CN115986878A - Balance system for local energy transfer and control method thereof - Google Patents
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Abstract
The invention relates to the technical field of battery equalization, in particular to an equalization system for local energy transfer and a control method thereof. By using the shared inductor, electric energy can be transmitted between adjacent electric cores, so that the local balance of the battery electric energy is realized, the total cost of the system is reduced, and the reliability of the system is effectively improved.
Description
Technical Field
The invention relates to the technical field of battery equalization, in particular to an equalization system for local energy transfer and a control method thereof.
Background
The traditional BMS uses passive equalization, the efficiency is not high, the capacity of an energy storage system is large, and the equalization time is long; therefore, a BMS active equalization scheme is gradually proposed, a cell end is selected through a channel in a conventional flyback topology at present, and a cell needing active equalization is connected to a power supply voltage, so that an active equalization mode is realized.
Disclosure of Invention
The invention provides a balance system for local energy transfer and a control method thereof based on a buck-boost control circuit principle and by combining concepts of energy transfer among cells and group control, aiming at the problems that the active balance circuit has more MOS (metal oxide semiconductor) tubes, higher bill of materials and higher price, has higher requirement on power supply capacity of power supply voltage, is easily failed due to voltage fluctuation and the like.
In order to achieve the above purpose, the invention provides the following technical scheme:
the utility model provides a balanced system of local energy transfer, includes at least one battery cluster, and the battery cluster includes a plurality of electric cores of series connection, and to any current electric core, still includes first switching return circuit and second switching return circuit, first switching return circuit includes current electric core, first change over switch and the inductance of series connection, the second switching return circuit includes current electric core, second change over switch and another inductance of series connection, the first switching return circuit sharing of adjacent electric core the inductance, the second switching return circuit sharing of adjacent electric core the another inductance, inductance in first switching return circuit and the inductance in the second switching return circuit are located the different electrode of current electric core.
Preferably, the battery system further comprises an isolation transformer, among the plurality of battery cells connected in series, the last battery cell in the battery cluster, the first port of the isolation transformer and the second switch form a series circuit, and the second port of the isolation transformer is connected in parallel to two ends of the first battery cell.
Preferably, the system further comprises a pre-charging switch, a pre-charging resistor and a main circuit switch, wherein the pre-charging resistor and the pre-charging switch are connected in series and then connected between the positive electrode of the battery cluster and the positive electrode of the direct current bus, and the main circuit switch is connected in parallel between the positive electrode of the direct current bus and the positive electrode of the battery cluster.
Preferably, the battery pack further comprises a discharge switch and a discharge resistor, wherein the discharge switch and the discharge resistor are connected in series to form a discharge branch, and two ends of the discharge branch are connected in parallel to two ends of the battery pack.
Preferably, the system also comprises a processor and an isolation driver,
the processor is connected with the first change-over switch and the second change-over switch through an isolation drive and is used for respectively controlling the first change-over switch and the second change-over switch to be switched on and off.
Based on the same concept, the control method of the local energy transfer equalization system is further provided, the local energy transfer equalization system is constructed, and the control method comprises the following steps:
marking the battery cell with the highest voltage as the current battery cell, and then comparing the voltage of the current battery cell, the voltage of the previous battery cell adjacent to the current battery cell and the voltage of the next battery cell; when the voltage of the current battery cell is greater than that of the next battery cell, closing a first change-over switch corresponding to the current battery cell to charge an inductor shared by the current battery cell and the previous battery cell, disconnecting the first change-over switch corresponding to the current battery cell and closing the first change-over switch corresponding to the previous battery cell at the same time to supplement power for the previous battery cell until the voltage difference between the current battery cell and the previous battery cell is less than a voltage difference threshold value; and closing a second change-over switch corresponding to the current battery cell to charge an inductor shared by the current battery cell and the next battery cell, disconnecting the second change-over switch corresponding to the current battery cell and closing the second change-over switch corresponding to the next battery cell to supplement power for the next battery cell at the same time until the pressure difference between the current battery cell and the next battery cell is less than a pressure difference threshold value.
Preferably, the last cell in the battery cluster supplies power to the first cell in the battery cluster through an isolation transformer.
Preferably, the method further comprises the following steps: when the system is electrified, the voltage of the battery cluster is detected, and if the voltage difference of the battery cluster is greater than or equal to the discharge threshold, the voltage in the battery cluster is subjected to passive balanced discharge through a discharge resistor connected in parallel to the battery cluster.
Preferably, when the system is powered on, if the voltage difference of the battery clusters is smaller than the discharge threshold, inter-cluster balance is performed among the plurality of battery clusters.
Preferably, if the voltage difference between the battery clusters is smaller than the threshold value of the voltage difference between the clusters, each battery cluster discharges electricity to the alternating current power grid through the positive electrode of the direct current bus and the negative electrode of the direct current bus or charges electricity from the alternating current power grid.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a balance system for local energy transfer, in a circuit structure, each battery cell shares an inductor with an adjacent battery cell through two switching loops, and electric energy of the adjacent battery cells can be transferred from the shared inductor through a change-over switch, so that local electric quantity balance of the battery cells is formed. And based on this circuit, can realize the local traversal of electric core and balance in groups, during initiative is balanced, and the switch quantity of simultaneous control reduces by a wide margin, and the switch data volume for initiative is balanced also reduces by a wide margin, has simplified the circuit, has reduced the material price. Meanwhile, even if the power supply capacity of the power supply voltage for active equalization is low, the equalization effect is not influenced.
Drawings
FIG. 1 is a topology diagram of an equalizing system for local energy transfer in embodiment 1;
FIG. 2 is a topology diagram of a local energy transfer equalization system with an isolation transformer and a passive equalization circuit in embodiment 1;
FIG. 3 is a diagram of a local energy transfer equalization system with a precharge circuit and an isolation driver according to embodiment 1;
FIG. 4 is a diagram of an equalizing system of a specific local energy transfer in embodiment 2;
FIG. 5 is a schematic diagram showing the discharge path between the cluster voltages of example 2 above 20V;
fig. 6 is a schematic diagram illustrating the balance between the cell 2 and the cell 1 in embodiment 2;
fig. 7 is a schematic diagram illustrating the balance between the cell 2 and the cell 3 in embodiment 2;
fig. 8 is a flowchart of a specific equalization policy method in embodiment 2.
Detailed Description
The present invention will be described in further detail with reference to test examples and specific embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.
Example 1
A topological diagram of a local energy transfer balancing system is shown in fig. 1, and the system comprises at least one battery cluster, wherein the battery cluster comprises a plurality of cells connected in series, a battery cluster 1 and a battery cluster 2 … … battery cluster n are taken as examples in fig. 1, each battery cluster comprises a plurality of cells connected in series, such as a cell 1, a cell 2, a cell 3, a cell 4 … … cell n-1 and a cell n shown in fig. 1, and two ends of the battery cluster are respectively connected with a positive electrode P + of a direct current bus and a negative electrode P-of the direct current bus, and are used for supplying power to the direct current bus or obtaining electric energy from the direct current bus. Also included are a number of inductors (e.g., L1, L2, L3 … … Ln, ln-1 in FIG. 1), a number of first switches (e.g., D1, D2, D3 … … Dn in FIG. 1), and a number of second switches (e.g., D1b, D2b, D3b … … Dnb in FIG. 1).
For any current battery cell, the battery further comprises a first switching loop and a second switching loop, wherein the first switching loop comprises the current battery cell, a first switch and an inductor which are connected in series, the second switching loop comprises the current battery cell, a second switch and another inductor which are connected in series, and the inductor in the first switching loop and the inductor in the second switching loop are located on different electrodes of the current battery cell. Using electricity core 2 as an example, when electricity core 2 is the current electricity core, electricity core 2 corresponds and has two switching loops: a first switching loop and a second switching loop. The battery cell 2, the first switch D2 and the inductor L1 are connected in series in the first switching loop, the battery cell 2, the second switch D2b and the inductor L2 are connected in series in the second switching loop, the inductor L1 is connected to the positive electrode of the battery cell 2, the inductor L2 is connected to the negative electrode of the battery cell 2, and the inductors L1 and L2 are not located at the same end of the battery cell 2. Each battery cell has a corresponding first switching loop and a corresponding second switching loop, the first switching loops of adjacent battery cells share an inductor, the second switching loops of adjacent battery cells share another inductor, for a battery cell 2, there are two battery cells adjacent to the battery cell 2, which are respectively a battery cell 1 with a front serial number and a battery cell 3 with a rear serial number, since the inductors L1 and L2 are not at the same end of the battery cell 2, the inductor L1 is shared by the first switching loop of the battery cell 1 and the first switching loop of the battery cell 2, the inductor L1 in the first switching loop of the battery cell 1 is also the inductor L1 in the first switching loop of the battery cell 2, the inductor L2 is shared by the second switching loop of the battery cell 3 and the second switching loop of the battery cell 2, and the inductor L2 in the second switching loop of the battery cell 3 is also the inductor L2 in the second switching loop of the battery cell 2, so as to form a structure in which inductors are respectively arranged in a staggered manner in the first switching loop and the second switching loop.
A topological diagram of a local energy transfer equalization system with an isolation transformer and a passive equalization circuit is shown in fig. 2, and a connection relationship among the battery cells, the first change-over switch, the second change-over switch and the inductor is described by taking a battery cell cluster 1 as an example, the serial numbers of the first change-over switch, the second change-over switch and the battery cells are in one-to-one correspondence, the right side of the battery cell 2 in the battery cell cluster 1 is connected in parallel with a first change-over switch D2, and the left side of the battery cell cluster 1 is connected in parallel with a second change-over switch D2b; for example, an inductance L1 is connected between the anode of the battery cell 2 and the first switch D2, and an inductance L2 is connected between the cathode of the battery cell 2 and the second switch D2b, because the structure has symmetry, the inductance L1 may also be connected between the cathode of the battery cell 2 and the first switch D2, and the inductance L2 is connected between the anode of the battery cell 2 and the second switch D2b; the inductance L1 is shared between the battery cell 2 and the previous battery cell (battery cell 1), and the inductance L2 is shared between the battery cell 2 and the next battery cell (battery cell 3).
Further, as shown in fig. 2, a last battery cell in each battery cluster, a first port of the isolation transformer, and the second switch form a series circuit, and a second port of the isolation transformer is connected in parallel to two ends of the first battery cell in the battery cluster. The cell cluster 1 in fig. 2 is taken as an example for explanation: the negative electrode of the last battery cell (battery cell n) in the battery cell cluster 1 is connected with the pin 1 of the first port of the isolation transformer Ln, after the pin 2 of the first port of the isolation transformer Ln is connected with the second change-over switch Dnb, the second change-over switch Dnb is connected back to the positive electrode of the battery cell n to form a series circuit. The pins 3 and 4 of the second port of the isolation transformer Ln are connected in parallel to the cell 1 of the cell cluster 1.
The system can realize local active equalization and also can realize passive equalization, each battery cluster also has a corresponding passive equalization circuit, as shown in fig. 2, the passive equalization circuit comprises a discharge switch (K1 b, K2b, K3b … … Knb) and a discharge resistor (R1 a, R2a, R3a … … Rna), the discharge switch and the discharge resistor are connected in series to form a discharge branch, two ends of the discharge branch are connected in parallel to two ends of the battery cluster, fig. 2 shows the passive equalization circuit of the battery cluster 1, and when the discharge switch Knb is closed, the electric core connected in series in the battery cluster is discharged through the discharge resistor Rna to realize passive equalization.
A partial energy transfer equalization system with a pre-charging circuit and an isolation drive is shown in a figure 3, and further comprises pre-charging switches (K1, K2, K3 … … Kn), pre-charging resistors (R1, R2, R3 … … Rn) and main circuit switches (K1 a, K2a, K3a … … Kna), wherein the pre-charging resistors and the pre-charging switches are connected in series and then connected between the positive pole of a battery cluster and the positive pole of a direct current bus, and the main circuit switches are connected in parallel between the positive pole of the direct current bus and the positive pole of the battery cluster to form the pre-charging circuit. Each battery cluster is provided with a corresponding pre-charging circuit, and the serial numbers of all devices in the pre-charging circuits are distinguished through natural numbers of 1, 2 and 3 … … n.
In the design of the system, a large number of switches are used, and the switching of the switches easily generates interference on the circuit, so the system further comprises a processor and an isolation drive, and the processor (MCU) is connected with a first switch (for example, D1, D2 and D3 … … Dn in FIG. 3) and a second switch (for example, D1b, D2b and D3b … … Dnb in FIG. 3) through the isolation drive and is used for respectively controlling the opening and closing of the first switch and the second switch.
Based on the same conception, the control method of the balance system for local energy transfer is also provided, and comprises the following steps:
marking the electric core with the highest voltage as the current electric core, and then comparing the voltage of the previous electric core and the voltage of the next electric core of the current electric core;
when the voltage of the current electric core is larger than that of the next electric core, the first change-over switch corresponding to the current electric core is closed, the inductor shared by the current electric core and the previous electric core is charged, the first change-over switch corresponding to the previous electric core is closed while the first change-over switch corresponding to the current electric core is disconnected, and electricity is supplemented for the previous electric core until the pressure difference between the current electric core and the previous electric core is smaller than the pressure difference threshold value. Taking the battery cell 2 in the battery cluster 1 in fig. 3 as an example for explanation, if the voltage of the battery cell 3 is greater than the voltage of the battery cell 1, the first switch D2 corresponding to the battery cell 2 is closed, the battery cell 2 charges the inductor L1 shared by the battery cell 2 and the battery cell 1, then the first switch D1 of the battery cell 1 is closed while the first switch D2 corresponding to the battery cell 2 is turned off, the inductor L1 discharges, and the electric quantity emitted by the inductor L1 supplements the electric quantity for the battery cell 1, so that the electric quantity on the battery cell 3 is transferred to the battery cell 1 through the inductor L1, and such conversion can be performed all the time until the voltage difference between the battery cell 1 and the battery cell 3 is less than the voltage difference threshold, and thus the local energy balance is completed.
And closing the second change-over switch corresponding to the current battery cell to charge the inductor shared by the current battery cell and the next battery cell, disconnecting the second change-over switch corresponding to the current battery cell and closing the second change-over switch corresponding to the next battery cell to supplement power for the next battery cell at the same time until the pressure difference between the current battery cell and the next battery cell is less than the pressure difference threshold value. Taking the battery cell 2 in the battery cluster 1 in fig. 3 as an example, if the voltage of the battery cell 3 is less than the voltage of the battery cell 1, the second switch D2b corresponding to the battery cell 2 is closed, the battery cell 2 charges the inductor L2 shared by the battery cell 2 and the battery cell 1, then the second switch D3b of the battery cell 3 is closed while the second switch D2b corresponding to the battery cell 2 is disconnected, the inductor L2 discharges, the electric quantity emitted by the inductor L2 supplements the electric quantity of the battery cell 3, so that the electric quantity of the battery cell 1 is transferred to the battery cell 3 through the inductor L2, and such conversion may be performed until the voltage difference between the battery cell 1 and the battery cell 3 is less than the voltage difference threshold, and the local energy balance is completed.
In the system, the cells connected in series realize balanced discharge or balanced power supplement through adjacent cells, but the first cell-cell 1 and the last cell-cell n in the battery cluster only have one adjacent cell, and the method that other cells realize balanced discharge or balanced power supplement through adjacent cells cannot be realized, the improvement is that the first cell-cell 1 and the last cell-cell n in the battery cluster are connected in parallel through an isolation transformer, after connection, the cells adjacent to the cell 1 are the cell 2 and the cell n, the cells adjacent to the cell n are the cell n-1 and the cell 1, and the last cell in the battery cluster supplements power to the first cell in the battery cluster through the isolation transformer.
Preferably, the method further comprises the following steps: when the system is powered on, the voltage of the battery cluster is detected, and if the voltage difference of one battery cluster is larger than or equal to a discharge threshold (for example, 20V), the voltage in the battery cluster is subjected to passive balanced discharge through discharge resistors (R1 a, R2a, R3a … … Rna) connected in parallel to the battery cluster. That is, before the inter-cluster energy equalization is performed, the passive equalization discharge of the battery clusters is performed, and after the differential pressure is smaller than the discharge threshold, the equalization between the battery clusters is performed.
If the voltage of the battery clusters is less than a discharge threshold (e.g., 20V) and greater than or equal to an inter-cluster voltage difference threshold (e.g., 5V), inter-cluster equalization between a plurality of battery clusters may be directly performed. If the voltage difference between the battery clusters is larger than or smaller than the threshold value of the voltage difference between the clusters, the energy between the clusters is balanced, and each battery cluster discharges to the alternating current power grid through the positive electrode of the direct current bus and the negative electrode of the direct current bus or charges from the alternating current power grid. By setting the discharge threshold and the inter-cluster pressure difference threshold, the power equalization stage division is finer, accurate monitoring is facilitated, and unnecessary time or capability consumption is avoided.
Example 2
The invention designs a specific equalizing system diagram for local energy transfer, which is shown in fig. 4 and comprises an isolation driving optocoupler, a switching tube, an inductor, an MCU (microprogrammed control unit), an isolation transformer, a resistor and the like, wherein the active equalizing circuit and the passive equalizing circuit are combined by the components. The circuit has the advantages of high equalization efficiency, high reliability, small volume, low BOM cost and the like, wherein the switch can be a switching device such as an MOS (metal oxide semiconductor), a triode and the like.
The detailed working principle of the system is as follows:
1) When the system is powered on, the voltage of each cluster is checked, if the voltage difference of each cluster is greater than the discharge threshold value 20V, the discharge switch Knb of the battery cluster with higher voltage difference is closed, so that the battery cluster is discharged through the discharge resistor Rna until the voltage difference is smaller than the discharge threshold value 20V (the discharge path is shown as the path marked by the arrow line on the right side in FIG. 5).
And if the voltage difference of each cluster is less than 20V and the voltage difference of each cluster is more than or equal to 5V, directly closing the pre-charging switches K1-Kn, and performing inter-cluster balance through the pre-charging resistor Rn. When the pressure difference of each cluster is less than 5V, the energy among the clusters is balanced, and then the battery clusters are connected to the direct current buses P + and P-.
Preferably, the battery clusters are not directly connected in parallel to the direct current buses P + and P-, the main circuit switches K1 a-Kna are closed, and the pre-charging switches K1-Kn are opened after 1s, so that the clusters are connected in parallel to the direct current buses P + and P-.
2) After high voltage is applied, the BMS periodically detects all cell voltages, marks the highest cell voltage position n, compares the cell voltages of n-1 and n +1, and closes the switch Dn (D) if the cell n-1 is larger than the cell n +1 1 、D 2 D 3 …… D n Is the first switch), then D1 is closed to supply power to the cell n-1 until the differential pressure is less than 10mV, if the cell n-1 is less than the cell n +1, the switch Dnb is closed, then Dn +1b is closed to supply power to the cell n +1 until the differential pressure is less than 10mV.
Examples are: assuming that the highest voltage is the battery cell 2, if the voltage of the battery cell 1 is greater than that of the battery cell 3, the MCU closes the D2 to charge the L1 (see an arrow path where the battery cell 2 is located in fig. 6), then disconnects the D2, and closes the adjacent D1, so that the energy stored in the L1 charges the battery cell 1 (see an arrow path where the battery cell 1 is located in fig. 6); the detailed current path is shown in fig. 5;
if the voltage of cell 1 is less than that of cell 3, the MCU closes D2b (D1 b, D2b, D3b … … Dnb is a second switch) to charge L2 (see the arrow path of cell 2 in fig. 7), then opens D2b, and closes the adjacent D3b, so that the energy stored in L2 charges cell 3 (see the arrow path of cell 3 in fig. 7).
3) And then continuously detecting the voltage to find out the highest cell voltage, closing and opening the corresponding switch tubes by the same method to carry out balanced power supply on the adjacent cells, so that the cell voltages of each cluster tend to be consistent continuously.
4) Since the last cell n is not electrically adjacent to the 1 st cell, an isolation transformer is used to form an energy transfer closed loop, and if the voltage of the cell n is too high, the corresponding MOS or BJT switch is controlled to supplement power to the cell 1.
Based on the above principle, a flowchart of a specific balancing policy method is shown in fig. 8, and specifically includes the following steps:
s1, completing BMS power-on self-test;
s2, detecting whether the voltage difference of each cluster is greater than 20V; if the voltage is greater than the preset voltage, marking the highest cluster voltage, and closing a highest cluster voltage switch Knb to discharge the highest cluster voltage until the voltage difference is less than 20V; otherwise, executing step S3;
s3, closing the switches K1-Kn;
s4, detecting whether the voltage difference of each cluster is greater than 5V, if so, returning to the step S3, otherwise, closing the switches K1 a-Kna, and disconnecting the switches K1-Kn after 1S;
s5, periodically detecting the voltage of each cluster of battery cells;
s6, marking the cell position n with the maximum voltage;
s7, judging whether the voltage of the cell n-1 is greater than the voltage of the cell n +1, if so, executing a step S8, otherwise, executing a step S10;
s8, closing the switch Dn, and then closing the D1 to supply power to the cell n-1;
and S9, judging whether the voltage of the cell n and the voltage of the cell n-1 are less than 10mV, if so, returning to the step S5, otherwise, returning to the step S8.
S10, closing a switch Dnb, and then closing Dn +1b to supply power to the battery cell n + 1;
and S11, if the voltage of the battery cell n and the voltage of the battery cell n +1 are smaller than 10mV, returning to the step S10 if the voltage of the battery cell n and the voltage of the battery cell n +1 are smaller than 10mV, otherwise, returning to the step S11.
The circuit and equalization strategy of the present invention have the advantages of: (1) The invention uses circuit components equivalent to the traditional passive equalization to realize the effect of active equalization; (2) the circuit is simple, the cost is low, and the reliability is good; (3) The balance effect can be good by matching with a proper balance strategy; (4) The scheme is high in compatibility and suitable for the balancing scheme of all the inter-cluster and intra-cluster battery modules. The scheme is not limited to an energy storage battery system and can be popularized to battery systems of any voltage platforms.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The equalizing system for local energy transfer is characterized by comprising at least one battery cluster, wherein the battery cluster comprises a plurality of battery cells connected in series, and further comprises a first switching loop and a second switching loop for any current battery cell, the first switching loop comprises the current battery cell, a first switch and an inductor which are connected in series, the second switching loop comprises the current battery cell, a second switch and another inductor which are connected in series, the first switching loop of an adjacent battery cell shares the inductor, the second switching loop of an adjacent battery cell shares the other inductor, and the inductor in the first switching loop and the inductor in the second switching loop are located at different electrodes of the current battery cell.
2. The system for equalizing local energy transfer according to claim 1, further comprising an isolation transformer, wherein a last cell of the plurality of cells connected in series forms a series circuit with the first port of the isolation transformer and the second switch, and the second port of the isolation transformer is connected in parallel to two ends of the first cell.
3. The system for equalizing partial energy transfer of claim 1, further comprising a pre-charge switch, a pre-charge resistor, and a main circuit switch, wherein the pre-charge resistor and the pre-charge switch are connected in series and then connected between the positive electrode of the battery cluster and the positive electrode of the dc bus, and the main circuit switch is connected in parallel between the positive electrode of the dc bus and the positive electrode of the battery cluster.
4. The system for equalizing partial energy transfer according to claim 1, further comprising a discharge switch and a discharge resistor, wherein the discharge switch and the discharge resistor are connected in series to form a discharge branch, and two ends of the discharge branch are connected in parallel to two ends of the battery cluster.
5. An equalizing system for localized energy transfer as in any one of claims 1 through 4, further comprising a processor and an isolation drive,
the processor is connected with the first change-over switch and the second change-over switch through an isolation drive and is used for respectively controlling the first change-over switch and the second change-over switch to be switched on and switched off.
6. A control method of a local energy transfer equalization system, characterized in that a local energy transfer equalization system according to any of claims 1-5 is constructed, the control method comprising the steps of:
marking the electric core with the highest voltage as the current electric core, and then comparing the voltage of the current electric core, the voltage of the previous electric core adjacent to the current electric core and the voltage of the next electric core;
when the voltage of the current battery cell is greater than that of the next battery cell, closing a first change-over switch corresponding to the current battery cell to charge an inductor shared by the current battery cell and the previous battery cell, disconnecting the first change-over switch corresponding to the current battery cell and closing the first change-over switch corresponding to the previous battery cell at the same time to supplement power for the previous battery cell until the voltage difference between the current battery cell and the previous battery cell is less than a voltage difference threshold value;
and closing the second change-over switch corresponding to the current battery cell to charge the inductor shared by the current battery cell and the next battery cell, disconnecting the second change-over switch corresponding to the current battery cell and closing the second change-over switch corresponding to the next battery cell to supplement power for the next battery cell at the same time until the pressure difference between the current battery cell and the next battery cell is less than the pressure difference threshold value.
7. The method of claim 6, wherein a last cell in the battery cluster is recharged to a first cell in the battery cluster through an isolation transformer.
8. The method for controlling a system for equalizing localized energy transfers of claim 6 or 7, wherein the steps further comprise: when the system is electrified, the voltage of the battery cluster is detected, and if the voltage difference of the battery cluster is greater than or equal to the discharge threshold, the voltage in the battery cluster is subjected to passive balanced discharge through a discharge resistor connected in parallel to the battery cluster.
9. The method as claimed in claim 8, wherein if the voltage difference between the battery clusters is less than the discharge threshold when the system is powered on, the inter-cluster balancing is performed between the plurality of battery clusters.
10. The method of claim 9, wherein each battery cluster discharges or charges the ac power grid through the positive pole of the dc bus and the negative pole of the dc bus if the voltage differential between the battery clusters is less than the threshold value of the voltage differential between the clusters.
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| CN202211732613.5A Pending CN115986878A (en) | 2022-12-30 | 2022-12-30 | Balance system for local energy transfer and control method thereof |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117175748A (en) * | 2023-10-30 | 2023-12-05 | 宁德时代新能源科技股份有限公司 | Battery state parameter balancing method, energy storage unit, BMS and storage medium |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117175748A (en) * | 2023-10-30 | 2023-12-05 | 宁德时代新能源科技股份有限公司 | Battery state parameter balancing method, energy storage unit, BMS and storage medium |
| CN117175748B (en) * | 2023-10-30 | 2024-04-02 | 宁德时代新能源科技股份有限公司 | Battery state parameter balancing method, energy storage unit, BMS and storage medium |
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