CN114006441A - Control method for battery equalization time and battery pack active equalization system - Google Patents
Control method for battery equalization time and battery pack active equalization system Download PDFInfo
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- CN114006441A CN114006441A CN202111415210.3A CN202111415210A CN114006441A CN 114006441 A CN114006441 A CN 114006441A CN 202111415210 A CN202111415210 A CN 202111415210A CN 114006441 A CN114006441 A CN 114006441A
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- battery
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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
- H02J7/0014—Circuits for equalisation of charge between batteries
- H02J7/0016—Circuits for equalisation of charge between batteries using shunting, discharge or bypass circuits
Abstract
The invention provides a control method of battery equalization time and a battery pack active equalization system, which comprise the following steps: presetting balance stop voltage and balance start time; acquiring the voltage of each single battery, and acquiring the accumulated value of the differential pressure of each single battery and the extreme difference of the battery pack; stopping the equalization if the range is less than the equalization stop voltage; and if the range is greater than the balance stop voltage, starting balance, calculating the ratio of the pressure difference accumulated value to the maximum pressure difference accumulated value of each single battery, and obtaining the balance time required by each single battery based on the balance starting time. The invention can accurately control the charging or discharging time of each single battery, prevent overcharge or overdischarge, ensure that the batteries in the battery pack can be fully charged or discharged at the same time, and has small energy loss and high balancing efficiency.
Description
Technical Field
The invention relates to the technical field of battery management, in particular to a battery equalization time control method and a battery pack active equalization system.
Background
When the batteries are produced, due to the fact that manufacturing materials, production processes and the like are inconsistent, parameters such as internal resistance and capacity of the single batteries are different to a certain extent, and installation positions, heat dissipation conditions and leakage current are different to a certain extent in the using process. Therefore, the battery pack is generally equipped with an active equalization system, and the charge and discharge time of the unit cells in the battery pack is controlled by an equalization method in the equalization system.
The conventional active equalization method is to collect all battery voltages of a battery pack, determine a single battery needing active equalization and corresponding charging time according to voltage data of the single batteries of the battery pack, and then charge the single battery needing equalization until all the single batteries needing equalization are completely charged.
Disclosure of Invention
In view of this, an object of the present invention is to provide a method for controlling battery equalization time, which accurately controls the equalization time of each battery and avoids overcharging or overdischarging of the battery.
In order to achieve the above object, the present invention provides a method for controlling battery equalization time, which is applied to an active equalization system of a battery pack, wherein the battery pack has N single batteries, and the method comprises the following steps: presetting balance stop voltage and balance start time; acquiring the voltage of each single battery, and acquiring a differential pressure accumulated value and a battery pack range of each single battery, wherein the differential pressure accumulated value is the sum of the voltage of each single battery and the average voltage from the 1 st battery to the ith battery, i is more than or equal to 1 and less than or equal to N, and the range is the differential pressure between the single battery with the highest voltage and the single battery with the lowest voltage; stopping the equalization if the range is less than the equalization stop voltage; and if the range is greater than the balance stop voltage, starting balance, calculating the ratio of the pressure difference accumulated value to the maximum pressure difference accumulated value of each single battery, and obtaining the balance time required by each single battery based on the balance starting time.
Optionally, the method comprises the following steps: presetting a first starting voltage, a second starting voltage and a third starting voltage of which the voltage values are from large to small; setting the balance opening time as a first opening time, a second opening time and a third opening time of which the time values are from large to small; if the range is greater than the first turn-on voltage, executing the first turn-on time; if the range is less than the first starting voltage and greater than the second starting voltage, executing the second starting time; and if the range is smaller than the second starting voltage and larger than a third starting voltage, executing the third starting time.
Optionally, the method comprises the following steps: presetting a first stop time, a second stop time and a third stop time of which the time values are from large to small, and respectively executing the first stop time, the second stop time and the third stop time correspondingly to the first starting time, the second starting time and the third starting time.
Optionally, if the accumulated value of the pressure difference of the ith single battery is less than 0, controlling the battery to enter an equalizing charge state; and if the accumulated value of the pressure difference of the ith single battery is greater than 0, controlling the battery to enter a balanced discharge state.
Optionally, the method comprises the following steps: comparing the single batteries in the charging state and the discharging state with the previous equilibrium state, and counting the number M of the single batteries with inconsistent equilibrium states; and if M is greater than or equal to 30% of the total number N of the single batteries, reducing the balance current, and otherwise, increasing the balance current.
Optionally, a balancing module is arranged in the active balancing system of the battery pack, the balancing current is not greater than the rated current of the balancing module, and the balancing current is not less than 10% of the rated current.
The invention also provides a battery pack active equalization system, which comprises a main control unit and a slave control unit which are connected with each other, wherein the slave control unit comprises N sub slave control units, the sub slave control units are correspondingly connected with N single batteries in the battery pack one by one, and the main control unit executes the control method of the battery equalization time.
Compared with the prior art, the technical scheme of the invention has the following advantages: different balancing time required by each single battery is obtained through calculation, the energy in the high-energy batteries in the battery pack is transferred to the low-energy batteries, and the balancing current is controlled. The invention can accurately control the charging or discharging time of each single battery, prevent overcharge or overdischarge, ensure that the batteries in the battery pack can be fully charged or discharged at the same time, and has small energy loss and high balancing efficiency.
Drawings
Fig. 1 is a schematic structural diagram of an active equalization system of a battery pack according to the present invention;
fig. 2 is a flowchart of a method for controlling battery equalization time according to the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only these embodiments. The invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention.
In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale, which is only used for convenience and clarity to assist in describing the embodiments of the present invention.
Referring to fig. 1, which illustrates a schematic structural diagram of a battery pack active equalization system of the present invention, an active equalization system of a battery pack 1 includes a master control unit 2 and a slave control unit 3 that are connected to each other, where the slave control unit includes N slave control units 31, the slave control units 31 are connected to N single batteries in the battery pack 1 in a one-to-one correspondence manner, a equalization module 311 is disposed in the slave control unit 31, and the master control unit 2 executes a battery equalization time control method of the present invention.
Referring to fig. 2, a flow chart of a method for controlling battery equalization time according to the present invention is illustrated, which includes the following steps:
and S1, presetting an equalization stop voltage Vb and an equalization start time Ta. In this embodiment, the setting of the equalization stop voltage Vb and the equalization start time Ta may be performed according to data in the equalization experiment performed for a plurality of times or data in practical application.
S2, obtaining the voltage Vi of each single battery and obtaining the accumulated value of the pressure difference of each single battery
And battery pole difference V'. Wherein, the accumulated value of the pressure difference of each single battery is obtained
The method comprises the following specific steps: collecting the voltage Vi of each single battery; using a formula
Calculating the average voltage of the battery pack 1
Using a formula
Calculating the voltage Vi and the average voltage of each single battery
A differential pressure Δ Vi therebetween, the differential pressure accumulated value
The voltage Vi and the average voltage of each single battery from the 1 st to the ith battery
Δ Vi, e.g. the accumulated value of the differential pressure of the 1 st cell
The accumulated value of the pressure difference of the 3 rd cell is
The accumulated value of the differential pressure of the 8 th single battery is
I is more than or equal to 1 and less than or equal to N. The range V' is the pressure difference between the monomer battery Vmax with the highest voltage and the monomer battery Vmin with the lowest voltage, and the calculation formula is as follows: v ═ Vmax-Vmin。
S3, judging whether the range difference V' is larger than the balance stop voltage Vb, if so, stopping the balance; if the voltage is larger than the balance stop voltage Vb, starting balance, and calculating the accumulated value of the voltage difference of each single battery
And the maximum accumulated value of the pressure difference
Based on the equilibrium start time Ta, the equilibrium time Ti required by each single battery is obtained, and the calculation formula is
Wherein Tmax is a preset equilibrium opening time Ta.
By the method, the equalization time of each battery is obtained, so that the time length of each battery entering an equalization state is accurately controlled, each battery is sequentially subjected to equalization charging or discharging according to the required equalization time, and equalization is stopped when the time is reached, so that overcharge or overdischarge is avoided. Referring to table 1, which is an example of the balancing time required by each battery calculated according to the above method, in table 1, the 7 th battery needs 30S of balancing time, and then performs balancing first, after 5S, the 6 th battery performs balancing, after 2S, the 8 th battery performs balancing, and so on, until the last 3S and 11 th batteries perform balancing, after that, all batteries reach the balancing time at the same time, and the balancing is stopped.
TABLE 1
Specifically, in step S1, the first, second, and third turn-on voltages Va1, Va2, and Va3 are also preset, andVa1>Va2>Va3(ii) a Setting the equilibrium opening time Ta as a first opening time Ta1, a second opening time Ta2 and a third opening time Ta3, and Ta1>Ta2>Ta3. In step S3, after equalization is turned on, it is also determined that: if V' is not less than Va1If the balancing time is started, executing a first starting time Ta1, and when the balancing time Ti required by each single battery is calculated, Tmax in the formula is Ta 1; if Va1>V′≥Va2If the current battery is in the first starting time, equalizing the starting time to execute a second starting time Ta2, and when the equalizing time Ti required by each single battery is calculated, Tmax in the formula is Ta 2; if Va2>V′≥Va3If the equalization opening time is executed for the third opening time Ta3 and the equalization opening time is executed for the third opening time Ta3, Tmax in the formula is equal to Ta3 when the equalization time Ti required for each unit cell is calculated. And the balance opening time is selected according to the range difference V' to calculate the balance time Ti, so that the calculation accuracy is improved.
Specifically, the first stop time Tb1, the second stop time Tb2 and the third stop time Tb3 are also preset in step S1, and Tb1>Tb2>Tb3Respectively corresponding to the first opening time Ta1, the second opening time Ta2 and the third opening time Ta3, and if the steps are performed, judging that V' is not less than V ≧ Va1After the equalization starting time reaches the first starting time Ta1, all the single batteries stop equalization, and after the equalization starting time reaches the first stopping time Tb1, the equalization time of a new round is calculated according to the steps, and the equalization is continuously started. When the single batteries are charged or discharged in an equalizing way, the voltage capacity can rapidly rise or fall by a certain amplitude, and the equalization needs to be stopped for a period of time to ensure that the voltage capacity reaches a stable state and then enters a new round of equalization, so that the pressure difference of each single battery is closer and closer, the single batteries are fully charged or emptied at the same time, and the energy loss is reduced.
Specifically, if the accumulated value of the pressure difference of the ith single battery
The battery is controlled to enter an equalizing charge state(ii) a If the accumulated value of the pressure difference of the ith single battery
The battery is controlled to enter an equalized discharge state. After the equalization is started, whether each single battery needs to be charged or discharged is determined according to the accumulated value of the pressure difference, and if the accumulated value of the pressure difference is 0, the single battery does not need to enter any equalization state.
Specifically, comparing the single batteries in the charging state and the discharging state with the previous equilibrium state, and counting the number M of the single batteries with inconsistent equilibrium states; and if M is greater than or equal to 30% of the total number N of the single batteries, reducing the balance current, and otherwise, increasing the balance current. If the single battery in the state of charge is being equalized, the equalization state is inconsistent if the last equalization state is discharge. As shown in table 2, the balance states of 5 batteries, i.e., 2#, 3#, 4#, 7#, and 12# are not consistent and are greater than 30% of the total number of the single batteries, so that the balance current is reduced, and the energy loss is reduced; and if the number of the single batteries with inconsistent equilibrium states is less than 30% of the total number of the single batteries, increasing the equilibrium current. And the magnitude of the equalization current is controlled by comparing the equalization states to improve the efficiency of active equalization.
TABLE 2
Specifically, a balancing module 311 is arranged in the battery pack active balancing system, the balancing current is not greater than the rated current of the balancing module 311, and the balancing current is not less than 10% of the rated current of the balancing module 311, so that the balancing module 311 is protected.
Although the embodiments have been described and illustrated separately, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and reference may be made to one of the embodiments not explicitly described, or to another embodiment described.
The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.
Claims (7)
1. A control method of battery equalization time is applied to a battery pack active equalization system, the battery pack is provided with N single batteries, and the method is characterized by comprising the following steps:
presetting balance stop voltage and balance start time;
acquiring the voltage of each single battery, and acquiring a differential pressure accumulated value and a battery pack range of each single battery, wherein the differential pressure accumulated value is the sum of the voltage of each single battery and the average voltage from the 1 st battery to the ith battery, i is more than or equal to 1 and less than or equal to N, and the range is the differential pressure between the single battery with the highest voltage and the single battery with the lowest voltage;
stopping the equalization if the range is less than the equalization stop voltage;
and if the range is greater than the balance stop voltage, starting balance, calculating the ratio of the pressure difference accumulated value to the maximum pressure difference accumulated value of each single battery, and obtaining the balance time required by each single battery based on the balance starting time.
2. The method for controlling the battery equalization time according to claim 1, comprising the steps of:
presetting a first starting voltage, a second starting voltage and a third starting voltage of which the voltage values are from large to small;
setting the balance opening time as a first opening time, a second opening time and a third opening time of which the time values are from large to small;
if the range is greater than the first turn-on voltage, executing the first turn-on time;
if the range is less than the first starting voltage and greater than the second starting voltage, executing the second starting time;
and if the range is smaller than the second starting voltage and larger than a third starting voltage, executing the third starting time.
3. The method for controlling the battery equalization time according to claim 2, comprising the steps of:
presetting a first stop time, a second stop time and a third stop time of which the time values are from large to small, and respectively executing the first stop time, the second stop time and the third stop time correspondingly to the first starting time, the second starting time and the third starting time.
4. The method for controlling the battery equalization time according to any one of claims 1 to 3, characterized by comprising the steps of:
if the accumulated value of the pressure difference of the ith single battery is less than 0, controlling the battery to enter an equalizing charge state; and if the accumulated value of the pressure difference of the ith single battery is greater than 0, controlling the battery to enter a balanced discharge state.
5. The method for controlling the battery equalization time according to claim 4, comprising the steps of:
comparing the single batteries in the charging state and the discharging state with the previous equilibrium state, and counting the number M of the single batteries with inconsistent equilibrium states;
and if M is greater than or equal to 30% of the total number N of the single batteries, reducing the balance current, and otherwise, increasing the balance current.
6. The method of claim 5, wherein: the battery pack active equalization system is internally provided with an equalization module, the equalization current is not more than the rated current of the equalization module, and the equalization current is not less than 10% of the rated current.
7. The utility model provides a group battery initiative equalizing system, includes interconnect's main control unit and slave control unit, the slave control unit includes N sub-slave control unit, sub-slave control unit with N section battery cell one-to-one in the group battery is connected which characterized in that: the main control unit executes the method for controlling battery equalization time according to any one of claims 1 to 6.
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