A high voltage dynamic switching algorithm for centralized parallel battery clusters

Abstract

The present invention belongs to the technical field of electrochemical energy storage batteries, and specifically relates to a centralized parallel battery cluster high-voltage dynamic switching algorithm, comprising detecting the difference between the total cluster voltage of the switching object and the bus high voltage, performing a merge operation on the switching object if the difference satisfies a preset start interval, and judging whether the current bus high voltage is greater than the total cluster voltage of the switching object; performing a discharge operation on the battery cluster merged into the bus until the current bus voltage value is less than or equal to the total voltage value of the switching object, until the current actual discharge current value satisfies a preset first interval, and until the current bus voltage value satisfies a preset second interval, and then performing a merge operation on the switching object; the switching algorithm proposed in the present invention adopts external energy storage conversion to charge and discharge specific clusters, the current is controllable during the implementation of the algorithm, and the control time is short and the efficiency is high, and normal charging and discharging when the switching algorithm in this embodiment is adopted will not cause damage to batteries and other equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical energy storage embedded devices, and in particular relates to a high-voltage dynamic switching algorithm for a centralized parallel battery cluster. Background Art

[0002] In existing energy storage systems, there are two ways to connect battery clusters to energy storage converters (PCS). One way is to directly connect each battery cluster to a PCS; the other way is to connect multiple battery clusters in parallel to the DC bus and then connect them to the PCS. In the second connection method, under the electrical structure of multiple battery clusters connected in parallel to the bus, if a battery cluster fails and needs to exit the high-voltage connection, that is, disconnect the high-voltage contactor, after the faulty cluster disconnects the high-voltage connection, other clusters in normal status continue to maintain stable operation and charging and discharging.

[0003] After the faulty cluster is manually maintained, it needs to be reconnected to the DC bus in parallel. During the maintenance of the faulty cluster, other normal clusters maintain normal charging and discharging operation, resulting in a certain difference in the total voltage of the normal cluster and the total voltage of the faulty cluster. When the total voltage difference between the two clusters is large, they are connected to the high-voltage bus in parallel at the same time. The battery cluster with a high total voltage will charge the battery cluster with a low total voltage, that is, a circulating current is generated between the battery clusters. The size of the circulating current at this time is the ratio of the difference in the total voltage of the two clusters to the internal resistance of the battery cluster. The internal resistance of the battery cluster is generally in the milliohm level, so the circulating current between the battery clusters is particularly large, causing damage to the battery cells, reducing the life of the battery cells, and even causing short circuits in the battery cells, resulting in thermal runaway, fire, and explosion hazards. Summary of the invention

[0004] The purpose of the present invention is to provide a centralized parallel battery cluster high voltage dynamic switching algorithm to solve the problems raised in the background technology.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] A centralized parallel battery cluster high voltage dynamic switching algorithm, including:

[0007] S1, real-time monitoring of the battery cluster that is not connected to the high-voltage DC bus and setting it as the switching object, detecting the difference between the total cluster voltage of the switching object and the bus high voltage, if the difference meets the preset start interval, the switching object is merged, if not, executing step S2;

[0008] S2, determine whether the current bus high voltage is greater than the total value of the cluster voltage of the switched object, if so, execute step S3, otherwise execute step S4;

[0009] S3, performing a discharge operation on the battery cluster that has been connected to the bus, until the current bus voltage value is less than or equal to the total voltage value of the switching object, until the current actual discharge current value satisfies a preset first interval, and until the current bus voltage value satisfies a preset second interval, and then performing a connection operation on the switching object;

[0010] S4, perform charging operation on the battery cluster that has been connected to the bus until the current bus voltage value is greater than or equal to the total voltage value of the cluster that is not at high voltage, and until the current actual charging current value satisfies the pre-set third interval, and then judge whether the current bus voltage value is in the fourth interval. If it is satisfied, perform the connection operation, otherwise execute step S2.

[0011] As a further optimization solution of the present invention, the startup interval includes: the difference is less than 10V.

[0012] As a further optimization solution of the present invention, the first interval includes: the current actual discharge current value ≤5A.

[0013] As a further optimization solution of the present invention, in step S3, if the current actual discharge current value does not satisfy the preset first interval, the discharge current value in the discharge operation is reduced to 0.8 times the current discharge current value.

[0014] As a further optimization solution of the present invention, the second interval includes: the current bus voltage value ≤ the total voltage value of the switching object cluster - 5A*the total internal resistance value of the battery cluster.

[0015] As a further optimization solution of the present invention, the third interval includes: the current actual charging current value ≤5A.

[0016] As a further optimization solution of the present invention, in step S4, if the current actual charging current value does not satisfy the preset third interval, the charging current value in the charging operation is reduced to 0.8 times the current charging current value.

[0017] As a further optimization solution of the present invention, the fourth interval includes: the current bus voltage value ≥ the total voltage value of the switching object cluster + 5A*the total internal resistance value of the battery cluster.

[0018] The beneficial effects of the present invention are:

[0019] (1) The switching algorithm proposed in the present invention supports the automatic switching of clusters into the parallel high-voltage bus system after the fault is cut off and restored to normal after maintenance, without the need for human intervention. It can also reduce the circulating current during cluster switching, ensure the stable and safe operation of the battery system, and reduce the load current value of the high-voltage contactor during operation through dynamic adjustment, thereby increasing its service life.

[0020] (2) The switching algorithm proposed in the present invention uses an external energy storage converter (PCS) to charge and discharge specific clusters. During the implementation of the algorithm, the current is controllable, and the control time is short and the efficiency is high. When the switching algorithm in this embodiment is used, normal charging and discharging will not cause damage to the battery and other equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flowchart of the overall method execution of the present invention;

[0022] Figure 2 It is a system framework diagram for implementing the overall method in the present invention. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0024] Example 1

[0025] like Figure 1-2 As shown, this embodiment proposes a centralized parallel battery cluster high voltage dynamic switching algorithm, including:

[0026] S1, real-time monitoring of the battery cluster that is not connected to the high-voltage DC bus and setting it as the switching object, detecting the difference between the total cluster voltage of the switching object and the bus high voltage, if the difference meets the preset start interval, the switching object is merged, if not, executing step S2;

[0027] The start-up interval includes: the difference is less than 10V.

[0028] S2, determine whether the current bus high voltage is greater than the total value of the cluster voltage of the switched object, if so, execute step S3, otherwise execute step S4;

[0029] S3, performing a discharge operation on the battery cluster that has been connected to the bus, until the current bus voltage value is less than or equal to the total voltage value of the switching object, until the current actual discharge current value satisfies a preset first interval, and until the current bus voltage value satisfies a preset second interval, and then performing a connection operation on the switching object;

[0030] The first interval includes: the current actual discharge current value ≤ 5A.

[0031] It can be understood that the limit value of the actual discharge current value here is only a value representing a smaller current, indicating that the difference of the total voltage values ​​of the two clusters within 10V is the real voltage equality, and it is not because of the existence of a large charging or discharging current. When there is a charging current, the total voltage value will be pulled up; when there is a discharging current, the total voltage value will be pulled down. The increase and decrease of the total voltage caused by a small current of a few amperes is acceptable.

[0032] Preferably, in step S3, if the current actual discharge current value does not satisfy the preset first interval, the discharge current value in the discharge operation is reduced to 0.8 times of the current discharge current value.

[0033] The second interval includes: the current bus voltage value ≤ the total voltage value of the switching object cluster - 5A*the total internal resistance value of the battery cluster.

[0034] S4, perform charging operation on the battery cluster that has been connected to the bus until the current bus voltage value is greater than or equal to the total voltage value of the cluster that is not at high voltage, and until the current actual charging current value satisfies the pre-set third interval, and then judge whether the current bus voltage value is in the fourth interval. If it is satisfied, perform the connection operation, otherwise execute step S2.

[0035] The third interval includes: the current actual charging current value ≤ 5A.

[0036] Preferably, in step S4, if the current actual charging current value does not meet the preset third interval, the charging current value in the charging operation is reduced to 0.8 times the current charging current value. The purpose of reducing it to 0.8 times here is to make the current current value smaller than the previous moment and gradually reduce the current value.

[0037] Preferably, the fourth interval includes: the current bus voltage value ≥ the total voltage value of the switching object cluster + 5A*the total internal resistance value of the battery cluster.

[0038] Through the above steps S1-S4, all clusters can be dynamically put into the parallel bus high voltage.

[0039] In this embodiment, after the battery fault cluster is restored to normal state through maintenance, the charging and discharging of the current normal state cluster is controlled by dynamically adjusting the current, and the total battery voltage of the normal state cluster is adjusted so that the total battery voltage of the normal state cluster is close to the total battery voltage of the cluster after the fault maintenance is completed, thereby reducing the circulation between the battery clusters to a safe range.

[0040] Compared with the prior art method of adding a resistor between a cluster with a higher total pressure and a cluster with a lower total pressure, so that the cluster with a higher total pressure charges the cluster with a lower total pressure, so that the total pressures of the two clusters slowly reach the same level, and then connecting other clusters to continue the charge and discharge balancing action to achieve the total pressure balance of all clusters, there are the following disadvantages:

[0041] 1. When the voltage difference between clusters is large, the balancing current passing through the pre-charge resistor will be very small, resulting in this method taking a very long time to achieve the balancing goal;

[0042] 2. The pre-charge resistor is easily damaged and exploded if the current passes through it for a long time, affecting the safety of the system.

[0043] According to an embodiment of the present invention, the switching algorithm uses an external energy storage converter (PCS) to charge and discharge specific clusters. During the implementation of the algorithm, the current is controllable, and the control time is short and efficient. When the switching algorithm in this embodiment is used, normal charging and discharging will not cause damage to the battery and other equipment.

[0044] It is obvious to those skilled in the art that the embodiments of the present invention are not limited to the details of the above exemplary embodiments, and that the embodiments of the present invention can be implemented in other specific forms without departing from the spirit or basic features of the embodiments of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the embodiments of the present invention is limited by the attached claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims in the embodiments of the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved. In addition, it is obvious that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units, modules or devices stated in the system, device or terminal claims can also be implemented by the same unit, module or device through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any particular order.

[0045] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A centralized parallel battery cluster high voltage dynamic switching algorithm, characterized in that: include: S1, real-time monitoring of the battery cluster that is not connected to the high-voltage DC bus and setting it as the switching object, detecting the difference between the total cluster voltage of the switching object and the bus high voltage, if the difference meets the preset start interval, the switching object is merged, if not, executing step S2; S2, determine whether the current bus high voltage is greater than the total value of the cluster voltage of the switched object, if so, execute step S3, otherwise execute step S4; S3, performing a discharge operation on the battery cluster that has been connected to the bus, until the current bus voltage value is less than or equal to the total voltage value of the switching object, until the current actual discharge current value satisfies a preset first interval, and until the current bus voltage value satisfies a preset second interval, and then performing a connection operation on the switching object; S4, charging the battery cluster that has been connected to the busbar until the current busbar voltage value is greater than or equal to the total voltage value of the cluster that is not connected to high voltage, and until the current actual charging current value satisfies the preset third interval, and then judging whether the current busbar voltage value is in the fourth interval, if so, performing the connection operation, otherwise executing step S2; The switching algorithm uses an external energy storage converter to charge and discharge the battery cluster connected to the busbar; The first interval includes: the current actual discharge current value ≤ 5A; the second interval includes: the current bus voltage value ≤ the total voltage value of the switching object cluster The total internal resistance of the battery cluster; the third interval includes: the current actual charging current value ≤ 5A; the fourth interval includes: the current bus voltage value ≥ the total voltage value of the switching object cluster The total internal resistance of the battery cluster.

2. According to claim 1, a centralized parallel battery cluster high voltage dynamic switching algorithm is characterized by: The start-up interval includes: the difference is less than 10V.

3. A centralized parallel battery cluster high voltage dynamic switching algorithm according to claim 1, characterized in that: In step S3, if the current actual discharge current value does not satisfy the preset first interval, the discharge current value in the discharge operation is reduced to 0.8 times of the current discharge current value.

4. A centralized parallel battery cluster high voltage dynamic switching algorithm according to claim 1, characterized in that: In step S4, if the current actual charging current value does not satisfy the preset third interval, the charging current value in the charging operation is reduced to 0.8 times of the current charging current value.

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