A parallel battery module and management method

Abstract

The present invention discloses a parallel battery module and management method, which belongs to the field of DC power supply technology in the electric power industry, and includes: a plurality of independent parallel units that are completely independent and can work in parallel, each independent parallel unit includes a battery unit and a bidirectional DC conversion device, the total voltage of the battery unit is lower than the normal voltage of the DC bus but higher than the voltage lower limit of the DC bus, and the bidirectional DC conversion device is connected between the battery unit and the DC bus; the DC bus is used to connect each independent parallel unit and the DC feeder to provide stable and reliable DC power supply for each branch of the DC feeder; the DC feeder is connected to the DC bus; and the freewheeling unit is connected between the input and output of the bidirectional DC conversion device. The beneficial effects of the present invention are: enabling multiple parallel units to operate independently not only improves the safety, reliability and fault tolerance of the system, but also avoids the complex operations and a large amount of manual intervention in traditional battery management methods, and reduces operation and maintenance costs.

Description

Technical Field

[0001] The present invention relates to the technical field of direct current power supply in the electric power industry, and more particularly to a parallel battery module and a management method thereof. Background Art

[0002] In recent years, as power systems have increasingly demanded greater reliability and redundancy for station DC power supplies, paralleling various battery packs has become increasingly common. However, existing technologies, which primarily employ traditional series topologies and various types of parallel topologies, while ensuring system redundancy and reliability, have limitations, particularly in battery management, system stability, and flexibility, which require further improvement.

[0003] Traditional station-use DC power systems typically utilize a single battery pack, consisting of multiple batteries connected in series. This battery pack is connected to a charger and provides a stable power source to the DC feeder via the DC bus. When the AC power supply is normal, the charger serves as the primary energy supply, and the battery pack is in a floating charge state, on standby. However, when the AC power supply fails, the battery pack switches to the primary energy supply, continuing to provide energy to the DC feeder until the AC power supply is restored. However, this traditional single-series battery pack structure presents certain hidden dangers. In particular, in the event of a battery failure, such as an open circuit in a single battery cell or a failure to reliably connect the battery pack, this can cause the battery pack to disconnect from the DC bus, resulting in a loss of backup energy for the DC bus. This can lead to a serious system depressurization problem, posing a significant risk to the stable operation of the system.

[0004] Furthermore, according to the power system's requirements for station DC power supplies, battery pack capacity verification requires a biennial discharge test for batteries under four years old, and annual testing for batteries older than four years. This test requires adding a backup battery pack connected to the DC bus to ensure unaffected system power supply, and then restoring the system to its original state after testing. This cumbersome, time-consuming, and labor-intensive process increases operational costs and workload, significantly impacting the efficiency of routine battery maintenance.

[0005] To address these issues, the industry has proposed a variety of technical solutions based on parallel topologies to improve the redundancy and reliability of battery systems. For example, traditional indirect parallel technology uses low-voltage battery cells, boosts them to the DC bus voltage through a power converter, and then connects them to the DC bus in parallel. However, because the voltage of these low-voltage battery cells is much lower than the DC bus voltage, their current capacity is limited and they cannot directly provide the required short-circuit current for the DC bus. As a result, in the event of a DC bus fault, the system cannot effectively provide sufficient short-circuit current, making it impossible to reliably trip the DC circuit breaker, creating a serious system safety hazard.

[0006] Therefore, although there are currently multiple technical solutions based on parallel topology applied to station DC power supply systems, the existing technology still has some limitations, especially in terms of improving system redundancy, ensuring the complete independence of battery packs, improving system stability and reducing operation and maintenance difficulties. A new parallel topology structure is needed to solve these problems. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, a parallel battery module and management method is proposed, which enables multiple parallel units to operate independently. This not only improves the safety, reliability and fault tolerance of the system, but also avoids the complex operations and large amounts of manual intervention in traditional battery management methods, thereby reducing operation and maintenance costs.

[0008] The technical solution adopted by the invention to solve the technical problem is: a parallel battery module, the improvement of which includes:

[0009] Multiple independent parallel units that are completely independent and can operate in parallel, each independent parallel unit includes a battery unit and a bidirectional DC converter device, the total voltage of the battery unit is lower than the normal voltage of the DC bus but higher than the lower voltage limit of the DC bus, and the bidirectional DC converter device is connected between the battery unit and the DC bus to boost the voltage of the battery unit to the DC bus voltage;

[0010] The DC bus is used to connect each independent parallel unit and the DC feeder, providing stable and reliable DC power supply to each branch of the DC feeder;

[0011] DC feeder, connected to the DC bus, used to distribute DC power to various electrical equipment;

[0012] The freewheeling unit is connected between the input and output of the bidirectional DC converter and is used to provide a freewheeling loop when the DC bus voltage drops.

[0013] In the above structure, the bidirectional DC conversion device contains multiple parallel bidirectional DC / DC modules. The bidirectional DC / DC modules are of boost type and have a low-voltage side and a high-voltage side. The low-voltage side is connected to the battery unit and the high-voltage side is connected to the DC bus. Each bidirectional DC / DC module can independently perform a boost operation according to the actual voltage of the battery unit to which it is connected to ensure that the battery unit always operates in the best working state.

[0014] In the above structure, the freewheeling unit includes at least one freewheeling diode, which is used to provide a current path when the DC bus voltage drops.

[0015] In the above structure, the battery unit includes at least one type of battery, and the type of battery includes valve-regulated lead-acid battery or lithium iron phosphate battery, and the voltage of the battery unit inside each parallel unit can be set according to different battery types and configurations to ensure adaptation to different battery types and optimization of system performance.

[0016] The present invention also provides a management method for parallel battery modules, which is improved in that it includes the following steps:

[0017] Determine the specific internal configuration of the battery cells of each parallel unit based on the DC bus voltage boundary, and dynamically adjust the number and charging status of the batteries in each parallel unit;

[0018] Under normal conditions, the battery pack is managed by floating charge, equalizing charge and discharge through the bidirectional DC conversion device;

[0019] In abnormal situations, such as AC voltage loss and DC bus short circuit, the bidirectional DC converter and freewheeling unit provide energy supply to the DC bus. When the DC bus voltage drops to the lower limit, the system automatically adjusts the working state of the freewheeling unit and directly provides the necessary short-circuit current through the freewheeling circuit to ensure safe operation of the system.

[0020] The management method also ensures that at any time there is at least one independent parallel unit in normal working condition to provide continuous energy output and avoid system failure.

[0021] Furthermore, at least one battery pack is ensured to be in normal mode and the availability of its freewheeling safety zone is not less than 100% to ensure continuous power supply to the system; other battery packs can be in maintenance mode or exit state for maintenance or repair, and the working status of different parallel units can be monitored and adjusted in real time through intelligent control algorithms to ensure that at any time there is at least one parallel unit that can provide sufficient energy output to avoid system failure.

[0022] Furthermore, the calculation formula for the availability of the freewheeling safety zone of the battery pack is:

[0023] =( - ) / ( - )*100%;

[0024] in, It is the normal voltage of the battery side, usually the float charge voltage; is the lower limit of DC bus voltage; is the real-time voltage on the battery side; Ri is the availability of the freewheeling safety zone of the battery pack.

[0025] Furthermore, the abnormal conditions include:

[0026] When the AC voltage is lost, the bidirectional DC converter automatically enters the voltage-stabilizing discharge state to provide energy for the DC bus;

[0027] When AC is restored, the bidirectional DC converter automatically switches to the equalization charging state to compensate for the energy loss caused by discharge.

[0028] Furthermore, the abnormal situation also includes that when the DC bus is short-circuited, energy is first provided by the bidirectional DC conversion device. If it cannot provide sufficient energy, the battery pack directly provides energy to the DC bus through the freewheeling unit until the bus voltage drops to the lower limit.

[0029] Furthermore, each parallel unit satisfies the following conditions: DC bus voltage> output voltage of bidirectional DC conversion device> total voltage of storage batteries inside the battery unit.

[0030] The beneficial effects of the present invention are: enabling multiple parallel units to operate independently not only improves the safety, reliability and fault tolerance of the system, but also avoids the complex operations and large amounts of manual intervention in traditional battery management methods, and reduces operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural principle diagram of a parallel battery module of the present invention;

[0032] Figure 2 This is a schematic diagram of a bidirectional DC conversion device for a parallel battery module of the present invention;

[0033] Figure 3 This is a schematic diagram of the battery voltage range configuration principle of a parallel battery module of the present invention;

[0034] Figure 4 This is a state transition diagram of a management method for parallel battery modules of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings and examples.

[0036] The following will clearly and completely describe the concept, specific structure and technical effects of the present invention in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components, but refer to the fact that a better connection structure can be formed by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the invention can be combined interactively without conflicting with each other.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. Secondly, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] See also Figure 1 As shown, the present invention provides a parallel battery module, comprising:

[0040] Multiple independent parallel units that are completely independent and can operate in parallel, each independent parallel unit includes a battery unit and a bidirectional DC converter device, the total voltage of the battery unit is lower than the normal voltage of the DC bus but higher than the lower voltage limit of the DC bus, and the bidirectional DC converter device is connected between the battery unit and the DC bus to boost the voltage of the battery unit to the DC bus voltage;

[0041] The DC bus is used to connect each independent parallel unit and the DC feeder, providing stable and reliable DC power supply to each branch of the DC feeder;

[0042] DC feeder, connected to the DC bus, used to distribute DC power to various electrical equipment;

[0043] The freewheeling unit is connected between the input and output of the bidirectional DC converter and is used to provide a freewheeling loop when the DC bus voltage drops.

[0044] In the present invention, through the design of multiple completely independent and parallel-operating independent parallel units, each unit can operate independently, avoiding the risks associated with the series connection of battery packs in traditional systems. If a battery unit fails, the other units can continue to supply power to the DC bus, greatly improving the redundancy and reliability of the system and ensuring the continuous and stable operation of the power system. The battery cell voltage of each independent parallel unit is lower than the normal voltage of the DC bus, but higher than the lower limit of the DC bus voltage. The battery voltage is boosted to the DC bus voltage through the bidirectional DC conversion device, achieving precise voltage regulation and charge and discharge management. This design ensures that the battery is always in optimal operating condition, extending battery life and reducing energy loss. In the event of a DC bus voltage drop or short circuit, the freewheeling unit can provide a freewheeling circuit to ensure that the system can continue to supply power to the load. This not only improves the system's short-circuit protection capability, but also ensures the stability of the DC bus, avoiding equipment damage and safety hazards caused by voltage fluctuations or short circuits. The voltage of each battery group is not far lower than the bus voltage like the indirect parallel type, nor is it exactly the same as the DC bus voltage like the grouped parallel type. Instead, there is a large elastic margin between the upper and lower limits of the DC bus, and each independent parallel unit is completely independent. The total voltage of each internal battery can be different, or it can be a variety of different types of batteries. They are decoupled through a bidirectional DC conversion device and boosted to a unified DC bus voltage, realizing control decoupling between each independent parallel unit, and there is no coupling relationship between them.

[0045] Further, such as Figure 2 As shown, the bidirectional DC conversion device internally contains a plurality of parallel bidirectional DC / DC modules. The bidirectional DC / DC modules are of boost type and have a low-voltage side and a high-voltage side. The low-voltage side is connected to the battery cell and the high-voltage side is connected to the DC bus. Each bidirectional DC / DC module can independently perform a boost operation according to the actual voltage of the battery cell to which it is connected to ensure that the battery cell always operates in the best working state. The design of the bidirectional DC / DC module enables the system to not only output the battery's electrical energy to the DC bus, but also perform charging control when needed. The charging and discharging management of the battery pack is more precise, thereby optimizing the battery charging strategy, preventing overcharging or discharging, and ensuring the battery's service life and the energy balance of the system. The bidirectional DC conversion device (in the dotted box) internally contains a plurality of parallel bidirectional DC / DC modules and freewheeling units 1 and 2, wherein the bidirectional DC / DC modules 1-n are of boost type, U bat The low voltage side is connected to the battery unit (below the dotted box), U busThis is the high-voltage side, connected to the DC bus (above the dotted box). As previously mentioned, under normal operating conditions, multiple parallel bidirectional DC / DC modules charge or discharge the battery. Due to the voltage difference between the high and low sides, freewheeling units 1 and 2 do not function. When insufficient energy supply causes the DC bus voltage to drop, and the high-side and low-side voltage difference cannot meet the requirements for the operation of multiple parallel bidirectional DC / DC modules, freewheeling units 1 and 2 come into play due to the droop characteristic of the DC voltage, providing a circuit for output current.

[0046] Furthermore, the freewheeling unit includes at least one freewheeling diode for providing a current path when the DC bus voltage drops. The freewheeling diode provides a current path when the DC bus voltage drops, which can prevent the current from being interrupted quickly. This design can effectively reduce voltage fluctuations and current shocks, and enhance the stability and protection capabilities in the event of voltage fluctuations or short circuit faults. The battery unit includes at least one type of battery, and the type of battery includes a valve-regulated lead-acid battery or a lithium iron phosphate battery. The voltage of the battery unit inside each parallel unit can be set according to different battery types and configurations to ensure adaptation to different battery types and optimize system performance.

[0047] The valve-regulated lead acid battery (VRLA) is a sealed lead-acid battery with a valve mechanism. A safety valve maintains internal gas pressure, ensuring stable operating conditions within the battery. This type of battery generates gas during charging, and the safety valve controls the internal gas pressure to prevent damage from gas expansion. The lithium iron phosphate battery, also known as the lithium iron phosphate lithium-ion battery, is a new type of lithium-ion battery. Its cell rated voltage is 3.2V, and its charge cutoff voltage is between 3.6V and 3.65V. During charging, some lithium ions in the lithium iron phosphate are released, transferred through the electrolyte to the negative electrode, and embedded in the negative electrode's carbon material. Simultaneously, electrons are released from the positive electrode and travel through an external circuit to the negative electrode, maintaining chemical equilibrium. The discharge process is the opposite: lithium ions are released from the negative electrode, travel through the electrolyte to the positive electrode, and electrons are released from the negative electrode and travel through an external circuit to the positive electrode, providing energy. VRLA batteries are generally lower cost and suitable for cost-sensitive applications, while lithium iron phosphate batteries offer a longer lifespan, higher energy density, and enhanced safety. Using different battery types in the same system allows for finding the optimal balance between cost and performance based on varying needs, providing flexible customization options. Lithium iron phosphate batteries offer longer cycle life and greater durability than valve-regulated lead-acid batteries. During long-term operation, the system can rationally allocate different battery types based on their varying characteristics, preventing degradation of overall system performance due to the degradation of a single battery type. This effectively extends the overall lifespan of the battery pack. By allowing the use of different battery types, parallel battery modules offer the flexibility to select the most appropriate battery type based on user needs and actual application scenarios.

[0048] The present invention also provides a method for managing parallel battery modules, comprising the following steps:

[0049] Determine the specific internal configuration of the battery cells of each parallel unit based on the DC bus voltage boundary, and dynamically adjust the number and charging status of the batteries in each parallel unit;

[0050] Under normal conditions, the battery pack is managed by floating charge, equalizing charge and discharge through the bidirectional DC conversion device;

[0051] Under abnormal circumstances, when the AC voltage loses and the DC bus is short-circuited, energy is supplied to the DC bus through the bidirectional DC conversion device and the freewheeling unit; when the DC bus voltage drops to the lower limit, the system automatically adjusts the working state of the freewheeling unit and directly provides the necessary short-circuit current through the freewheeling circuit to ensure the safe operation of the system: the management method also ensures that at any time there is at least one independent parallel unit in normal working condition to provide continuous energy output and avoid the occurrence of system failures.

[0052] Furthermore, at least one battery pack is ensured to be in normal mode and the availability of its freewheeling safety zone is not less than 100% to ensure continuous power supply to the system; other battery packs can be in maintenance mode or exit state for maintenance or repair, and the working status of different parallel units can be monitored and adjusted in real time through intelligent control algorithms to ensure that at any time there is at least one parallel unit that can provide sufficient energy output to avoid system failure.

[0053] The management method of the present invention, combined with the bidirectional DC conversion device, can achieve floating charge, equalization charge and discharge management of each battery pack, ensuring the optimal operation of the battery pack under different working conditions. In particular, for battery packs with a long service life, the present invention can extend the service life of the battery through precise voltage management methods, and reduce the performance degradation of the battery pack due to aging. The present invention also adopts a flexible operation and maintenance mode. By calculating the availability of the freewheeling safety zone of the battery pack, the system can intelligently select the battery pack in normal working condition, and switch the battery pack that needs inspection or maintenance to maintenance mode or exit state, thereby effectively improving the efficiency of daily operation and maintenance. This innovative design reduces the tedious manual intervention in traditional operation and maintenance, making battery management more efficient and intelligent.

[0054] like Figure 3 As shown in the figure, based on the single-cell charge and discharge parameters of different types of batteries, the range of battery quantity required on the corresponding battery side can be known. The parameters in the figure are:

[0055] The nominal voltage of the DC bus is usually 110V or 220V;

[0056] The upper limit voltage of the DC bus, usually 112.5% of the nominal voltage;

[0057] The DC bus lower limit voltage, usually 87.5% of the nominal voltage;

[0058] The upper limit voltage of the battery side, usually the equalization charging voltage;

[0059] The lower limit voltage of the battery side, usually the lowest discharge cut-off voltage;

[0060] It is the normal voltage of the battery side, usually the float charge voltage;

[0061] is the real-time voltage on the battery side;

[0062] It is the minimum voltage difference between the DC bus and the battery side of the bidirectional DC converter, which is a fixed value.

[0063] Which needs to be satisfied, ≤ - ;

[0064] ≥ ;

[0065] According to the number of battery cells in each parallel unit, the availability of the corresponding freewheeling safety zone A3 under normal working conditions Different (Note: The freewheeling unavailable area A2 is just unable to guarantee that the battery unit in this area can provide sufficient short-circuit current through the freewheeling unit when it is lower than the lower limit of the DC bus voltage. Because if the DC bus voltage is lower than the lower limit at this time, the equipment powered by the DC bus will not be able to work normally, which is equivalent to the DC bus voltage loss. However, the battery side voltage that is lower than the lower limit of the DC bus voltage can still be boosted to above the lower limit of the DC bus voltage through the bidirectional DC conversion device to provide the energy required for conventional loads. The availability of the freewheeling safety zone represents the proportion of the voltage range with freewheeling safety guarantee for the i-th parallel unit under normal working conditions. It is used to evaluate the degree to which freewheeling safety is provided for different types of batteries and their number of battery cells at different discharge cut-off voltages), as shown in the following formula, according to the required freewheeling safety zone availability According to the situation, determine the specific number of batteries required on the battery side.

[0066] The calculation formula for the availability of the freewheeling safety zone of the battery pack is:

[0067] =( - ) / ( - )*100%;

[0068] in, It is the normal voltage of the battery side, usually the float charge voltage; is the lower limit of DC bus voltage; is the real-time voltage on the battery side; Ri is the availability of the freewheeling safety zone of the battery pack.

[0069] The minimum voltage difference between the DC bus and the battery side of the bidirectional DC converter =10V as an example:

[0070] The nominal 2V valve-regulated lead-acid battery has a minimum discharge cut-off voltage of 1.80V, a float charge voltage of 2.25V, and an equalization charge voltage of 2.35V. Taking a 110V system as an example, the maximum number of cells in a single battery pack is 48. When the single cell voltage = 1.80V, then is 54.40%. When the single cell voltage is ≥2.01V, ≥100%, the minimum number of batteries is 43, when the voltage of a single battery = 1.80V, then is 2.58%. When the single cell voltage is ≥2.24V, ≥100%. Taking the 220V system as an example, the maximum number of batteries in a single battery pack is 96. When the voltage of a single battery is 1.80V, then is 54.40%. When the single cell voltage is ≥2.01V, ≥100%, the minimum number of batteries is 86, when the voltage of a single battery = 1.80V, then is 2.58%. When the single cell voltage is ≥2.24V, ≥100%.

[0071] The nominal 12V valve-regulated lead-acid battery has a minimum discharge cut-off voltage of 10.8V, a float charge voltage of 13.5V, and an average charge voltage of 14.1V. Taking a 110V system as an example, the maximum number of cells in a single battery pack is 8. When the single cell voltage = 10.8V, then is 54.40%. When the single cell voltage is ≥12.1V, ≥100%, minimum battery quantity is 8, when single cell voltage = 10.8V, then is 54.40%. When the single cell voltage is ≥12.1V, ≥100%. Taking the 220V system as an example, the maximum number of batteries in a single battery pack is 16. When the voltage of a single battery is 10.8V, then is 54.40%. When the single cell voltage is ≥12.1V, ≥100%, the minimum number of batteries is 15, when the voltage of a single battery = 10.8V, then is 24.69%. When the single cell voltage is ≥12.9V, ≥100%.

[0072] The nominal 3.2V lithium iron phosphate battery has a minimum discharge cut-off voltage of 3.00V, a float charge voltage of 3.40V, and an average charge voltage of 3.55V. Taking a 110V system as an example, the maximum number of cells in a single battery pack is 32. When the single cell voltage = 3.00V, then is 98.05%. When the single cell voltage is ≥3.01V, ≥100%, minimum battery quantity 29, when single cell voltage = 3.00V, then is 20.26%. When the single cell voltage is ≥3.32V, ≥100%. Taking the 220V system as an example, the maximum number of batteries in a single battery pack is 64. When the voltage of a single battery is 3.00V, then is 98.05%. When the single cell voltage is ≥3.01V, ≥100%, the minimum number of batteries is 57, when the voltage of a single battery = 3.00V, then is 5.70%. When the single cell voltage is ≥3.38V, ≥100%.

[0073] As mentioned above, the availability of each independent parallel unit itself , the number of its internal batteries and their real-time voltage Therefore, according to the battery configuration (battery type, battery quantity, charge and discharge parameters) in the independent parallel unit, the battery type used is first determined, and the charge and discharge parameters of the battery are determined according to the battery type used to obtain the upper and lower limits of the battery side voltage. 、 and normal voltage , and then determine the upper and lower limits of the DC bus voltage according to the voltage level of the DC bus 、 , because the minimum voltage difference between the DC bus and the battery side As a constant, the range of the maximum and minimum battery numbers in the independent parallel unit is obtained, and the number of batteries currently in use is determined within the range, with the real-time voltage on the battery side as the actual value. As a variable, real-time calculation and evaluation are performed to obtain the availability of the freewheeling safety zone A3 of the independent parallel unit. The availability of the system-level freewheeling safety zone A3 for a DC system consisting of multiple independent parallel units is equal to the availability of the independent parallel units. The largest value in .

[0074] Furthermore, the abnormal conditions include:

[0075] When the AC voltage is lost, the bidirectional DC converter automatically enters the voltage-stabilizing discharge state to provide energy for the DC bus;

[0076] When AC is restored, the bidirectional DC converter automatically switches to the equalization charging state to compensate for the energy loss caused by discharge.

[0077] When the DC bus is short-circuited, the bidirectional DC converter first provides energy. If it cannot provide enough energy, the battery pack directly provides energy to the DC bus through the freewheeling unit until the bus voltage drops to the lower limit.

[0078] like Figure 4As shown in the figure, under normal conditions, the battery is in a float charge state. Scheduled or manual equalization can initiate equalization mode, which returns to float charge after equalization completion. Depending on system operation, scheduled maintenance (such as capacity increase / activation) or manual maintenance (such as capacity increase / activation) can initiate maintenance mode during normal system operation, returning to float charge after maintenance. When AC voltage drops and there is no external energy supply, the bidirectional DC converter automatically enters a voltage-stabilized discharge state to provide the required energy to the DC bus. When AC is restored, the system switches to equalization mode to replenish the energy lost during discharge. If the bidirectional DC converter cannot meet the energy requirements of the DC bus during this process, the freewheeling portion of the battery pack will directly provide energy to the DC bus due to the DC voltage droop characteristics until the bus voltage drops to the lower limit. Thereafter, the system switches to equalization mode after the DC bus short circuit ends or AC is restored to replenish the energy lost during discharge.

[0079] Each parallel unit satisfies the following conditions: DC bus voltage > bidirectional DC converter output voltage > total battery voltage inside the battery unit. Based on the boundary value of the DC bus voltage, the specific configuration of the battery unit inside each parallel unit is determined to ensure that the condition of "DC bus voltage > bidirectional DC converter output voltage > total battery voltage inside the battery unit" is met. This ensures that when a short circuit occurs in the DC bus, the system will respond according to the predetermined DC voltage threshold gradient based on the DC voltage droop characteristics. First, the system's original charger will provide energy, and then the bidirectional DC converter will intervene to provide energy. If the energy supply is still insufficient, causing the DC bus voltage to drop, the freewheeling unit in each independent parallel unit will start, provide a freewheeling circuit, and directly provide short-circuit current to the DC circuit breaker.

[0080] During this process, the DC bus voltage remains within the set limits, ensuring sufficient short-circuit current for the DC bus while avoiding the risk of DC bus voltage loss. This design effectively handles situations where individual batteries become open-circuited or disconnected from the bus. Serious system failures only occur if all parallel units fail simultaneously, ensuring a high level of system safety and redundancy. Furthermore, the system exhibits strong adaptability due to its flexibility in battery configuration within the parallel units.

[0081] As a possible implementation, each independent parallel unit in the system structure includes not only a battery unit and a bidirectional DC converter, but also a supercapacitor and a wireless communication module. This design expands the functionality of the traditional system and lays the foundation for subsequent intelligent management.

[0082] Under normal operating conditions, the system first monitors the health status of each battery cell in real time through the intelligent management module. Based on artificial intelligence algorithms, this module analyzes the battery's charge and discharge curves, predicts its remaining lifespan, and dynamically adjusts the charge and discharge strategy. For example, when the health of a battery cell deteriorates, the system reduces its depth of discharge to prevent premature aging. Simultaneously, the intelligent power distribution algorithm integrated into the bidirectional DC converter dynamically adjusts the energy output of each parallel cell based on load demand and battery status, ensuring the system operates at its optimal efficiency point. This precise energy management not only extends the battery lifespan but also reduces the system's overall energy consumption.

[0083] When the system detects a drop in the DC bus voltage, the supercapacitor in the freewheeling unit quickly intervenes, providing a high current to stabilize the bus voltage. The supercapacitor's rapid response compensates for the dynamic performance deficiencies of traditional freewheeling diodes, effectively reducing the impact of voltage fluctuations on load devices. Furthermore, the wireless communication module enables real-time data sharing and coordinated control between parallel units. For example, if a parallel unit fails, the other units can obtain this information through the wireless communication module and automatically adjust their operating status to ensure stable system operation despite the failure. This design significantly improves the system's redundancy and reliability, avoiding system paralysis caused by a single point of failure in traditional systems.

[0084] To enhance battery compatibility, the improved system incorporates a multi-type battery adapter module. This module dynamically adjusts the bidirectional DC converter parameters based on the characteristics of different battery types, such as voltage range and charge / discharge profile. For example, for lithium iron phosphate batteries, the system automatically adjusts the charge cutoff voltage and depth of discharge to prevent overcharging or over-discharging. For valve-regulated lead-acid batteries, the system optimizes the float charge voltage and equalization charge cycle to extend their service life. This flexible adaptability enables the system to be compatible with a variety of battery types and meet the needs of diverse application scenarios.

[0085] In abnormal situations, such as AC voltage loss or a DC bus short circuit, the system can quickly switch to emergency mode. First, the bidirectional DC converter automatically enters a voltage-stabilized discharge state to provide energy to the DC bus. If the power supply is still insufficient, the supercapacitor and freewheeling unit jointly provide a freewheeling circuit to ensure continuous operation of the load equipment. When AC is restored, the system automatically switches to equalization charging mode to replenish the energy lost during the discharge process. This fully automatic exception handling mechanism significantly reduces the need for manual intervention and improves the system's intelligence.

[0086] Through the technical solutions of the above embodiments, the system's dynamic response capability and energy management efficiency are significantly improved, and it can effectively cope with load fluctuations and fault conditions. Secondly, the artificial intelligence-based battery health management system extends the battery life and reduces maintenance costs. In addition, the multi-type battery adapter module enhances the system's compatibility and flexibility, enabling it to adapt to the needs of different battery types and application scenarios. Finally, the wireless communication module and collaborative control mechanism improve the system's redundancy and reliability, ensuring stable operation under various abnormal conditions.

[0087] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A parallel battery module, characterized in that: include: Multiple independent parallel units that are completely independent and can operate in parallel, each independent parallel unit including a battery unit and a bidirectional DC converter device, wherein the battery unit is a battery pack including at least one type of battery; the total voltage of the battery units is lower than the normal voltage of the DC bus but higher than the lower voltage limit of the DC bus; the bidirectional DC converter device is connected between the battery unit and the DC bus and is used to boost the voltage of the battery unit to the DC bus voltage; The DC bus is used to connect each independent parallel unit and the DC feeder, providing stable and reliable DC power supply to each branch of the DC feeder; DC feeder, connected to the DC bus, used to distribute DC power to various electrical equipment; A freewheeling unit is connected between the input and output of the bidirectional DC converter and is used to provide a freewheeling circuit when the DC bus voltage drops; The bidirectional DC converter device comprises a plurality of bidirectional DC / DC modules connected in parallel and independently controllable. Each bidirectional DC / DC module can dynamically adjust its operating state according to the actual voltage of the battery cell to which it is connected, so as to optimize the charge and discharge performance of the battery. The management method of the parallel battery module includes: Determine the specific internal configuration of the battery cells of each parallel unit based on the DC bus voltage boundary, and dynamically adjust the number and charging status of the batteries in each parallel unit; Under normal conditions, the battery pack is managed by floating charge, equalizing charge and discharge through the bidirectional DC conversion device; In abnormal situations, such as AC voltage loss and DC bus short circuit, the bidirectional DC converter and freewheeling unit provide energy supply to the DC bus. When the DC bus voltage drops to the lower limit, the system automatically adjusts the working state of the freewheeling unit and directly provides the necessary short-circuit current through the freewheeling circuit to ensure safe operation of the system. The management method also ensures that at any time at least one independent parallel unit is in normal working condition to provide continuous energy output and avoid system failure. Ensure that at least one battery pack is in normal mode, and the freewheeling safety zone availability of the battery pack in normal mode is not less than 100% to ensure continuous power supply to the system; other battery packs can be in maintenance mode or exit state for maintenance or repair; the working status of different parallel units is monitored and adjusted in real time through intelligent control algorithms to ensure that at all times at least one parallel unit can provide sufficient energy output to avoid system failures; The calculation formula for the availability of the freewheeling safety zone of the battery pack is: =（ - ） / （ - ）*100%； in, It is the normal voltage of the battery side, usually the float charge voltage; is the lower limit of DC bus voltage; is the real-time voltage on the battery side; R i It is the availability of the freewheeling safety zone of the battery pack.

2. The parallel battery module according to claim 1, characterized in that: The bidirectional DC / DC module is a boost type, having a low-voltage side and a high-voltage side. The low-voltage side is connected to the battery cell, and the high-voltage side is connected to the DC bus. Each bidirectional DC / DC module can independently perform a boost operation according to the actual voltage of the battery cell to which it is connected, to ensure that the battery cell always operates in the best working state.

3. The parallel battery module according to claim 1, characterized in that: The freewheeling unit includes at least one freewheeling diode, which is used to provide a current path when the DC bus voltage drops.

4. The parallel battery module according to claim 1, characterized in that: The types of batteries include valve-regulated lead-acid batteries or lithium iron phosphate batteries, and the voltage of the battery cells inside each parallel unit can be set according to different battery types and configurations to ensure adaptation to different battery types and optimize system performance.

5. The parallel battery module according to claim 1, characterized in that: The abnormal situations include: When the AC voltage is lost, the bidirectional DC converter automatically enters the voltage-stabilizing discharge state to provide energy for the DC bus; When AC is restored, the bidirectional DC converter automatically switches to the equalization charging state to compensate for the energy loss caused by discharge.

6. The parallel battery module according to claim 5, characterized in that: The abnormal situation also includes that when the DC bus is short-circuited, the bidirectional DC conversion device first provides energy. If it cannot provide sufficient energy, the battery pack directly provides energy to the DC bus through the freewheeling unit until the bus voltage drops to the lower limit.

7. The method for managing parallel battery modules according to claim 1, characterized in that: Each parallel unit meets the following conditions: DC bus voltage> output voltage of bidirectional DC converter device> total voltage of storage batteries inside the battery unit.

Images