Parallel storage battery module and management method

Abstract

The invention discloses a parallel storage battery module and a management method, and belongs to the technical field of direct current power supply in the power industry, the parallel storage battery module comprises a plurality of independent parallel units which are completely independent and can work in parallel, and each independent parallel unit comprises a battery unit and a bidirectional direct current conversion device, the total voltage of the battery unit is lower than the normal voltage of the direct-current bus but higher than the lower voltage limit of the direct-current bus, and the bidirectional direct-current conversion device is connected between the battery unit and the direct-current bus; the direct-current bus is used for connecting each independent parallel unit and the direct-current feeder line and providing stable and reliable direct-current power supply for each branch circuit of the direct-current feeder line; the direct current feeder line is connected to the direct current bus; and the follow current unit is connected between the input and the output of the bidirectional direct current conversion device. The method has the advantages that the multiple parallel units operate independently, the safety, reliability and fault-tolerant capability of the system are improved, complex operation and a large amount of manual intervention in a traditional battery management method are avoided, and the operation and maintenance cost is reduced.

Description

Technical Field

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

[0002] In recent years, as the power system has increased its requirements for the reliability and redundancy of station DC power supplies, various battery pack parallel technologies have been widely used. However, the existing technologies mostly use traditional series topologies and different types of parallel topologies. While ensuring system redundancy and reliability, there are certain limitations, especially in terms of battery management, system stability and flexibility, which need to be improved.

[0003] Traditional station DC power supply systems usually use a single battery pack, which is composed of multiple batteries connected in series and connected to a charger to provide stable power to the DC feeder through the DC bus. When the AC power is normal, the charger serves as the main energy supply device, and the battery pack is in a floating charge state and on standby. When the AC power fails, the battery pack will switch to the main energy supply device and continue to provide energy to the DC feeder until the AC power is restored. However, this traditional single-series structure battery pack has certain hidden dangers, especially when the battery fails, such as a single battery open circuit or the battery pack fails to be reliably connected, which may cause the battery pack to detach from the DC bus, causing the DC bus to lose backup energy, and then cause serious system pressure loss problems, posing a major hidden danger to the stable operation of the system.

[0004] In addition, according to the power system's requirements for station DC power supply, when verifying the capacity of the battery pack, it is required to conduct a verification discharge test every two years for battery packs that have been in operation for less than four years, and once a year for battery packs that have been in use for more than four years. When implementing this test requirement, it is necessary to add a backup battery pack to the DC bus to ensure that the system power supply is not affected, and then restore it to its original state after the test is completed. This process is cumbersome, time-consuming and labor-intensive, which increases the operation and maintenance costs and work intensity, and seriously affects the efficient implementation of daily battery maintenance work.

[0005] In response to the above problems, the industry has proposed a variety of technical solutions based on parallel topology to improve the redundancy and reliability of the battery system. For example, the traditional indirect parallel technology uses low-voltage battery cells, which are boosted to the DC bus voltage through a power conversion device and connected to the DC bus in parallel. However, since the voltage of these low-voltage battery cells is much lower than the DC bus voltage, the current capacity they provide is limited and they cannot directly provide the required short-circuit current for the DC bus. As a result, when a DC bus fault occurs, the system cannot effectively provide sufficient short-circuit current, and thus cannot reliably disconnect the DC circuit breaker, resulting in serious system safety hazards.

[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 that the battery pack operates completely independently, 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] In order to overcome the shortcomings of the existing technology, a parallel battery module and management method are proposed, which enable multiple parallel units to operate independently, which 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.

[0008] The technical solution adopted by the invention to solve the technical problem is: a parallel battery module, the improvement of which is that it includes: A plurality of independent parallel units that are completely independent and can work in parallel, each of which includes a battery unit and a bidirectional DC conversion device, wherein 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 conversion device is connected between the battery unit and the DC bus 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 to provide stable and reliable DC power supply for each branch of the DC feeder; A DC feeder, connected to the DC bus, is used to distribute DC power to various electrical equipment; The freewheeling unit is connected between the input and output of the bidirectional DC conversion device and is used to provide a freewheeling loop when the DC bus voltage drops.

[0009] In the above structure, the bidirectional DC conversion device contains a plurality of parallel bidirectional DC / DC modules. 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 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, so as to ensure that the battery unit always operates in the best working state.

[0010] 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.

[0011] 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.

[0012] The present invention also provides a management method for parallel battery modules, the improvement of which is that it comprises the following steps: Determine the specific internal configuration of the battery cells of each parallel unit according to the boundary of the DC bus voltage, and dynamically adjust the number and charging state of the batteries of 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, when the AC voltage is lost and the DC bus is short-circuited, the bidirectional DC conversion device and the freewheeling unit provide energy supply to the DC bus; when the DC bus voltage drops to the lower limit, the system will automatically adjust the working state of the freewheeling unit and directly provide the necessary short-circuit current through the freewheeling circuit to ensure the safe operation of the system; The management method also ensures that at least one independent parallel unit is in normal working state at any time to provide continuous energy output and avoid system failure.

[0013] 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 overhaul, 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.

[0014] Furthermore, the calculation formula for the availability of the freewheeling safety zone of the battery pack is: =( - ) / ( - )*100%; in, It is the normal voltage on the battery side, usually the floating 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 battery pack's freewheeling safety zone.

[0015] Furthermore, the abnormal conditions 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 equalizing charging state to compensate for the energy loss caused by discharge.

[0016] 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.

[0017] 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.

[0018] 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural principle diagram of a parallel battery module of the present invention; Figure 2 A schematic diagram of a bidirectional DC conversion device for a parallel battery module of the present invention; Figure 3 A battery voltage range configuration principle diagram of a parallel battery module of the present invention; Figure 4 The present invention is a state transition diagram of a parallel battery module management method. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] 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 technicians in this field without creative work are all 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 formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the invention can be combined interchangeably without conflicting with each other.

[0022] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0023] 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 used for descriptive purposes and cannot be understood as indicating or suggesting 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 the features. Secondly, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to 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.

[0024] See also Figure 1 As shown, the present invention provides a parallel battery module, comprising: A plurality of independent parallel units that are completely independent and can work in parallel, each of which includes a battery unit and a bidirectional DC conversion device, wherein 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 conversion device is connected between the battery unit and the DC bus 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 to provide stable and reliable DC power supply for each branch of the DC feeder; A DC feeder, connected to the DC bus, is used to distribute DC power to various electrical equipment; The freewheeling unit is connected between the input and output of the bidirectional DC conversion device and is used to provide a freewheeling loop when the DC bus voltage drops.

[0025] In the present invention, through the design of multiple independent parallel units that are completely independent and can work in parallel, each unit can work independently, avoiding the risks brought by the series connection of battery packs in traditional systems. If a battery unit fails, 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, realizing accurate voltage regulation and charge and discharge management. This design ensures that the battery is always in the best working state, prolongs the battery life, and reduces 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 short-circuit protection capability of the system, 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 much 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, thereby achieving control decoupling between independent parallel units, and there is no coupling relationship between them.

[0026] Further, such as Figure 2 As shown, the bidirectional DC conversion device internally includes 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 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. 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 necessary. 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 (within the dotted box) internally includes a plurality of parallel bidirectional DC / DC modules and freewheeling units 1 and 2, wherein 1-n bidirectional DC / DC modules are of boost type, U bat The low voltage side is connected to the battery unit (below the dotted box), U busIt is the high-voltage side and is connected to the DC bus (above the dotted box). As mentioned above, under normal working conditions, multiple parallel bidirectional DC / DC modules charge or discharge the battery side. Because of the voltage difference between the high and low sides, the freewheeling unit 1 and the freewheeling unit 2 do not work. When the energy supply is insufficient and the DC bus voltage drops, the high and low side voltage difference cannot meet the operation of multiple parallel bidirectional DC / DC modules. Based on the drooping characteristics of the DC voltage, the freewheeling unit 1 and the freewheeling unit 2 work at this time to provide a loop for output current.

[0027] 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 when voltage fluctuations or short circuit faults occur. 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.

[0028] The valve-regulated lead acid battery (VRLA battery) is a sealed lead acid battery with valve equipment. It maintains internal gas pressure through a safety valve to ensure stable working conditions inside the battery. This type of battery will generate gas when charging, and the safety valve can control the pressure of the internal gas to prevent the battery from being damaged by gas expansion. Lithium iron phosphate battery, full name lithium iron phosphate lithium-ion battery, is a new type of lithium-ion battery. Its single-cell rated voltage is 3.2V, and the charging cut-off voltage is 3.6V to 3.65V. During the charging process, some lithium ions in lithium iron phosphate are released, transferred to the negative electrode through the electrolyte, and embedded in the negative electrode carbon material; at the same time, electrons are released from the positive electrode and reach the negative electrode through the external circuit to maintain the balance of the chemical reaction. The discharge process is the opposite, lithium ions are released from the negative electrode, reach the positive electrode through the electrolyte, and at the same time, the negative electrode releases electrons through the external circuit to reach the positive electrode to provide energy to the outside world. Valve-regulated lead acid batteries are usually low-cost and suitable for cost-sensitive applications, while lithium iron phosphate batteries have longer service life, higher energy density and stronger safety. Using different types of batteries in the same system can find the best balance between cost and performance according to different needs, providing flexible customization options. Compared with valve-regulated lead-acid batteries, lithium iron phosphate batteries have longer cycle life and higher durability. In the long-term operation process, the system can reasonably allocate the use of different types of batteries according to the different characteristics of the batteries to avoid the degradation of the overall system performance caused by the decline of a single battery type. This can effectively extend the overall service life of the battery pack. By allowing the use of different types of batteries, the parallel battery module can flexibly select the most suitable battery type according to user needs and actual application scenarios.

[0029] The present invention also provides a management method for parallel battery modules, comprising the following steps: Determine the specific internal configuration of the battery cells of each parallel unit according to the boundary of the DC bus voltage, and dynamically adjust the number and charging state of the batteries of each parallel unit; Under normal conditions, the battery pack is managed by floating charge, equalizing charge and discharge through the bidirectional DC conversion device; Under abnormal circumstances, when the AC voltage is lost and the DC bus is short-circuited, the DC bus is provided with energy supply through the bidirectional DC conversion device and the freewheeling unit; wherein, when the DC bus voltage drops to the lower limit, the system will automatically adjust the working state of the freewheeling unit, and directly provide the necessary short-circuit current through the freewheeling circuit to ensure the safe operation of the system: wherein, the management method also ensures that at any time at least one independent parallel unit is in a normal working state to provide continuous energy output and avoid the occurrence of system failures.

[0030] 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 overhaul, 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.

[0031] 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 to be inspected or maintained to maintenance mode or exit state, thereby effectively improving the efficiency of daily operation and maintenance. This innovative design reduces the cumbersome manual intervention in traditional operation and maintenance, making battery management more efficient and intelligent.

[0032] like Figure 3 As shown in the figure, according to the single-cell charging and discharging 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: The nominal voltage of the DC bus, usually 110V or 220V; The upper limit voltage of the DC bus, usually 112.5% ​​of the nominal voltage; The DC bus voltage limit is usually 87.5% of the nominal voltage. The upper limit voltage of the battery side, usually the equalization charging voltage; It is the lower limit voltage of the battery side, usually the lowest discharge cut-off voltage; It is the normal voltage on the battery side, usually the floating charge voltage; is the real-time voltage on the battery side; It is the minimum voltage difference between the DC bus and the battery side of the bidirectional DC converter, which is a fixed value.

[0033] Among them, ≤ - ; ≥ ; 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 just cannot 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 interval with freewheeling safety guarantee for the i-th parallel unit under normal working conditions. It is used to evaluate the degree of freewheeling safety 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.

[0034] The calculation formula of the battery pack freewheeling safety zone availability is: =( - ) / ( - )*100%; in, It is the normal voltage on the battery side, usually the floating 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 battery pack's freewheeling safety zone.

[0035] The minimum voltage difference between the DC bus and the battery side of the bidirectional DC converter =10V as an example: For a nominal 2V valve-regulated lead-acid battery, the minimum discharge cut-off voltage is 1.80V, the floating charge voltage is 2.25V, and the equalization charge voltage is 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%.

[0036] For a nominal 12V valve-regulated lead-acid battery, the minimum discharge cut-off voltage is 10.8V, the floating charge voltage is 13.5V, and the equalization charge voltage is 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 8, when single battery 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%.

[0037] For a nominal 3.2V lithium iron phosphate battery, the minimum discharge cut-off voltage is 3.00V, the floating charge voltage is 3.40V, and the equalization charge voltage is 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 = 3.00V, then is 98.05%. When the single cell voltage is ≥3.01V, ≥100%, the minimum number of batteries is 57, when the single cell voltage = 3.00V, then is 5.70%. When the single cell voltage is ≥3.38V, ≥100%.

[0038] As mentioned above, the availability of each independent parallel unit itself , and the number of 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 battery charge and discharge parameters 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 actually used is determined within the range, with the real-time voltage on the battery side 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 each independent parallel unit. The largest value in .

[0039] Furthermore, the abnormal conditions 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 equalizing charging state to compensate for the energy loss caused by discharge.

[0040] 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.

[0041] like Figure 4As shown, under normal conditions, the battery is in a floating charge state. Scheduled equalization charging or manual equalization charging can start the equalization charging mode and return to the floating charge state after the equalization charging is completed. According to the operation of the system, when the system is operating normally, scheduled maintenance (such as core capacity / activation) or manual maintenance (such as core capacity / activation) can start the maintenance mode and return to the floating charge state after the maintenance mode is completed. When AC voltage loss occurs and there is no external energy supply, the bidirectional DC converter will automatically enter the voltage-stabilized discharge state to provide the required energy for the DC bus. When AC is restored, the system will switch to the equalization charging mode to replenish the energy lost during the discharge process. If the bidirectional DC converter cannot meet the energy required by the DC bus during the above process, according to the DC voltage droop characteristics, the freewheeling part of the battery group will directly provide energy to the DC bus until the bus voltage drops to the lower limit. Thereafter, the system will switch to the equalization charging mode after the DC bus short circuit ends or AC is restored to replenish the energy loss caused by discharge.

[0042] Each parallel unit satisfies the following conditions: DC bus voltage> output voltage of bidirectional DC converter> total voltage of batteries inside the battery unit. According to 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> output voltage of bidirectional DC converter> total voltage of batteries 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.

[0043] During this process, the DC bus voltage is always kept within the set limit range, which can provide sufficient short-circuit current for the DC bus and avoid the risk of DC bus voltage loss. This design can effectively deal with the situation where individual batteries are open-circuited or disconnected from the bus. Only when all parallel units fail at the same time will the system have serious problems, thus ensuring that the system has high safety redundancy. In addition, since the system has greater flexibility in the configuration of batteries inside the parallel units, it also shows strong application adaptability.

[0044] As a possible embodiment, in terms of system structure, each independent parallel unit includes not only a battery unit and a bidirectional DC conversion device, but also a supercapacitor and a wireless communication module. This design achieves functional expansion of the traditional system and lays the foundation for subsequent intelligent management.

[0045] Under normal working 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 can analyze the battery's charge and discharge curves, predict the remaining life of the battery, and dynamically adjust the charge and discharge strategy. For example, when the health status of a battery cell decreases, the system will reduce the discharge depth of the cell to prevent it from aging prematurely. At the same time, the intelligent power distribution algorithm integrated in the bidirectional DC converter will dynamically adjust the energy output of each parallel unit according to the load demand and battery status to ensure that the system operates at the optimal efficiency point. This precise energy management not only extends the battery life, but also reduces the overall energy consumption of the system.

[0046] When the system detects that the DC bus voltage drops, the supercapacitor in the freewheeling unit will quickly intervene to provide a large current to stabilize the bus voltage. The fast response capability of the supercapacitor makes up for the shortcomings of the traditional freewheeling diode in dynamic performance, effectively reducing the impact of voltage fluctuations on the load equipment. In addition, the wireless communication module realizes real-time data sharing and collaborative control between the parallel units. For example, when a parallel unit fails, other units can obtain fault information through the wireless communication module and automatically adjust their working status to ensure that the system can still operate stably in the event of a fault. This design significantly improves the redundancy and reliability of the system and avoids system paralysis caused by a single fault point in the traditional system.

[0047] In terms of battery type compatibility, the improved system introduces a multi-type battery adapter module. This module can dynamically adjust the parameters of the bidirectional DC converter according to the characteristics of different types of batteries (such as voltage range, charge and discharge curve). For example, for lithium iron phosphate batteries, the system will automatically adjust the charge cut-off voltage and discharge depth to avoid overcharging or over-discharging; for valve-regulated lead-acid batteries, the system will optimize the floating charge voltage and equalization charge cycle to extend its service life. This flexible adaptation capability enables the system to be compatible with multiple battery types and meet the needs of different application scenarios.

[0048] In abnormal situations, such as AC voltage loss or DC bus short circuit, the system can quickly switch to emergency mode. First, the bidirectional DC converter will automatically enter the voltage-stabilized discharge state to provide energy for the DC bus. If the power supply is still insufficient, the supercapacitor and the freewheeling unit will jointly provide a freewheeling circuit to ensure that the load equipment can continue to operate. When the AC is restored, the system will automatically switch to the equalization charging mode to replenish the energy lost during the discharge process. This fully automatic abnormal handling mechanism greatly reduces the need for manual intervention and improves the intelligence level of the system.

[0049] Through the technical solutions of the above embodiments, the dynamic response capability and energy management efficiency of the system are significantly improved, and it can effectively cope with load fluctuations and fault conditions. Secondly, the battery health management system based on artificial intelligence extends the service life of the battery and reduces maintenance costs. In addition, the multi-type battery adapter module enhances the compatibility and flexibility of the system, 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 redundancy and reliability of the system, ensuring stable operation under various abnormal conditions.

[0050] 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: A plurality of independent parallel units that are completely independent and can work in parallel, each of which includes a battery unit and a bidirectional DC conversion device, wherein 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 conversion device is connected between the battery unit and the DC bus 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 to provide stable and reliable DC power supply for each branch of the DC feeder; A DC feeder, connected to the DC bus, is 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 loop when the DC bus voltage drops; The bidirectional DC conversion device contains a plurality of bidirectional DC / DC modules connected in parallel and independently controllable, and each bidirectional DC / DC module can dynamically adjust the working state according to the actual voltage of the battery unit to which it is connected, so as to optimize the charging and discharging performance of the battery.

2. A 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, wherein 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, so as to ensure that the battery cell always operates in the best working state.

3. A 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. A parallel battery module according to claim 1, characterized in that: The battery unit includes at least one type of battery, the type of battery includes a valve-regulated lead-acid battery or a 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.

5. A method for managing parallel battery modules, characterized in that: The following steps are involved: Determine the specific internal configuration of the battery cells of each parallel unit according to the boundary of the DC bus voltage, and dynamically adjust the number and charging state of the batteries of 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, when the AC voltage is lost and the DC bus is short-circuited, the bidirectional DC conversion device and the freewheeling unit provide energy supply to the DC bus; when the DC bus voltage drops to the lower limit, the system will automatically adjust the working state of the freewheeling unit and directly provide the necessary short-circuit current through the freewheeling circuit to ensure the safe operation of the system; The management method also ensures that at least one independent parallel unit is in normal working state at any time to provide continuous energy output and avoid system failure.

6. A method for managing parallel battery modules according to claim 5, characterized in that: 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 overhaul, 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 at least one parallel unit can provide sufficient energy output to avoid system failure.

7. A method for managing parallel battery modules according to claim 5, characterized in that: The calculation formula of the battery pack freewheeling safety zone availability is: =（ - ） / （ - ）*100%； in, It is the normal voltage on the battery side, usually the floating 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 battery pack's freewheeling safety zone.

8. A method for managing parallel battery modules according to claim 5, 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 equalizing charging state to compensate for the energy loss caused by discharge.

9. A method for managing parallel battery modules according to claim 8, 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 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.

10. A method for managing parallel battery modules according to claim 5, characterized in that: Each parallel unit meets the following conditions: DC bus voltage> output voltage of bidirectional DC conversion device> total voltage of storage batteries inside the battery unit.

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