CN116569380A - Method, device and system for determining state of charge - Google Patents
Method, device and system for determining state of charge Download PDFInfo
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- CN116569380A CN116569380A CN202180081981.5A CN202180081981A CN116569380A CN 116569380 A CN116569380 A CN 116569380A CN 202180081981 A CN202180081981 A CN 202180081981A CN 116569380 A CN116569380 A CN 116569380A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
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Abstract
The method, the device and the system for determining the state of charge can acquire the electric energy parameter value in the first battery pack (105) within a preset time period when the battery system (100) is in a state without energy output (under-vehicle high-voltage), and judge whether circulation current or zero drift current is generated in the current first battery pack (105) according to a comparison result of the electric energy parameter value and the preset electric parameter value, so that the state of charge in the first battery pack (105) can be calculated more accurately based on the comparison result.
Description
The present disclosure relates to the field of battery technologies, and in particular, to a method, an apparatus, and a system for determining a state of charge.
The State of Charge (SOC) of the battery is used to reflect the State of remaining capacity of the battery, and the accurate SOC plays an important role in achieving the electric quantity indication, the remaining mileage, the overcharge and overdischarge protection, the battery equalization, the Charge control, the battery health status prediction, and the like of the battery.
However, the accuracy of the current calculation method of the SOC is low.
Disclosure of Invention
The embodiment of the application provides a method, a device and a system for determining a state of charge.
In one aspect, embodiments of the present application provide a method of determining a state of charge, the method being applied to a sub-battery management unit, the sub-battery management unit being communicatively coupled to a main battery management unit,
the main battery management unit is used for controlling the energy output state of a battery system, and the battery system at least comprises a first battery pack and a second battery pack which are connected in parallel;
a sub-battery management unit for controlling an energy output state of the first battery pack;
the method comprises the following steps:
after receiving a first signal sent by a main battery management unit, acquiring an electric parameter value in a first battery pack within a preset time period; wherein the first signal is used to characterize the battery system in a state of no energy output;
and determining the charge state of the first battery pack according to a comparison result of the electric parameter value and a preset electric parameter threshold value.
According to the method for determining the state of charge, the energy electric parameter value in the first battery pack can be obtained within the preset time period when the battery system is in the state without energy output (under-vehicle high-voltage), and whether the current circulation current or the zero drift current is generated in the first battery pack can be judged according to the comparison result of the electric parameter value and the preset electric parameter value, so that the state of charge in the battery pack can be determined more accurately based on the comparison result.
In one possible implementation manner, after receiving the first signal sent by the main battery management unit, acquiring the electrical parameter value in the first battery pack within a preset duration, including: after receiving a first signal sent by a main battery management unit, controlling a first battery pack to be in an energy output state within a preset duration; the preset duration is determined based on the duration of the circulation current in the first battery pack; and acquiring the electric parameter value in the first battery pack within the preset time period.
Through the technical scheme of the implementation mode, after the main battery management unit cuts off the energy output of the battery system, the sub-battery management unit controls the first battery pack to be in an energy state, namely, a current loop is formed in the first battery pack, so that the situation that large loop current impact is formed due to the fact that the internal current loop is frequently cut off to increase voltage difference between the parallel battery packs can be avoided, and adverse effects on the safety of the battery system are avoided.
In one possible implementation, calculating the first state of charge value of the first battery pack according to the comparison result of the electrical parameter value and the preset electrical parameter threshold value includes: and under the condition that the electric parameter value is larger than a preset electric parameter threshold value, calculating a first charge state value of the first battery pack according to the electric parameter value.
In one possible implementation, determining the state of charge of the first battery pack according to a comparison of the electrical parameter value and a preset electrical parameter threshold value includes:
under the condition that the electric parameter value is smaller than a preset electric parameter threshold value, calculating a first state of charge value of the first battery pack according to a preset electric parameter reference value;
and determining the charge state of the first battery pack according to the first charge state value.
According to the technical scheme of the implementation mode, according to different comparison results of the electric parameter value and the preset electric parameter value, the real current condition (circulation or zero drift current) existing in the first battery pack is judged, so that different calculation modes are adopted to calculate the first state of charge value, and a more accurate SOC calculation result is obtained.
In one possible implementation, determining the state of charge of the first battery pack from the first state of charge value includes: the first state of charge value and a preset error value are subjected to difference to obtain a second state of charge value, wherein the preset error value comprises preset power consumption of the sub-battery management unit; and determining the state of charge corresponding to the second state of charge value as the state of charge of the first battery pack.
After the first state of charge value is calculated according to the current condition in the first battery pack, the first state of charge is corrected by utilizing the error value such as the power consumption of the preset sub-battery management unit, so that the accurate state of charge of the first battery pack can be obtained.
In a second aspect, embodiments of the present application provide a method for operating a sub-battery management unit in communication with a main battery management unit,
the main battery management unit is used for controlling the energy output state of a battery system, and the battery system at least comprises a first battery pack and a second battery pack which are connected in parallel;
a sub-battery management unit for controlling an energy output state of the first battery pack;
the device comprises:
the acquisition module is used for acquiring the electric parameter value in the first battery pack within a preset duration after receiving the first signal sent by the main battery management unit; wherein the first signal is used to characterize the battery system in a state of no energy output;
and the determining module is used for determining the charge state of the first battery pack according to the comparison result of the electric parameter value and the preset electric parameter threshold value.
In a third aspect, embodiments of the present application provide an electronic device including a memory and a processor; the memory is used for storing executable program codes;
the processor is configured to read executable program code stored in the memory to perform the method of determining the state of charge in the first aspect.
In a fourth aspect, embodiments of the present application provide a computer-readable storage medium comprising instructions that, when run on a computer, cause the computer to perform the method of determining a state of charge in the first aspect.
In a fifth aspect, embodiments of the present application provide a battery management system, including a main battery management unit and a sub-battery management unit,
the main battery management unit is in communication connection with the sub battery management units and is used for controlling the energy output state of the battery system; the battery system includes a first battery pack and a second battery pack connected in parallel,
a sub-battery management unit for controlling an energy output state of the first battery pack;
the sub-battery management unit is further configured to perform the method of determining the state of charge in the first aspect.
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and that other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic view of a battery system according to an embodiment of the present disclosure;
FIG. 2 is a flow chart of a method for determining a state of charge according to an embodiment of the present disclosure;
FIG. 3 is a flow chart of a method for determining state of charge according to an example disclosed herein;
FIG. 4 is a flow chart of a method of determining state of charge as disclosed in another example of the present application;
FIG. 5 is a flow chart of a method of determining state of charge as disclosed in yet another example of the present application;
FIG. 6 is a schematic diagram of a state of charge determining device according to an embodiment of the present disclosure;
fig. 7 is a schematic hardware structure of an electronic device according to an embodiment of the present disclosure.
In the drawings, the drawings are not drawn to scale.
Marking:
a 100-cell system; 101-charging a main circuit; 102-an input terminal; 1021-positive terminal; 1022-negative terminal; 103-an output terminal; 104-a master battery management unit; 105-a first battery pack; 106-a second battery pack; 107-charging branch; 1081-positive terminal; 1082-a negative terminal; 109-sub-battery management unit.
Embodiments of the present application are described in further detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the present application and are not intended to limit the scope of the application, i.e., the application is not limited to the embodiments described.
In the description of the present application, it is to be noted that, unless otherwise indicated, the meaning of "plurality" is two or more; the terms "upper," "lower," "left," "right," "inner," "outer," and the like indicate an orientation or positional relationship merely for convenience of description and to simplify the description, and do not indicate or imply that the devices or elements in question must have a particular orientation, be constructed and operate in a particular orientation, and therefore are not to be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The "vertical" is not strictly vertical but is within the allowable error range. "parallel" is not strictly parallel but is within the tolerance of the error.
The directional terms appearing in the following description are all directions shown in the drawings and do not limit the specific structure of the present application. In the description of the present application, it should also be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the terms in the present application can be understood as appropriate by one of ordinary skill in the art.
Currently, most of the battery systems on the market are of a primary architecture, that is, the battery systems generally comprise single battery packs connected in series, and the intelligent management of the battery systems is realized through a battery management system (Battery Management System, BMS) arranged in the system. After the whole vehicle is powered down, a BMS in a battery system controls a current loop in a single battery pack to be disconnected, and acquires a zero drift current calculation SOC (State of Charge) when the battery pack is switched to be disconnected.
Because the battery system with the primary architecture has lower capacity, the applicant designs a battery system with a secondary architecture for improving the battery capacity, the battery system comprises a plurality of battery packs (battery packs) connected in parallel, wherein the energy output state of each battery pack is controlled by a sub-battery management unit (Slave Battery Management Nnit, SBMU), the energy output state of the battery system is controlled by a main battery management unit (Master Nattery Management Unit, MBMU), the corresponding SBMU of each battery pack is in communication connection with the MBMU, and the SBMU, the MBMU and the like form the BMS of the battery system.
When the SOC of the battery system is calculated, the SOC of each battery pack is calculated first, and then the SOC of the battery system is calculated according to the SOC of each battery pack. When calculating the SOC of a single battery pack, it is often necessary to cut off the current loop in each battery pack and collect the current value when the current loop is cut off to calculate the SOC.
However, the inventors of the present application have found that frequent cutting of the current loop in the battery packs results in an increase in the pressure difference between the parallel battery packs. When the pressure difference is excessively large, a circulation generated between the battery packs may impact devices within the battery packs, thereby affecting the safety of the battery packs.
However, if the current loop in the parallel battery pack is kept in the path state in the process of calculating the SOC, the current in the current battery pack is directly used for calculating the SOC no matter whether the current is actually consumed or not, so that the accuracy of the finally obtained SOC value is low due to low sampling accuracy of the current value.
In order to ensure the accuracy of calculation of the SOC in the battery system with the secondary architecture, the embodiment of the present application provides a method, an apparatus and a system for determining the state of charge, where the method and the apparatus for determining the state of charge of the present application may be applied to a sub-battery management unit in the battery system with the secondary architecture.
The battery system according to the embodiment of the present application will be described first with reference to the drawings.
By way of example, fig. 1 shows a schematic diagram of a two-level architecture battery system.
As shown in fig. 1, a battery system 100 includes a charging trunk 101, where the charging trunk 101 includes a plurality of groups of power input terminals 102 and a plurality of groups of power output terminals 103 (a group of output terminals or output terminals each include a positive terminal and a negative terminal), the plurality of groups of power input terminals 102 are connected in parallel and then connected to the power output terminals 103, and a first switch module K1 is disposed between each group of power input terminals 102 and the power output terminals 103. The main battery control unit 104 in the battery system BMS may control the power output of the battery system 100 by controlling the on-off of the first switch module K1.
Each of the parallel battery packs (105, 106) in the battery system 100 includes a charging branch, and the charging branch 107 in the first battery pack 105 is described as an example. The charging branch 107 includes a power module E1, a protection module S1 and a second switch module K2, where the protection module S1, the power module E1 and the second switch module K2 are connected in series in sequence and then correspondingly connected to positive and negative output terminals (1081, 1082) of the first battery pack 105, and the positive and negative output terminals (1081, 1082) of the first battery pack 105 are correspondingly connected to one set of electrical energy input terminals (1021, 1022) on the charging main circuit 101. The sub-battery management unit 109 corresponding to the first battery pack 105 controls the on/off of the second switch module K2, thereby controlling the energy output in the first battery pack 105.
For example, the first switch module K1 and the second switch module K2 may be relays, the protection module S1 may be a fuse, and the power module E1 may be a battery cell or a battery cell (cell).
For example, in a battery system, the entirety of a single battery pack may be collectively referred to as a battery. The battery may be any type of battery, including but not limited to: lithium ion batteries, lithium metal batteries, lithium sulfur batteries, lead acid batteries, nickel-metal batteries, nickel-hydrogen batteries, or lithium air batteries, among others.
Alternatively, the battery system as a whole may be provided in a distribution box (Battery Disconnect Unit, BDU).
Optionally, a voltage converter (not labeled in the figure) is further connected to the charging branch in the first battery pack, and the voltage converter is configured to convert the high voltage output by the charging branch into a low voltage, so as to supply power to the corresponding sub-battery management unit.
It should be understood that the first battery pack further includes a sampling module (not labeled in the figure) for collecting the electrical parameter values on the charging branches in the first battery pack and transmitting the electrical parameter values to the corresponding sub-battery management units. Optionally, the sampling module may be an open/closed loop hall element, a fluxgate or a shunt, and may collect the current value on the charging branch.
It should be understood that the battery packs in the battery system may all have the structure of the first battery pack as shown in fig. 1.
It should be appreciated that the above battery system may be a battery system in an electric vehicle (including a pure electric vehicle and a plug-in hybrid electric vehicle) or a battery system in other application scenarios.
Fig. 2 shows a flow diagram of a method of determining a state of charge in one embodiment of the present application. The determining method of the embodiment of the application can be applied to a sub-battery management unit, wherein the sub-battery management unit is in communication connection with a main battery management unit, the main battery management unit is used for controlling the energy output state of a battery system, and the battery system at least comprises a first battery pack and a second battery pack which are connected in parallel; and the sub-battery management unit is used for controlling the energy output state of the first battery pack.
As shown in fig. 2, the method may include steps S201 to S203:
s201, after receiving a first signal sent by a main battery management unit, acquiring an electric parameter value in a first battery pack within a preset duration; wherein the first signal is used to characterize the battery system in a state of no energy output.
After the whole vehicle is powered down, the VCU (Vehicle Control Unit, whole vehicle controller) sends information of the whole vehicle power down to the MBMU, the MBMU switches the battery system into a state without energy output, and transmits first signal communication representing the state to the SBMU corresponding to the first battery pack.
Under the condition that the SBMU receives the first signal, the SBMU acquires the electric parameter value in the first battery pack from the sampling unit in the first battery pack within a preset time period.
Alternatively, the electrical parameter value may be a current value.
S202, determining the charge state of the first battery pack according to a comparison result of the electric parameter value and a preset electric parameter threshold value.
The preset electrical parameter threshold is a threshold for distinguishing the current in the battery pack as circulating current or zero drift current.
In the working process of parallel battery packs in the two-stage architecture current system, if a voltage difference exists between the battery packs, a phenomenon that the battery packs with high voltage charge the battery packs with low voltage is formed between the battery packs, and current in the phenomenon is circulation. When the whole vehicle is powered down, the instant pressure difference between the battery packs can cause instant circulation to exist in the battery packs. In the embodiment of the application, the circulation is the real energy consumption when calculating the SOC.
When the input signal of the amplifying circuit is zero (i.e. no alternating current is input), the zero drift is the phenomenon that the voltage of the output end of the circuit deviates from the original fixed value and floats up and down due to the fact that the static working point is changed and amplified and transmitted step by step due to the influence of factors such as ambient temperature change, unstable power supply voltage and the like. In the embodiment of the application, the zero drift current is not consumed as true energy when calculating the SOC.
The zero drift current is smaller than the current value of the circulating current, so in the embodiment of the application, the zero drift current and the circulating current can be distinguished by presetting an electric parameter value threshold value.
After the SBMU acquires the electric parameter value in the first battery pack, the electric parameter value is compared with a preset electric parameter threshold value, and whether the electric parameter value is a circulation value or a zero drift current value is judged, namely whether the first battery pack has real energy consumption or not is judged, so that the state of charge of the first battery pack can be correspondingly determined according to a comparison result, and the calculation accuracy of the state of charge value is improved.
Fig. 3 shows a flow chart of a method of determining a state of charge in one example of the present application.
In order to accurately calculate the SOC while guaranteeing the safety of the battery pack, optionally, as shown in fig. 3, in the embodiment of the present application, after receiving the first signal sent by the main battery management unit in step S201, the obtaining the electrical parameter value in the first battery pack within the preset duration may specifically include steps S301 to S302:
s301, after receiving a first signal sent by a main battery management unit, controlling a first battery pack to be in an energy output state within a preset time period;
s302, acquiring an electric parameter value in the first battery pack within a preset time period.
As shown in fig. 3, at a high voltage under the vehicle, the MBMU cuts off the energy output of the battery system to the outside and transmits a first signal to the SBMU corresponding to the first battery pack through step S300. At this time, the whole battery system does not output energy to the outside, but there may be an instantaneous current in the first battery pack, so after the SBMU corresponding to the first battery pack receives the first signal, the current loop (charging branch) in the first battery pack is controlled to maintain a channel state through step S301, so as to avoid the impact of the instantaneous current on the switch module on the branch caused by the operation of cutting off the charging branch, thereby affecting the safety of the battery pack.
The preset time period is determined based on the time period during which the circulation current exists in the first battery pack. For example, the duration of the circulation current in the corresponding battery pack may be determined through a preset number of tests, and the average value or the maximum value of the duration may be calculated as the preset duration.
The current existing in the first battery pack may be a circulating current or a zero drift current within the preset time period, and may be determined by the electrical parameter value of the first battery pack acquired in step S302.
After a preset period of time, the second switch module on the charging branch in the first battery pack can be controlled to switch to an open state, or can be kept closed.
In this embodiment, after the main battery management unit cuts off the energy output of the battery system, the sub-battery management unit controls the first battery pack to be in an energy output state, that is, a current loop is formed in the first battery pack, so that the situation that large loop current impact is generated due to frequent cutting off of an internal current loop to increase a voltage difference between the parallel battery packs can be avoided, and adverse effects on the safety of the battery system are avoided.
Fig. 4 shows a flow chart of a method of determining a state of charge in another example of the present application.
In order to accurately determine that the current in the battery pack is a circulating current or a zero drift current, so as to accurately calculate the SOC in the battery pack, optionally, as shown in fig. 4, step S202 determines the state of charge of the first battery pack according to a comparison result between the electrical parameter value and a preset electrical parameter threshold, and may specifically include S401 to S404:
s401, comparing the electric parameter value with a preset electric parameter threshold value;
s402, calculating a first state of charge value of the first battery pack according to the electrical parameter value under the condition that the electrical parameter value is larger than a preset electrical parameter threshold value;
s403, under the condition that the electrical parameter value is smaller than a preset electrical parameter threshold value, calculating a first state of charge value of the first battery pack according to the preset electrical parameter reference value;
s404, determining the charge state of the first battery pack according to the first charge state value.
The preset electrical parameter value is a reference current value capable of judging whether the current instantaneous current in the battery pack is circulation current or zero drift current, and optionally, in the embodiment of the application, the preset electrical parameter value is 300mA, the electrical parameter value lower than 300mA is the zero drift current value, and the electrical parameter value higher than 300mA is the circulation current value.
After comparing the values in step S401, if the electrical parameter value of the first battery pack is greater than the preset electrical parameter value, it may be determined that the current in the current battery pack is a circulating current, that is, it is determined that there is real power consumption in the current battery pack, and the SOC of the first battery pack may be calculated according to the electrical parameter value collected correspondingly in step S402.
Otherwise, if the electrical parameter value of the first battery pack is smaller than the preset electrical parameter value, it may be determined that the current in the current battery pack is zero drift current, that is, it is determined that there is no real power consumption in the current battery pack, and then the SOC of the first battery pack may be directly calculated according to the preset electrical parameter reference value through step S403.
Optionally, the preset electrical parameter value is 0, which indicates that no real current is consumed in the current battery pack.
Alternatively, when calculating the SOC by using the electrical parameter value or the electrical parameter reference value, the SOC may be calculated by using an ampere-hour integration method, or may be calculated by using other suitable calculation methods, which is not limited only in the embodiment of the present application.
In the embodiment of the present application, according to different comparison results of the electrical parameter value and the preset electrical parameter value, the real current condition (circulation or zero drift current) existing in the first battery pack is determined, so that different calculation modes can be adopted to calculate the first state of charge value, and a more accurate SOC calculation result can be obtained.
After the first state of charge value is calculated, the state of charge of the corresponding battery pack can be determined in step S404, and the accuracy is high because the first state of charge value is calculated according to the actual power consumption condition in the battery pack.
Fig. 5 shows a flow chart of a method for determining a state of charge in yet another example of the present application.
In order to obtain a more accurate SOC, in this embodiment of the present application, as shown in fig. 5, step S404 determines the state of charge of the first battery pack according to the first state of charge value, which may specifically include S501 to S502:
s501, performing difference between the first state of charge value and a preset error value to obtain a second state of charge value;
s502, determining the state of charge corresponding to the second state of charge value as the state of charge of the first battery pack.
Because the battery system is in a state without energy output, other components in the first battery pack may consume power, the first state of charge value can be corrected through the corresponding preset error value, so that the more accurate state of charge of the first battery pack is determined.
Optionally, the preset error value may include power consumption of the sub-battery management unit, and may also include power consumption of components in other battery packs.
Because some components in the battery pack consume electric energy when the charging branch in the battery pack is controlled to be in a passage state within a preset time, a certain error may exist in the calculated SOC. In this embodiment of the present application, the power consumption of the components consuming the energy is used as an error value, the first state of charge value is corrected in step S501, and a second state of charge value is obtained after the correction, and the second state of charge value is determined as the actual state of charge of the first battery pack in step S502, so as to obtain a more accurate state of charge determination result.
The sub-battery management unit may send the calculated second state of charge value to the main battery management unit, and the main battery management unit may calculate the state of charge of the entire battery system according to the second state of charge value of the first battery pack and the second state of charge values of the other batteries.
The state of charge calculation of the battery system is a well-known technology in the art, and will not be described in detail herein.
The sub-battery management unit of the first battery pack may determine the SOC of the first battery pack by using the method of the embodiment of the present application, and the sub-battery management units corresponding to other battery packs in the battery system may determine the SOC of the corresponding battery pack by using the method of the embodiment of the present application. The sub-battery management unit of each battery pack transmits the determined SOC value (the second state of charge value) to the main battery management unit, and the main battery management unit can calculate the SOC of the whole battery system according to the received SOC value of each battery pack.
Fig. 6 shows a schematic structure of a state of charge determining device according to an embodiment of the present application. The device can be applied to a sub-battery management unit, the sub-battery management unit is in communication connection with a main battery management unit, the main battery management unit is used for controlling the energy output state of a battery system, and the battery system at least comprises a first battery pack and a second battery pack which are connected in parallel; and the sub-battery management unit is used for controlling the energy output state of the first battery pack.
As shown in fig. 6, the apparatus may include:
the acquiring module 601 is configured to acquire an electrical parameter value in a first battery pack within a preset duration after receiving a first signal sent by a main battery management unit; wherein the first signal is used to characterize the battery system in a state of no energy output;
the determining module 602 is configured to determine a state of charge of the first battery pack according to a comparison result between the electrical parameter value and a preset electrical parameter threshold.
Alternatively, the battery system according to the embodiment of the present application may be a structure of a battery system having a two-stage architecture as shown in fig. 1, which is not described herein.
After the whole vehicle is powered down, the VCU (Vehicle Control Unit, whole vehicle controller) sends information of the whole vehicle power down to the MBMU, the MBMU switches the battery system into a state without energy output, and transmits first signal communication representing the state to the SBMU corresponding to the first battery pack.
Under the condition that the SBMU receives the first signal, the SBMU acquires the electric parameter value in the first battery pack from the sampling unit in the first battery pack within a preset time period.
Alternatively, the electrical parameter value may be a current value.
The preset electrical parameter threshold is a threshold for distinguishing the current in the battery pack as circulating current or zero drift current.
In the working process of parallel battery packs in the two-stage architecture current system, if a voltage difference exists between the battery packs, a phenomenon that the battery packs with high voltage charge the battery packs with low voltage is formed between the battery packs, and current in the phenomenon is circulation. When the whole vehicle is powered down, the instant pressure difference between the battery packs can cause instant circulation to exist in the battery packs. In the embodiment of the application, the circulation is the real energy consumption when calculating the SOC.
When the input signal of the amplifying circuit is zero (i.e. no alternating current is input), the zero drift is the phenomenon that the voltage of the output end of the circuit deviates from the original fixed value and floats up and down due to the fact that the static working point is changed and amplified and transmitted step by step due to the influence of factors such as ambient temperature change, unstable power supply voltage and the like. In the embodiment of the application, the zero drift current is not consumed as true energy when calculating the SOC.
The zero drift current is smaller than the current value of the circulating current, so in the embodiment of the application, the zero drift current and the circulating current can be distinguished by presetting an electric parameter value threshold value.
After the SBMU acquires the electric parameter value in the first battery pack, the electric parameter value is compared with a preset electric parameter threshold value, and whether the electric parameter value is a circulation value or a zero drift current value is judged, namely whether the first battery pack has real energy consumption is judged, so that the state of charge of the first battery pack can be correspondingly determined according to a comparison result, and the calculation accuracy of the state of charge value is improved.
Since other components may consume power in the first battery pack after the battery system is in the state without energy output, the first state of charge value may be corrected according to the corresponding preset error value, so as to determine a more accurate state of charge of the first battery pack.
Optionally, in order to ensure the safety of the battery pack while accurately calculating the SOC, in this embodiment of the present application, the acquiring module 601 may specifically include:
the control submodule 6011 is used for controlling the first battery pack to be in an energy output state within a preset duration after receiving a first signal sent by the main battery management unit;
the acquiring submodule 6012 is configured to acquire an electrical parameter value in the first battery pack within a preset duration.
And at a high voltage under the vehicle, the MBMU cuts off the external energy output of the battery system and sends a first signal to the SBMU corresponding to the first battery pack. At this time, the whole battery system does not have energy output to the outside, but an instantaneous current may exist in the first battery pack, so after the SBMU corresponding to the first battery pack receives the first signal, the current loop (charging branch) in the first battery pack is controlled to maintain a channel state, and the impact of the instantaneous current on the switch module on the branch caused by the operation of cutting off the charging branch is avoided, thereby affecting the safety of the battery pack.
The preset time period is determined based on the time period during which the circulation current exists in the first battery pack.
The current existing in the first battery pack may be a circulating current or a zero drift current within a preset time period, and may be determined by collecting an electrical parameter value of the first battery pack.
After a preset period of time, the second switch module on the charging branch in the first battery pack can be controlled to switch to an open state, or can be kept closed.
In this embodiment, after the main battery management unit cuts off the energy output of the battery system, the sub-battery management unit controls the first battery pack to be in an energy output state, that is, a current loop is formed in the first battery pack, so that the situation that large loop current impact is formed due to frequent cutting off of an internal current loop to increase a voltage difference between the parallel battery packs can be avoided, and adverse effects on the safety of the battery system are avoided.
In order to accurately determine that the current in the battery pack is a circulating current or a zero drift current, so as to accurately calculate the SOC in the battery pack, the determining module 602 may specifically include:
a comparison module 6021 for comparing the electrical parameter value with a preset electrical parameter value;
a first calculating submodule 6022 for calculating a first state of charge value of the first battery pack according to the electrical parameter value if the electrical parameter value is greater than a preset electrical parameter threshold;
a second calculation submodule 6023 for calculating a first state of charge value of the first battery pack according to a preset electrical parameter reference value if the electrical parameter value is less than a preset electrical parameter threshold value;
a determination submodule 6024 is configured to determine a state of charge of the first battery pack based on the first state of charge value.
The preset electrical parameter value is a reference current value capable of judging whether the current instantaneous current in the battery pack is circulation current or zero drift current, and optionally, in the embodiment of the application, the preset electrical parameter value is 300mA, the electrical parameter value lower than 300mA is the zero drift current value, and the electrical parameter value higher than 300mA is the circulation current value.
If the electric parameter value of the first battery pack is larger than the preset electric parameter value, the current in the current battery pack can be judged to be circulation, namely the current battery pack is judged to have real electric energy consumption, and the SOC of the first battery pack can be calculated according to the electric parameter value which is correspondingly acquired.
Otherwise, if the electrical parameter value of the first battery pack is smaller than the preset electrical parameter value, the current in the current battery pack can be judged to be zero drift current, that is, the current battery pack is judged to have no real electric energy consumption, and the SOC of the first battery pack is directly calculated according to the preset electrical parameter reference value. Wherein, the preset electric parameter value is 0, which indicates that no real current is consumed in the current battery pack.
Alternatively, when calculating the SOC by using the electrical parameter value or the electrical parameter reference value, the SOC may be calculated by using an ampere-hour integration method, or may be calculated by using other suitable calculation methods, which is not limited only in the embodiment of the present application.
In the embodiment of the present application, according to different comparison results of the electrical parameter value and the preset electrical parameter value, the real current condition (circulation or zero drift current) existing in the first battery pack is determined, so that different calculation modes can be adopted to calculate the first state of charge value, and a more accurate SOC calculation result can be obtained.
After the first state of charge value is calculated, the state of charge of the corresponding battery pack can be determined by the determination submodule 6024, and the accuracy is high because the first state of charge value is calculated according to the actual power consumption condition in the battery pack.
In order to obtain a more accurate SOC, optionally, in the embodiment of the present application, the determining submodule 6024 may specifically be used to:
the first state of charge value and the preset error value are subjected to difference to obtain a second state of charge value;
and determining the state of charge corresponding to the second state of charge value as the state of charge of the first battery pack.
Because the battery system is in a state without energy output, other components in the first battery pack may consume power, the first state of charge value can be corrected through the corresponding preset error value, so that the more accurate state of charge of the first battery pack is determined.
Optionally, the preset error value may include power consumption of the sub-battery management unit, and may also include power consumption of components in other battery packs.
Because some components in the battery pack consume electric energy when the charging branch in the battery pack is controlled to be in a passage state within a preset time, a certain error may exist in the calculated SOC. In this embodiment of the present application, the power consumption of the component consuming the energy is used as an error value, and the first state of charge value is corrected, so as to obtain the accurate state of charge of the first battery pack.
The sub-battery management unit of the first battery pack may determine the SOC of the first battery pack by using the method of the embodiment of the present application, and the sub-battery management units corresponding to other battery packs in the battery system may determine the SOC of the corresponding battery pack by using the method of the embodiment of the present application. The sub-battery management unit of each battery pack transmits the determined SOC value (the second state of charge value) to the main battery management unit, and the main battery management unit can calculate the SOC of the whole battery system according to the received SOC value of each battery pack.
Fig. 7 shows a schematic hardware structure of an electronic device in an embodiment of the present application. As shown in fig. 7, an electronic device 700 includes a memory 701 and a processor 702; the memory 702 is used for storing executable program codes;
the processor 701 is configured to read the executable program code stored in the memory 702 to execute the processes of the above embodiment of the method for determining a state of charge, and achieve the same technical effects, and for avoiding repetition, a detailed description is omitted herein.
The embodiment of the application provides a readable storage medium, which includes instructions, when the instructions run on a processor, the processes of the embodiment of the method for determining the state of charge can be implemented, and the same technical effects can be achieved, so that repetition is avoided, and no further description is given here.
Wherein the processor is a processor in the electronic device described in the above embodiment. The readable storage medium includes a computer readable storage medium such as Read-Only Memory (ROM) or random access Memory (Random Access Memory, RAM).
The embodiment of the application further provides a chip, the chip includes a processor and a communication interface, the communication interface is coupled with the processor, the processor is configured to run a program or an instruction, implement each process of the above embodiment of the method for determining a state of charge, and achieve the same technical effect, so that repetition is avoided, and no further description is provided here.
It should be understood that the chips referred to in the embodiments of the present application may also be referred to as system-on-chip chips, chip systems, or system-on-chip chips, etc.
While the present application has been described with reference to a preferred embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the present application. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.
Claims (9)
- A method of determining state of charge is applied to a sub-battery management unit, which is communicatively connected to a main battery management unit,the main battery management unit is used for controlling the energy output state of a battery system, and the battery system at least comprises a first battery pack and a second battery pack which are connected in parallel;the sub battery management unit is used for controlling the energy output state of the first battery pack;the method comprises the following steps:after receiving a first signal sent by the main battery management unit, acquiring an electric parameter value in the first battery pack within a preset duration; wherein the first signal is used to characterize the battery system in a state of no energy output;and determining the charge state of the first battery pack according to a comparison result of the electric parameter value and a preset electric parameter threshold value.
- The method of claim 1, wherein the obtaining the electrical parameter value in the first battery pack for a preset duration after receiving the first signal sent by the main battery management unit comprises:after receiving a first signal sent by the main battery management unit, controlling the first battery pack to be in an energy output state within a preset duration; the preset duration is a duration in which the circulation current is expected to exist in the first battery pack;and acquiring the electric parameter value in the first battery pack within the preset time period.
- The method of claim 1, wherein the determining the state of charge of the first battery pack based on the comparison of the electrical parameter value to a preset electrical parameter threshold comprises:calculating a first state of charge value of the first battery pack according to the electrical parameter value when the electrical parameter value is greater than a preset electrical parameter threshold;and determining the charge state of the first battery pack according to the first charge state value.
- The method of claim 1, wherein the determining the state of charge of the first battery pack based on the comparison of the electrical parameter value to a preset electrical parameter threshold comprises:calculating a first state of charge value of the first battery pack according to a preset electrical parameter reference value under the condition that the electrical parameter value is smaller than a preset electrical parameter threshold value;and determining the charge state of the first battery pack according to the first charge state value.
- The method of claim 3 or 4, wherein the determining the state of charge of the first battery pack from the first state of charge value comprises:the first state of charge value is subjected to difference with a preset error value to obtain a second state of charge value, wherein the preset error value comprises preset power consumption of a sub-battery management unit;and determining the state of charge corresponding to the second state of charge value as the state of charge of the first battery pack.
- A state of charge determining device is applied to a sub-battery management unit which is in communication connection with a main battery management unit,the main battery management unit is used for controlling the energy output state of a battery system, and the battery system at least comprises a first battery pack and a second battery pack which are connected in parallel;the sub battery management unit is used for controlling the energy output state of the first battery pack;the device comprises:the acquisition module is used for acquiring the electric parameter value in the first battery pack within a preset duration after receiving the first signal sent by the main battery management unit; wherein the first signal is used to characterize the battery system in a state of no energy output;and the determining module is used for determining the charge state of the first battery pack according to the comparison result of the electric parameter value and a preset electric parameter threshold value.
- An electronic device, the device comprising a memory and a processor; the memory is used for storing executable program codes;the processor is configured to read executable program code stored in the memory to perform the method of determining a state of charge of any one of claims 1 to 5.
- A readable storage medium comprising instructions which, when executed on a processor, implement the method of determining a state of charge as claimed in any one of claims 1 to 5.
- A battery system comprising a plurality of battery packs connected in parallel, the battery system further comprising a battery management system,the battery management system includes a main battery management unit and a plurality of sub battery management units,the main battery management unit is in communication connection with the sub battery management units and is used for controlling the energy output state of the battery system;the plurality of sub-battery management units are used for controlling the energy output states of the plurality of battery packs in a one-to-one correspondence manner;the sub-battery management unit is further configured to perform the method of determining a state of charge according to any one of claims 1-5.
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| PCT/CN2021/122357 WO2023050377A1 (en) | 2021-09-30 | 2021-09-30 | Method, apparatus and system for determining state of charge |
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| KR20170037260A (en) * | 2015-09-25 | 2017-04-04 | 현대자동차주식회사 | Battery Management System for vehicle and controlling method thereof |
| CN110896156A (en) * | 2018-09-12 | 2020-03-20 | 宁德时代新能源科技股份有限公司 | Energy storage module |
| CN112379282B (en) * | 2020-12-08 | 2022-02-18 | 东风汽车集团有限公司 | Method for improving SOC estimation precision of power battery based on ampere-hour integration method |
| CN112798968A (en) * | 2020-12-24 | 2021-05-14 | 重庆峘能电动车科技有限公司 | Battery parallel connection method, method for estimating SOC of battery parallel connection system and related equipment |
| CN112865264A (en) * | 2021-03-24 | 2021-05-28 | 东莞新能安科技有限公司 | Method for controlling energy storage device, power supply system and power utilization device |
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