CN114465314A - Battery module short-plate battery monomer optimization circuit - Google Patents

Abstract

The invention relates to a short-plate battery monomer optimization circuit of a battery module, which is used for controlling a plurality of battery monomers connected in series in the battery module. The battery module short plate battery monomer optimization circuit can control the independent working state of each battery monomer in the whole series battery module, realizes the independent control of the energy of each battery monomer, ensures the consistency of the battery monomers in the working state of the series battery module, greatly reduces the requirement on the consistency of the battery monomers when the battery module is assembled, and improves the charging and discharging performance of the battery module.

Description

Battery module short-plate battery monomer optimization circuit

Technical Field

The invention relates to the technical field of short-plate batteries of battery modules, in particular to a single battery optimization circuit of a short-plate battery of a battery module.

Background

The conventional battery module has a working scheme that the whole series battery module is completely charged and discharged. When the batteries are used in series, in order to protect the battery cells, when one of the battery cells in the battery module is discharged to a cut-off voltage, the other batteries in the battery module must stop discharging. However, most of the battery cells in the battery module are still in a state of discharging electricity, which causes a problem that the energy of the whole battery module cannot be fully utilized; similarly, the above problem also occurs at the time of charging. This is the "short plate effect" caused by the short plate battery cell existing in the battery module during the charging and discharging process. In the working process, the charging and discharging of each single battery in the battery module are difficult to reach the consistency, and the charging and discharging performance of the whole battery module can be seriously restricted by a certain short-plate single battery which reaches the charging and discharging voltage cut-off threshold value in the battery module at first.

The service life of the battery module is seriously influenced by the inconsistency of the batteries, and the cycle life and the capacity utilization rate of the battery module are obviously inferior to the performance of a single battery. Along with the recycling of the battery module, the inconsistency of the single battery is aggravated, the service life of the single short-plate battery is further shortened, and therefore the performance of the battery module is greatly attenuated, and even serious accidents such as combustion and explosion can occur under extreme conditions.

Disclosure of Invention

Therefore, it is necessary to provide a short-plate cell optimization circuit for a battery module, which can improve the charging and discharging performance of the battery module.

A battery module short plate battery monomer optimization circuit is used for controlling a plurality of battery monomers connected in series in a battery module and comprises a transformer and a plurality of switching units respectively connected with the transformer, wherein one switching unit is connected between two adjacent connected battery monomers;

the switching unit comprises at least four controllable switching elements, a first terminal of a first controllable switching element is connected with one electrode of one battery cell, a first terminal of a second controllable switching element is respectively connected with the other electrode of the battery cell and one terminal of the primary winding of the transformer, a first terminal of a third controllable switching element is connected with the other terminal of the primary winding of the transformer, a first terminal of a fourth controllable switching element is connected with one terminal of the secondary winding of the transformer, and the other terminal of the secondary winding of the transformer is connected with the other electrode of the battery cell; the four second connection terminals of the four controllable switching elements are connected in common and are connected with the electrode of the battery cell which is adjacent to the battery cell and is opposite to the electrode.

Furthermore, the controllable switch element is formed by connecting two unidirectional MOS tubes in reverse parallel.

Further, the number of the switching units is the same as the number of the battery cells in the battery module.

Furthermore, the optimization circuit further comprises a standby battery monomer and a standby switching unit, wherein the standby battery monomer is connected with the plurality of battery monomers in series, and the standby switching unit is respectively connected with the standby battery monomer and the transformer.

The battery module short plate battery monomer optimization circuit can control the independent working state of each battery monomer in the whole series battery module, realizes the independent control of the energy of each battery monomer, ensures the consistency of the battery monomers in the working state of the series battery module, greatly reduces the requirement on the consistency of the battery monomers when the battery module is assembled, and improves the charging and discharging performance of the battery module.

Drawings

Fig. 1 is a schematic diagram of a short plate cell optimization circuit of a battery module according to an embodiment;

fig. 2 is a circuit diagram of the battery module of fig. 1 for optimizing a short plate battery cell;

FIG. 3 shows a battery cell B₁Is transferred to the primary winding N₁Current patterns of (1);

FIG. 4 shows the primary winding N₁The electric energy is transferred and stored to the battery cell B_nCurrent patterns of (1);

FIG. 5 shows a battery cell B_n+1The bypass function of the battery module charges the current direction diagram of the battery module;

FIG. 6 shows a battery cell B_nThe current directional diagram of the bypass function battery module discharging outwards;

FIG. 7 shows the discharge of the battery module and the spare battery cell B₁A current pattern that conveys electrical energy.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1 and 2, in one embodiment, a battery module short plate battery cell optimization circuit for controlling a plurality of battery cells connected in series in a battery module includes atransformer 110 and a plurality ofswitching units 120 respectively connected to thetransformer 110, wherein oneswitching unit 120 is connected between two adjacent battery cells. Theswitching unit 120 comprises at least fourcontrollable switching elements 121, 122, 123, 124, hereinafter two battery cells B connected in an adjacent manner₁、B₂For example, a first terminal of the firstcontrollable switching element 121 is connected to a cell B₁With reference to fig. 2, the first connection terminal of the second controllable switch element 122 is connected to the one battery cell B respectively₁And the other electrode (cathode) of thetransformer 110 and the primary winding N of thetransformer 110₁And a first terminal of the thirdcontrollable switching element 123 is connected to the primary winding N of thetransformer 110₁And a first connection terminal of a fourthcontrollable switching element 124 is connected to the secondary winding N of the transformer 110₂A terminal of (2). Secondary winding N oftransformer 110₂Another connecting terminal of the battery unit B is connected with the battery unit B₁The other electrode (negative electrode). Four second connection terminals of fourcontrollable switching elements 121, 122, 123, 124 are connected in common and connected to the one battery cell B₁Adjacent connected battery cell B₂The electrode (negative electrode) having the opposite polarity to the one electrode.

In the present embodiment, thecontrollable switching elements 121, 122, 123, and 124 are formed by connecting two unidirectional MOS transistors in parallel in an inverse manner. It can also be formed by connecting triodes in parallel or by using individually controllable transistors. The number of theswitching units 120 is the same as the number of the battery cells in the battery module, and each battery cell is provided with oneswitching unit 120 to control each battery cell to be connected to or bypassed from the battery module and to control each battery cell to transfer electric energy.

In this embodiment, the optimization circuit further includes a backup battery cell and a backup switching unit, the backup battery cell is connected in series with the plurality of battery cells, and the backup switching unit is respectively connected to the backup battery cell and thetransformer 110. The spare switching unit has the same circuit structure as theswitching unit 120, and the connection relationship between the spare switching unit and the spare battery cell and the connection relationship between the spare switching unit and thetransformer 110 are also the same as the connection relationship between theswitching unit 120 and the corresponding battery cell and thetransformer 110.

As shown in FIG. 2, the circuit scheme of the invention is that one n +1 battery cells B₁～B_n+1The battery modules are formed by connecting the battery modules in series, the actual battery module adopts a working mode of putting n battery monomers and 1 standby battery monomer in operation, and the standby battery monomer and other n battery monomers of the battery module adopt a mode of putting into operation in turn. The circuit scheme of the invention can essentially ensure that each battery monomer can be charged and discharged to the target cut-off voltage threshold value, thereby achieving the maximum utilization of the performance of the battery module.

One is composed of n +1 battery monomers B₁～B_n+1For example, according to the circuit scheme of the invention, n +1 battery monomers are connected in series to form a module, and the circuit scheme consisting of a transformer, a unidirectional MOS tube switch, a control unit and the like can realize the control and the balance of the independent charging and discharging working state of each battery monomer in the series battery module and can make a control strategy and means for solving the problem of short-plate battery monomers.

Wherein J₁～J_n+1、K₁～K_n+1、W₁～W_n+1、X₁～X_n+1、Y₁～Y_n+1、V₁～V_n+1、E₁～E_n+1、F₁～F_n+1Are all unidirectional MOS tube switches.

Unidirectional MOS tube switch W₁～W_n+1、X₁～X_n+1、Y₁～Y_n+1、V₁～V_n+1The control of the operating state of each cell can be achieved by the control action of the control unit of the battery management system. Unidirectional MOS tube switch W₁～W_n+1、X₁～X_n+1For controlling charging or discharging of each cell, e.g. one-way MOS-tube switch W₁And X₁Controlling battery cell B together₁Charging and discharging when the battery monomer B₁During discharging, one-way MOS tube switch X₁Is conducted and W₁Closing; when the battery cell B₁During charging, the one-way MOS tube switch W₁Is conducted and X₁And closing. Unidirectional MOS tube switch Y₁～Y_n+1、V₁～V_n+1For controlling the bypass function of each cell, e.g. one-way MOS-tube switch Y₂And V₂Controlling battery cell B together₂When the battery cell B is in the bypass state₂Stopping discharging to quit the discharging working state, but allowing the unidirectional MOS tube switch V to continue discharging when other battery monomers in the battery module continue discharging₂Is turned on and Y₂Closing; when the battery cell B₂Stopping charging and quitting the charging working state, but simultaneously enabling the one-way MOS tube switch Y to continue charging other battery monomers in the battery module₂Is turned on and V₂And closing.

All the single batteries B of the whole series module₁～B_n+1And a transformer balancing module is shared, and each battery cell is connected with thetransformer 110 balancing module in parallel.

In the transformer equalizing module, N₁、N₂Primary winding and secondary winding of transformer respectively, winding coil turn ratio N₁:N₂1:1, namely the input voltage value and the output voltage value of the transformer are equal; t is the magnetic core of the transformer; primary winding N₁Secondary winding N₂And the magnetic core T and the transformer balance module are formed together.

Unidirectional MOS tube switch J₁～J_n+1、K₁～K_n+1、E₁～E_n+1、F₁～F_n+1And respectively controlling the working states of each battery monomer and the transformer balancing module. For example, a unidirectional MOS transistor switch J₁～J_n+1、K₁～K_n+1Positive circuit and transformer balancing module for respectively controlling each battery monomerAnd the secondary winding N of the transformer equalizing module₂Connecting; unidirectional MOS tube switch E₁～E_n+1、F₁～F_n+1Respectively controlling the working states of the positive circuit of each battery cell and the transformer equalizing module and the primary winding N of the transformer equalizing module₁Are connected.

The working states of all the unidirectional MOS tube switches in the circuit integration scheme are uniformly commanded and integrally controlled by a control unit of a battery management system, and the working process is as follows: the control unit can control the one-way MOS tube switch J₁～J_n+1、K₁～K_n+1、W₁～W_n+1、X₁～X_n+1、Y₁～Y_n+1、V₁～V_n+1、E₁～E_n+1、F₁～F_n+1The switching-off and the switching-on of the MOS tubes are realized, the working logic among the MOS tubes is integrated, the working state information of the whole circuit scheme can be received and monitored, the received information is judged and processed, and finally the working strategy of each one-way MOS tube is worked out. The working state logics of all the unidirectional MOS tube switches can be designed according to the specific strategy requirements through the control unit.

The working principle of the circuit is that the working battery module needs one battery monomer B consisting of n batteries in actual work₁～B_nWhen the series module is formed, the circuit scheme of the invention adopts a series module consisting of n +1 battery monomers B₁～B_n+1The formed series module is actually put into operation, but when the series module works, only n battery monomers form the series module to be used, and the rest (n + 1) th battery monomer is flexibly used when other battery monomers directly work and use, so that the working efficiency and the service life of the battery module can be greatly improved by adopting the working logic mode.

The embodiment of the present invention will now be described in detail with reference to the operation of the entire battery module as an example. The specific implementation steps are as follows:

in the first case, the energy of the transformer of the battery module is transferred in an equalizing way.

Transformer equalizing module and each battery monomer B of whole series battery module₁～B_n+1Each battery monomer in the whole series battery module shares the same transformer balancing module for a parallel circuit. Any two battery monomers in the battery module can directly transfer energy for balancing through the intermediary action of the transformer balancing module.

In order to improve the equalization efficiency, energy transfer equalization between the highest voltage battery cell and the lowest voltage battery cell is preferentially performed. The specific equalization steps are as follows:

suppose a battery cell B in a battery module₁Voltage value of than battery cell B_nThe voltage value of (2) is high, and is the highest voltage battery cell and the lowest voltage battery cell of the battery module at the moment respectively, and the two battery cells can be balanced preferentially at the moment.

Step 1, a unidirectional MOS tube is switched on and off X by a control unit₁、F₁On, the battery cell B₁And a transformer primary winding N₁Forming a current path, a primary winding N of the transformer₁Begin in the operational mode. Along with the battery cell B₁For the primary winding N₁Charging is carried out, primary winding N₁The charging current I is gradually increased to the peak current, and the unidirectional MOS tube switch X is closed at the moment₁、F₁. Thus, the battery cell B₁Part of the electric energy is transferred and stored to the primary winding N of the transformer₁In (1).

Battery cell B₁Part of the electric energy is transferred and stored to the primary winding N of the transformer₁The direction of the current in (a) is shown in fig. 3.

Step 2, after the electric energy is transferred in thestep 1, the primary winding N of the transformer is formed at the time₁Voltage value at two ends and battery monomer B₁Has a voltage value equivalent to that of the battery monomer B_nHas a primary winding N₁Transferring the stored electric energy to a battery cell B_nThe conditions of (1).

The control unit controls the one-way MOS tube to switch K_n、W_nOn, the battery cell B_nAnd a secondary winding N of the transformer₂Forming a current path such that the primary winding N of the transformer₁The stored electric energy is coupled to the secondary winding N of the transformer after 1 step₂Secondary winding N of middle transformer₂Begin in the operational mode. With the secondary winding N of the transformer₂For battery monomer B_nCharging is carried out, the secondary winding N₂The electric energy is gradually discharged, the discharge current I is gradually reduced to zero from the peak current, and the one-way MOS tube switch K is closed at the moment_n、W_n. The primary winding N of such a transformer₁The electric energy is transferred and stored to the battery monomer B_nIn (1).

Primary winding N of transformer₁The electric energy is transferred and stored to the battery monomer B_nThe direction of the current in (a) is shown in fig. 4.

Thestep 1 and the step 2 form a complete transformer energy balance transfer process. After the 1 st step to the 2 nd step, the single battery B can be transferred₁Specific battery monomer B_nTransferring half of the electric energy to the battery monomer B_nThereby finally making the battery cell B₁And battery cell B_nThe stored electric energy is consistent and the voltage is basically equal.

Similarly, the electric energy transfer between any two battery monomers in the battery module can be completed through the similar steps of the steps 1-2, so that the state that the electric energy of all the battery monomers in the battery module is basically consistent can be finally achieved.

In the second case, the battery module charging process.

If all the battery cells in the battery module are supposed to be charged at first, and as the charging of the battery module is carried out, one of the battery cells firstly reaches a cut-off charging voltage threshold, and if the situation occurs according to the existing circuit method, all other battery cells in the battery module are not fully charged, so that the chargeable capacity of the battery module is greatly reduced, and the circuit scheme of the invention has two measures in the situation:

1) the first strategy is that the first time is,suppose a cell B in a battery module_n+1The charge cut-off threshold value is reached first, and the battery monomer B is adopted at the moment_n+1By-pass function of (A) for the battery cell B_n+1The charging is stopped, and other battery cells in the battery module continue to be charged.

Control unit command and battery cell B_n+1Related unidirectional MOS tube switch Y_n+1Is conducted and W_n+1、X_n+1、V_n+1When the charging current i is turned off, the charging current i passes through a one-way MOS tube switch Y_n+1Bypass the battery monomer B_n+1And the current is bypassed therefrom to continue charging the battery module.

Battery cell B_n+1The direction of the current for charging the battery module is shown in fig. 5.

2) And in the process of charging the battery module, the voltage value of each battery monomer in the battery module is monitored in real time through the control unit, and the process of transferring the electric energy from the highest-voltage battery monomer to the lowest-voltage battery monomer in the battery module through the transformer balancing module is carried out at any time. The strategy charging method can greatly improve the charging speed of the battery module.

Through the cooperation of the first strategy and the second strategy, each battery cell in the battery module can be charged to the charge cut-off threshold value, so that the maximum utilization of the chargeable capacity of the battery module can be realized.

In the third case, the battery module is discharged.

If all the battery cells in the battery module are supposed to be discharged, and as the battery module is discharged, one of the battery cells firstly reaches a cut-off discharge voltage threshold, and if the situation occurs according to the existing circuit method, all other battery cells in the battery module are not discharged to the cut-off discharge threshold, so that the dischargeable capacity of the battery module is greatly reduced, and the circuit scheme of the invention has two measures in the situation:

1) strategy one, assume that a battery cell B in a battery module_nThe discharge cut-off threshold value is reached first, and the battery monomer B is adopted at the moment_nBy-pass function of (A) for the battery cell B_nThe discharge is stopped and the other cells in the battery module continue to discharge.

Control unit command and battery cell B_nRelated unidirectional MOS tube switch V_nIs conducted and W_n、X_n、Y_nWhen the discharge current i is turned off, the discharge current i passes through a unidirectional MOS tube switch V_nBypass the battery monomer B_nThe current is bypassed therefrom and the battery module continues to be discharged to the outside.

Battery cell B_nThe current direction of the external discharge of the bypass-function battery module is shown in fig. 6.

2) And in the process of discharging the battery module, the voltage value of each battery monomer in the battery module is monitored in real time through the control unit, and the process of transferring the electric energy from the highest-voltage battery monomer to the lowest-voltage battery monomer in the battery module through the transformer balancing module is carried out at any time. The strategic discharging method can delay the arrival time of the short-plate battery monomer in the discharging process to the maximum extent.

Through the cooperation of the strategy one and the strategy two, each battery monomer in the battery module can be discharged to a discharge cut-off threshold value, so that the maximum discharge capacity utilization of the battery module can be realized.

In the fourth case, a certain cell is used as a backup process.

Suppose n +1 cells B in the scheme of the invention₁～B_n+1The battery module that constitutes in series only needs to use wherein n battery monomer to establish ties the battery module that constitutes among them in the in-service use process, and then unnecessary battery monomer just can regard as the backup battery monomer that can flexible use, and specific use strategy is as follows:

1) in the charging process of the battery module, the bypass function of the battery monomers is adopted, so that at any moment, the serial number of the battery monomers of the battery module directly connected to the charging circuit is always n, the redundant battery monomer performs balanced energy transfer with the battery monomer which is being charged in the battery module in real time, the redundant battery monomer is connected to the battery module for charging every short time, the battery monomer with the highest voltage value in the battery module which is being charged is required to be replaced, the charging of the battery monomers is alternated in such a way, n +1 battery monomers can be charged to the charging cut-off threshold value, and the charging capacity of each battery monomer is fully utilized.

2) In the discharging process of the battery module, the bypass function of the battery monomers is adopted, so that at any moment, the serial number of the battery monomers of the battery module directly connected to the discharging circuit is always n, the redundant battery monomer performs balanced energy transfer with the discharging battery monomer in the battery module in real time, the redundant battery monomer is connected to the battery module to discharge every short time, the battery monomer with the lowest voltage value in the discharging battery module is required to be replaced, the discharging of the battery monomers is alternated, n +1 battery monomers can be discharged to the discharging cut-off threshold value, and the discharging capacity of each battery monomer is fully utilized.

3) With the use of the battery module, when one of the n +1 battery cells becomes a short-plate battery cell, the short-plate battery cell can still be used as a backup battery cell by adopting the above method.

The specific use scheme of the short plate backup battery cell is as follows:

suppose that the n +1 battery cells B₁～B_n+1The battery module formed by connecting the battery cells in series is fully charged, the battery module formed by connecting n battery cells in series needs to be used for discharging outwards, and the short plate battery cells in n +1 battery cells are assumed to be arranged in sequence as B₁、B_n+1In this case, B is used₂～B_n+1The battery module composed of the series connection discharges to the outside, and the battery monomer B₁As a backup battery cell. Due to B_n+1The short plate battery monomer is used in the process of discharging the battery module, so that the standby battery monomer B is needed from the beginning of discharging the battery module₁Short-plate battery monomer B continuously transferring self electric energy to battery module through transformer balancing module_n+1。

Battery with a battery cellWhen the module is discharged, the spare battery monomer B₁Working in a discharge bypass function mode and providing a short plate battery monomer B_n+1The electrical energy is transferred and the current pattern of the operating circuit is shown in fig. 7.

As shown in fig. 7, the working current of the battery module discharging to the outside is I₁Short plate backup battery cell B₁Charging current of equalizing module of transformer by discharging is I₂And the transformer equalizing module discharges to the short plate battery monomer B_n+1The current charged is I₃。

As the battery module is discharged and the backup battery cell B₁Discharging short plate battery monomer B_n+1The supplementary electric energy is carried out, and when a certain time arrives, the short plate battery cell B_n+1May not be a short plate cell, at this time, the spare cell B₁The supply of the battery cell B is stopped_n+1The electrical energy is replenished, instead replenishing energy to other cells that are considered short plates. The circulation is repeated until the electric energy stored by the n +1 battery cells is exhausted. Such an operation mode can bring out the functions of the battery module to the utmost.

The single battery optimizing circuit of the short plate battery of the battery module can be switched on and off by the unidirectional MOS tube₁～W_n+1、X₁～X_n+1、Y₁～Y_n+1、V₁～V_n+1The independent working state control is carried out on each single battery in the whole series battery module, the independent control of the energy of each single battery is realized, the consistency of the single batteries in the working state of the series battery module is ensured, the requirement on the consistency of the single batteries during the assembly of the battery module is greatly reduced, and the charging and discharging performance of the battery module is improved. In addition, the scheme of the standby battery monomer is adopted, each battery monomer can be fully charged and emit self energy, and therefore the energy of the battery module is utilized to the maximum. In addition, any two single batteries in the battery module can directly transfer electric energy through the transformer balancing module, so that the balancing speed and efficiency of the single batteries are greatly improved, and the single batteries cannot be subjected to direct electric energy transfer due to a certain short plate in the battery moduleThe use of the whole battery module is influenced by the appearance, and the service life of the battery module is greatly prolonged.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (4)

1. A battery module short plate battery monomer optimization circuit is used for controlling a plurality of battery monomers connected in series in a battery module and is characterized by comprising a transformer and a plurality of switching units respectively connected with the transformer, wherein one switching unit is connected between two adjacent connected battery monomers;

the switching unit comprises at least four controllable switching elements, a first terminal of a first controllable switching element is connected with one electrode of one battery cell, a first terminal of a second controllable switching element is respectively connected with the other electrode of the battery cell and one terminal of the primary winding of the transformer, a first terminal of a third controllable switching element is connected with the other terminal of the primary winding of the transformer, a first terminal of a fourth controllable switching element is connected with one terminal of the secondary winding of the transformer, and the other terminal of the secondary winding of the transformer is connected with the other electrode of the battery cell; the four second connection terminals of the four controllable switching elements are connected in common and are connected with the electrode of the battery cell which is adjacent to the battery cell and is opposite to the electrode.

2. The battery module shorting plate cell optimization circuit according to claim 1, wherein the controllable switching element is formed by connecting two unidirectional MOS transistors in anti-parallel.

3. The battery module shorting plate cell optimization circuit according to claim 1, wherein the number of switching units is the same as the number of cells in the battery module.

4. The battery module shorting plate battery cell optimization circuit of claim 1, further comprising a backup battery cell connected in series with the plurality of battery cells and a backup switching unit connecting the backup battery cell and the transformer, respectively.

Images