CN116094119B - Reconstituted electrochemical energy storage system and method - Google Patents
Reconstituted electrochemical energy storage system and method Download PDFInfo
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- CN116094119B CN116094119B CN202310189618.6A CN202310189618A CN116094119B CN 116094119 B CN116094119 B CN 116094119B CN 202310189618 A CN202310189618 A CN 202310189618A CN 116094119 B CN116094119 B CN 116094119B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0013—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries acting upon several batteries simultaneously or sequentially
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The application discloses a reconstructed electrochemical energy storage system and a method, wherein a target battery is cut out from a battery module in the electrochemical energy storage system, so that the battery module after the target battery is cut out is obtained; connecting the first capacitor in the first converter module and the third capacitor in the second converter module in series with the battery module after cutting out the target battery; and transmitting the energy of the first capacitor to the third capacitor, and cutting the first converter module out of the electrochemical energy storage system when the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state, so as to obtain the reconstructed electrochemical energy storage system. In the application, the sum of the voltages of the third capacitor and the first capacitor is the same as the voltage of the target battery in the normal working state, so that the total voltage of the system is in a stable state before and after the target battery is cut out from the system, the battery damage caused by voltage abrupt change is avoided, and the reliability of the system is improved.
Description
Technical Field
The application relates to the technical field of electrochemical energy storage, in particular to a reconstructed electrochemical energy storage system and method.
Background
A battery energy storage system is a technology for storing electric energy, which generally needs to be connected in series by a plurality of batteries to reach a required voltage, and after a period of use, the probability of abnormality, failure and safety risk of the batteries is greatly increased, so that under the condition that the batteries are abnormal, failed or have safety risk, the reconstruction of the battery energy storage system is particularly important.
In the prior art, a switch is generally adopted to switch a battery with abnormality, fault or safety risk from a system so as to be in a bypass state.
However, cutting the battery directly from the system may result in a sudden drop in the total voltage of the battery module, and after the sudden drop in the voltage of the battery module, the direct current side capacitor of the energy storage converter (PCS) is directly connected with the battery in the system, the energy of the capacitor may be directly transferred to the battery in the system, and an excessive current may cause damage to the battery in the system, resulting in a reduced reliability of the system.
Disclosure of Invention
Based on the above problems, the present application provides a reconstituted electrochemical energy storage system and method.
The embodiment of the application discloses the following technical scheme:
first aspect: an embodiment of the present application provides a reconstituted electrochemical energy storage system comprising: the switching device comprises a battery module, a switching electronic switch group, a first converter module and a second converter module;
the battery module is formed by connecting a plurality of sub-battery modules in series, and the negative electrode of the battery module is connected with the negative electrode of the total system;
the switching electronic switch group comprises a first selection switch group and a second selection switch group;
for a first selection switch corresponding to a target battery in the first selection switch group, a first end of the first selection switch is connected with the positive electrode of the target battery, and a second end of the first selection switch is connected with the positive electrode of a first capacitor in the first converter module;
for a second selection switch corresponding to the target battery in the second selection switch group, a first end of the second selection switch is connected with a negative electrode of the target battery, and a second end of the second selection switch is connected with a negative electrode of the first capacitor in the first converter module;
the second converter module comprises a third selection switch group and a sub second converter module;
the third selection switch group is formed by connecting a protection switch with the first switch in parallel and then connecting the protection switch with the second switch in series; the first end of the third selection switch group is used as the second end of the second converter module and is connected with the positive electrode of the total system, and the second end of the third selection switch group is used as the first end of the second converter module and is connected with the positive electrode of the battery module;
the battery module is used for cutting the target battery out of the battery module in the electrochemical energy storage system to obtain a battery module from which the target battery is cut out;
the second converter module is configured to control the third selection switch group, and connect a third capacitor in the sub second converter module and a first capacitor in the first converter module in series with the battery module from which the target battery is cut, where a sum of a voltage of the first capacitor and a voltage of the third capacitor is equal to a voltage of the target battery in a normal working state; receiving energy transferred from the first capacitor to the third capacitor, and obtaining voltage after the third capacitor transfers the energy;
the switching electronic switch group is used for connecting the first capacitor with the battery module after the target battery is cut out in series; and when the voltage of the third capacitor after energy transfer is equal to the voltage of the target battery in a normal working state, cutting the first converter module out of the electrochemical energy storage system to obtain the reconstructed electrochemical energy storage system.
Further, the sub second converter module consists of a second electronic switch group, a second high-frequency transformer, a third capacitor and a fourth capacitor; the first end of the third capacitor is connected with the third end of the third selection switch group, and the second end of the third capacitor is connected with the second end of the third selection switch group.
Further, the sub-battery module includes: a battery, a first change-over switch, a bypass switch and a second change-over switch;
the battery and the first switching switch are connected in series to form a first branch;
the first branch is connected with the bypass switch in parallel to form a second branch;
the second change-over switch is connected with the second branch and the change-over electronic switch group.
Second aspect: the embodiment of the application provides a reconstructed electrochemical energy storage method, which comprises the following steps:
cutting out a target battery from a battery module in an electrochemical energy storage system to obtain a battery module after cutting out the target battery;
connecting a first capacitor in a first converter module and a third capacitor in a second converter module in series with the battery module after the target battery is cut, wherein the sum of the voltage of the first capacitor and the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state;
controlling the first converter module and the second converter module to transfer the energy of the first capacitor to the third capacitor to obtain the voltage of the third capacitor after energy transfer;
and when the voltage of the third capacitor after energy transfer is equal to the voltage of the target battery in a normal working state, cutting the first converter module out of the electrochemical energy storage system to obtain the reconstructed electrochemical energy storage system.
Further, before the first capacitor in the first converter module and the third capacitor in the second converter module are connected in series with the battery module after the target battery is cut, the method further includes:
and precharging the first capacitor to enable the voltage of the first capacitor to be equal to a preset voltage value.
Further, the preset voltage value is an average value of voltages of the batteries in the battery module.
Further, the controlling the first converter module and the second converter module to transfer the energy of the first capacitor to the third capacitor to obtain the voltage after the energy transfer of the third capacitor includes:
and controlling the first converter module and the second converter module, reducing the voltage of the first capacitor according to a preset step length, and increasing the voltage of the third capacitor according to a preset step length to obtain the voltage of the third capacitor after energy transmission.
Further, the method further comprises the following steps:
when the charge state of the battery in the battery module exceeds a preset range, connecting the first converter module with the battery module in parallel;
and controlling the on-off time of a first electronic switch group in the first converter to enable the battery with the charge state exceeding a preset range to transfer energy with a total system.
Further, the preset range is that the value of the charge state is greater than 0 and less than 1.
Compared with the prior art, the application has the following beneficial effects:
according to the method provided by the embodiment of the application, the target battery is cut out from the battery module in the electrochemical energy storage system, so that the battery module with the target battery cut out is obtained; connecting a first capacitor in a first converter module and a third capacitor in a second converter module in series with the battery module after the target battery is cut, wherein the sum of the voltage of the first capacitor and the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state; controlling the first converter module and the second converter module to transfer the energy of the first capacitor to the third capacitor to obtain the voltage of the third capacitor after energy transfer; and when the voltage of the third capacitor after energy transfer is equal to the voltage of the target battery in a normal working state, cutting the first converter module out of the electrochemical energy storage system to obtain the reconstructed electrochemical energy storage system. In the application, after a target battery is cut out, a first capacitor and a third capacitor are connected in series, and when the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state, the first converter module is cut out from the total battery system, so that the reconstructed electrochemical energy storage system is obtained. The sum of the voltages of the third capacitor and the first capacitor is the same as the voltage of the target battery in a normal working state, and the total voltage of the electrochemical energy storage system is in a stable state in the whole process from cutting the target battery out of the electrochemical energy storage system to obtaining the reconstructed electrochemical energy storage system, so that the battery damage caused by voltage abrupt change is avoided, and the reliability of the system is improved.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the application, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a schematic topology of a battery or battery cluster reconstruction;
FIG. 2 is a schematic diagram of a system for reconstructing electrochemical energy storage according to an embodiment of the present application;
fig. 3 is a schematic diagram of a sub-battery module according to an embodiment of the present application;
FIG. 4 is a flow chart of a method of reconstructing electrochemical energy storage according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a current path in a system reconstruction process according to an embodiment of the present application;
fig. 6 is a schematic diagram of a current path after a system is reconfigured according to an embodiment of the present application.
Detailed Description
At present, most of the electrochemical energy storage systems are reconfigured by adopting a switch switching mode, and batteries with abnormality, fault or safety risk are cut out from the electrochemical energy storage systems so as to be in a bypass state. As shown in FIG. 1, the diagram is a topological schematic diagram of a battery pack or a battery cluster reconstruction, in the diagram, B1-Bn are battery packs (pack) or battery cells, S1-Sn are bypass switches, K1-Kn are battery series switches, and S1-Sn and K1-Kn can be common mechanical switches or quick electronic switches. Taking B1-Bn as a battery pack for illustration, when B1-Bn are the battery packs, B1-Bn are connected in series to form a battery cluster, and when the battery cluster is in a normal condition, K1-Kn switches are closed, S1-Sn switches are opened, and B1-Bn are connected in series. When detecting that the battery group Bm has faults, the Km switch is opened, the Sm switch is closed, other switches keep unchanged, the battery group Bm is cut out of the battery cluster to be in a bypass state, and when detecting that a plurality of groups of battery groups have faults, all the faulty battery groups are cut out of the battery cluster, so that the total voltage of the battery cluster is suddenly reduced. As is known, a capacitor is generally connected to the dc side of an energy storage converter (PCS), and when the voltage of a battery cluster is suddenly reduced, the capacitor is directly connected to the battery cluster, the energy of the capacitor is directly transferred to the battery cluster, the battery cluster is in a charged state, the magnitude of the charging current is uncontrollable, and an excessive charging current can damage the battery, so that the reliability of the electrochemical energy storage system is reduced.
It should be noted that, when B1 to Bn are battery monomers, B1 to Bn are connected in series to form a battery pack, and the principle of reconstructing the battery pack is the same as that of reconstructing the battery cluster, which is not described herein.
When the target battery is cut out of the electrochemical energy storage system, the first capacitor in the first converter module and the third capacitor in the second converter module are connected in series with the battery module after the target battery is cut out, energy of the first capacitor is transferred to the third capacitor, and when the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state, the first capacitor is disconnected. Therefore, the voltage of the whole electrochemical energy storage system can be basically kept unchanged before and after the target battery is cut, battery damage caused by voltage abrupt change is avoided, and the reliability of the system is further improved.
In order to make the present application better understood by those skilled in the art, the following description will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
An embodiment of the present application provides a reconstituted electrochemical energy storage system comprising: the switching device comprises a battery module, a switching electronic switch group, a first converter module and a second converter module; the battery module is formed by connecting a plurality of sub-battery modules in series, and the negative electrode of the battery module is connected with the negative electrode of the total system; the switching electronic switch group comprises a first selection switch group and a second selection switch group; for a first selection switch corresponding to a target battery in the first selection switch group, a first end of the first selection switch is connected with the positive electrode of the target battery, and a second end of the first selection switch is connected with the positive electrode of a first capacitor in the first converter module; for a second selection switch corresponding to the target battery in the second selection switch group, a first end of the second selection switch is connected with a negative electrode of the target battery, and a second end of the second selection switch is connected with a negative electrode of the first capacitor in the first converter module; the second converter module comprises a third selection switch group and a sub second converter module; the third selection switch group is formed by connecting a protection switch with the first switch in parallel and then connecting the protection switch with the second switch in series; and the first end of the third selection switch group is used as the second end of the second converter module and is connected with the positive electrode of the total system, and the second end of the third selection switch group is used as the first end of the second converter module and is connected with the positive electrode of the battery module. Fig. 2 is a schematic diagram of a system for reconstructing electrochemical energy storage according to an embodiment of the present application.
Specifically, the battery module 1101 is composed of a plurality of sub-battery modules connected in series, the positive electrode of the battery module 1101 is connected to the first end of the second inverter module 1104, and the negative electrode of the battery module 1101 is connected to the overall system. A battery module for cutting out the target battery from the battery module in the electrochemical energy storage system to obtain the battery module after cutting out the target battery
Wherein, for each sub-battery module in battery modules 1101, the sub-battery module includes: the battery, first change over switch, bypass switch and second change over switch. The battery and the first switch are connected in series to form a first branch, the first branch and the bypass switch are connected in parallel to form a second branch, and the second switch is connected with the second branch and the switch electronic switch group.
Illustratively, as battery B i The sub-battery module is illustrated as an example, and as shown in fig. 3, the sub-battery module is a schematic diagram of a sub-battery module according to an embodiment of the present application, in which a battery B i The corresponding first change-over switch is Q 2i-1 The bypass switch is K i The second change-over switch is Q 2i Wherein i is an integer greater than 0. First change-over switch Q 2i-1 And a second change-over switch Q 2i For corresponding battery B i Cut from the electrochemical energy storage system, a second switch Q 2i Connecting a second branch with the switching electronic switch group; bypass switch K i For connecting battery B i And (5) breaking.
The switching electronic switch group 1102 includes: the first selection switch group and the second selection switch group. For a first selection switch corresponding to a target battery in the first selection switch group, a first end of the first selection switch is connected with the positive electrode of the target battery, and a second end of the first selection switch is connected with the positive electrode of a first capacitor in the first converter module. The first selection switch is shown as S1 and S2 in fig. 2. And aiming at a second selection switch corresponding to the target battery in the second selection switch group, a first end of the second selection switch is connected with the negative electrode of the target battery, and a second end of the second selection switch is connected with the negative electrode of the first capacitor in the first converter module. The second selection switch is shown as S3 and S4 in fig. 2. The switching electronic switch group is used for connecting the first capacitor in series with the battery module after the target battery is cut out; and when the voltage of the third capacitor after energy transfer is equal to the voltage of the target battery in a normal working state, cutting the first converter module out of the electrochemical energy storage system to obtain the reconstructed electrochemical energy storage system.
For example, when the number i of the target battery is an odd number, S1 and S4 may be closed to connect the first capacitor (C1) in the first converter module (DC/DC 1) 1103 in series with the battery module after cutting out the target battery, in which case S1 is a first selection switch corresponding to the target battery in the first selection switch group, and S4 is a second selection switch corresponding to the target battery in the second selection switch; when the number i of the target battery is even, S2 and S3 may be closed so that the first capacitor in the first inverter module (DC/DC 1) 1103 is connected in series with the battery module after cutting out the target battery, in which case S2 is a first selection switch corresponding to the target battery among the first selection switches and S3 is a second selection switch corresponding to the target battery among the second selection switches.
First variationThe converter module (DC/DC 1) 1103 is formed by a first electronic switch bank (T x1 ~T x8 ) First high-frequency transformer (T) r1 ) A first capacitor (C 1 ) A second capacitor (C 2 ). Wherein the first capacitor (C 1 ) A second capacitor (C 2 ) May be a dc capacitor. The first capacitor in DC/DC1 is connected to the switching electronic switch group 1102, and is connected to the battery module through the switching electronic switch group 1102. The charge and discharge power of a certain battery can be controlled by controlling the power of the first end of the DC/DC1, and the battery balancing function is achieved. The second end of the DC/DC1 is used for being connected with the total system to extract energy from the total system or feed back energy to the total system.
The second converter module 1104 includes: a third set of selection switches and a sub-second converter module (DC/DC 2). And the first end of the third selection switch group is used as the second end of the second converter module and is connected with the positive electrode of the total battery system, and the second end of the third selection switch group is used as the first end of the second converter module and is connected with the positive electrode of the battery module. The second converter module is used for controlling the third selection switch group, connecting a third capacitor in the sub second converter module and a first capacitor in the first converter module in series with the battery module after the target battery is cut, wherein the sum of the voltage of the first capacitor and the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state; and receiving the energy transferred from the first capacitor to the third capacitor, and obtaining the voltage of the third capacitor after transferring the energy.
Wherein the third selection switch group comprises a protection switch (K n+1 ) First switch (Q) 2n+1 ) And a second switch (Q) 2n+2 ). In particular, the third group of selection switches is formed by a protection switch (K n+1 ) And a first switch (Q) 2n+1 ) In parallel with a second switch (Q 2n+2 ) And (3) connecting in series. DC/DC2 is formed by a second electronic switch group (T y1 ~T y8 ) Second high-frequency transformer (T) r2 ) A third capacitor (C 3 ) Fourth capacitor (C) 4 ). Wherein the third capacitor (C 3 ) And a fourth capacitor (C 4 ) Can be used forTo be a dc capacitor.
The first end of the third capacitor is connected with the third end of the third selection switch group, and the second end of the third capacitor is connected with the second end of the third selection switch group. And the first end of the third selection switch group is connected with the total system, and the second end of the third selection switch group is connected with the positive electrode of the battery module. Thus when the first switch (Q 2n+1 ) Closing, protective switch (K) n+1 ) And a second switch (Q) 2n+2 ) When the battery is disconnected, the positive electrode of the battery module is connected with the total system; when the first switch (Q 2n+1 ) And protection switch (K) n+1 ) Open, second switch (Q 2n+2 ) When closed, the positive electrode of the battery module and the third capacitor (C 3 ) Is connected to the second terminal of the third capacitor (C 3 ) And a second switch (Q) 2n+2 ) Is connected through a second switch (Q 2n+2 ) A third capacitor (C 3 ) Is connected with the total system to realize the battery module and the third capacitor (C 3 ) Is a series of (a) and (b).
Illustratively, the target battery is not cut from the electrochemical energy storage system when the battery module and the DC/DC2 are in normal operation, the first switch (Q 2n+1 ) Closing, protective switch (K) n+1 ) And a second switch (Q) 2n+2 ) The third selection switch group is used for connecting the battery module and the total system; when the target cell is cut out of the electrochemical energy storage system, a first switch (Q 2n+1 ) And protection switch (K) n+1 ) Open, second switch (Q 2n+2 ) And closing the third selection switch group, wherein the third selection switch group is used for connecting a third capacitor in the second converter module with the battery module with the cut-out target battery in series. Protection switch (K) n+1 ) Can function to protect the electrochemical energy storage system in the event of a DC/DC2 abnormality, i.e. when DC/DC2 is abnormal, the first switch (Q 2n+1 ) And a second switch (Q) 2n+2 ) Closing protection switch (K) n+1 ) The DC/DC2 is put in an off state.
The first end of the second converter module 1104 is used for being connected in series with the battery module, the total voltage can be controlled by controlling the voltage of the first end, the second end of the second converter module 1104 is used for being connected with a total system, and energy can be extracted from the total system or fed back to the total system.
Further description will be given below in connection with specific embodiments.
Fig. 4 is a flow chart of a method for reconstructing electrochemical energy storage according to an embodiment of the present application. The embodiment of the application provides a reconstructed electrochemical energy storage method which can be realized through S101-S104.
S101: and cutting the target battery out of the battery module in the electrochemical energy storage system to obtain the battery module with the target battery cut out.
The target battery can be one battery or a plurality of batteries, and meanwhile, the battery can comprise a battery cell and a battery pack. When one or more batteries in the battery module fail, the failed battery is taken as a target battery, and the failed battery is cut out of the battery module, so that the target battery does not influence the normal operation of other normal batteries, and the obtained battery in the battery module with the cut-out target battery can normally operate.
S102: and connecting a first capacitor in the first converter module and a third capacitor in the second converter module in series with the battery module after the target battery is cut, wherein the sum of the voltage of the first capacitor and the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state.
Exemplary, as shown in FIG. 2, under normal conditions, the first switch Q 1 、Q 3 、Q 5 、……、Q 2n-1 And a first switch Q in the second converter module 2n+1 Closed, other switches open, total voltage (V Bat ) Is the sum of the voltages of the batteries, i.e. V Bat =V B1 +V B2 +V B3 +…+V Bn . When battery B i When the battery is the target battery, the target battery B is required to be i Cut out from system, disconnect target battery B i Corresponding first change-over switch Q 2i-1 Closing the second change-over switch Q 2i And Q 2(i+1) When the battery number i is an odd numberS1 and S4 are closed; when i is even, S2 and S3 are closed and the other switch states are unchanged. Thereby, the target battery B can be connected i Cut out the first capacitor C 1 And the battery module is connected with the battery module after the target battery is cut out in series. Disconnect Q 2n+1 Close Q 2n+2 Third capacitor C 3 In series with the battery module after cutting out the target battery, thereby leading the current battery system to be formed by the battery B 1 ~B n (excluding battery B) i ) First capacitor C 1 And a third capacitor C 3 And (3) connecting in series.
By controlling a first capacitance C in DC/DC1 1 Voltage V of (2) C1 And a third capacitor C in DC/DC2 3 Voltage V of (2) C3 Make V C1 And V is equal to C3 And is equal to battery B i Voltage V in normal operation state Bi I.e. to make V C1 +V C3 =V Bi And the voltage of the electrochemical energy storage system is basically kept unchanged before and after the target battery Bi is cut out.
S103: and controlling the first converter module and the second converter module to transfer the energy of the first capacitor to the third capacitor so as to obtain the voltage of the third capacitor after transferring the energy.
Specifically, the first converter module and the second converter module may be controlled to reduce the voltage of the first capacitor according to a preset step size, and the voltage of the third capacitor increases according to a preset step size, so as to obtain the voltage of the third capacitor after energy transfer.
S104: and when the voltage of the third capacitor after energy transfer is equal to the voltage of the target battery in a normal working state, cutting the first converter module out of the electrochemical energy storage system to obtain the reconstructed electrochemical energy storage system.
Exemplary, when the target cell is B 2 In this case, the current path of the battery system is shown by the dotted line in fig. 5, and fig. 5 is a schematic diagram of the current path in the system reconstruction process according to the embodiment of the present application. Control DC/DC2 Module C 3 Voltage of V C3 To make the voltage V C3 Slow from zero according to preset step lengthIncrease, eventually to V Bi Simultaneously controlling DC/DC1 module C 1 Voltage V C1 Slowly reducing according to a preset step length to finally reduce to zero, and ensuring V in the whole process C3 +V C1 =V B2 Realize seamless switching in the switching process from DC/DC1 power to DC/DC2 power, and make the total voltage V of the electrochemical energy storage system Bat And remains stable. When the voltage of the third capacitor after energy transfer is equal to the voltage of the target battery in a normal working state, closing the battery B 2 Corresponding bypass switch K 2 And S2-S3, cutting out the first converter module from the electrochemical energy storage system, and completing the reconstruction of the electrochemical energy storage system to obtain the reconstructed electrochemical energy storage system.
FIG. 6 is a schematic diagram of a current path after system reconfiguration according to an embodiment of the present application, the current path being shown by the dotted line in FIG. 6, wherein battery B 2 Is the target battery. Battery B in the reconstructed electrochemical energy storage system 1 ~B n (not including B) 2 ) And a third capacitor C 3 Series connection of total voltage V Bat =V B1 +V B3 +V B4 +……+V Bn +V C3 (excluding battery B) 2 ）。
In summary, when the target battery is cut out from the electrochemical energy storage system, the first capacitor in the first converter module and the third capacitor in the second converter module are connected in series with the battery module after the target battery is cut out, the energy of the first capacitor is transferred to the third capacitor, and when the voltage of the third capacitor after the energy transfer is equal to the voltage of the target battery in a normal working state, the first capacitor is disconnected. Therefore, the voltage of the electrochemical energy storage system can be basically kept unchanged before and after the target battery is cut, battery damage caused by voltage abrupt change is avoided, and the reliability of the electrochemical energy storage system is further improved.
Further, before the first capacitor in the first converter module and the third capacitor in the second converter module are connected in series with the battery module after the target battery is cut, the method further includes:
and precharging the first capacitor to enable the voltage of the first capacitor to be equal to a preset voltage value. Therefore, after the target battery is cut out and the first capacitor is connected in series, the voltage of the first capacitor can be close to the voltage of the target battery in a normal working state, so that the switching process is smoother, and abrupt voltage changes are avoided.
Specifically, the preset voltage value is an average value of voltages of the batteries in the battery module. Because the voltage between the batteries is different, when the preset voltage value is the average value of the voltages of the batteries in the battery module, and any battery is cut out, the voltage of the first capacitor can be close to the voltage of the target battery in a normal working state, so that the switching process is smoother, and voltage abrupt change is avoided.
Further, the method further comprises:
when the charge state of the battery in the battery module exceeds a preset range, connecting the first converter module with the battery module in parallel;
and controlling the on-off time of a first electronic switch group in the first converter to enable the battery with the charge state exceeding a preset range to transfer energy with a total system. The preset range may be a state of charge value greater than 0 and less than 1.
Specifically, the battery module is formed by connecting a plurality of sub-battery modules in series, and under the condition of charging or discharging, due to the voltage difference among the batteries, a certain battery is charged or discharged first. In the prior art, in the process of charging, when the voltage of one battery reaches a maximum set value, charging of all batteries in the battery module is stopped, and in the process of discharging, when the voltage of one battery reaches a minimum set value, discharging of all batteries in the battery module is stopped. Due to the inherent difference of each battery cell, especially after the number of times of use of the battery is increased, the consistency of the battery cells becomes worse, thereby causing system failure and affecting the use efficiency of the battery system.
Describing an embodiment of the present application with reference to FIG. 2, under normal conditions, the first switch is openedOff Q 1 、Q 3 、Q 5 、……、Q 2n-1 And a first switch Q in the second converter module 2n+1 The other switches are closed and the other switches are opened. Under the condition of charging, the state of charge (SOC) of each battery can be calculated by collecting the voltage and the current of each battery. When battery B i When the voltage exceeds a preset threshold or the charge is full, for example, the value of SOC is equal to 1, the first switch Q 1 、Q 3 、Q 5 、……、Q 2n-1 And a first switch Q in the second converter module 2n+1 Closure, Q 2i And Q 2(i+1) Closed, S1 and S4 are closed when the battery number i is odd, S2 and S3 are closed when i is even, and the other switches are open. Battery B i And the first terminal of the DC/DC1 is connected with the first selection switch group in the switching switch groups. For example, pulse Width Modulation (PWM) may be used to control the first electronic switch set (T x1 ~T x8 ) On-off time of (a) to make battery B i The energy of the battery with the largest electric quantity is transferred to the residual battery, and the battery with high energy is transferred to the battery with low energy.
Likewise, under discharge conditions, the state of charge (SOC) of each battery can be calculated by collecting the voltage and current of each battery, when battery B i A first switch Q when the voltage is lower than a predetermined threshold or the charge is empty, e.g. the value of SOC is equal to 0 1 、Q 3 、Q 5 、……、Q 2n-1 And a first switch Q in the second converter module 2n+1 Closure, Q 2i And Q 2(i+1) Closing, when the battery number i is an odd number, S1 and S4 are closed; when i is even, S2 and S3 are closed and the other switches are open. B (B) i The battery is connected to the first terminal of the DC/DC1 via a first selection switch group of the switch groups, and the first electronic switch group (T) can be controlled by Pulse Width Modulation (PWM) x1 ~T x8 ) On-off time of (a), to battery B through DC/DC1 i Charging due to DC/DC1 is connected with a total system, and energy can be transferred from the total system to the battery B i The transfer can realize the transfer of energy from a battery with high energy to a battery with low energy, and realize the function of energy balance among the batteries.
In summary, when the target battery is cut out from the electrochemical energy storage system, the first capacitor in the first converter module and the third capacitor in the second converter module are connected in series with the battery module after the target battery is cut out, the energy of the first capacitor is transferred to the third capacitor, and when the voltage of the third capacitor after the energy transfer is equal to the voltage of the target battery in a normal working state, the first capacitor is disconnected. Therefore, the voltage of the whole system can be basically kept unchanged before and after the target battery is cut, battery damage caused by voltage abrupt change is avoided, and the reliability of the system is further improved.
The foregoing is only one specific embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the technical scope of the present application should be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims (8)
1. A reconstituted electrochemical energy storage system, comprising: the switching device comprises a battery module, a switching electronic switch group, a first converter module and a second converter module;
the battery module is formed by connecting a plurality of sub-battery modules in series, and the negative electrode of the battery module is connected with the negative electrode of the total system;
the switching electronic switch group comprises a first selection switch group and a second selection switch group;
for a first selection switch corresponding to a target battery in the first selection switch group, a first end of the first selection switch is connected with the positive electrode of the target battery, and a second end of the first selection switch is connected with the positive electrode of a first capacitor in the first converter module;
for a second selection switch corresponding to the target battery in the second selection switch group, a first end of the second selection switch is connected with a negative electrode of the target battery, and a second end of the second selection switch is connected with a negative electrode of the first capacitor in the first converter module;
the second converter module comprises a third selection switch group and a sub second converter module;
the third selection switch group is formed by connecting a protection switch with the first switch in parallel and then connecting the protection switch with the second switch in series; the first end of the third selection switch group is used as the second end of the second converter module and is connected with the positive electrode of the total system, and the second end of the third selection switch group is used as the first end of the second converter module and is connected with the positive electrode of the battery module; the third end of the third selection switch group is connected with the positive electrode of the third capacitor in the sub-second converter module, and the second end of the third selection switch group is connected with the negative electrode of the third capacitor;
the battery module is used for cutting the target battery out of the battery module in the electrochemical energy storage system to obtain a battery module from which the target battery is cut out;
the second converter module is used for controlling the third selection switch group, connecting a third capacitor in the sub second converter modules and a first capacitor in the first converter module in series with the battery module after the target battery is cut, wherein the sum of the voltage of the first capacitor and the voltage of the third capacitor is equal to the voltage of the target battery in a normal working state; receiving energy transferred from the first capacitor to the third capacitor, and obtaining voltage after the third capacitor transfers the energy;
the switching electronic switch group is used for connecting the first capacitor with the battery module after the target battery is cut out in series; and when the voltage of the third capacitor after energy transfer is equal to the voltage of the target battery in a normal working state, cutting the first converter module out of the electrochemical energy storage system to obtain the reconstructed electrochemical energy storage system.
2. The system of claim 1, wherein the sub-second converter module is comprised of a second electronic switch bank, a second high frequency transformer, a third capacitor, and a fourth capacitor.
3. The system of claim 1, wherein the sub-battery module comprises: a battery, a first change-over switch, a bypass switch and a second change-over switch;
the battery and the first switching switch are connected in series to form a first branch;
the first branch is connected with the bypass switch in parallel to form a second branch;
the second change-over switch is connected with the second branch and the change-over electronic switch group.
4. The system of claim 1, wherein the second converter module is further configured to:
and pre-charging the first capacitor before the third capacitor in the sub second converter module and the first capacitor in the first converter module are connected in series with the battery module after the target battery is cut out by controlling the third selection switch group, so that the voltage of the first capacitor is equal to a preset voltage value.
5. The system of claim 4, wherein the predetermined voltage value is an average value of voltages of cells in the battery module.
6. The system of claim 1, wherein the second converter module is configured to:
and controlling the voltage of the third capacitor to increase according to a preset step length to obtain the voltage of the third capacitor after energy transmission.
7. The system of any one of claims 1-6, further comprising:
when the charge state of the battery in the battery module exceeds a preset range, connecting the first converter module with the battery module in parallel;
and controlling the on-off time of a first electronic switch group in the first converter module to enable the battery with the charge state exceeding a preset range to transfer energy with a total system.
8. The system of claim 7, wherein the predetermined range is a state of charge value greater than 0 and less than 1.
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| US11358492B2 (en) * | 2018-09-04 | 2022-06-14 | GM Global Technology Operations LLC | Self-balancing switching control of dual-pack rechargeable energy storage system with series and parallel modes |
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