De-rating control method and energy storage device

Abstract

The application discloses a derating control method and an energy storage device. The derating control method comprises the following steps: acquiring a current air pressure and a current ambient temperature; determining an inverter allowable power, a battery allowable power and a control module allowable power respectively according to the current air pressure and the ambient temperature; taking the minimum value among the three as the upper limit of the system output power; and controlling the energy storage device to operate at an output power less than the upper limit. The application simultaneously takes the inverter, the battery and the control module into the derating decision, adopts a short board constraint mechanism, and dynamically calculates the allowable powers based on a physical model chain of the air pressure, the altitude, the air density and the convective heat transfer capacity, while setting an early derating strategy for the control module, so that the problem that other modules fail before a single module in a high-altitude and high-temperature environment is effectively solved, and the safety and reliability of the energy storage device in a harsh environment are improved.

Description

Technical Field

[0001] This invention relates to energy storage technology, and in particular to a derating control method and an energy storage device. Background Technology

[0002] Energy storage devices typically consist of batteries, control modules, and inverters. The control module includes a battery management system (BMS) and a mainboard. In harsh environments such as high altitudes and high temperatures, reduced air density leads to decreased heat dissipation, necessitating a reduction in the rated output power of the energy storage device (derating) to prevent overheating and thermal runaway. In related technologies, since the inverter is the primary heat source, derating primarily considers the inverter, simply reducing its output power based on ambient temperature or altitude. However, in actual operation, when the battery pack's internal resistance increases or its state of charge (SOC) is low, its permissible charge / discharge power may reach its limit before the inverter. While the BMS or mainboard generates relatively little heat, deteriorating heat dissipation conditions can cause their temperature to rise, leading to decreased sampling accuracy, malfunctioning protection logic, or even system crashes. Summary of the Invention

[0003] This application provides a derating control method and an energy storage device.

[0004] The derating control method for energy storage devices according to embodiments of this application includes: Get the current air pressure and current ambient temperature; Based on the current air pressure and the current ambient temperature, determine the allowable power of the inverter, the allowable power of the battery, and the allowable power of the control module; The upper limit of system output power is determined based on the allowable power of the inverter, the allowable power of the battery, and the allowable power of the control module; and The energy storage device is controlled to operate at an output power lower than the upper limit of the system output power.

[0005] The derating control method of this application incorporates the three core components—inverter, battery, and control module—into the derating decision-making process simultaneously, with the system output power limit constrained by the allowable power of all three. Therefore, when the battery's allowable power is limited due to low state of charge, increased internal resistance, or abnormal temperature, or when the control module needs to reduce power due to deteriorating heat dissipation, the energy storage device can automatically use the most stringent limit among the three as the output upper limit. This avoids situations where the inverter can still output power but the battery or control module has already reached its safety limit, significantly reducing the risk of unexpected downtime or hardware damage, and improving the operational reliability and safety of the energy storage device in harsh environments such as high altitudes and high temperatures.

[0006] In some implementations, determining the inverter's allowable power, the battery's allowable power, and the control module's allowable power includes: Calculate the current altitude based on the current air pressure; Calculate the current air density based on the current altitude. Based on the current air density, the current ambient temperature, and the current fan speed of the energy storage device, the convective heat transfer capacity is estimated; and The allowable power of the inverter is determined based on the convective heat transfer capacity, the heat dissipation area of ​​the energy storage device, and the difference between the maximum allowable temperature of the inverter of the energy storage device and the current ambient temperature.

[0007] Thus, the derating control method of this application calculates air density and convective heat transfer capacity in real time, enabling the inverter's allowable power to change continuously and dynamically with altitude, ambient temperature and fan speed, eliminating the inaccuracy of derating caused by discrete jumps.

[0008] In some implementations, determining the allowable power of the inverter includes: The maximum heat that the inverter can safely dissipate under the current environment is calculated based on the convective heat transfer capacity, the heat dissipation area, and the difference to obtain the initial allowable power of the inverter.

[0009] The allowable power of the inverter is obtained by adjusting the initial allowable power of the inverter downward based on the current actual temperature of the inverter.

[0010] The derating control method of this application uses the current actual temperature of the inverter to adjust the allowable power downwards. This can further limit the power of the inverter when it is already overheated, preventing the inverter from continuing to operate at high power even when environmental conditions allow but its own temperature is already high. This achieves precise and dynamic inverter derating, avoiding both insufficient derating leading to overheating and excessive derating causing power waste.

[0011] In some implementations, determining the inverter's allowable power, the battery's allowable power, and the control module's allowable power includes: Calculate the current altitude based on the current air pressure; Calculate the current air density based on the current altitude. The convective heat transfer capacity is estimated based on the current air density, the current ambient temperature, and the current rotational speed of the fan in the energy storage device. The thermal constraint power limit of the battery of the energy storage device is determined based on the convective heat transfer capacity. The upper limit of the electrical constraint power of the battery is determined based on the battery's current state of charge, current voltage, and current temperature. The allowable power of the battery is determined based on the upper limit of the thermal constraint power and the upper limit of the electrical constraint power.

[0012] The derating control method of this application considers both the thermal and electrochemical constraints of the battery. The upper limit of the thermal constraint power is calculated using a physical chain of air pressure, altitude, air density, and convective heat transfer capacity. The upper limit of the electrical constraint power is calculated by combining the battery's state of charge, voltage, and temperature. This ensures that the battery's allowable power comprehensively reflects the dual limitations of the heat dissipation environment and the battery's own state, preventing overheating or damage due to insufficient heat dissipation or electrochemical limits, and maximizing the battery's usable power while ensuring safety.

[0013] In some embodiments, determining the allowable battery power based on the thermally constrained power limit and the electrically constrained power limit includes: The minimum value between the thermal constraint power limit and the electrical constraint power limit is taken as the allowable power of the battery.

[0014] The derating control method of this application explicitly takes the minimum value between the thermal constraint power limit and the electrical constraint power limit as the battery's allowable power. This bottleneck decision ensures that the battery's allowable power is determined by the more stringent constraint under any operating condition, preventing misjudgments caused by conflicts between the thermal and electrical boundaries, and further improving battery safety.

[0015] In some implementations, determining the inverter's allowable power, the battery's allowable power, and the control module's allowable power includes: Obtain the current temperature of the control module of the energy storage device; If the current temperature is lower than the first temperature threshold, the power allowed by the control module is set to infinity; When the current temperature is greater than or equal to the first temperature threshold and less than the second temperature threshold, the control module allows the power to gradually decrease at a first rate as the current temperature increases, wherein the first rate is greater than the rate at which the inverter's allowed power and the battery's allowed power decrease within the same temperature range; If the current temperature is greater than or equal to the second temperature threshold, the power allowed by the control module is set to zero.

[0016] The derating control method of this application sets two temperature thresholds for the control module. Derating is performed in advance between these thresholds at a faster rate. Once the second threshold is exceeded, output is forcibly limited. By setting two thresholds lower than the traditional high-temperature shutdown threshold, preventative protection for the control module is achieved. The output power of the energy storage device is proactively reduced while the control module temperature is still relatively low, and the derating rate is higher than that of the inverter and battery. This provides sufficient safety margin for the control module, preventing its temperature from rising further to dangerous levels. This effectively prevents sampling errors, logic disturbances, or system crashes caused by overheating of the control module, thus improving the reliability of the entire energy storage device from the control system level.

[0017] In some implementations, determining the upper limit of the system output power based on the inverter's allowable power, the battery's allowable power, and the control module's allowable power includes: The minimum value among the inverter's allowable power, the battery's allowable power, and the control module's allowable power is taken as the upper limit of the system's output power.

[0018] The derating control method of this application explicitly uses the minimum of the three allowable power values ​​as the upper limit of the system output power. By using the minimum value decision rule, the allowable power of the three core components is uniformly incorporated into the weakest link constraint mechanism, ensuring that the output power of the energy storage device does not exceed the safety tolerance of the weakest link at any time. This eliminates conflicts and blind spots between the independent limits of each module, fundamentally avoiding unexpected protection or hardware failures caused by one module reaching its limit before other modules, and achieving collaborative safety at the energy storage device level.

[0019] In some implementations, it also includes: Calculate the current altitude based on the current air pressure; Calculate the current air density based on the current altitude. The target rotational speed of the fan in the energy storage device is adjusted according to the current air density, wherein the lower the current air density, the higher the target rotational speed.

[0020] The derating control method of this application dynamically adjusts the target speed of the fan based on the current air density; the lower the air density, the higher the speed, thereby actively compensating for the decrease in convective heat transfer capacity caused by the thin air at high altitudes. This compensation mechanism improves heat dissipation performance within the fan's capacity range, reduces unnecessary power derating due to insufficient heat dissipation, and increases the usable output power in high-altitude environments.

[0021] In some embodiments, adjusting the target rotational speed of the fan in the energy storage device based on the current air density includes: Determine the current noise and current power consumption of the fan; If the current noise level is greater than or equal to a predetermined noise limit or the current power consumption is greater than or equal to a predetermined power consumption limit, the target rotational speed shall be stopped from being increased.

[0022] The derating control method of this application monitors the current noise and power consumption in real time during fan speed adjustment, and stops increasing the speed when the noise or power consumption reaches a preset upper limit. This limitation avoids acoustic pollution or fan motor overheating caused by blindly increasing the speed, and achieves a balanced optimization between fan compensation and derating strategies, obtaining a reasonable trade-off between heat dissipation capacity, user experience and hardware lifespan.

[0023] In some implementations, it also includes: Determine the air thinning factor based on the current altitude; Determine the temperature difference influence factor based on the current ambient temperature; The product of the air thinning effect factor and the temperature difference effect factor is used as the depreciation coefficient; The derating factor is used to correct at least one of the allowable power of the inverter, the allowable power of the battery, or the allowable power of the control module.

[0024] The derating control method of this application decomposes the derating coefficient into the product of an air rarefaction factor and a temperature difference factor. The air rarefaction factor characterizes the weakening of heat-carrying capacity due to decreased air density, while the temperature difference factor characterizes the reduction in heat dissipation driving force due to increased ambient temperature. The product of the two has a clear physical meaning, independently reflecting two components of heat dissipation capacity. This multiplicative decomposition method allows for flexible adjustment of the calculation models of each factor in derating control, facilitating optimization according to different environmental conditions. It also simplifies the calibration process of the derating coefficient and improves the versatility and scalability of the control method.

[0025] This application provides an energy storage power supply, including: a battery, an inverter, a control module, and a controller, wherein the controller is used to execute the derating control method.

[0026] Thus, the derating control method of this application incorporates the three core components—inverter, battery, and control module—into the derating decision simultaneously, with the system output power limit constrained by the allowable power of all three. Consequently, when the battery's allowable power is limited due to low state of charge, increased internal resistance, or abnormal temperature, or when the control module needs to reduce power due to deteriorating heat dissipation, the energy storage device can automatically use the most stringent limit among the three as the output upper limit. This avoids situations where the inverter can still output power but the battery or control module has already reached its safety limit, significantly reducing the risk of unexpected downtime or hardware damage, and improving the operational reliability and safety of the energy storage device in harsh environments such as high altitudes and high temperatures. Attached Figure Description

[0027] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, wherein: Figure 1 This is a flowchart of a derating control method according to certain embodiments of this application; Figure 2 This is a perspective view of an energy storage device according to certain embodiments of this application; Figure 3 This is a cross-sectional schematic diagram of an energy storage device according to certain embodiments of this application; Figure 4 This is a perspective view of an energy storage device according to certain embodiments of this application with its outer casing removed; Figure 5 This is a functional block diagram of an energy storage device according to certain embodiments of this application; Figure 6-14 This is a flowchart illustrating a frequency reduction control method according to certain embodiments of this application.

[0028] Explanation of main component symbols Energy storage device 10, battery 11, inverter 12, control module 13, battery management system 131, motherboard 132, controller 14, barometric pressure sensor 15, temperature sensor 16, fan 17, housing 18, air inlet 181, air outlet 182, air duct 183 Detailed Implementation The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the embodiments of this application, and should not be construed as limiting the embodiments of this application.

[0029] In the field of portable or stationary energy storage technology, energy storage devices refer to devices capable of storing electrical energy and outputting it when needed, such as outdoor emergency power supplies and household backup power supplies. These energy storage devices typically include three core components: a battery, a control module, and an inverter. The battery stores direct current (DC) energy; the inverter converts the DC output from the battery into alternating current (AC) for use by the power grid or AC loads; and the control module monitors and manages the operating status of the energy storage device.

[0030] The control module specifically includes a Battery Management System (BMS) and a mainboard. The BMS is an electronic control unit used to monitor the battery's voltage, current, temperature, and state of charge (SOC) in real time, and to perform functions such as overcharge protection, over-discharge protection, overcurrent protection, and temperature protection. The mainboard is the central control unit of the energy storage device, responsible for coordinating the operating logic of the inverter, BMS, and other auxiliary modules.

[0031] At high altitudes or in high-temperature environments, air density decreases significantly. Air density refers to the mass contained in a unit volume of air, and its value decreases with increasing altitude or temperature. This decrease in air density leads to reduced heat dissipation capacity, meaning less heat can be carried away by air convection per unit time. To prevent thermal runaway of energy storage devices due to overheating, derating control measures are required. Derating control refers to actively limiting the actual output power of energy storage devices to a value lower than their rated output power. Rated output power refers to the maximum power that an energy storage device can safely and stably output over a long period under standard environmental conditions (typically sea-level air pressure and an ambient temperature of 25°C). Thermal runaway refers to a state where the internal temperature of the device continuously rises due to insufficient heat dissipation or excessive heat generation, becoming unstable and potentially leading to equipment damage or safety accidents.

[0032] In existing technologies, derating control primarily targets the inverter, meaning it only reduces the inverter's output power based on ambient temperature or altitude. However, in actual operation, when the battery pack's internal resistance increases or its state of charge (SOC) is low, its permissible charging and discharging power may reach its limit before the inverter. Internal resistance refers to the resistance within the battery to current flow, and its value increases with battery aging or temperature decreases. State of charge (SOC) represents the percentage of current remaining charge compared to the battery's capacity when fully charged. When internal resistance increases or SOC is low, the battery itself limits its charging and discharging power to prevent accelerated aging or triggering electrical protection.

[0033] Furthermore, although the BMS and motherboard in the control module generate far less heat than the inverter, their temperature can still rise under deteriorating heat dissipation conditions, leading to decreased sampling accuracy, malfunctioning protection logic, or even system crashes. Sampling accuracy refers to the deviation between the sensor's measured value and the true value. As temperature rises, the reference voltage of electronic components drifts, and noise increases, thus reducing sampling accuracy. Malfunctioning protection logic refers to the protection circuit incorrectly triggering protection when preset protection conditions are not met, such as misinterpreting overcurrent or overtemperature and cutting off the output. System crashes occur when the processor or logic circuit of the control module stops responding due to excessive temperature or abnormal voltage, causing the entire energy storage device to malfunction.

[0034] Please see Figure 1In view of this, this application provides a derating control method, including: S11: Obtain the current air pressure and current ambient temperature; S12: Determine the inverter's allowable power, the battery's allowable power, and the control module's allowable power based on the current air pressure and the current ambient temperature; S13: Determine the upper limit of system output power based on the allowable power of the inverter, the allowable power of the battery, and the allowable power of the control module; and S14: Control the energy storage device to operate at an output power lower than the upper limit of the system output power.

[0035] Please see Figure 2-5 This application also provides an energy storage device 10 including a battery 11, an inverter 12, a control module 13, and a controller 14. The controller 14 is used to execute a derating control method.

[0036] To facilitate understanding of the derating control method of the embodiments of this application, the following discussion will take the implementation of the derating control method by the energy storage device 10 of the embodiments of this application as an example. Of course, the derating control method of the embodiments of this application is not limited to being implemented by the energy storage device 10, but can be implemented by other suitable devices in other embodiments, such as a dedicated device independent of the energy storage device 10.

[0037] To better understand the derating control method of the embodiments of this application, the energy storage device 10 of the embodiments of this application will be introduced below.

[0038] Battery 11 is used to store electrical energy. Battery 11 can be a lithium-ion battery, a lithium iron phosphate battery, a ternary lithium battery, or other chemical energy storage units. Its rated output power (e.g., 1000W) is calibrated under standard environmental conditions.

[0039] Inverter 12 is electrically connected to battery 11 and is used to convert direct current to alternating current. Inverter 12 can be a pure sine wave inverter or a modified sine wave inverter, and it integrates power switching transistors (such as IGBTs or MOSFETs) and drive circuitry.

[0040] The control module 13 includes a battery management system 131 and a main board 132. The battery management system 131 is electrically connected to the battery 11 and is used to monitor the status of the battery 11 and perform protection. The main board 132 is electrically connected to the inverter 12, the battery management system 131, and the controller 14 and is used to coordinate the operation of each module.

[0041] The controller 14 can be a standalone chip (such as an STM32 series MCU), a processor integrated into the battery management system 131, or a main control chip integrated on the motherboard 132. It can also be implemented by the battery management system 131 and the motherboard 132 together.

[0042] In addition, the energy storage device 10 also includes a pressure sensor 15, a temperature sensor 16, a fan 17, and a housing 18. The housing 18 has an air inlet 181, an air outlet 182, and an air duct 183 that communicates with the outside of the housing 18 through the air inlet 181 and the air outlet 182.

[0043] A barometric pressure sensor 15 is located near the air inlet 181 to detect ambient air pressure. The barometric pressure sensor 15 can be a MEMS piezoresistive sensor or a capacitive sensor, and outputs a digital or analog barometric pressure signal to the controller 14.

[0044] Temperature sensor 16 is located inside housing 18 near air inlet 181 and is used to detect ambient temperature. Temperature sensor 16 can be a thermistor, thermocouple, or integrated temperature sensor chip (such as DS18B20).

[0045] The barometric pressure sensor 15 is used to detect the current barometric pressure of the environment where the energy storage device 10 is located. The temperature sensor 16 is used to detect the current ambient temperature.

[0046] Fan 17 is installed inside air duct 183 and is used for air cooling of inverter 12 and control module 13. Fan 17 can be an axial fan or a centrifugal fan, and its speed is adjusted by controller 14 via PWM signal.

[0047] The controller 14 is electrically connected to the pressure sensor 15, temperature sensor 16, fan 17, battery management system 131, inverter 12 and motherboard 132.

[0048] In step S11, the controller 14 collects the current atmospheric pressure value in real time through the barometric pressure sensor 15, denoted as P. The controller 14 collects the current ambient temperature value in real time through the temperature sensor 16, denoted as T_env.

[0049] As an alternative implementation, in some embodiments, the energy storage device 10 may omit the independent barometric pressure sensor 15 and instead use a GPS module to obtain the altitude, then calculate the barometric pressure using a standard atmospheric model. If the energy storage device 10 has a wireless communication module (e.g., 4G, 5G, Wi-Fi, or Bluetooth), the controller 14 can also obtain the current altitude or meteorological data online from a meteorological server or mobile terminal via the wireless communication module, and then calculate or obtain the current barometric pressure and ambient temperature. For example, after obtaining the current altitude from the network, the controller 14 uses a standard atmospheric model to infer the barometric pressure; or it can directly obtain real-time barometric pressure and temperature data published by a meteorological station. The energy storage device 10 can communicate with a mobile APP, allowing the user to manually input the current altitude, and the controller 14 can calculate the barometric pressure accordingly. In other embodiments, the temperature sensor 16 can be integrated inside the controller 14 (e.g., a temperature sensor built into the MCU) to measure the temperature near the controller 14 and estimate the ambient temperature using a thermal model.

[0050] In step S12, the controller 14 calculates three independent safety constraint values ​​based on the acquired current air pressure P and current ambient temperature T_env: The inverter's allowable power P_inv_lim is the maximum power that inverter 12 is allowed to output under the current environment; The battery's allowable power P_bat_lim is the maximum power that battery 11 is allowed to output under the current environment; and The allowable power P_ctrl_lim of the control module is the maximum power that the control module 13 is allowed to output under the current environment. The calculation methods for the above three allowable powers are detailed in subsequent embodiments. It should be noted that the calculation of the three allowable powers can be performed in parallel or in sequence, and this application does not limit their execution order.

[0051] In step S13, the controller 14 determines the upper limit of the system output power P_sys_lim based on the inverter's allowed power P_inv_lim, the battery's allowed power P_bat_lim, and the control module's allowed power P_ctrl_lim.

[0052] In step S14, the controller 14 sends a power limiting command to the inverter 12, ensuring that the actual output power P_out of the inverter 12 always satisfies P_out ≤ P_sys_lim. In specific implementations, the controller 14 can use pulse width modulation (PWM) or digital control to adjust the output voltage and current of the inverter 12 in real time, thereby limiting the output power below the system output power upper limit P_sys_lim. When environmental conditions or equipment status change (e.g., altitude decreases, ambient temperature drops, module temperature falls), the controller 14 dynamically updates the system output power upper limit P_sys_lim.

[0053] As an alternative implementation, the controller 14 can also send the system output power limit P_sys_lim to the motherboard 132, which will coordinate the power output of the inverter 12; or the battery management system 131 can autonomously limit the discharge current of the battery 11 according to the battery's allowable power, while the inverter 12 limits its output according to its own allowable power.

[0054] The derating control method or energy storage device of this application incorporates the three core components—inverter 12, battery 11, and control module 13—into the derating decision simultaneously, with the system output power limit constrained by the allowable power of all three. Therefore, when the battery 11 limits its allowable power due to low state of charge, increased internal resistance, or abnormal temperature, or when the control module 13 needs to reduce power due to deteriorating heat dissipation, the energy storage device 10 can automatically use the most stringent limit among the three as the output limit. This avoids situations where the inverter 12 can still output power, but the battery 11 or control module 13 has already reached its safety limit, significantly reducing the risk of unexpected shutdowns or hardware damage, and improving the operational reliability and safety of the energy storage device 10 in harsh environments such as high altitudes and high temperatures.

[0055] Please see Figure 6 In some implementations, step S12 includes: S121: Calculate the current altitude h based on the current air pressure P; S122: Calculate the current air density rho based on the current altitude h; S123: Estimate the convective heat transfer capacity hc based on the current air density rho, the current ambient temperature T_env, and the current rotational speed n_fan of fan 17; and S124: Determine the inverter's allowable power P_inv_lim based on the convective heat transfer coefficient hc, the heat dissipation area A_inv of the energy storage device 10, and the difference delta_T_inv between the maximum allowable temperature T_inv_max of the inverter 12 and the current ambient temperature T_env.

[0056] The derating control method of this application calculates the air density rho and the convective heat transfer coefficient hc in real time, enabling the inverter's allowable power P_inv_lim to change continuously and dynamically with altitude h, ambient temperature T_env, and fan speed n_fan, eliminating the inaccuracy of derating caused by discrete jumps. Specifically, the method uses a standard atmospheric model to calculate the altitude h from the air pressure P, obtains the air density rho based on the exponential decay model, estimates hc using empirical correlations for convective heat transfer, and finally calculates the maximum safe output power of the inverter 12 under the current environment based on the heat balance equation P_inv_lim = eta_inv * hc * A_inv * (T_inv_max - T_env) (where eta_inv is the inverter efficiency). This physical model chain avoids insufficient or excessive derating caused by fixed lookup table methods or discrete threshold methods, thus balancing the inverter's thermal safety and usable power in harsh environments such as high altitude and high temperature.

[0057] In step S121, the controller 14 acquires the current atmospheric pressure value P (unit: kPa) via the barometric pressure sensor 15. The controller 14 internally stores a standard atmospheric pressure model, typically employing the International Standard Atmosphere (ISA) formula. Specifically, the controller 14 calculates the current altitude h (unit: m) according to the following relationship: h = 44330 * [1 - (P / P0)^0.1903] Where P0 is the standard atmospheric pressure at sea level, with a value of 101.325 kPa. This formula reflects the physical law that air pressure decreases nonlinearly with increasing altitude. Controller 14 obtains the value of h through mathematical operations (e.g., looking up a table combined with linear interpolation or directly calculating a power function). The calculated h can be an integer or a floating-point number, and its precision affects the accuracy of subsequent air density calculations.

[0058] As an alternative implementation, if the energy storage device 10 is equipped with a GPS module (not shown in the figure), the controller 14 can also directly obtain the current altitude h from the GPS module, thus omitting the barometric pressure conversion step. If the energy storage device 10 obtains meteorological data (including altitude) of its current location from the Internet via a wireless communication module (e.g., 4G, 5G, Wi-Fi, or Bluetooth module), the controller 14 can also directly obtain h. In another alternative implementation, when the barometric pressure sensor 15 fails or has insufficient accuracy, the controller 14 can prompt the user to manually input the current altitude via a mobile app, and use this as the value of h.

[0059] In step S122, the controller 14 calculates the air density rho (unit: kg / m³) in the current environment based on the altitude h obtained in step S121. Air density decreases exponentially with increasing altitude, and its calculation formula can be obtained using the standard atmospheric density model: rho = rho0 * exp(-k * h) Where rho0 is the standard sea-level air density, taken as 1.225 kg / m³ (corresponding to 15℃); k is the density attenuation coefficient, ranging from 1.0e-4 to 2.0e-4 m. - ¹, In this embodiment, k = 1.3e-4 m - ¹. Controller 14 calculates rho using an exponential function.

[0060] It should be noted that air density is also affected by ambient temperature. In a more precise implementation, controller 14 can introduce a temperature correction factor, modifying the above formula to: rho = rho0 * ( (273.15 + T_ref) / (273.15 + T_env) ) * exp(-k * h) Where T_ref is the standard reference temperature (usually 15℃), and T_env is the current ambient temperature (unit: ℃) obtained in step S11. The controller 14 corrects the air density in real time based on the current ambient temperature T_env to improve the accuracy of subsequent calculations.

[0061] As an alternative implementation, the controller 14 can pre-store an altitude-air density lookup table (e.g., one data point per 100 meters) and obtain rho by looking up the table and linear interpolation, thereby avoiding real-time calculation of the exponential function and reducing the computational load on the controller 14. Another alternative implementation is that the controller 14 directly measures the air density using a density sensor (not shown) located at the air inlet 181 of the energy storage device 10.

[0062] In step S123, the controller 14 estimates the convective heat transfer coefficient hc (unit: W / (m²·K)) based on the air density rho obtained in step S122, the current ambient temperature T_env obtained in step S11, and the current fan speed n_fan (unit: rpm) obtained through the drive feedback of the fan 17. The convective heat transfer coefficient characterizes the heat density that air convection can carry away per unit temperature difference.

[0063] Controller 14 uses the following empirical correlation formula to estimate hc: hc = C * (rho * v)^beta Where v is the wind speed generated by fan 17 (unit: m / s), which is proportional to the fan speed n_fan, i.e., v = alpha * n_fan, where alpha is the conversion coefficient determined by the fan structure (which can be calibrated experimentally). C is a constant related to the geometry of the radiator, and beta is the heat transfer index, ranging from 0.4 to 0.6. In this embodiment, beta = 0.5 (i.e., a square root relationship). Controller 14 calculates v based on the current n_fan and then substitutes it into the above formula to obtain hc.

[0064] For simplicity, controller 14 can also directly use a simplified model that includes air density and fan speed: hc = hc0 * (rho / rho0) * (n_fan / n_fan0)^beta Where hc0 is the reference convective heat transfer coefficient at sea level and standard rotational speed, n_fan0 is the reference rotational speed, and rho0 is the standard air density. This simplified model avoids calculating wind speed and directly uses the rotational speed ratio and density ratio for scaling.

[0065] In an alternative implementation, the current rotational speed n_fan of the fan 17 can be obtained by a Hall sensor or back EMF detection. If the fan 17 is a variable-speed fan, the controller 14 can directly read its PWM duty cycle and convert it into rotational speed. If the energy storage device 10 is not equipped with a speed sensor, the controller 14 can default to the fan 17 operating at its rated speed, in which case n_fan takes a constant value.

[0066] Another alternative implementation is that the controller 14 infers the convective heat transfer coefficient based on the real-time temperature rise rate of the inverter 12, for example by briefly changing the fan speed and observing the rate of temperature change to identify hc online.

[0067] In step S124, the controller 14 calculates the maximum heat that the inverter 12 can safely dissipate under the current environment based on the convective heat transfer coefficient hc obtained in step S123, the heat sink area A_inv (unit: m², this value is a fixed parameter of structural design and is pre-stored in the memory of the controller 14), and the difference delta_T_inv between the maximum allowable temperature T_inv_max (unit: ℃, determined by the power device datasheet of the inverter 12) and the current ambient temperature T_env. This calculation yields the allowable power P_inv_lim (unit: W) of the inverter. The difference delta_T_inv is defined as: delta_T_inv = T_inv_max - T_env According to the principle of thermal balance, the heat Q_inv (unit: W) generated by inverter 12 must be equal to its heat dissipation, that is: Q_inv = hc * A_inv * delta_T_inv Under steady-state conditions, there is a linear relationship between the output power P_inv and the heat generation Q_inv of inverter 12, i.e., P_inv = eta_inv * Q_inv, where eta_inv is the efficiency of inverter 12 (typically close to 0.9 to 0.95). Therefore, the formula for controller 14 to calculate the allowable power of the inverter is: P_inv_lim = eta_inv * hc * A_inv * delta_T_inv Ignoring efficiency variations, controller 14 can directly use P_inv_lim = K * hc * delta_T_inv, where K = eta_inv * A_inv is the global coefficient, which can be obtained through experimental calibration.

[0068] In the above calculation steps, all parameters are known or estimated, and the controller 14 can obtain the value of P_inv_lim through arithmetic operations.

[0069] It should be noted that the above P_inv_lim is a theoretical upper limit considering only the ambient heat dissipation capacity. In actual operation, if the current temperature T_inv_cur of the inverter 12 is higher than the ambient temperature but has not yet reached T_inv_max, the controller 14 can further reduce P_inv_lim (for example, according to the linear derating function), please refer to the following text.

[0070] In some implementations, the heat dissipation area A_inv in step S124 may not be the area of ​​the inverter 12 alone, but rather the overall effective heat dissipation area including the inverter 12 and its heat sink. This area can be calibrated by thermal simulation or experimental measurement before leaving the factory and is stored in the memory unit of the controller 14.

[0071] Another alternative implementation is that the controller 14 does not calculate P_inv_lim separately, but instead combines it with the calculation of the battery's allowable power P_bat_lim and the control module's allowable power P_ctrl_lim. For example, the controller 14 first calculates a "maximum allowable total heat dissipation power" based on the ambient heat dissipation capacity, and then allocates the power limit according to the heat dissipation ratio of each module. However, this method is more complex and is not preferred.

[0072] Please see Figure 7 In some embodiments, step S124 further includes: Step S1241: Based on the convective heat transfer coefficient hc, the heat dissipation area A_inv, and the difference delta_T_inv, calculate the maximum heat Q_inv_max that the inverter 12 can safely dissipate under the current environment, and then obtain the initial allowable power P_inv_initial of the inverter.

[0073] Step S1242: Based on the current actual temperature T_inv_cur of the inverter 12, the initial allowable power P_inv_initial of the inverter is adjusted downward to obtain the allowable power P_inv_lim of the inverter.

[0074] The derating control method of this application uses the current actual temperature T_inv_cur of the inverter to adjust the allowable power downward. This can further limit the power of the inverter 12 when it is already overheated, preventing the inverter 12 from continuing to operate at high power even when environmental conditions allow but its own temperature T_inv_cur is already high. This achieves precise and dynamic inverter derating, avoiding both insufficient derating leading to overheating and excessive derating causing power waste.

[0075] In step S1241, the controller 14, based on the convective heat transfer coefficient hc (unit: W / (m²·K)) obtained in step S123, the heat dissipation area A_inv (unit: m²) used in step S124, and the temperature difference delta_T_inv = T_inv_max - T_env (unit: ℃), first calculates the maximum heat Q_inv_max (unit: W) that the inverter 12 can safely dissipate under the current environment. This is based on the principle of thermal balance. Q_inv_max = hc * A_inv * delta_T_inv Then, controller 14 multiplies Q_inv_max by the efficiency eta_inv of inverter 12 to obtain the initial allowable power P_inv_initial of the inverter (unit: W): P_inv_initial = eta_inv * Q_inv_max = eta_inv * hc * A_inv * delta_T_inv The inverter's initial allowable power P_inv_initial is the theoretical maximum power that inverter 12 can output when only considering the ambient heat dissipation capacity, without taking into account the influence of the inverter 12's current temperature.

[0076] In step S1242, the controller 14 obtains the current actual temperature T_inv_cur of the inverter 12 through a temperature sensor (e.g., an NTC thermistor, not shown in the figure, but readable via the motherboard 132 or a separate channel) located on the power module of the inverter 12. The controller 14 internally stores a linear derating function, typically in the following form: P_inv_lim = P_inv_initial * f(T_inv_cur) Where f(T_inv_cur) is the temperature correction factor. In one implementation, when T_inv_cur is lower than the initial derating temperature T_inv_start (e.g., 80°C), f(T_inv_cur) = 1, i.e., no correction is applied; when T_inv_cur is between T_inv_start and the maximum allowable temperature T_inv_max (e.g., 100°C), f(T_inv_cur) decreases linearly, for example: f(T_inv_cur) = 1 - kT * (T_inv_cur - T_inv_start) In the formula, kT is the temperature derating factor, ranging from 0.01 to 0.05; in this embodiment, kT = 0.02. When T_inv_cur ≥ T_inv_max, f(T_inv_cur) = 0, i.e., forced shutdown. The controller 14 calculates f(T_inv_cur) based on the current T_inv_cur, and then multiplies it by P_inv_initial to obtain the final inverter allowable power P_inv_lim.

[0077] Alternative implementation: The temperature correction function can also be piecewise linear or exponential, for example, P_inv_lim = P_inv_initial * (T_inv_max - T_inv_cur) / (T_inv_max - T_inv_start). In some implementations, if the temperature sensor of inverter 12 is integrated inside the driver chip of inverter 12, controller 14 can directly read the digital temperature value via I2C or SPI bus. Another alternative implementation is that controller 14 does not use a separate derating function, but instead uses closed-loop control: when T_inv_cur increases, P_inv_lim is gradually reduced until the temperature stabilizes. This method also falls within the scope of protection of this application.

[0078] Please see Figure 8 In some embodiments, step S12 further includes: Step S125: Determine the upper limit of the thermal constraint power P_bat_thermal of the battery 11 of the energy storage device 10 according to the convective heat transfer coefficient hc.

[0079] Step S126: Determine the upper limit of the electrical constraint power P_bat_elec of the battery 11 based on the current state of charge (SOC), current voltage (V_bat), and current temperature (T_bat) of the battery 11.

[0080] Step S127: Determine the battery allowable power P_bat_lim based on the thermal constraint power limit P_bat_thermal and the electrical constraint power limit P_bat_elec.

[0081] The derating control method of this application considers both the thermal and electrochemical constraints of the battery 11. The thermal constraint power limit P_bat_thermal is calculated using a physical chain of air pressure P, altitude h, air density rho, and convective heat transfer coefficient hc. The electrochemical constraint power limit P_bat_elec is calculated by combining the battery's state of charge (SOC), voltage V_bat, and temperature T_bat. This ensures that the battery's allowable power P_bat_lim comprehensively reflects the dual limitations of the heat dissipation environment and the battery's own state, preventing the battery 11 from overheating or being damaged due to insufficient heat dissipation or electrochemical limits. This maximizes the usable power of the battery 11 while ensuring safety.

[0082] In step S125, the controller 14 calculates the thermal constraint power limit P_bat_thermal of the battery 11 based on the convective heat transfer coefficient hc. Similar to the inverter 12, the heat dissipation of the battery 11 also relies on air convection. The battery 11 typically has its own heat dissipation area A_bat (unit: m², including the battery casing or heat sink, pre-stored in the controller 14's memory). The maximum allowable temperature T_bat_max of the battery 11 (unit: °C, e.g., 60 °C) is determined by the battery datasheet. The ambient temperature remains T_env. Therefore, the thermal constraint power limit is: P_bat_thermal = eta_bat * hc * A_bat * (T_bat_max - T_env) Where eta_bat is the heat generation coefficient of battery 11 (i.e., the ratio of output power to heat generation, usually close to 1 because the battery efficiency is high). For simplicity, it can be directly taken as P_bat_thermal = hc * A_bat * (T_bat_max - T_env). Controller 14 obtains this value through arithmetic operations.

[0083] In step S126, the controller 14 obtains the current state of charge (SOC) (percentage), current voltage (V), and current temperature (T_bat) of the battery 11 through the battery management system 131. The upper limit of the electrical constraint power, P_bat_elec, is determined by the charge and discharge characteristics of the battery 11. In one embodiment, the controller 14 internally stores a table of the battery 11's discharge power capabilities (e.g., the maximum allowable discharge power at different SOCs and temperatures). The controller 14 obtains the base power value by looking up the table or interpolating based on the current SOC and T_bat, and then corrects it based on the deviation between the current voltage V_bat and the rated voltage to finally obtain P_bat_elec. For example, when the SOC is below 20% or T_bat is below 0°C, P_bat_elec will decrease significantly to prevent over-discharge or low-temperature lithium plating.

[0084] In step S127, the controller 14 determines the battery's allowable power P_bat_lim based on the thermal constraint power limit P_bat_thermal and the electrical constraint power limit P_bat_elec. The specific determination method is further specified below (taking the minimum value).

[0085] In some implementations, the thermally constrained power limit of battery 11 can also be calculated directly from air density and ambient temperature using experimentally calibrated empirical formulas, without explicitly calculating hc. For example, P_bat_thermal = P_bat_rated *(rho / rho0) * (T_bat_max - T_env) / (T_bat_max - T_ref). Alternatively, controller 14 can use a Kalman filter or machine learning model to fuse SOC, voltage, temperature, and heat dissipation parameters to estimate P_bat_lim online.

[0086] Please see Figure 9 In some implementations, step S127 includes: Step S1271: Take the minimum value between the thermal constraint power limit P_bat_thermal and the electrical constraint power limit P_bat_elec as the battery allowable power P_bat_lim.

[0087] The derating control method of this application explicitly takes the minimum value between the thermal constraint power limit P_bat_thermal and the electrical constraint power limit P_bat_elec as the battery's allowable power P_bat_lim. This bottleneck decision ensures that the battery 11's allowable power is determined by the more stringent constraint under any operating condition, preventing misjudgments caused by conflicts between the thermal and electrical boundaries, and further improving the safety of the battery 11.

[0088] Specifically, controller 14 uses a numerical comparison instruction to select the smaller value between the two: P_bat_lim = min(P_bat_thermal, P_bat_elec) For example, on a hot summer afternoon (T_env=40℃), P_bat_thermal might only be 300W, while P_bat_elec is 500W at SOC=80%, so P_bat_lim=300W; conversely, in a cold environment (T_env=0℃) and SOC=15%, P_bat_thermal might reach 800W (due to the large temperature difference), while P_bat_elec is only 200W (low charge limitation), so P_bat_lim=200W. This minimum value logic ensures that battery 11 will never exceed its actual safety boundary.

[0089] In addition to taking the minimum value, in some implementations, the controller 14 can also set a safety margin, such as P_bat_lim = 0.9 * min(P_bat_thermal, P_bat_elec), to allow for a safety margin. Alternatively, the controller 14 can compare the two, select the smaller one, and further multiply it by a time-dependent decay factor.

[0090] Please see Figure 10 In some embodiments, step S12 further includes: Step S128: Obtain the current temperature T_ctrl of the control module 13 of the energy storage device 10. The control module 13 includes a battery management system 131 and a motherboard 132. T_ctrl can be the highest temperature of both or monitored independently.

[0091] Step S129: When the current temperature T_ctrl is lower than the first temperature threshold T1, set the allowable power P_ctrl_lim of the control module to infinity (in actual implementation, set it to a sufficiently large value, such as 10 times the rated power, or directly do not impose any limit on it, that is, P_ctrl_lim does not participate in the bottleneck of minimum value decision).

[0092] Step S12a: When the current temperature T_ctrl is greater than or equal to the first temperature threshold T1 and less than the second temperature threshold T2, the control module allows the power P_ctrl_lim to gradually decrease at a first rate R1 as the current temperature T_ctrl increases, wherein the first rate R1 is greater than the rate at which the inverter's allowed power P_inv_lim and the battery's allowed power P_bat_lim decrease within the same temperature range.

[0093] Step S12b: When the current temperature T_ctrl is greater than or equal to the second temperature threshold T2, set the control module's allowable power P_ctrl_lim to zero.

[0094] The derating control method of the embodiment of the present application sets two temperature thresholds T1 and T2 for the control module 13, performs early derating between the thresholds with a faster derating rate, and forcibly limits the output after exceeding the second threshold. By setting two thresholds lower than the traditional high-temperature shutdown threshold, preventive protection for the control module 13 is achieved. When the temperature T_ctrl of the control module 13 is still at a relatively low level, the output power of the energy storage device 10 is actively reduced, and the derating rate is higher than that of the inverter 12 and the battery 11, thereby reserving a sufficient safety margin for the control module 13 and preventing its temperature from further rising to the dangerous area, effectively preventing sampling errors, logic disorders, or system crashes caused by overheating of the control module 13, and improving the reliability of the entire energy storage device 10 at the control system level.

[0095] In step S128, the controller 14 respectively obtains the BMS temperature T_bms and the motherboard temperature T_mb through temperature sensors (usually on-chip temperature sensors or external NTCs) provided on the battery management system 131 and the motherboard 132. The current temperature T_ctrl of the control module 13 is defined as the maximum of the two: T_ctrl = max(T_bms, T_mb). The controller 14 uses T_ctrl for subsequent decisions.

[0096] In step S129, the first temperature threshold T1 is set to a lower value, such as 60 °C (lower than the recommended maximum operating temperature of 85 °C in the device data sheet). When T_ctrl < T1, it indicates that the thermal condition of the control module 13 is good and no limitation is required. At this time, set P_ctrl_lim to infinity. In actual code implementation, the controller 14 can set P_ctrl_lim to a very large value (such as 999999 W), or skip the comparison of the control module's allowable power in the minimum value operation (equivalent to infinity). Another implementation is to directly set P_ctrl_lim = P_sys_max (the maximum physical upper limit allowed by the system), so it will not become a bottleneck.

[0097] In step S12a, the second temperature threshold T2 is set to a higher value, such as 80 °C. When T1 ≤ T_ctrl < T2, the controller 14 performs early derating. Let the derating function be linear: P_ctrl_lim = P_ctrl_max * (T2 - T_ctrl) / (T2 - T1) Where P_ctrl_max is the rated power (or a reference value). The derating slope (rate) is P_ctrl_max / (T2 - T1). To satisfy the requirement that "the first rate is greater than the rate of reduction of the inverter's allowable power and the battery's allowable power within the same temperature range", the controller 14 can set a steeper slope, for example, by using a smaller temperature range (such as a smaller T2 - T1), or by setting P_ctrl_max to a larger value (although the rate comparison is actually within the same temperature range). In practice, it can be experimentally calibrated so that when T_ctrl increases from T1 to T2, P_ctrl_lim drops from the rated power to 0, while the inverter's allowable power may only drop from the rated power to 70% within that temperature range, thus demonstrating a faster derating rate.

[0098] In step S12b, when T_ctrl ≥ T2, the controller 14 sets P_ctrl_lim = 0, which forces the upper limit of the system output power to zero, and the energy storage device 10 stops outputting.

[0099] In some alternative implementations, T_ctrl can also be processed independently; for example, if the BMS temperature is higher than the motherboard temperature, the BMS temperature should be used; or the allowable power can be calculated separately for both and the minimum value can be taken. The derating function can also be exponential or piecewise linear. In some implementations, the controller 14 can also record the rate of temperature change and activate derating in advance when T_ctrl rises rapidly.

[0100] Please see Figure 11 In some implementations, step S13 includes: Step S131: Take the minimum value among the inverter's allowable power P_inv_lim, the battery's allowable power P_bat_lim, and the control module's allowable power P_ctrl_lim as the upper limit of the system output power P_sys_lim.

[0101] The derating control method of this application explicitly uses the minimum of the three allowable power values ​​as the upper limit of the system output power P_sys_lim. Through the minimum value decision rule, the allowable power of the three core components is uniformly incorporated into the weakest link constraint mechanism, ensuring that the output power of the energy storage device 10 never exceeds the safety tolerance of the weakest link at any time. This eliminates conflicts and blind spots between the independent limits of each module, fundamentally avoiding unexpected protection or hardware failures caused by one module reaching its limit before others, and achieving collaborative safety at the energy storage device 10 level.

[0102] Controller 14 calculates using a numerical comparison instruction: P_sys_lim = min(P_inv_lim, P_bat_lim, P_ctrl_lim) For example, under certain high-altitude operating conditions, P_inv_lim=656W, P_bat_lim=700W, and P_ctrl_lim=900W, then P_sys_lim=656W; if the temperature of the control module rises, causing P_ctrl_lim to drop to 500W, then P_sys_lim is updated to 500W. This minimum value is used in the power limiting command in step S14.

[0103] In some alternative implementations, in addition to directly taking the minimum value, the controller 14 can also multiply the minimum value by a safety factor (e.g., 0.95), or perform closed-loop regulation based on the principle that the maximum value does not exceed the minimum value. Furthermore, when two or three values ​​are equal, any one of them can be chosen.

[0104] Please see Figure 12 In some embodiments, the derating control method further includes, after step S122: Step S15: Adjust the target rotational speed n_target of the fan 17 of the energy storage device 10 according to the current air density rho, wherein the lower the current air density rho, the higher the target rotational speed n_target.

[0105] The derating control method of this application dynamically adjusts the target rotational speed n_target of the fan 17 according to the current air density rho. The lower the air density rho, the higher the rotational speed, thereby actively compensating for the decrease in convective heat transfer capacity caused by the thin air at high altitudes. This compensation mechanism improves the heat dissipation performance within the capacity range of the fan 17, reduces unnecessary power derating caused by insufficient heat dissipation, and increases the usable output power in high-altitude environments.

[0106] In step S15, the controller 14 calculates the target rotational speed n_target of the fan 17 based on the air density rho. A simple compensation strategy is: n_target = n_rated * (rho0 / rho), where n_rated is the standard rotational speed at sea level and rho0 is the standard air density. That is, when the air density is halved, the rotational speed is doubled. However, due to the physical limitations of the fan 17, the controller 14 sets an upper limit. Another commonly used model is: n_target = n_rated * (rho0 / rho)^γ, where γ is the compensation index (0 < γ ≤ 1), γ = 1 for full compensation (maintaining the same air mass flow rate), and γ = 0.5 for partial compensation. In this embodiment, γ = 0.5 is used.

[0107] The controller 14 adjusts the speed of the fan 17 through a PWM signal to make it approach n_target. At the same time, the controller 14 monitors the speed feedback of the fan 17 in real time (via Hall signal or back EMF) to form a closed-loop control.

[0108] In some alternative implementations, the compensation strategy can also be based on a direct lookup table of altitude, for example, increasing the speed by 10% for every 500m increase in altitude. Alternatively, instead of continuous adjustment, a tiered adjustment can be used (e.g., three levels: low altitude, medium altitude, and high altitude). In other implementations, the controller 14 can adaptively adjust the speed based on the rate of temperature change of the inverter 12 or battery 11, rather than solely based on air density.

[0109] Please see Figure 13 In some implementations, step S15 includes: Step S151: Determine the current noise L_noise and current power consumption P_fan of the fan 17.

[0110] Step S152: If the current noise L_noise is greater than or equal to the predetermined noise limit L_max or the current power consumption P_fan is greater than or equal to the predetermined power consumption limit P_fan_max, stop increasing the target rotation speed n_target, that is, maintain the current rotation speed or reduce the rotation speed.

[0111] The derating control method of this application monitors the current noise (L_noise) and power consumption (P_fan) in real time during the fan speed adjustment process. When the noise or power consumption reaches a preset upper limit, the speed increase is stopped. This limitation avoids acoustic pollution or fan motor overheating caused by blind speed increase, and achieves a balanced optimization between fan compensation and derating strategy, obtaining a reasonable trade-off between heat dissipation capacity, user experience and hardware lifespan.

[0112] In step S151, the controller 14 acquires noise and power consumption through various methods. Noise can be obtained using a pre-calibrated speed-noise mapping table, i.e., by looking up the table based on the current speed n_cur to obtain the estimated noise L_noise (unit: dBA). Alternatively, the energy storage device 10 can be configured with a microphone (not shown) to directly measure the noise. The power consumption P_fan of the fan 17 can be calculated by measuring the supply voltage V_fan and current I_fan of the fan 17: P_fan = V_fan * I_fan.

[0113] In step S152, the controller 14 compares L_noise with a preset noise limit L_max (e.g., 45 dBA, set according to product standards), and P_fan with a preset power consumption limit P_fan_max (e.g., 5W, to prevent the fan motor from overheating). If L_noise ≥ L_max or P_fan ≥ P_fan_max, the controller 14 stops increasing the speed and may even slightly reduce the speed to return to a safe range. At this time, the remaining heat dissipation gap is compensated by a derating strategy (i.e., reducing P_inv_lim, etc.).

[0114] In some alternative implementations, the upper limits for noise and power consumption can be dynamically adjusted; for example, L_max can be reduced in night mode. A weighting function can also be introduced to slow down the rate of RPM increase rather than stopping it immediately when noise approaches its upper limit.

[0115] Please see Figure 14 In some embodiments, the derating control method further includes: Step S16: Determine the air thinning factor F_air based on the current altitude h.

[0116] Step S17: Determine the temperature difference influence factor F_temp based on the current ambient temperature T_env.

[0117] Step S18: The product of the air thinning influence factor F_air and the temperature difference influence factor F_temp is used as the depreciation coefficient D.

[0118] Step S19: Use the derating factor D to correct at least one of the inverter allowable power P_inv_lim, the battery allowable power P_bat_lim, or the control module allowable power P_ctrl_lim.

[0119] The derating control method of this application decomposes the derating coefficient D into the product of an air thinning factor F_air and a temperature difference factor F_temp. The air thinning factor F_air characterizes the weakening of heat-carrying capacity due to decreased air density, while the temperature difference factor F_temp characterizes the reduction in the heat dissipation driving force due to increased ambient temperature. The product of the two has a clear physical meaning, independently reflecting two components of heat dissipation capacity. This multiplicative decomposition method allows for flexible adjustment of the calculation models of each factor in derating control, facilitating optimization according to different environmental conditions. It also simplifies the calibration process of the derating coefficient and improves the versatility and scalability of the control method.

[0120] In step S16, the controller 14 calculates the air thinning effect factor F_air based on the altitude h. An exponential decay model is typically used: F_air = exp(-k * h), where k is the decay coefficient (e.g., 1.3e-4 m^{-1}). This factor is 1 when h=0 and decreases as h increases.

[0121] In step S17, the controller 14 calculates the temperature difference influence factor F_temp based on the ambient temperature T_env. A linear model is used: F_temp = (T_inv_max - T_env) / (T_inv_max - T_ref), where T_ref is the standard reference temperature (e.g., 25°C). F_temp is 1 when T_env = T_ref, and decreases as T_env increases. Alternatively, the allowable temperature of the battery or control module can be used.

[0122] In step S18, the controller 14 calculates the derating factor D = F_air * F_temp.

[0123] In step S19, controller 14 applies D to the correction of each allowable power. For example, for the inverter's allowable power: P_inv_lim_final = D * P_inv_rated, where P_inv_rated is the rated power of inverter 12. Alternatively, the correction can be applied only to one or two of the inverter, battery, and control module; for example, only the inverter's allowable power can be corrected, while the battery and control module are calculated using other methods. The correction can be an additional multiplication of D on top of the original physical model, or it can replace some calculations in the original physical model.

[0124] In some alternative implementations, the product form can be extended to a weighted sum or a more complex combination. Additional factors such as humidity and wind speed can also be introduced. Furthermore, the derating factor D can be used to directly limit the upper limit of the system output power: P_sys_lim = D * P_rated, without needing to calculate the allowable power of each module separately and then take the minimum value, although the latter is more precise.

[0125] To better understand the derating control method of this application, two specific examples are given below: First example: Energy storage device 10 operates under normal conditions at an altitude of 3000 meters and an ambient temperature of 40℃. The user brings an energy storage device 10 with a rated output power of 1000 watts to a plateau region at an altitude of approximately 3000 meters. The controller 14 detects the current air pressure P as 70 kPa via the barometric pressure sensor 15 and measures the current ambient temperature T_env as 40 degrees Celsius via the temperature sensor 16.

[0126] The controller 14 first calculates the current altitude h based on the air pressure P. Using the international standard atmospheric formula: h = 44330 × [1-(P / P0)^0.1903], where P0 is 101.325 kPa. Substituting P=70, we get h≈3000 meters. Next, the controller 14 calculates the current air density rho based on h. Using the exponential decay model: rho = rho0 × exp(-k×h), where rho0 is 1.225 kg / m³, and k is taken as 1.3e-4, we get rho≈1.225×0.82≈1.00 kg / m³, approximately 0.82 times the air density at sea level. Considering that the actual ambient temperature T_env is 15°C higher than the standard reference temperature, the controller 14 also performs a temperature correction, but for simplicity, we still estimate it at 0.82 times.

[0127] Controller 14 reads the current rotational speed n_fan of fan 17. Assume fan 17 is currently operating at its rated speed of 2000 rpm. Based on air density rho and n_fan, controller 14 estimates the convective heat transfer coefficient hc. A simplified model is used: hc = hc0 × (rho / rho0) × (n_fan / n_fan0)^beta, where hc0 is the reference heat transfer coefficient at the standard rotational speed at sea level, n_fan0 = 2000 rpm, and beta is taken as 0.5. The calculated hc is approximately 0.9 times that at sea level.

[0128] The controller 14 then calculates the allowable power P_inv_lim of the inverter 12. The heat dissipation area A_inv of the inverter 12 is 0.05 square meters, and the maximum allowable temperature T_inv_max is 100°C. The temperature difference delta_T_inv = T_inv_max - T_env = 60°C. According to the heat balance equation, the initial allowable power of the inverter 12 is the inverter efficiency eta_inv (taken as 0.95) multiplied by hc, A_inv, and delta_T_inv, resulting in approximately 720 watts. Then, the controller 14 reads the current actual temperature T_inv_cur of the inverter 12 as 85°C using a temperature sensor. Since T_inv_cur has exceeded the initial derating temperature T_inv_start (80℃), controller 14 adjusts the derating function according to the linear derating function f(T_inv_cur) = 1 - kT × (T_inv_cur - T_inv_start), where kT is 0.02, resulting in f = 0.9. Finally, P_inv_lim = 720 × 0.9 ≈ 656 watts.

[0129] Meanwhile, controller 14 calculates the allowable power P_bat_lim of battery 11. The thermal constraint power limit P_bat_thermal of battery 11 is determined by the same hc, the battery heat dissipation area A_bat (0.04 square meters), and the temperature difference (20°C) between the battery's maximum allowable temperature T_bat_max (60°C) and the ambient temperature T_env, which is calculated to be approximately 700 watts. Controller 14 obtains the state of charge (SOC) of battery 11 as 80%, the voltage V_bat as 48 volts, and the current temperature T_bat as 35°C from the battery management system 131, and obtains the electrical constraint power limit P_bat_elec as 800 watts from the table. Controller 14 takes the minimum of the two values, i.e., P_bat_lim = 700 watts.

[0130] The controller 14 also obtains the current temperature T_ctrl of the control module 13. The control module 13 includes a battery management system 131 and a motherboard 132. The controller 14 takes the maximum value of the two temperatures, assuming T_ctrl = 65℃. The controller 14 presets a first temperature threshold T1 = 60℃ and a second temperature threshold T2 = 80℃. Since T_ctrl is between T1 and T2, the controller 14 performs early derating, reducing the allowable power P_ctrl_lim of the control module from the rated power to 0 according to a linear function. At this time, P_ctrl_lim ≈ 900 watts is calculated.

[0131] Finally, controller 14 selects the minimum of the three allowable power values ​​as the upper limit of system output power P_sys_lim: P_sys_lim = min(656, 700, 900) = 656 watts. Controller 14 sends a command to inverter 12 to limit the actual output power below 656 watts. Simultaneously, controller 14 adjusts the target speed n_target of fan 17 according to the current air density rho: n_target = n_rated × (rho0 / rho)^0.5, increasing the speed to approximately 2200 rpm to compensate for the reduced heat dissipation capacity. Controller 14 monitors the noise and power consumption of fan 17 in real time to ensure that it does not exceed the preset upper limit.

[0132] The second example: An abnormal operating condition where the control module 13 of the energy storage device 10 experiences excessively high temperature in a high-altitude environment. Continuing with the previous example, after the energy storage device 10 operates continuously for a period of time in an environment with an altitude of 3000 meters and an ambient temperature of 40°C, the temperature T_ctrl of the control module 13 gradually rises to 75°C due to partial blockage of the ventilation openings or prolonged full load. At this time, the current temperature T_inv_cur of the inverter 12 rises slightly to 88°C, and after correction, P_inv_lim drops to approximately 620 watts; the temperature T_bat of the battery 11 rises to 42°C, its electrical power limit P_bat_elec is still relatively high, but its thermal power limit P_bat_thermal drops slightly to 680 watts, taking the minimum value P_bat_lim = 680 watts. The current temperature T_ctrl of the control module 13 is 75°C, between T1 = 60°C and T2 = 80°C. The controller 14 reduces P_ctrl_lim to 400 watts (far below the allowable power of the inverter and battery) at a faster derating rate (first rate R1).

[0133] Controller 14 executes step S131, calculating P_sys_lim = min(620, 680, 400) = 400 watts. Since the updated power limit (400 watts) is lower than the current actual output power (previously approximately 600 watts), controller 14 gradually reduces the output power at a rate not exceeding the preset maximum rate of change to avoid sudden power fluctuations. Simultaneously, controller 14 further reduces the target speed increase of fan 17 (as noise may already be close to the limit), with the remaining heat dissipation gap covered by the derating strategy. Once the temperature of control module 13 gradually drops below 60°C, controller 14 gradually restores the power limit.

[0134] This example demonstrates how the early derating mechanism of control module 13 serves as a safety net for the system. It proactively and significantly reduces the system output power before control module 13 reaches the critical temperature (80°C), thereby preventing a decrease in sampling accuracy or system crash due to overheating of control module 13. In this specification, the terms "specifically," "furthermore," "particularly," "understandably," etc., refer to specific features, structures, materials, or characteristics described in connection with embodiments or examples, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0135] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of executable request code comprising one or more steps for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0136] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A derating control method for an energy storage device, characterized in that, include: Get the current air pressure and current ambient temperature; Based on the current air pressure and the current ambient temperature, determine the allowable power of the inverter, the allowable power of the battery, and the allowable power of the control module; The upper limit of system output power is determined based on the allowable power of the inverter, the allowable power of the battery, and the allowable power of the control module; and The energy storage device is controlled to operate at an output power lower than the upper limit of the system output power.

2. The method according to claim 1, characterized in that, The determination of the inverter's allowable power, the battery's allowable power, and the control module's allowable power includes: Calculate the current altitude based on the current air pressure; Calculate the current air density based on the current altitude. Based on the current air density, the current ambient temperature, and the current fan speed of the energy storage device, the convective heat transfer capacity is estimated; and The allowable power of the inverter is determined based on the convective heat transfer capacity, the heat dissipation area of ​​the energy storage device, and the difference between the maximum allowable temperature of the inverter of the energy storage device and the current ambient temperature.

3. The method according to claim 2, characterized in that, Determining the allowable power of the inverter includes: The maximum heat that the inverter can safely dissipate under the current environment is calculated based on the convective heat transfer capacity, the heat dissipation area, and the difference to obtain the initial allowable power of the inverter. The allowable power of the inverter is obtained by adjusting the initial allowable power of the inverter downward based on the current actual temperature of the inverter.

4. The method according to claim 1, characterized in that, The determination of the inverter's allowable power, the battery's allowable power, and the control module's allowable power includes: Calculate the current altitude based on the current air pressure; Calculate the current air density based on the current altitude. The convective heat transfer capacity is estimated based on the current air density, the current ambient temperature, and the current rotational speed of the fan in the energy storage device. The thermal constraint power limit of the battery of the energy storage device is determined based on the convective heat transfer capacity. The upper limit of the electrical constraint power of the battery is determined based on the battery's current state of charge, current voltage, and current temperature. The allowable power of the battery is determined based on the upper limit of the thermal constraint power and the upper limit of the electrical constraint power.

5. The method according to claim 4, characterized in that, Determining the allowable power of the battery based on the thermally constrained power limit and the electrically constrained power limit includes: The minimum value between the thermal constraint power limit and the electrical constraint power limit is taken as the allowable power of the battery.

6. The method according to claim 1, characterized in that, The determination of the inverter's allowable power, the battery's allowable power, and the control module's allowable power includes: Obtain the current temperature of the control module of the energy storage device; If the current temperature is lower than the first temperature threshold, the power allowed by the control module is set to infinity; When the current temperature is greater than or equal to the first temperature threshold and less than the second temperature threshold, the control module allows the power to gradually decrease at a first rate as the current temperature increases, wherein the first rate is greater than the rate at which the inverter's allowed power and the battery's allowed power decrease within the same temperature range; If the current temperature is greater than or equal to the second temperature threshold, the power allowed by the control module is set to zero.

7. The method according to claim 1, characterized in that, The upper limit of system output power is determined based on the allowable power of the inverter, the allowable power of the battery, and the allowable power of the control module, including: The minimum value among the inverter's allowable power, the battery's allowable power, and the control module's allowable power is taken as the upper limit of the system's output power.

8. The method according to claim 1, characterized in that, Also includes: Calculate the current altitude based on the current air pressure; Calculate the current air density based on the current altitude. The target rotational speed of the fan in the energy storage device is adjusted according to the current air density, wherein the lower the current air density, the higher the target rotational speed.

9. The method according to claim 8, characterized in that, The step of adjusting the target rotational speed of the fan in the energy storage device based on the current air density includes: Determine the current noise and current power consumption of the fan; If the current noise level is greater than or equal to a predetermined noise limit or the current power consumption is greater than or equal to a predetermined power consumption limit, the target rotational speed shall be stopped from being increased.

10. The method according to claim 1, characterized in that, Also includes: Determine the air thinning factor based on the current altitude; Determine the temperature difference influence factor based on the current ambient temperature; The product of the air thinning effect factor and the temperature difference effect factor is used as the depreciation coefficient; The derating factor is used to correct at least one of the allowable power of the inverter, the allowable power of the battery, or the allowable power of the control module.

11. An energy storage power source, characterized in that, include: Battery; Inverter; Control module; and A controller for performing the method as described in any one of claims 1-10.

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