signal is triggered. Optocoupler isolation components provide electrical isolation, preventing interference from the high-voltage side on the low-voltage control side while ensuring accurate signal transmission.

[0053] A phase error of less than 1 degree means the circuit can trigger switching very close to the actual zero-crossing point, minimizing voltage and current fluctuations caused by improper switching timing. Because switching occurs near the zero point of the voltage waveform, shocks caused by the sudden application or removal of voltage are avoided. This not only protects connected devices from damage but also reduces electromagnetic interference (EMI). Precise phase control ensures that the switching process from one power source to another is as smooth as possible, maintaining the continuity of load power supply. This is particularly important for applications with extremely high requirements for power supply stability, such as data centers and communication base stations.

[0054] In some embodiments of the present application, the pre-driver chip is configured with an on-resistance of 4.7Ω±1%, an off-resistance of 100Ω±1%, and a Miller clamp tube, wherein the BSS138MOSFET in the Miller clamp tube is connected in series with a 2.2kΩ resistor.

[0055] The on-resistance limits the gate charging current, thereby controlling the MOSFET's turn-on speed. A smaller on-resistance value speeds up the MOSFET's turn-on process, but also increases transient current and potential electromagnetic interference (EMI). The 4.7Ω value was chosen to strike a balance between fast response and reduced EMI.

[0056] A relatively large off-resistance value (100Ω) is used to slow down the MOSFET's turn-off process, helping to reduce voltage spikes and ringing caused by rapid turn-off. This not only protects the MOSFET from damage but also helps reduce EMI in the system.

[0057] The Miller effect is a significant factor affecting MOSFET switching performance, particularly under high dv / dt conditions, which can cause unintended turn-on or prolonged turn-off times. The introduction of a Miller clamp circuit provides a low-impedance path during the MOSFET's turn-off process, rapidly draining charge from parasitic capacitance and accelerating the shutdown process. The BSS138 MOSFET acts as the switching element, and its series 2.2kΩ resistor limits the current flowing through this path, preventing excessive current from damaging the MOSFET.

[0058] By fine-tuning the turn-on and turn-off resistor values, ideal switching speeds can be achieved, ensuring a fast response while effectively suppressing potential voltage spikes and EMI issues. The Miller clamp circuit significantly reduces the delay and instability caused by Miller capacitance, ensuring that the MOSFET accurately turns off within the expected timeframe, enhancing the stability and reliability of the entire system. Proper resistor configuration and Miller clamp design help reduce high-frequency noise generated during switching, making it easier for devices to meet stringent electromagnetic compatibility standards (such as CISPR 32 Class B) and facilitating normal operation in complex electromagnetic environments.

[0059] In some embodiments of the present application, the switching response time is less than 10 ns. This is a key performance indicator for the pre-driver chip in the battery-to-mains switching device used in solar charging, demonstrating the system's extremely high speed and accuracy in controlling the switching of power MOSFETs.

[0060] Specifically, the TI ISO5852S-Q1 gate driver has an isolation withstand voltage of 5kVRms and a transmission delay of 76ns±5ns. It can quickly respond to control signals and pass them to the gate of the MOSFET, ensuring extremely short switching response time.

[0061] By using an on-resistance of 4.7Ω±1% and an off-resistance of 100Ω±1%, the charging and discharging speed of the gate charge can be effectively managed. A smaller on-resistance allows more current to flow into the gate quickly, accelerating the turn-on of the MOSFET; while a larger off-resistance helps control the release rate of the gate charge, preventing voltage spikes or ringing caused by too rapid a turn-off.

[0062] The BSS138 MOSFET acts as a Miller clamp transistor, and a 2.2kΩ resistor is connected in series to provide a low-impedance path during the MOSFET shutdown process to quickly extract the charge on the parasitic capacitance, thereby speeding up the shutdown process and reducing the delay caused by the Miller capacitance.

[0063] A switching response time of less than 10ns means that the system can complete the operation from on to off or vice versa in a very short time. This is especially important for application scenarios that require fast response (such as communication base stations, data centers, etc.). It can significantly reduce the time of power interruption and improve the availability and reliability of the system. Fast and accurate switching operations reduce the risk of prolonged exposure to high voltage and reduce the possibility of equipment damage. In addition, it also helps to reduce energy loss during the switching process and improve overall efficiency. Although high-speed switching may increase electromagnetic interference (EMI), the designed pre-driver circuit (including appropriate resistance values ​​and Miller clamping circuit) can effectively suppress high-frequency noise, allowing the device to meet strict electromagnetic compatibility standards (such as IEC 61000-4-4 Level 4) and ensure stable operation in various environments.

[0064] In some embodiments of the present application, the third coulomb metering chip is suitable for combining a temperature compensation formula to perform high-precision estimation over the entire temperature range, wherein the temperature compensation formula is:

[0065] SOC_corrected=SOC_raw×[1+0.003×(T-25℃)]+0.0015×(T-25℃)2.

[0066] The BQ34Z100-R1 uses the ampere-hour integration method (also known as coulomb counting) combined with open-circuit voltage correction technology to estimate SOC. The ampere-hour integration method calculates the degree of battery charge and discharge by integrating the current over time, while the open-circuit voltage correction method makes corrections based on the relationship between the open-circuit voltage (OCV) and SOC of the battery at rest.

[0067] Battery performance is significantly affected by temperature, especially at extreme temperatures, where SOC estimation errors increase. Temperature not only affects the rate of chemical reactions within the battery but also alters its internal resistance and capacity, resulting in varying SOC performance at different temperatures.

[0068] The above formula is used to adjust the raw SOC value (SOC_raw) to take into account the effect of temperature on the battery SOC estimate. Where T represents the current battery temperature and 25°C is used as the reference temperature. The linear term (0.003×(T-25°C)) and the quadratic term (0.0015×(T-25°C)) in the formula are 2 ) work together to compensate for temperature changes and ensure the accuracy of SOC estimation in a wide temperature range.

[0069] By introducing a temperature compensation mechanism, the SOC estimation error can be significantly reduced, especially in low or high temperature environments. According to experimental data, the SOC estimation error can be controlled within ±3% within a wide temperature range of -40°C to 85°C, and the estimation accuracy in a -20°C environment reaches ±2.7%, which is far superior to traditional methods. Accurate SOC estimation helps avoid battery damage caused by overcharging or over-discharging, extends battery life, and improves the overall reliability of the system. For example, in low-light conditions such as rainy weather, accurate SOC estimation can prevent unnecessary switching to AC power and reduce misoperation. This temperature compensation strategy makes the device suitable for applications in various climatic conditions, whether in the cold north or the hot south, ensuring good performance and enhancing the product's market competitiveness.

[0070] In some embodiments of the present application, the SOC estimation error is within ±3%. High-precision SOC estimation can effectively avoid premature or late switching to the mains due to estimation errors, especially in low-light conditions such as rainy days, reducing unnecessary switching to the mains and lowering the risk of misoperation.

[0071] Accurate SOC estimation helps prevent overcharging or overdischarging of the battery, protecting its health and extending its service life. According to experimental data, this adaptive feature significantly extends the battery cycle life from the industry average of 800 times to 1200 times (tested according to IEC 61427 standard), equivalent to extending the battery service life by 50%.

[0072] A stable power management solution not only improves system reliability, but also reduces problems such as device restarts or data loss caused by unstable power supply, thereby enhancing user satisfaction.

[0073] In some embodiments of the present application, the fourth impedance conversion chip communicates with the main control MCU via a high-speed SPI interface.

[0074] The AD5933 is a high-precision impedance converter capable of performing frequency sweeps and measuring complex impedance. It is commonly used in battery state-of-health (SOH) monitoring, evaluating the battery's internal resistance growth rate and capacity decay by measuring the battery's AC impedance. The chip generates an excitation signal at a specific frequency and measures the amplitude and phase of the response signal to calculate the impedance value of the device under test.

[0075] SPI is a synchronous serial communication interface standard widely used in short-distance communications. It supports full-duplex communication and offers high-speed data transmission capabilities. In this device, data exchange between the AD5933 and the host MCU is accomplished via the high-speed SPI interface, ensuring real-time and accurate data transmission.

[0076] The communication process is as follows: the master MCU first sends initialization commands and configuration parameters to the AD5933 via the SPI interface, including settings for the starting frequency, frequency increment, and number of sweep points. Once the configuration is complete, the AD5933 begins measuring the battery impedance according to the set parameters. The measurement results (including real and imaginary components) are stored in its internal registers. The master MCU then reads these measurement data via the SPI interface. Thanks to the high-speed SPI interface, this process is extremely fast, ensuring the system's real-time responsiveness. The acquired data is further analyzed and processed in the MCU, for example, to calculate the specific impedance value, internal resistance growth rate, and estimate the battery's capacity decay rate based on pre-defined algorithms.

[0077] The high-speed SPI interface enables efficient data transmission within a short timeframe, ensuring the system can quickly respond to changes and make appropriate adjustments. This is crucial for applications that require real-time monitoring of battery health. This efficient communication mechanism reduces data transmission latency, improving overall system efficiency. Furthermore, accurate impedance measurement enables more precise assessment of battery health and extends battery life. The SPI interface is a common communication method in embedded systems. Its ease of implementation and strong compatibility simplify hardware design and software development, facilitating integration with other components.

[0078] In some embodiments of the present application, the fast recovery diode connected in series in the main circuit is of model C4D10120A, and has a reverse recovery time of 30ns;

[0079] The RCD absorption circuit includes a 10Ω / 5W pulse-resistant carbon film resistor and a 0.1μF / 1kV low-ESR film capacitor.

[0080] Specifically, the fast-recovery diode connected in series in the main circuit is the C4D10120A model, which has a reverse recovery time of only 30ns. This fast recovery characteristic means that the diode can be quickly cut off when the current switches from forward to reverse, reducing energy loss and heat generation during the reverse recovery period.

[0081] Fast recovery diodes are primarily used to prevent current backflow and protect power devices from reverse voltage damage. In high-frequency switching applications, such as the solar energy storage system used in this device, fast recovery capability is particularly important, effectively reducing switching losses and improving overall efficiency.

[0082] The RCD absorption circuit components include the following two parts:

[0083] Resistor: 10Ω / 5W pulse-resistant carbon film resistor. This resistor has the ability to withstand instantaneous high-energy pulses, absorbing a large amount of energy in a short period of time, protecting other circuit components from damage.

[0084] Capacitors: Use 0.1μF / 1kV low-ESR (equivalent series resistance) film capacitors. Low-ESR capacitors can quickly store and release energy, effectively suppressing voltage spikes and reducing electromagnetic interference (EMI) while maintaining low power consumption.

[0085] The primary function of an RCD (Remote Control Device) snubber circuit is to absorb overvoltage and ringing generated during switching, thereby protecting switching devices and other sensitive electronic components. When a switch is opened, parasitic inductance and capacitance in the circuit generate voltage spikes. The RCD circuit smoothes these voltage fluctuations by providing an energy dissipation path, preventing damage to the circuit.

[0086] The use of fast recovery diodes significantly reduces the energy loss and thermal stress caused by reverse recovery, improving system reliability and durability. At the same time, the RCD absorption circuit effectively manages the voltage peak at the switching moment, reducing the potential damage risk to power devices.

[0087] By carefully selecting the resistor and capacitor values ​​in the RCD circuit, switching losses can be minimized and electromagnetic interference can be suppressed, making the entire system more efficient and compliant with strict electromagnetic compatibility standards.

[0088] Efficient energy management and protection mechanisms not only improve equipment operating efficiency, but also extend the service life of key components by reducing the working stress and reducing maintenance costs.

[0089] In some embodiments of the present application, the battery and mains switching device under solar charging conditions includes a four-layer high-density PCB with a power loop area of ​​2 cm 2 Within.

[0090] A four-layer PCB typically consists of a top and bottom layer for signal routing, with the middle two layers serving as the power and ground planes, respectively. This layered design helps reduce electromagnetic interference (EMI) and provides better signal integrity and power distribution. The use of high-density PCB materials allows for finer trace widths and spacing, enabling the integration of more functional components within a limited space while maintaining low parasitic parameters.

[0091] Concentrating critical power loops (such as current paths and switching elements) within a smaller area significantly reduces parasitic inductance and resistance, improving efficiency and reducing energy losses. A smaller power loop area means heat is concentrated in a relatively small region, making it easier to employ localized heat dissipation measures (such as heat sinks or cooling systems) to ensure efficient heat dissipation and maintain device operating temperatures within a safe range.

[0092] The compact power circuit design reduces parasitic inductance and capacitance, improving system response speed and stability. The four-layer PCB design effectively isolates the signal and power layers, reducing electromagnetic interference and ensuring signal transmission purity. Due to the small power circuit area, heat generated is relatively concentrated, facilitating targeted cooling measures to ensure stable system operation under high load conditions. The rational layout ensures more even heat distribution, avoiding localized hot spots and extending the life of electronic components. By optimizing the PCB layout and reducing the power circuit area, high-frequency noise and radiation are reduced, making it easier for the system to meet stringent electromagnetic compatibility standards (such as CISPR 32 Class B). The ground and power layers in the four-layer PCB provide excellent shielding, further minimizing the impact of external electromagnetic interference on the system. The four-layer high-density PCB design makes the entire device more compact, facilitating miniaturization and adapting to a wider range of application scenarios. Compared to traditional designs, this solution achieves lightweight equipment while maintaining high performance, making installation and maintenance easier.

[0093] Anything not described in this application can be achieved by adopting or drawing on existing technologies.

[0094] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0095] The foregoing is merely an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included in the protection scope of the present application.

Claims

1. A device for switching between a battery and mains electricity in the case of solar charging, characterized in that: include: A power conversion module, wherein the power conversion module includes a silicon carbide MOSFET power device, wherein the silicon carbide MOSFET power device has a blocking voltage of 900V and an on-state resistance of 65mΩ; A hardware zero-crossing detection circuit, comprising a first comparator and an optocoupler isolation element for phase detection; A pre-driver chip, the pre-driver chip including a second gate driver, wherein the pre-driver chip has an isolation withstand voltage of 5kVRms and a transmission delay of 76ns±5ns; The third coulomb metering chip is used to combine ampere-hour integration and open-circuit voltage correction technology to estimate SOC. Among them, it automatically enters the static mode for 15 minutes every 24 hours, during which time the SOC-OCV characteristic curve is fitted using the least squares method; The fourth impedance conversion chip is used to measure the internal resistance growth rate and calculate the capacity attenuation rate; The main circuit includes a fast recovery diode connected in series and an RCD absorption circuit.

2. The battery and mains switching device for solar charging according to claim 1, characterized in that: The two silicon carbide MOSFET power devices are connected in parallel to form a bridge arm and fixed on an AlN ceramic substrate through a silver sintering process. The power terminals of the silicon carbide MOSFET power devices are connected with 4mm thick silver-plated copper busbars and fastened with M5 titanium alloy screws, with the torque controlled at 2.5N·m±0.2N·m.

3. The battery and mains switching device for solar charging according to claim 1, characterized in that: The phase error of the hardware zero-crossing detection circuit is less than 1 degree, so as to perform a smooth switching process without voltage shock.

4. The battery and mains switching device for solar charging according to claim 1, characterized in that: The pre-driver chip is configured with an on-resistor with a resistance of 4.7Ω±1%, an off-resistor with a resistance of 100Ω±1%, and a Miller clamp tube, wherein the BSS138 MOSFET in the Miller clamp tube is connected in series with a 2.2kΩ resistor.

5. The battery and mains switching device for solar charging according to claim 4, characterized in that: The switching response time is less than 10ns.

6. The battery and mains switching device for solar charging according to claim 1, characterized in that: The third coulomb metering chip is suitable for performing high-precision estimation over the entire temperature range in combination with a temperature compensation formula, wherein the temperature compensation formula is: SOC_corrected=SOC_raw×[1+0.003×(T-25℃)]+0.0015×(T-25℃)2.

7. The battery and mains switching device for solar charging according to claim 6, characterized in that: The SOC estimation error is within ±3%.

8. The battery and mains switching device for solar charging according to claim 1, characterized in that: The fourth impedance conversion chip communicates with the main control MCU via a high-speed SPI interface.

9. The battery and mains switching device for solar charging according to claim 1, characterized in that: The fast recovery diode connected in series in the main circuit is model C4D10120A, and its reverse recovery time is 30ns; The RCD absorption circuit includes a 10Ω / 5W pulse-resistant carbon film resistor and a 0.1μF / 1kV low ESR film capacitor.

10. The battery and mains switching device for solar charging according to claim 1, characterized in that: The battery and mains switching device under the solar charging condition includes a four-layer high-density PCB with a power loop area of ​​2cm 2 Within.

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