Hybrid inverter two-way battery off-grid power distribution method

Abstract

The application relates to a hybrid inverter two-way battery off-grid power distribution method, which is applied to the field of energy storage system control and comprises the following steps: judging the working mode of a two-way battery, and calculating the total effective capacity of the two-way battery according to the working mode; calculating a current distribution proportion coefficient of the two-way battery according to the total effective capacity and the real-time acquired terminal voltage of the two-way battery; and distributing the total current reference value of the real-time acquired bus voltage to the two-way battery according to the current distribution proportion coefficient, so as to realize off-grid power distribution of the two-way battery. The application has the technical effect that the total power of the two-way battery can be accurately and quickly distributed in an off-grid scene, and the mutation of the load power demand can be matched in real time.

Description

Technical Field

[0001] This application relates to the field of energy storage system control technology, and in particular to a method for off-grid power distribution of dual-battery hybrid inverters. Background Technology

[0002] In off-grid dual-path independent battery energy storage systems, the voltage, capacity, allowable charge / discharge current, and state of charge (SOC) of the two connected independent batteries may differ. Furthermore, load fluctuations are characterized by suddenness and uncertainty. Without a power grid as a buffer, the system needs to respond quickly to load changes to maintain stable bus voltage. Therefore, real-time balanced distribution of battery charge / discharge power is crucial for ensuring stable system operation and extending battery life. Unlike grid-connected systems, off-grid systems cannot rely on the grid for power dispatch and cannot achieve balance through slow power dispatch adjustments. They must rely on local control strategies to match load changes with battery power output in real time.

[0003] Since battery power equals the product of terminal voltage and charging / discharging current, existing dual-battery power distribution methods mostly only allocate power proportionally based on current, without considering the impact of real-time fluctuations in battery terminal voltage on power distribution. Furthermore, some solutions follow the power scheduling and distribution approach of grid-connected systems, resulting in slow response speeds and an inability to adapt to sudden changes in off-grid load demands. This leads to unbalanced actual charging and discharging power, and problems such as single-battery power overload, sudden changes in bus voltage, and unstable load power supply are likely to occur. Summary of the Invention

[0004] To address the shortcomings of existing dual-battery power distribution methods, which fail to consider the impact of real-time battery voltage fluctuations on power allocation and rely on grid-connected system power scheduling approaches, resulting in unsuitability for sudden changes in off-grid load demands and uneven charging / discharging power, leading to unstable load power supply, this application provides a dual-battery off-grid power distribution method for hybrid inverters. The method comprises the following technical solution:

[0005] Determine the operating mode of the dual-battery system and calculate the total effective capacity of the dual-battery system based on the operating mode. Based on the total effective capacity and the real-time acquired terminal voltage of the dual-battery system, calculate the current distribution ratio coefficient of the dual-battery system. Based on the current distribution ratio coefficient, the total current reference value of the bus voltage acquired in real time is distributed to the dual batteries to achieve off-grid power distribution of the dual batteries.

[0006] In one specific implementation scheme, determining the operating mode of the dual-battery system and calculating the total effective capacity of the dual-battery system based on the operating mode includes: If both batteries are charging, the total effective capacity of the two batteries can be calculated as follows: , , , in, This indicates the effective charging capacity of the first battery. This indicates the state of charge of the first battery. This indicates the rated capacity of the first battery. This indicates the effective charging capacity of the second battery. This indicates the state of charge of the second battery. Indicates the rated capacity of the second battery. Indicates the total effective charging capacity; If both batteries are in a discharged state, the total effective capacity of the two batteries can be calculated as follows: , , , in, This indicates the effective discharge capacity of the first battery. This indicates the state of charge of the first battery. This indicates the rated capacity of the first battery. This indicates the effective discharge capacity of the second battery. This indicates the state of charge of the second battery. Indicates the rated capacity of the second battery. This indicates the total effective discharge capacity.

[0007] In one specific implementation scheme, calculating the current distribution ratio coefficient of the dual-battery system based on the total effective capacity and the real-time acquired terminal voltage of the dual-battery system includes: The capacity weight of the dual-channel batteries is calculated based on the total effective capacity. The current distribution ratio coefficient of the dual-battery is calculated based on the capacity weight and the real-time acquired terminal voltage of the dual-battery.

[0008] In one specific implementation scheme, the calculation of the capacity weight of the dual-channel batteries based on the total effective capacity includes: Determine whether the total effective capacity is greater than a preset capacity threshold; If the total effective capacity is greater than a preset capacity threshold, the capacity weight calculation method for the dual-battery system includes: When both batteries are in charging mode , , in, This indicates the weight of the charging capacity of the first battery. This indicates the weight of the charging capacity of the second battery. This indicates the effective charging capacity of the first battery. Indicates the total effective charging capacity; When both batteries are in discharge mode , , in, This indicates the weight of the discharge capacity of the first battery. This indicates the weight of the discharge capacity of the second battery. This indicates the effective discharge capacity of the first battery. Indicates the total effective discharge capacity; If the total effective capacity is not greater than the preset capacity threshold, then the capacity weights of both batteries are set to the preset default capacity weights.

[0009] In one specific implementation scheme, the calculation of the current allocation ratio coefficient of the dual-battery based on the capacity weight and the real-time acquired terminal voltage of the dual-battery includes: Determine whether the terminal voltage of the dual batteries is within the preset operating voltage range; If the terminal voltages of both batteries are within the operating voltage range, the current distribution ratio coefficient of the two batteries is calculated according to the capacity weight. Otherwise, the current distribution ratio of both batteries is set to the preset default value.

[0010] In one specific implementation, calculating the current allocation ratio coefficient of the dual-battery system based on the capacity weight includes: When both batteries are in charging mode , , , in, This represents the charging current distribution ratio coefficient of the first battery. This indicates the weight of the charging capacity of the first battery. This indicates the terminal voltage of the first battery. This represents the charging current distribution ratio coefficient of the second battery. This indicates the weight of the charging capacity of the second battery. This indicates the terminal voltage of the second battery; When both batteries are in discharge mode , , , in, This represents the discharge current distribution ratio coefficient of the first battery. This indicates the weight of the discharge capacity of the first battery. This indicates the terminal voltage of the first battery. This represents the discharge current distribution ratio coefficient of the second battery. This indicates the weight of the discharge capacity of the second battery. This indicates the terminal voltage of the second battery.

[0011] In one specific implementation scheme, after calculating the current distribution ratio coefficient of the dual-battery based on the total effective capacity and the real-time acquired terminal voltage of the dual-battery, the method further includes: The calculated current distribution ratio coefficient of the dual-channel battery is normalized and limited, and a current distribution limiting coefficient is generated. The step of allocating the total current reference value of the bus voltage acquired in real time to the dual-battery circuit according to the current allocation ratio coefficient includes: Based on the current distribution limiting coefficient, the total current reference value of the bus voltage acquired in real time is distributed to the dual batteries.

[0012] In one specific implementation, the step of allocating the total current reference value of the bus voltage acquired in real time to the dual-battery according to the current allocation ratio coefficient includes: When both batteries are in charging mode , , in, This represents the total current reference value of the bus voltage acquired in real time. This represents the charging current distribution ratio coefficient of the first battery. This indicates the charging current reference value allocated to the first battery based on the total current reference value. This indicates the charging current reference value allocated to the second battery based on the total current reference value; When both batteries are in discharge mode , , in, This represents the total current reference value of the bus voltage acquired in real time. This represents the discharge current distribution ratio coefficient of the first battery. This indicates the discharge current reference value allocated to the first battery based on the total current reference value. This indicates the discharge current reference value allocated to the second battery based on the total current reference value.

[0013] In one specific implementation scheme, after allocating the total current reference value of the bus voltage acquired in real time to the dual-battery according to the current allocation ratio coefficient, the method further includes: The current obtained by the dual batteries based on the total current reference value of the bus voltage acquired in real time is set as the initial current reference value. The current obtained from the dual-battery distribution is set as the current reference value, and the initial value of the current reference value is the initial current reference value. When the current reference value is obtained, the current reference value is limited within a preset operating current range, and a current limiting reference value is generated. Calculate the remaining current reference value of the dual-channel battery based on the current limiting reference value; Determine whether the residual current reference value is within the preset residual current threshold range; If the remaining current reference value is within the preset remaining current threshold range, then the total remaining current distribution capacity of the dual-battery system is calculated. The current is redistributed based on the total remaining current capacity of the dual-battery system and the current distribution ratio coefficient, and the redistributed current is set as the current reference value. Otherwise, the initial current reference value is set as the final current reference value for the dual-battery system.

[0014] In one specific implementation, the step of redistributing the current based on the remaining current of the dual-battery system to allocate the total capacity and the current allocation ratio includes: Determine whether the total remaining current allocation capacity is greater than the total remaining capacity threshold; If the total remaining current allocation capacity is greater than the total remaining capacity threshold, then the total remaining current allocation capacity is allocated to the dual-battery according to the current allocation ratio coefficient. Otherwise, the initial current reference value is set as the final current reference value for the dual-battery system; The calculation method for the total capacity of the remaining current distribution includes: When both batteries are in charging mode , , , in, This indicates the remaining charge capacity allocated to the first battery. This indicates the charging current limit for the first battery. This indicates the current limiting reference value in the first battery charging mode. This indicates the remaining charge capacity allocated to the second battery. This indicates the charging current limit for the second battery. This indicates the current limiting reference value in the second battery charging mode. This indicates the total capacity of the remaining current allocation under charging mode; When both batteries are in discharge mode , , , in, This indicates the remaining discharge capacity allocated to the first battery. This indicates the discharge current limit of the first battery. This indicates the current limiting reference value in the first battery discharge mode. This indicates the remaining discharge capacity allocated to the second battery. This indicates the discharge current limit of the second battery. This indicates the current limiting reference value in the second battery discharge mode. This indicates the total capacity of the remaining current distribution in discharge mode.

[0015] In summary, this application has the following beneficial technical effects: 1. Based on the essential differences in charging and discharging conditions, the effective charging / discharging capacity is calculated separately. The calculation method is simple, efficient, and updated in real time. It abandons the complex capacity scheduling logic of traditional power scheduling and can quickly respond to changes in power demand caused by load mutations. It accurately matches the actual power carrying capacity of the battery, provides an accurate and fast basis for power balance distribution, and adapts to the needs of off-grid load mutations. 2. Combining dynamic proportional algorithms of voltage and capacity, the real-time battery terminal voltage is introduced as a core influencing factor to optimize the current ratio allocation. This ensures that the current ratio adapts to voltage changes (caused by sudden load changes) in real time, guaranteeing that the voltage × current (power) of the two batteries tends to be balanced. This solves the core defect of existing technologies that only control current and power imbalance. At the same time, it abandons the power scheduling allocation approach and uses local real-time calculation, resulting in a fast response speed. It can quickly respond to sudden off-grid load changes and achieve precise balance and rapid response at the power level. 3. Through a two-stage current distribution mechanism of "initial allocation - current limiting - residual current supplementary allocation", local real-time adjustment is achieved without the need for external power scheduling commands. This not only achieves accurate and even distribution of total power but also avoids overload of a single battery. At the same time, threshold design avoids invalid calculations, improving system robustness and operational stability. It can also quickly absorb power differences caused by load changes, match load power demand in real time, and solve the problem that load changes in off-grid scenarios cannot be handled by power scheduling allocation. It balances power balance, system safety, and rapid load response, and extends battery life. Attached Figure Description

[0016] Figure 1 This is a flowchart of the off-grid power distribution method for dual-battery hybrid inverters in an embodiment of this application; Figure 2 This is an overall architecture diagram of the off-grid dual-path independent battery energy storage system in the embodiments of this application; Figure 3 This is a flowchart of a method for complete power balancing distribution of dual batteries in a hybrid inverter, as described in this application embodiment. Detailed Implementation

[0017] The following combination Figures 1-3 This application will be described in further detail.

[0018] This application discloses a method for off-grid power distribution of dual-battery systems in a hybrid inverter. This method enables balanced power distribution between the two batteries in off-grid scenarios. It is applied to an off-grid dual-battery energy storage system comprising a single bus voltage control outer loop and independent current control inner loops for both batteries. The bus voltage control outer loop responds to load changes in real time, outputting a total current reference value (positive values ​​indicate discharging, negative values ​​indicate charging), without relying on external power dispatch commands.

[0019] This method addresses the challenges of off-grid scenarios, such as lack of grid support, frequent load fluctuations, and the inability to utilize power scheduling. With the dual objectives of power balancing and rapid response to load changes, it abandons the control logic of traditional power scheduling. Instead, it relies solely on local real-time data acquisition and dynamic adjustment. First, it calculates the effective charge / discharge capacity of the battery. Then, it incorporates the real-time battery terminal voltage as an influencing factor to optimize current ratio allocation. Finally, through a two-stage current allocation mechanism, it achieves accurate and rapid allocation of total power without exceeding the power limit of a single battery, thus matching sudden changes in load power demand in real time.

[0020] In off-grid dual-path independent battery energy storage systems, the voltage, capacity, allowable charge / discharge current, and state of charge (SOC) of the two connected independent batteries may differ. Furthermore, load fluctuations are characterized by suddenness and uncertainty. Without a power grid as a buffer, the system needs to respond quickly to load changes to maintain stable bus voltage. Therefore, real-time balanced distribution of battery charge / discharge power is crucial for ensuring stable system operation and extending battery life. Unlike grid-connected systems, off-grid systems cannot rely on the grid for power dispatch and cannot achieve balance through slow power dispatch adjustments. They must rely on local control strategies to match load changes with battery power output in real time.

[0021] Since battery power equals the product of terminal voltage and charging / discharging current, existing dual-battery power distribution methods mostly only allocate power proportionally based on current, without considering the impact of real-time fluctuations in battery terminal voltage on power distribution. Furthermore, some solutions follow the power scheduling and distribution approach of grid-connected systems, resulting in slow response speeds and an inability to adapt to sudden changes in off-grid load demands. This leads to unbalanced actual charging and discharging power, and problems such as single-battery power overload, sudden changes in bus voltage, and unstable load power supply are likely to occur.

[0022] In existing technologies, dual-battery power allocation methods typically employ fixed ratios, single SOC, or single capacity allocation, failing to adapt to differences in battery charge / discharge capabilities under charging and discharging conditions. Furthermore, they suffer from slow response times and cannot handle sudden changes in off-grid loads. Secondly, the lack of voltage influence factors means that current allocation is disconnected from voltage changes, hindering precise power balancing. Moreover, the reliance on power scheduling allocation is unsuitable for off-grid scenarios. Additionally, one-time current allocation can easily lead to a mismatch between total power and single-cell power limits, further exacerbating power imbalances and failing to quickly respond to power demand fluctuations caused by load changes. Therefore, there is an urgent need for a precise dynamic power balancing method that combines voltage influence, adapts to different operating conditions, eliminates the need for power scheduling allocation, and can quickly respond to load changes, meeting the core requirements of off-grid scenarios. To help solve the problem of dual-battery power allocation in off-grid scenarios, this application provides a dual-battery off-grid power allocation method for hybrid inverters.

[0023] Reference Figure 1 The method includes: S10: Determine the operating mode of the dual-battery circuit and calculate the total effective capacity of the dual-battery circuit based on the operating mode.

[0024] Specifically, first determine the operating mode of the dual batteries, and then calculate the total effective capacity of the dual batteries based on the operating mode. If both batteries are in a charging state, the calculation method for the total effective capacity of the dual batteries can be expressed as: , , , in, This indicates the effective charging capacity of the first battery. This indicates the state of charge of the first battery. This indicates the rated capacity of the first battery. This indicates the effective charging capacity of the second battery. This indicates the state of charge of the second battery. Indicates the rated capacity of the second battery. This indicates the total effective charging capacity; among which, and The values ​​are in percentage form.

[0025] If both batteries are in a discharged state, the total effective capacity of the two batteries can be calculated as follows: , , , in, This indicates the effective discharge capacity of the first battery. This indicates the state of charge of the first battery. This indicates the rated capacity of the first battery. This indicates the effective discharge capacity of the second battery. This indicates the state of charge of the second battery. Indicates the rated capacity of the second battery. This represents the total effective discharge capacity; where, and The values ​​are in percentage form.

[0026] The effective charge / discharge capacity of a battery directly determines its power carrying capacity and is the basis for rapid response to sudden changes in load power. This method calculates the effective capacity of each battery path separately, taking into account the differences in charging and discharging operating modes. It abandons the complex capacity scheduling logic of traditional power scheduling and uses simple and efficient calculations to quickly obtain the real-time power carrying capacity of the battery. This capacity can be updated rapidly in real time, providing a foundation for subsequent power balancing and load response.

[0027] S20: Calculate the current distribution ratio coefficient of the dual-battery based on the total effective capacity and the real-time terminal voltage of the dual-battery.

[0028] Specifically, the current allocation ratio is calculated using the total effective capacity and the real-time battery terminal voltage. Power = Voltage × Current. To achieve power balance and rapid response to load changes, the traditional power scheduling and allocation ratio adjustment logic is abandoned. Instead, the real-time battery terminal voltage is introduced as a core influencing factor, combined with the calculated effective capacity, and a dynamic current allocation ratio adapted to power balance and load surge response is obtained through local real-time calculation. In practical implementation, the calculation is performed based on the total effective capacity corresponding to different operating modes; that is, the total effective capacity for charging is used in charging mode, and the total effective capacity for discharging is used in discharging mode.

[0029] S30, based on the current distribution ratio coefficient, distributes the total current reference value of the bus voltage obtained in real time to the dual batteries to realize off-grid power distribution of the dual batteries.

[0030] Specifically, considering that the total current reference value output from the outer loop of the bus voltage changes in real time with the load, it is necessary to obtain the total current reference value in real time. Then, based on the calculated current distribution ratio coefficient, the total current reference value is distributed in two stages to the two batteries. In the specific implementation process, the corresponding parameters are selected for calculation according to different operating modes. The specific distribution calculation method can be expressed as follows: When both batteries are in charging mode , , in, This represents the total current reference value of the bus voltage acquired in real time. This represents the charging current distribution ratio coefficient of the first battery. This indicates the charging current reference value allocated to the first battery based on the total current reference value. This indicates the charging current reference value allocated to the second battery based on the total current reference value; When both batteries are in discharge mode , , in, This represents the total current reference value of the bus voltage acquired in real time. This represents the discharge current distribution ratio coefficient of the first battery. This indicates the discharge current reference value allocated to the first battery based on the total current reference value. This indicates the discharge current reference value allocated to the second battery based on the total current reference value.

[0031] Since power = voltage × current, proper current distribution, combined with the terminal voltages of the two batteries, can ultimately achieve balanced power distribution between them. The specific current distribution ratio is determined based on the battery's charging and discharging mode. It's the charging current distribution ratio during battery charging and the discharging current distribution ratio during battery discharging. While the power values ​​differ depending on whether they are positive or negative during charging or discharging, the calculation method for the distribution ratio remains the same. The battery current distribution process is completed in real time, with no scheduling delay, and can quickly respond to changes in total current caused by sudden load fluctuations.

[0032] In this application, the effective charge / discharge capacity is calculated separately for the fundamental differences in charging and discharging conditions. The calculation method is simple, efficient, and updates in real time, abandoning the complex capacity scheduling logic of traditional power scheduling. It can quickly respond to power demand changes caused by load surges, accurately match the actual power carrying capacity of the battery, and provide a precise and rapid foundation for power balance allocation, adapting to off-grid load surges. In addition, the real-time battery terminal voltage is introduced as a core influencing factor to optimize the current ratio allocation, ensuring that the current ratio adapts to voltage changes (caused by load surges) in real time, ensuring that the power of the two batteries tends to be balanced, eliminating the need for power scheduling allocation, and achieving precise power balance and rapid response.

[0033] In one embodiment, the method for calculating the current distribution ratio coefficient of the dual-battery system based on the total effective capacity and the real-time acquired terminal voltage of the dual-battery system can be specifically implemented as follows: First, the capacity weight of the dual-battery system is calculated based on the total effective capacity. Specifically, under different operating modes, it is determined whether the total effective capacity is greater than a preset capacity threshold. If the total effective capacity is greater than the preset capacity threshold, the capacity weight calculation method for the dual-battery system includes: When both batteries are in charging mode, the calculation method can be expressed as follows: , , in, This indicates the weight of the charging capacity of the first battery. This indicates the weight of the charging capacity of the second battery. This indicates the effective charging capacity of the first battery. Indicates the total effective charging capacity; When both batteries are in discharge mode, the calculation method can be expressed as follows: , , in, This indicates the weight of the discharge capacity of the first battery. This indicates the weight of the discharge capacity of the second battery. This indicates the effective discharge capacity of the first battery. This indicates the total effective discharge capacity.

[0034] If the total effective capacity is not greater than a preset capacity threshold, the capacity weights of both batteries are set to the preset default values. For example, in this embodiment, the preset capacity threshold is set to 0, and the preset default capacity weight is set to 0.5. If the total effective capacity is greater than 0, the battery capacity weight is calculated according to the working mode of the two batteries; if the total effective capacity is not greater than 0, that is, the total effective capacity is less than or equal to 0, the capacity weights of both batteries are set to 0.5.

[0035] After calculating the battery capacity weights, the current distribution ratio coefficient for the dual-battery system is calculated based on the capacity weights and the real-time acquired terminal voltages of the dual batteries. Specifically, it is determined whether the terminal voltages of the dual batteries are within the preset operating voltage range. Considering the correlation between power and voltage, and the characteristic of voltage fluctuations during sudden changes in off-grid loads, the capacity weights are adjusted based on the real-time battery terminal voltages to ensure that the current ratio quickly adapts to voltage changes, guaranteeing power balance without requiring power scheduling intervention. If the terminal voltages of both batteries are within the operating voltage range, the current distribution ratio coefficient for the dual batteries in the corresponding operating mode is calculated based on the capacity weights. The calculation method for the current distribution ratio coefficient can be expressed as: When both batteries are in charging mode , , , in, This represents the charging current distribution ratio coefficient of the first battery. This indicates the weight of the charging capacity of the first battery. This indicates the terminal voltage of the first battery. This represents the charging current distribution ratio coefficient of the second battery. This indicates the weight of the charging capacity of the second battery. This indicates the terminal voltage of the second battery; When both batteries are in discharge mode , , , in, This represents the discharge current distribution ratio coefficient of the first battery. This indicates the weight of the discharge capacity of the first battery. This indicates the terminal voltage of the first battery. This represents the discharge current distribution ratio coefficient of the second battery. This indicates the weight of the discharge capacity of the second battery. This indicates the terminal voltage of the second battery.

[0036] By adjusting the capacity weight of the dual-battery system based on the terminal voltage, the battery with higher voltage will have a smaller current ratio, thereby balancing the voltage × current (power) of the two batteries and responding in real time to voltage fluctuations (voltage changes caused by sudden load changes) without the need for power scheduling adjustments.

[0037] Otherwise, the current distribution ratio coefficients of both batteries are set to the preset default values. This can also be understood as follows: if the terminal voltage of one battery in the dual-battery system is outside the preset operating voltage range, or if the terminal voltages of both batteries are outside the preset operating voltage range, resulting in abnormal battery voltage, then the current distribution ratio coefficients of both batteries are directly set to the preset default values. In this embodiment, the preset default value for the current distribution coefficient is set to 0.5 to ensure basic system balance, quickly stabilize the voltage, and cope with voltage anomalies caused by sudden load changes.

[0038] In this application, a dynamic proportional algorithm combining voltage and capacity is used to achieve power-level balance and rapid response without the need for power scheduling and allocation. The real-time battery terminal voltage is introduced as a core influencing factor to optimize current proportional allocation, ensuring that the current ratio adapts in real time to voltage changes (caused by sudden load changes). This guarantees that the voltage × current (power) of the two batteries tends to be balanced, overcoming the shortcomings of existing technologies that only control current and power imbalance. Furthermore, through local real-time calculation, the response is fast, enabling rapid handling of sudden off-grid load changes.

[0039] In one embodiment, considering that the calculated current allocation ratio may be unreasonable, after calculating the current allocation ratio of the dual batteries based on the total effective capacity and the real-time acquired terminal voltage of the dual batteries, the following steps can also be performed: The calculated current distribution ratio coefficients of the dual-battery system are normalized and limited, and a current distribution limiting coefficient is generated. First, the calculated current distribution ratio coefficients of the dual-battery system are normalized. Then, the normalized coefficients are limited; in this embodiment, the normalized coefficients are limited to the range [0, 1]. Specifically, it is determined whether the normalized current distribution ratio coefficients are within the range [0, 1]. If they are within the range [0, 1], the current distribution limiting coefficient is the normalized distribution coefficient; if they are not within the range [0, 1], the coefficients exceeding the range are set to 0 or 1. For example, suppose the calculated current distribution coefficients of the dual-battery circuit are normalized to 0.4 and 0.6, both of which are in the range [0, 1]. Then, 0.4 and 0.6 are the final current distribution limiting coefficients. If the calculated current distribution coefficients are normalized to 1.2 and -0.2, then 1.2 becomes 1 after limiting and -0.2 becomes 0 after limiting. In this case, the final current distribution limiting coefficients are 0 and 1.

[0040] The process of allocating the total current reference value of the bus voltage acquired in real time to the dual-battery system according to the current allocation ratio coefficient includes: allocating the total current reference value of the bus voltage acquired in real time to the dual-battery system according to the current allocation limiting coefficient.

[0041] In this application, normalization and limiting are used to avoid current distribution exceeding a reasonable range and to prevent errors in the calculation process, thus ensuring the stability of power distribution when responding quickly to load changes.

[0042] In one embodiment, the current allocated to the dual batteries may exceed the maximum current limit of the batteries. Therefore, after allocating the total current reference value of the bus voltage acquired in real time to the dual batteries according to the current allocation ratio coefficient, the following steps can also be performed: First, the current allocated by the dual batteries based on the real-time acquired total current reference value of the bus voltage is set as the initial current reference value. The initial value of the current reference value is the initial value of the current allocated by the dual batteries. When the current reference value is acquired, it is limited within a preset operating current range, and a current limit reference value is generated. The preset operating current range is determined based on the charging and discharging current limit of a single battery to avoid overloading the single battery while ensuring rapid current regulation to adapt to power fluctuations during sudden load changes. Assuming that in charging mode, the charging current limits of the first and second batteries are respectively... and The operating current range is then set to [ ,0] and [ [0]; In discharge mode, the discharge current limits of the first battery and the second battery are respectively and The operating current range is set to [0, ] and [0, Then, in the corresponding working mode, it is determined whether the current reference value obtained by the dual-battery distribution is within the corresponding working current range. First, it is determined whether the initial current reference value is within the working current range. If it is within the range, the initial current reference value is set as the current limiting reference value. If it is not within the range, it is determined whether the initial current reference value is greater than the maximum value of the range or less than the minimum value of the range. If it is greater than the maximum value of the range, the maximum value of the range is set as the current limiting reference value. If it is less than the minimum value of the range, the minimum value of the range is set as the current limiting reference value.

[0043] Next, the remaining current reference value for both batteries is calculated based on the current limiting reference value. Considering that residual current may exist after current limiting, the remaining portion is redistributed to ensure that all current is distributed, resulting in a balanced power distribution between the two batteries. The calculation method for the residual current value can be expressed as follows: When both batteries are in charging mode , in, This indicates the remaining current value in charging mode. This represents the total current reference value of the bus voltage acquired in real time. This indicates the current limiting reference value in the first battery charging mode. This indicates the current limit reference value in the second battery charging mode; When both batteries are in discharge mode , in, This indicates the residual current value in discharge mode. This represents the total current reference value of the bus voltage acquired in real time. This indicates the current limiting reference value in the first battery discharge mode. This indicates the current limit reference value in the second battery discharge mode.

[0044] The system determines whether the remaining current reference value is within a preset remaining current threshold range. The remaining current reference value is determined based on the operating mode: in charging mode, the calculated remaining current value is used; in discharging mode, the calculated remaining current value is used. If the remaining current reference value is within the preset remaining current threshold range, the total remaining current allocation capacity of the dual-battery system is calculated. Based on the total remaining current allocation capacity and the current allocation ratio coefficient, the current is redistributed, and the redistributed current is set as the current reference value. This process is repeated until the remaining current is within the preset threshold range. Otherwise, the initial current reference value is set as the final current reference value for the dual-battery system. The calculation method for the total remaining current allocation capacity can be expressed as follows: When both batteries are in charging mode , , , in, This indicates the remaining charge capacity allocated to the first battery. This indicates the charging current limit for the first battery. This indicates the current limiting reference value in the first battery charging mode. This indicates the remaining charge capacity allocated to the second battery. This indicates the charging current limit for the second battery. This indicates the current limiting reference value in the second battery charging mode. This indicates the total capacity of the remaining current allocation under charging mode; When both batteries are in discharge mode , , , in, This indicates the remaining discharge capacity allocated to the first battery. This indicates the discharge current limit of the first battery. This indicates the current limiting reference value in the first battery discharge mode. This indicates the remaining discharge capacity allocated to the second battery. This indicates the discharge current limit of the second battery. This indicates the current limiting reference value in the second battery discharge mode. This indicates the total capacity of the remaining current distribution in discharge mode.

[0045] It should be noted that the residual current value refers to the total current reference value of the bus voltage obtained in real time after the initial allocation and limiting process, minus the current limiting reference value obtained after the initial allocation and limiting process of the dual batteries; the total residual current allocation capacity is the sum of the current limits of the dual batteries minus the current limiting reference value, and the total residual current allocation capacity can be understood as the current to be allocated.

[0046] It should be noted that the residual current threshold range is determined based on the actual operating mode of the battery. For example, the threshold range is set to be no less than 0.1A under discharge conditions and no greater than -0.1A under charging conditions. When under discharge conditions, if the calculated residual current is less than 0.1A, the loop exits, and the final allocated current is obtained. If the calculated residual current is not less than 0.1A, the residual current needs to be calculated and redistributed. Similarly, when under charging conditions, if the calculated residual current is greater than -0.1A, the loop exits, and the final allocated current is obtained. If the calculated residual current is not greater than -0.1A, the residual current needs to be calculated and redistributed. Generally, if the initial reference values ​​of the calculated current are all within the corresponding current operating range and do not exceed the limit, the residual current is 0, and no secondary redistribution is needed. If the initially allocated current value exceeds the limit of the corresponding battery, after limiting, there is residual current, requiring redistribution or even multiple redistributions.

[0047] Specifically, the method of redistributing current based on the total remaining current capacity and current distribution ratio of the dual-battery system can be implemented as follows: First, it is determined whether the total remaining current capacity allocation exceeds the remaining total capacity threshold. This determination is based on the battery's operating mode. For battery charging, the remaining current capacity allocation in charging mode is used; for battery discharging, the remaining current capacity allocation in charging mode is used. The parameters used differ between modes, but the specific allocation method is consistent. The remaining total capacity threshold is determined by the operating mode and can be set by the user according to their actual needs. For example, it can be set to... To avoid division by zero errors in actual calculations, the value is generally not set directly to 0. Instead, a very small constant close to 0 can be preset. If the total remaining current allocation capacity is greater than the remaining total capacity threshold, the total remaining current allocation capacity is allocated to the dual-battery system according to the calculated current allocation ratio coefficient. Otherwise, the initial current reference value is set as the final current reference value for the dual-battery system. In other words, if the total remaining current allocation capacity is less than the threshold, the initial current reference value is directly set as the final current reference value for the dual-battery system, and no further current allocation is performed.

[0048] In this application, a two-stage current allocation mechanism of "initial allocation - current limiting - residual current supplementary allocation" is adopted to adjust the current in real time locally without the need for external power scheduling commands. This achieves accurate and even distribution of total power while avoiding overload of a single battery. At the same time, threshold design avoids invalid calculations, improving system robustness and operational stability. It can also quickly absorb the power difference caused by load changes and match the load power demand in real time, solving the problem that load changes in off-grid scenarios cannot be handled by power scheduling allocation. It balances power balance, system safety, and rapid load response to extend battery life.

[0049] Reference Figure 2 This is the overall architecture diagram of a dual-path independent battery energy storage system in an off-grid scenario, characterized by the absence of a power grid. The bidirectional arrows in the diagram indicate the direction of power transmission; since the batteries are both charging and discharging, power transmission is bidirectional. Battery 1 and Battery 2 are dual-path batteries, connected to a common DC bus via their respective independently driven bidirectional DC / DC converters. The power from the common DC bus is then supplied to the off-grid inverter (not shown in the diagram). The local real-time controller does not connect to an external power dispatch module. It collects the battery's SOC (State of Charge), terminal voltage, and current in real time, and autonomously calculates the current allocation for both batteries to obtain current reference values ​​for Battery 1 and Battery 2, achieving balanced power distribution between the two batteries. The system's control loop structure is as follows: the bus voltage controls the outer loop, outputting the total current reference value; the currents of Battery 1 and Battery 2 independently control their respective inner loops.

[0050] Reference Figure 3 This is a flowchart illustrating the complete power balancing method for dual-battery hybrid inverters in this embodiment. First, the system's bus voltage, load power, and total current reference value are collected in real time. The bus voltage controls the outer loop output of the total current reference value. Next, the battery's operating mode is determined. If both batteries are in charging / discharging mode, the effective capacity under each mode is calculated, and then the total effective capacity of both batteries is calculated. Then, the capacity weights of the dual batteries are calculated based on their terminal voltages, and it is determined whether the terminal voltages are within a preset operating voltage range. If the terminal voltages are within the preset range, the capacity weights are adjusted based on the real-time terminal voltages, and the current allocation coefficient is calculated. If the terminal voltages are not within the preset range, the current allocation coefficient is set to 0.5 by default. After calculating the current allocation coefficient, normalization and limiting processing are performed to ensure the coefficient is limited to the range [0, 1].

[0051] After coefficient limiting, initial current allocation is performed according to the limited coefficients to obtain an initial current reference value. It is then determined whether the allocated initial current reference value is within the preset operating current range. If it is, the initial current reference value is limited, and the remaining current is calculated. If the remaining current does not exceed a set threshold, the final current allocation reference value is output. If it exceeds the set threshold, a secondary allocation is performed, and this process is repeated until the remaining current does not exceed the set threshold, at which point the loop exits. After outputting the final current allocation reference value, it is input to the dual-channel battery current inner loop control, with each battery controlled independently.

[0052] Figure 1 This is a flowchart illustrating a dual-battery off-grid power distribution method for a hybrid inverter in one embodiment. It should be understood that, although... Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows; unless explicitly stated otherwise, there is no strict order requirement for the execution of these steps, and they can be executed in other orders; and Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0053] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for off-grid power distribution of a dual-battery hybrid inverter, characterized in that: The method includes: Determine the operating mode of the dual-battery system and calculate the total effective capacity of the dual-battery system based on the operating mode. Based on the total effective capacity and the real-time acquired terminal voltage of the dual-battery system, calculate the current distribution ratio coefficient of the dual-battery system. Based on the current distribution ratio coefficient, the total current reference value of the bus voltage acquired in real time is distributed to the dual batteries to achieve off-grid power distribution of the dual batteries.

2. The method according to claim 1, characterized in that: The process of determining the operating mode of the dual-battery system and calculating the total effective capacity of the dual-battery system based on the operating mode includes: If both batteries are charging, the total effective capacity of the two batteries can be calculated as follows: ， ， ， in, This indicates the effective charging capacity of the first battery. This indicates the state of charge of the first battery. This indicates the rated capacity of the first battery. This indicates the effective charging capacity of the second battery. This indicates the state of charge of the second battery. Indicates the rated capacity of the second battery. Indicates the total effective charging capacity; If both batteries are in a discharged state, the total effective capacity of the two batteries can be calculated as follows: ， ， ， in, This indicates the effective discharge capacity of the first battery. This indicates the state of charge of the first battery. This indicates the rated capacity of the first battery. This indicates the effective discharge capacity of the second battery. This indicates the state of charge of the second battery. Indicates the rated capacity of the second battery. This indicates the total effective discharge capacity.

3. The method according to claim 1, characterized in that: The calculation of the current distribution ratio coefficient of the dual-battery system based on the total effective capacity and the real-time acquired terminal voltage of the dual-battery system includes: The capacity weight of the dual-channel batteries is calculated based on the total effective capacity. The current distribution ratio coefficient of the dual-battery is calculated based on the capacity weight and the real-time acquired terminal voltage of the dual-battery.

4. The method according to claim 3, characterized in that: The calculation of the capacity weight of the dual-battery system based on the total effective capacity includes: Determine whether the total effective capacity is greater than a preset capacity threshold; If the total effective capacity is greater than a preset capacity threshold, the capacity weight calculation method for the dual-battery system includes: When both batteries are in charging mode ， ， in, This indicates the weight of the charging capacity of the first battery. This indicates the weight of the charging capacity of the second battery. This indicates the effective charging capacity of the first battery. Indicates the total effective charging capacity; When both batteries are in discharge mode ， ， in, This indicates the weight of the discharge capacity of the first battery. This indicates the weight of the discharge capacity of the second battery. This indicates the effective discharge capacity of the first battery. Indicates the total effective discharge capacity; If the total effective capacity is not greater than the preset capacity threshold, then the capacity weights of both batteries are set to the preset default capacity weights.

5. The method according to claim 3, characterized in that: The calculation of the current allocation ratio coefficient of the dual-battery based on the capacity weight and the real-time acquired terminal voltage of the dual-battery includes: Determine whether the terminal voltage of the dual batteries is within the preset operating voltage range; If the terminal voltages of both batteries are within the operating voltage range, the current distribution ratio coefficient of the two batteries is calculated according to the capacity weight. Otherwise, the current distribution ratio of both batteries is set to the preset default value.

6. The method according to claim 5, characterized in that: The calculation of the current distribution ratio coefficient of the dual-battery system based on the capacity weight includes: When both batteries are in charging mode ， ， ， in, This represents the charging current distribution ratio coefficient of the first battery. This indicates the weight of the charging capacity of the first battery. This indicates the terminal voltage of the first battery. This represents the charging current distribution ratio coefficient of the second battery. This indicates the weight of the charging capacity of the second battery. This indicates the terminal voltage of the second battery; When both batteries are in discharge mode ， ， ， in, This represents the discharge current distribution ratio coefficient of the first battery. This indicates the weight of the discharge capacity of the first battery. This indicates the terminal voltage of the first battery. This represents the discharge current distribution ratio coefficient of the second battery. This indicates the weight of the discharge capacity of the second battery. This indicates the terminal voltage of the second battery.

7. The method according to claim 1, characterized in that: After calculating the current distribution ratio coefficient of the dual-battery based on the total effective capacity and the real-time acquired terminal voltage of the dual-battery system, the method further includes: The calculated current distribution ratio coefficient of the dual-channel battery is normalized and limited, and a current distribution limiting coefficient is generated. The step of allocating the total current reference value of the bus voltage acquired in real time to the dual-battery circuit according to the current allocation ratio coefficient includes: Based on the current distribution limiting coefficient, the total current reference value of the bus voltage acquired in real time is distributed to the dual batteries.

8. The method according to claim 1, characterized in that: The step of allocating the total current reference value of the bus voltage acquired in real time to the dual-battery circuit according to the current allocation ratio coefficient includes: When both batteries are in charging mode ， ， in, This represents the total current reference value of the bus voltage acquired in real time. This represents the charging current distribution ratio coefficient of the first battery. This indicates the charging current reference value allocated to the first battery based on the total current reference value. This indicates the charging current reference value allocated to the second battery based on the total current reference value; When both batteries are in discharge mode ， ， in, This represents the total current reference value of the bus voltage acquired in real time. This represents the discharge current distribution ratio coefficient of the first battery. This indicates the discharge current reference value allocated to the first battery based on the total current reference value. This indicates the discharge current reference value allocated to the second battery based on the total current reference value.

9. The method according to claim 1, characterized in that: After allocating the total current reference value of the bus voltage acquired in real time to the dual batteries according to the current allocation ratio coefficient, the method further includes: The current obtained by the dual batteries based on the total current reference value of the bus voltage acquired in real time is set as the initial current reference value. The current obtained from the dual-battery distribution is set as the current reference value, and the initial value of the current reference value is the initial current reference value. When the current reference value is obtained, the current reference value is limited within a preset operating current range, and a current limiting reference value is generated. Calculate the remaining current reference value of the dual-channel battery based on the current limiting reference value; Determine whether the residual current reference value is within the preset residual current threshold range; If the remaining current reference value is within the preset remaining current threshold range, then the total remaining current distribution capacity of the dual-battery system is calculated. The current is redistributed based on the total remaining current capacity of the dual-battery system and the current distribution ratio coefficient, and the redistributed current is set as the current reference value. Otherwise, the initial current reference value is set as the final current reference value for the dual-battery system.

10. The method according to claim 9, characterized in that: The step of redistributing the current based on the remaining current of the dual batteries and the current distribution ratio coefficient includes: Determine whether the total remaining current allocation capacity is greater than the total remaining capacity threshold; If the total remaining current allocation capacity is greater than the total remaining capacity threshold, then the total remaining current allocation capacity is allocated to the dual-battery according to the current allocation ratio coefficient. Otherwise, the initial current reference value is set as the final current reference value for the dual-battery system; The calculation method for the total capacity of the remaining current distribution includes: When both batteries are in charging mode ， ， ， in, This indicates the remaining charge capacity allocated to the first battery. This indicates the charging current limit for the first battery. This indicates the current limiting reference value in the first battery charging mode. This indicates the remaining charge capacity allocated to the second battery. This indicates the charging current limit for the second battery. This indicates the current limiting reference value in the second battery charging mode. This indicates the total capacity of the remaining current allocation under charging mode; When both batteries are in discharge mode ， ， ， in, This indicates the remaining discharge capacity allocated to the first battery. This indicates the discharge current limit of the first battery. This indicates the current limiting reference value in the first battery discharge mode. This indicates the remaining discharge capacity allocated to the second battery. This indicates the discharge current limit of the second battery. This indicates the current limiting reference value in the second battery discharge mode. This indicates the total capacity of the remaining current distribution in discharge mode.

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