CN101777784A - Equalizing charge device and equalizing charge method - Google Patents

Abstract

The equalizing charging device for series battery packs provided by the present invention includes a plurality of charging branches, each charging branch is used to charge corresponding single cells in the series series battery packs respectively, and the equalizing charging device also includes a controller ( 4), the controller (4) is used to obtain the SOC value of each single battery in real time and calculate and update the SOC average value of the series battery pack in real time according to the SOC value, and convert the SOC value of the obtained single battery The minimum SOC value is compared with the SOC average value, and when the difference between the minimum SOC value and the SOC average value is greater than the first threshold, the charging branch that controls the charging of the single battery corresponding to the minimum SOC value is closed until the single battery When the difference between the SOC value of the bulk battery and the SOC average value updated in real time is less than a second threshold, the charging branch for controlling the charging of the single battery is disconnected. The balanced charging device and the balanced charging method provided by the invention solve the problem of unbalanced charging of series battery packs.

Description

Balanced charging device and balanced charging method

technical field

The invention relates to a charging device, in particular to an equalizing charging device and an equalizing charging method for series battery packs.

Background technique

Rechargeable power batteries are widely used in various electronic products, especially electric vehicles or hybrid vehicles, because of their good utilization. For electric vehicles or hybrid vehicles, a power battery pack is provided as a power supply device formed by connecting multiple single cells in series. Due to the differences in the manufacturing and use environments of rechargeable power batteries, after multiple charging and discharging cycles of power batteries, the differences of battery cells show a gradually increasing trend, which is easy to cause battery packs connected in series during the charging process. The unbalanced charging of single cells directly affects the service life and performance of the battery pack, which is a problem that cannot be ignored for electric vehicles and hybrid vehicles.

Existing power battery cell equalization methods include resistance discharge equalization method, capacitive energy transfer method and inductive energy transfer method. The resistance discharge equalization method is a passive discharge method of energy consumption, which can only discharge the single battery with high power, but cannot charge the single battery with low power; both the capacitive energy transfer method and the inductive energy transfer method are energy transfer. The active equalization method can realize the high charge and low charge of the single battery, but the cost of this method is very high, and the reliability is poor due to the immature technology of the inductor and capacitor devices, so it is difficult to apply it on a large scale in electric vehicles and hybrid vehicles.

Contents of the invention

The purpose of the present invention is to solve the problems of small effective capacity and poor performance of battery packs caused by unbalanced charging of series-connected battery packs, and provide a low-cost, high-reliability equalized charging device and equalized charging method for series-connected battery packs.

The balanced charging device for series battery packs provided by the present invention includes a plurality of charging branches, and each charging branch is used to charge the corresponding single cells in the series connected battery packs respectively. The balanced charging device It also includes a controller, the controller is used to obtain the SOC value of each single battery in real time and calculate and update the SOC average value of the battery pack in series according to the SOC value in real time, and convert the obtained SOC value of the single battery The minimum SOC value is compared with the SOC average value, and when the difference between the minimum SOC value and the SOC average value is greater than the first threshold, the charging branch that controls the charging of the single battery corresponding to the minimum SOC value is closed until the single battery When the difference between the SOC value of the bulk battery and the SOC average value updated in real time is less than a second threshold, the charging branch for controlling the charging of the single battery is disconnected.

The balanced charging method for series battery packs provided by the present invention includes the following steps: obtaining the SOC value of each single battery in real time, and calculating and updating the SOC average value of the series battery packs in real time according to the SOC value; Comparing the minimum SOC value among the SOC values of the single battery with the average SOC value; and starting to charge the single battery corresponding to the minimum SOC value when the difference between the minimum SOC value and the average SOC value is greater than a first threshold Stop charging the single battery until the difference between the SOC value of the single battery and the SOC average value updated in real time is less than a second threshold.

The equalized charging device and equalized charging method for a series battery pack provided by the present invention calculate and update the SOC average value of the series battery pack by obtaining the SOC value of each single battery in the series battery pack in real time, and adopt the series battery pack The real-time updated SOC average value of the group is used as the judgment condition for whether the battery pack in series is balanced or not. By comparing the minimum SOC value among the obtained SOC values of the single cells with the average SOC value, the cells that need to be balanced are judged. The battery, and then connect the single battery with the charging power source to realize the supplementary power of the single battery with the lowest power, and disconnect the single battery from the charging power source until the SOC value of the single battery meets the balanced charging condition. This achieves charge equalization of the battery pack in series. The balanced charging device and balanced charging method for series battery packs provided by the present invention can correctly select the battery cells that need balanced charging, and the cost is low and the reliability is high, which solves the problem of unbalanced charging of series battery packs and fully realizes The voltage balance of the battery pack in series is improved, and the performance of the battery pack is effectively improved.

Description of drawings

Fig. 1 is the structural schematic diagram of the equalizing charging device that is used for series battery pack provided by the present invention;

Fig. 2 is a flow chart of the balanced charging method for series battery packs provided by the present invention.

Detailed ways

The equalizing charging device and equalizing charging method for series-connected battery packs provided by the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 is a schematic structural diagram of an equalizing charging device for series-connected battery packs provided by the present invention. As shown in Figure 1, the equalizing charging device for series battery packs provided by the present invention includes a plurality of charging branches, each charging branch is used to charge the corresponding single cells in the series battery packs respectively, wherein the The equalizing charging device also includes a controller 4, the controller 4 is used to obtain the SOC value of each single battery in real time and calculate and update the SOC average value of the battery pack connected in series according to the SOC value in real time, and the obtained single battery The minimum SOC value in the SOC value of the battery is compared with the SOC average value, and when the difference between the minimum SOC value and the SOC average value is greater than the first threshold, the charging support for charging the single battery corresponding to the minimum SOC value is controlled. The circuit is closed until the difference between the SOC value of the single battery and the SOC average value updated in real time is less than a second threshold value, and the charging branch for controlling the charging of the single battery is disconnected.

The SOC (State Of Charge) of the battery is used to indicate the remaining power of the battery, and is an important parameter describing the charging and discharging performance of the battery, which is well known to those skilled in the art. During the use of the power battery, the difference in the SOC value of the single battery reflects the difference of the battery cells.

As shown in Figure 1, the equalizing charging device preferably further includes a plurality of controllable switches 2, each controllable switch 2 is located in each charging branch, and the controller 4 has a plurality of output terminals, each output Terminals are respectively connected to the control terminal of each controllable switch 2, and the controller 4 controls the closing or opening of the charging branch by controlling the closing or opening of the controllable switch 2.

The controllable switch 2 is any switch element with a control terminal, the opening and closing of which can be controlled by electrical signals, such as diodes, triodes or relays. The controllable switch 2 is in a normally open state when it does not receive a control signal from the controller 4 to control its closing or opening. Preferably, the controllable switch 2 is a MOSFET. The MOSFET can withstand a current greater than 5A, has a high-voltage isolation function, and can achieve a balanced charge of up to 5A for a single battery. Using MOSFET as the controllable switch 2 can reduce the cost and volume of the equalizing charging device, and increase the reliability of the system.

As shown in Figure 1, the series battery pack is composed of multiple cells connected in series, and each cell’s positive and negative terminals are connected to a charging branch. If the number of cells is N, the charging branch The number of roads is N+1, so that only one single battery can be connected to the charging power source at a time, and only one single battery can be balancedly charged at the same time, so there is no need to consider the inside of the equalization charging device during the equalization process. The problem of voltage isolation reduces system complexity and reduces the cost of isolation circuits. The input terminal of the controller 4 is connected to each single battery through the CAN bus, and is used to collect the voltage of each single battery and calculate the SOC value of each single battery. The calculation process of the SOC value of a single battery is well known to those skilled in the art. The operator can arbitrarily set the order of voltage acquisition on the premise that voltage acquisition is performed on each single cell in the series battery pack to obtain the SOC value of each single cell. Preferably, the voltage collection sequence is set to sequentially collect the voltage of each single battery from the first single battery connected in series until the last single battery.

The controller 4 calculates and updates the SOC average value of the series battery pack in real time by obtaining the SOC value of each single battery in real time, and the SOC average value is divided by the sum of the SOC values of all the single battery cells connected in series It is obtained by the number of single batteries, and the calculation process is well known to those skilled in the art. The controller 4 is preset with a first threshold and a second threshold, and the controller 4 also compares the minimum SOC value among the acquired SOC values of the single cells with the average value of the SOC of the battery pack in series, and when the minimum When the difference between the SOC value and the SOC average value is greater than the preset first threshold, the charging branch that controls the charging of the single battery corresponding to the minimum SOC value is closed, thereby charging the single battery until the single battery When the difference between the SOC value of the battery and the SOC average value updated in real time is less than the second threshold, the controller 4 controls the charging branch for charging the single battery to be disconnected, thereby completing the charging process of the single battery . In order to continuously maintain the charge balance of the series battery pack, after the controller 4 completes the charging process of the single battery, continue to perform the above-mentioned steps, that is, update the SOC average value of the series battery pack in real time and continue the minimum SOC value The comparison step with the SOC average value is used to continuously determine the single battery that needs to be charged and charge it, so as to realize the continuous charge balance of the battery pack in series. The first threshold and the second threshold can be preset in the controller 4 by the operator, preferably, the first threshold is any one of 4%-10%, and the second threshold is 0-10%. Any value within 3%. More preferably, the first threshold is 5%, and the second threshold is 2%, so as to make the balance among the individual cells better.

The controller 4 is any one that can obtain the SOC value of each single battery in the series battery pack in real time according to the instructions of the program, calculate and update the SOC average value of the series battery pack in real time, and control the controllable switch 2 according to the instructions of the program The switch controller, for example, can be a PLC or a single-chip microcomputer.

In order to prevent the occurrence of the overcharge situation of the single battery, as shown in Figure 1, the described equalizing charging device also includes a voltage conversion device 3, the input terminal of the voltage conversion device 3 is used to input the charging voltage, and the output terminal is connected to a plurality of The charging branches are connected, and the voltage conversion device 3 is used to convert the input charging voltage into a voltage within the rated voltage range of the single battery, and output the converted voltage to each charging branch.

The single battery can be charged by connecting an external power source, and the external power source can be an AC power source or a DC power source. Since the single battery needs to be charged under DC voltage, when the external power supply is an AC power supply, the voltage conversion device is an AC/DC converter, which is used to convert the AC voltage provided by the power supply into the rated voltage range of the single battery DC voltage; when the external power supply is a DC power supply, the voltage conversion device is a DC/DC converter, which is used to convert the DC voltage provided by the power supply into a DC voltage within the rated voltage range of the single battery.

The voltage conversion device 3 is any AC/DC converter capable of converting an AC voltage into a DC voltage within a required range or any DC/DC converter capable of converting a DC voltage into a DC voltage within a required range Converters, such as isolated step-down AC/DC converters, isolated step-down DC/DC converters.

In order to save energy, preferably, the voltage conversion device 3 is a DC/DC converter, and the input charging voltage can come from any battery, preferably from a vehicle-mounted 12V lead-acid battery. The 12V DC voltage from the on-board 12V lead-acid battery is converted into a DC low voltage that meets the charging requirements of the single battery.

Fig. 2 is a flow chart of the balanced charging method for series battery packs provided by the present invention. The balanced charging method of the series battery pack provided by the present invention comprises the following steps: obtaining the SOC value of each monomer battery in real time, and calculating and updating the SOC average value of the series battery pack in real time according to the SOC value; Comparing the minimum SOC value among the SOC values of the battery with the SOC average value; and when the difference between the minimum SOC value and the SOC average value is greater than a first threshold value, start charging the single battery corresponding to the minimum SOC value until Stop charging the single battery when the difference between the SOC value of the single battery and the SOC average value updated in real time is less than a second threshold.

In order to prevent the occurrence of overcharging of the single battery, the method further includes the following steps: after converting the charging voltage for charging the single battery into a voltage within the rated voltage range of the single battery, and then using the converted voltage Charge the single battery.

The single battery can be charged by connecting an external power source, for example, the charging voltage for charging the single battery can come from any battery, preferably, the input charging voltage for charging the single battery comes from the vehicle-mounted 12V lead-acid Battery.

According to the method provided by the present invention, as shown in Figure 2, the SOC value of each single cell in the series battery pack is first obtained in real time, starting from the first single cell connected in series, and the SOC of each single cell is sequentially obtained value until the last single battery; then calculate and update the SOC average value of the battery pack in series through the obtained SOC value of the single battery in real time; after that, the minimum SOC in the obtained SOC value of the single battery value is compared with the SOC average value; when the comparison result is that the difference between the minimum SOC value and the SOC average value is greater than the first threshold value, it is determined that the single battery corresponding to the minimum SOC value needs to be charged, thereby controlling the battery with the minimum SOC value A pair of controllable switches 2 connected to the single battery corresponding to the value are closed, and the charging voltage for charging the single battery is introduced into the single battery by the closed controllable switch 2 after voltage conversion to carry out Charging; when the difference between the SOC value of the charged single battery and the SOC average value updated in real time is less than the second threshold, the pair of controllable switches 2 connected to the single battery are disconnected, and the charging is stopped. The single battery is charged.

Claims (10)

1. balanced charging device that is used for series battery, this balanced charging device comprises a plurality of charging paths, each charging paths is used for respectively the cell charging to the correspondence of series battery, wherein, this balanced charging device also comprises controller (4), the SOC mean value that described controller (4) is used for obtaining the SOC value of each cell in real time and calculates and upgrade series battery according to described SOC value in real time, minimum SOC value and described SOC mean value in the SOC value of the cell that obtained are compared, when the difference of minimum SOC value and SOC mean value during greater than first threshold control to the charging paths closure of the pairing cell charging of this minimum SOC value, until the charging paths disconnection that control is charged to this cell during less than second threshold value of the difference of the described SOC mean value of the SOC of this cell value and real-time update.

2. balanced charging device according to claim 1, wherein, described first threshold is any one value among the 4%-10%, described second threshold value is any one value among the 0-3%.

3. balanced charging device according to claim 1, wherein, described balanced charging device also comprises voltage conversion device (3), the input of this voltage conversion device (3) is used for input charging voltage, output links to each other with described a plurality of charging paths, the charging voltage that this voltage conversion device (3) is used for being imported converts the voltage in the cell range of nominal tension to, and the voltage after will changing outputs to each charging paths.

4. balanced charging device according to claim 3, wherein, described voltage conversion device (3) is the DC/DC transducer, the charging voltage of being imported comes from vehicle-mounted 12V lead-acid battery.

5. according to the described balanced charging device of each claim among the claim 1-4, wherein, described balanced charging device also comprises a plurality of gate-controlled switches (2), each gate-controlled switch (2) lays respectively in each charging paths, described controller (4) has a plurality of outputs, each output is connected with the control end of each gate-controlled switch (2) respectively, and described controller (4) is controlled the closed of charging paths by control gate-controlled switch (2) closure or disconnection or disconnected.

6. balanced charging device according to claim 5, wherein, described gate-controlled switch (2) is MOSFET.

7. balanced charging method that is used for series battery, wherein, this method may further comprise the steps:

Obtain the SOC value of each cell in real time, and calculate and upgrade the SOC mean value of series battery according to described SOC value in real time;

Minimum SOC value and described SOC mean value in the SOC value of the cell that obtained are compared; And

When the difference of minimum SOC value and SOC mean value begins the pairing cell charging of this minimum SOC value during greater than first threshold, stop this cell is charged during less than second threshold value until the difference of the described SOC mean value of the SOC of this cell value and real-time update.

8. method according to claim 7, wherein, described first threshold is any one value among the 4%-10%, described second threshold value is any one value among the 0-3%.

9. according to claim 7 or 8 described methods, wherein, this method also comprises: after will converting the voltage in the cell range of nominal tension to the charging voltage of described cell charging to, utilize the voltage after changing that described cell is charged again.

10. balanced charging method according to claim 9, wherein, the charging voltage of being imported comes from vehicle-mounted 12V lead-acid battery.

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