CN111323722A - Method and device for determining state of charge of battery - Google Patents
Method and device for determining state of charge of battery Download PDFInfo
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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]
- G01R31/396—Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
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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]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
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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]
- G01R31/389—Measuring internal impedance, internal conductance or related variables
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Abstract
The invention provides a method and a device for determining the state of charge of a battery, aiming at solving the problem of low calculation accuracy caused by simultaneous divergence of capacity and ohmic internal resistance in the existing method for determining the state of charge. The method comprises the following steps: acquiring current, voltage, auxiliary parameters and stored parameters of a battery, wherein the auxiliary parameters comprise open-circuit voltage, polarization internal resistance and polarization capacitance; determining and storing the capacity parameter of the battery according to the current, the auxiliary parameter and the stored parameter; determining and storing the ohmic internal resistance parameters of the battery according to the current, the voltage, the auxiliary parameters and the stored parameters; determining and storing the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter; an updating step: and updating the stored parameters according to the real-time charge state, and returning to execute the acquisition step. According to the method, the capacity and the ohmic internal resistance are respectively determined, so that the capacity and the ohmic internal resistance are prevented from being diffused at the same time, and the estimation precision of the charge state is improved.
Description
Technical Field
The invention relates to the technical field of power battery packs, in particular to a method and a device for determining the state of charge of a battery.
Background
The two parameters of the internal resistance and the capacity of the battery gradually change along with the aging degree of the battery, and if the parameter change is not considered in the estimation of the state of charge of the battery, the estimation precision is obviously deteriorated, so that the performance of a battery management system and the effect of an energy management strategy of the whole vehicle are influenced.
The state of charge (SOC) of the battery represents the remaining capacity of the battery, and is a core parameter of the battery management system. The state of charge of the battery is a calculation basis of parameters such as the power state of the battery (SOP) and the like and a decision basis of the energy management strategy of the whole vehicle, so the estimation precision of the SOC directly influences the performance of the battery and the vehicle.
The current SOC determination method mainly adopts ampere-hour integration combined with an open-circuit voltage correction method or a Kalman filtering method. Both methods require battery parameters, which greatly affect the SOC estimation accuracy. As the battery ages, the capacity in the battery parameters gradually decreases and the internal resistance gradually increases. Therefore, if the SOC estimation does not consider parameter changes caused by battery aging, the estimation accuracy is affected, and the battery performance and the whole vehicle performance are further affected.
The SOC determination method of the current mainstream scheme has the following problems: the estimated values of the capacity and the internal resistance are diffused at the same time, and the SOC estimation is inaccurate; the capacity estimation is highly related to the SOC estimation precision, and the SOC estimation depends on the capacity estimation to influence the SOC estimation precision; the internal resistance estimated value fluctuates largely.
Therefore, it is necessary to provide a solution to the problem of low estimation accuracy caused by the simultaneous divergence of the capacity and internal resistance estimation values in the existing state of charge determination method.
Disclosure of Invention
In order to solve the problem of low calculation accuracy caused by simultaneous divergence of capacity and ohmic internal resistance in the existing determination method of the state of charge, the invention provides a method and a device for determining the state of charge of a battery.
The invention provides a method for determining the state of charge of a battery, which comprises the following steps:
an acquisition step: acquiring current, voltage, auxiliary parameters and stored parameters of a battery, wherein the auxiliary parameters comprise open-circuit voltage, polarization internal resistance and polarization capacitance;
capacity parameter determination: determining and saving a capacity parameter of the battery according to the current, the auxiliary parameter and the saved parameter;
determining ohmic internal resistance parameters: determining and storing the ohm internal resistance parameters of the battery according to the current, the voltage, the auxiliary parameters and the stored parameters;
a state of charge determining step: determining and storing the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
an updating step: and updating the stored parameters according to the real-time state of charge, and returning to execute the acquiring step.
In a further development of the method of determining the state of charge of a battery according to the invention, the saved parameters comprise a saved capacity;
a judging step is further included after the acquiring step and before the capacity parameter determining step, the working state information of the battery is acquired in real time, and the working state of the battery is judged according to the working state information;
the capacity parameter determining step includes: if the working state is a charging state, determining the real-time capacity of the battery according to the current, the auxiliary parameters and the stored state of charge, and taking the real-time capacity as the capacity parameter;
if the working state is a discharging state, taking the saved capacity as the capacity parameter;
in the updating step, before the obtaining step is executed, the stored parameters are updated according to the real-time capacity.
In a further improvement of the method of determining the state of charge of a battery of the present invention, the saved parameters further comprise a saved ohmic internal resistance and a saved polarization voltage;
the ohmic internal resistance parameter determining step comprises the following steps: if the working state is a discharging state, determining the real-time ohmic internal resistance of the battery according to the current, the voltage, the auxiliary parameter, the stored state of charge, the stored polarization voltage and the stored capacity, and taking the real-time ohmic internal resistance as the ohmic internal resistance parameter;
if the working state is a charging state, taking the stored ohmic internal resistance as the ohmic internal resistance parameter;
in the charge state determining step, the real-time polarization voltage of the battery is determined and stored according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
in the updating step, before the obtaining step is executed, the stored parameters are updated according to the real-time ohmic internal resistance and the real-time polarization voltage.
In a further improvement of the method of determining battery state of charge of the present invention, the capacity parameter determining step further comprises, after determining the real-time capacity, performing a delay process on the real-time capacity;
the ohmic internal resistance parameter determining step further comprises the step of carrying out time delay processing on the real-time ohmic internal resistance after the real-time ohmic internal resistance is determined.
A further improvement of the method of determining the state of charge of a battery according to the invention is that, in the capacity parameter determining step, the real-time capacity is determined based on an extended kalman filter method or a least square method;
in the step of determining the ohmic internal resistance parameters, the real-time ohmic internal resistance is determined based on a Kalman filtering method or a least square method;
in the charge state determining step, the real-time charge state is determined based on an extended Kalman filtering method or a least square method.
A further improvement of the method of determining the state of charge of a battery of the present invention is that the capacity parameter determining step further comprises, after determining the real-time capacity, smoothing the real-time capacity based on a kalman filtering method;
the ohmic internal resistance parameter determining step further comprises the step of smoothing the real-time ohmic internal resistance based on a Kalman filtering method after the real-time ohmic internal resistance is determined;
and the step of determining the state of charge further comprises the step of smoothing the real-time state of charge based on a Kalman filtering method after the real-time state of charge is determined.
In addition, the invention also provides a device for determining the state of charge of the battery, wherein the device is used for executing the method and comprises an acquisition module, a capacity parameter determination module, an ohm internal resistance parameter determination module, a state of charge determination module and an updating module;
the acquisition module is used for acquiring current, voltage, auxiliary parameters and saved parameters of the battery, wherein the auxiliary parameters comprise open-circuit voltage, polarization internal resistance and polarization capacitance;
the capacity parameter determining module is used for determining and saving the capacity parameter of the battery according to the current, the auxiliary parameter and the saved parameter;
the ohmic internal resistance parameter determining module is used for determining and storing the ohmic internal resistance parameter of the battery according to the current, the voltage, the auxiliary parameter and the stored parameter;
the charge state determining module comprises a charge state determining unit and a triggering unit, and the charge state determining unit is used for determining and storing the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
the updating module is used for updating the stored parameters according to the real-time charge state and triggering the acquiring module after updating.
In a further development of the apparatus for determining the state of charge of a battery according to the invention, the saved parameters comprise a saved capacity;
the device also comprises a judging module, wherein the judging module is used for acquiring the working state information of the battery in real time and judging the working state of the battery according to the working state information;
the capacity parameter determination module comprises a first capacity determination unit and a second capacity determination unit;
the first capacity determining unit is used for determining the real-time capacity of the battery according to the current, the auxiliary parameters and the stored charge state when the working state is a charging state, and taking the real-time capacity as the capacity parameter;
the second capacity determining unit is configured to use the stored capacity as the capacity parameter when the operating state is a discharge state;
the updating module is further configured to update the saved parameters according to the real-time capacity before triggering the obtaining module.
In a further improvement of the apparatus for determining the state of charge of a battery of the present invention, the stored parameters further include a stored ohmic internal resistance and a stored polarization voltage;
the ohmic internal resistance parameter determining module comprises a first ohmic internal resistance determining unit and a second ohmic internal resistance determining unit;
the first ohmic internal resistance determining unit is used for taking the stored ohmic internal resistance as the ohmic internal resistance parameter when the working state is a charging state;
the second ohmic internal resistance determining unit is configured to determine a real-time ohmic internal resistance of the battery according to the current, the voltage, the auxiliary parameter, the stored state of charge, the stored polarization voltage, and the stored capacity when the operating state is a discharging state, and use the real-time ohmic internal resistance as the ohmic internal resistance parameter;
the state of charge determining module further comprises a polarization voltage determining unit, and the polarization voltage determining unit is used for determining and storing the real-time polarization voltage of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
the updating module is further configured to update the saved parameters according to the real-time ohmic internal resistance and the real-time polarization voltage before triggering the obtaining module.
In a further improvement of the apparatus for determining a state of charge of a battery according to the present invention, the capacity parameter determining module further comprises a capacity delaying unit, wherein the capacity delaying unit is configured to perform a delay process on the real-time capacity determined by the first capacity determining unit;
the ohmic internal resistance parameter determining module further comprises an ohmic internal resistance delay unit, and the ohmic internal resistance delay unit is used for carrying out delay processing on the real-time ohmic internal resistance determined by the second ohmic internal resistance determining unit.
By adopting the technical scheme, the method and the device for determining the state of charge of the battery have the following beneficial effects:
(1) the capacity and the ohmic internal resistance are separated (isolated), the capacity and the ohmic internal resistance are isolated, the condition that the capacity and the ohmic internal resistance are diffused simultaneously is avoided, and the charge state estimation precision is improved;
(2) the capacity is determined in real time only in the charging state of the battery, so that the calculation accuracy of the capacity is higher;
(3) and smoothing the real-time capacity, the real-time ohmic internal resistance and the real-time charge state, and removing noise to ensure that the result is more accurate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for determining a state of charge of a battery according to embodiment 1 of the present invention.
Fig. 2 is a block diagram of an apparatus for determining a state of charge of a battery according to embodiment 2 of the present invention.
Fig. 3 is a schematic diagram of a signal transmission relationship of a device for determining a state of charge of a battery according to embodiment 2 of the present invention in a battery charging state.
Fig. 4 is a schematic diagram of a signal transmission relationship of an apparatus for determining a state of charge of a battery according to embodiment 2 of the present invention in a battery discharging state.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In order to solve the problem of low calculation accuracy caused by simultaneous divergence of capacity and ohmic internal resistance in the existing determination method of the state of charge, the invention provides a method and a device for determining the state of charge of a battery.
Example 1:
referring to fig. 1, a method for determining a state of charge of a battery according to embodiment 1 of the present invention includes:
acquisition step S101: acquiring current, voltage, auxiliary parameters and stored parameters of a battery, wherein the auxiliary parameters comprise open-circuit voltage, polarization internal resistance and polarization capacitance;
capacity parameter determination step S102: determining and storing the capacity parameter of the battery according to the current, the auxiliary parameter and the stored parameter;
ohmic internal resistance parameter determination step S103: determining and storing the ohmic internal resistance parameters of the battery according to the current, the voltage, the auxiliary parameters and the stored parameters;
state of charge determination step S104: determining and storing the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
update step S105: and updating the stored parameters according to the real-time state of charge, and returning to execute the acquisition step S101.
In the prior art, the capacity and the ohmic internal resistance are determined simultaneously in the same step, so that the capacity and the ohmic internal resistance are diffused simultaneously, the diffusion time of the capacity and the diffusion time of the ohmic internal resistance cannot be distinguished independently, and the estimation accuracy of the state of charge is low.
In this embodiment 1, the capacity parameter and the ohmic internal resistance parameter are respectively determined through the capacity parameter determining step S102 and the ohmic internal resistance parameter determining step S103, so that the capacity and the ohmic internal resistance are prevented from being simultaneously diffused, and the estimation accuracy of the state of charge is improved.
In the present embodiment 1, one cycle includes an acquisition step S101, a capacity parameter determination step S102, an ohmic internal resistance parameter determination step S103, a state of charge determination step S104, and an update step S105. In the obtaining step S101 of this embodiment 1, the current and voltage of the battery are obtained in real time by measurement; the saved parameters include the state of charge saved in the previous cycle; inquiring the calibrated open-circuit voltage according to the real-time charge state stored in the previous period and a preset corresponding relation; and acquiring the temperature of the battery in real time through measurement, and inquiring the calibrated polarization internal resistance and polarization capacitance according to the temperature, the charge state stored in the previous period and a preset corresponding relation. The first time the method of determining the state of charge of the battery is performed, the auxiliary parameters and the stored parameters are both initial values.
Further, the saved parameters include saved capacity;
after the obtaining step S101 and before the capacity parameter determining step S102, a determining step is further included, in which the working state information of the battery is obtained in real time, and the working state of the battery is determined according to the working state information;
the capacity parameter determination step S102 includes: if the working state is the charging state, determining the real-time capacity of the battery according to the current, the auxiliary parameters and the stored charge state, and taking the real-time capacity as a capacity parameter;
if the working state is the discharging state, the stored capacity is used as a capacity parameter;
in the update step S105, the saved parameters are also updated according to the real-time capacity before returning to the acquisition step S101.
Further, the stored parameters further include a stored ohmic internal resistance and a stored polarization voltage;
the ohmic internal resistance parameter determining step S103 includes: if the working state is a discharging state, determining the real-time ohmic internal resistance of the battery according to the current, the voltage, the auxiliary parameters, the stored charge state, the stored polarization voltage and the stored capacity, and taking the real-time ohmic internal resistance as an ohmic internal resistance parameter;
if the working state is the charging state, the stored ohmic internal resistance is used as an ohmic internal resistance parameter;
in the charge state determining step S104, the real-time polarization voltage of the battery is determined and stored according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
in the updating step S105, before returning to the obtaining step S101, the stored parameters are also updated according to the real-time ohmic internal resistance and the real-time polarization voltage.
In this embodiment 1, the real-time capacity or the real-time ohmic internal resistance is selectively determined according to the charging or discharging state of the battery. The real-time capacity is determined only when the battery is in a charging state, because the battery current is stable in the charging process, and the estimation of the state of charge is relatively accurate, so that the capacity estimation precision is higher and more accurate; the real-time ohmic internal resistance is determined only in the discharging state of the battery, because the current fluctuation is obvious in the discharging process, the voltage change caused by the ohmic internal resistance is also more obvious, and the internal resistance estimation precision is higher.
In this embodiment 1, the real-time capacity or the real-time ohmic internal resistance is selectively determined according to the charging or discharging state of the battery, so that the estimation values of the capacity and the ohmic internal resistance are more stable and accurate, and the estimation accuracy of the state of charge is further improved.
If the battery is in a charging state, determining the real-time capacity, and taking the real-time capacity as a capacity parameter; the real-time determination of the ohmic internal resistance is not carried out, but the stored ohmic internal resistance (the real-time ohmic internal resistance which is finally determined and stored in the discharge state of the battery) is used as the ohmic internal resistance parameter; and executing a charge state determining step S104, determining the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter, and storing. After the real-time state of charge is saved, the saved state of charge may be used for determining the real-time capacity in the next cycle of the state of charge. In the charging state, in the ohmic internal resistance parameter determining step S103, the real-time ohmic internal resistance stored in the step S103 is determined by using the ohmic internal resistance parameter in the discharging state; when the ohmic internal resistance parameter determining step S103 is not performed, the initial value of the ohmic internal resistance is used as the ohmic internal resistance parameter.
If the battery is in a discharging state, determining real-time ohmic internal resistance, and taking the real-time ohmic internal resistance as an ohmic internal resistance parameter; instead of real-time determination of capacity, the saved capacity (the real-time capacity that is finally determined and saved at the time of battery charge state) is taken as a capacity parameter; and executing a charge state determining step S104, determining the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter, and storing. After the real-time charge state is stored, the stored charge state can be used as the stored charge state in the next period of the discharge state, and is used for determining the real-time ohmic internal resistance in the next period of the discharge state. After the real-time polarization voltage is stored, the stored polarization voltage can be used as the stored polarization voltage in the next period of the discharge state for determining the real-time capacity in the next period of the discharge state.
In the discharge state, in the capacity parameter determination step S102, the real-time capacity saved in the charge-state capacity parameter determination step S102 is used; when the capacity parameter determination step S102 is not performed, the initial value of the capacity is used as the capacity parameter.
Furthermore, the capacity parameter determining step S102 further includes performing a delay process on the real-time capacity after determining the real-time capacity; the step S103 of determining the ohmic internal resistance parameter further includes performing a delay process on the real-time ohmic internal resistance after determining the real-time ohmic internal resistance. In this embodiment 1, the real-time capacity and the real-time ohmic internal resistance can be used as the stored parameters for determining the parameters of the next cycle through the delay processing.
Further, in the capacity parameter determining step S102, a real-time capacity is determined based on an extended kalman filter method or a least square method, and the algorithm assumes that the capacity does not change in a short time; in the ohmic internal resistance parameter determining step S103, real-time ohmic internal resistance is determined based on a Kalman filtering method or a least square method, and the algorithm assumes that the ohmic internal resistance does not change in a short time; in the state of charge determining step S104, a real-time state of charge is determined based on an extended kalman filter method or a least square method.
Furthermore, the capacity parameter determining step S102 further includes, after determining the real-time capacity, performing a smoothing process on the real-time capacity based on a kalman filtering method; the ohmic internal resistance parameter determining step S103 further comprises the step of smoothing the real-time ohmic internal resistance based on a Kalman filtering method after the real-time ohmic internal resistance is determined; the state of charge determining step S104 further includes, after determining the real-time state of charge, smoothing the real-time state of charge based on a kalman filtering method. In this embodiment 1, signal noise can be removed by smoothing processing.
Example 2:
as shown in fig. 2 to 4, embodiment 2 provides an apparatus 100 for determining a state of charge of a battery, configured to perform the above method, including an obtaining module 10, a capacity parameter determining module 20, an ohmic internal resistance parameter determining module 30, a state of charge determining module 40, and an updating module 50;
the acquisition module 10 is configured to acquire current, voltage, auxiliary parameters and saved parameters of a battery, where the auxiliary parameters include open-circuit voltage, polarization internal resistance and polarization capacitance;
the capacity parameter determining module 20 is configured to determine and store a capacity parameter of the battery according to the current, the auxiliary parameter, and the stored parameter;
the ohmic internal resistance parameter determining module 30 is used for determining and storing the ohmic internal resistance parameter of the battery according to the current, the voltage, the auxiliary parameter and the stored parameter;
the state of charge determining module 40 comprises a state of charge determining unit and a triggering unit, wherein the state of charge determining unit is used for determining and storing the real-time state of charge of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
the update module 50 is configured to update the saved parameters according to the real-time state of charge, and trigger the acquisition module 10 after the update.
Further, the saved parameters include saved capacity;
the device also comprises a judging module, wherein the judging module is used for acquiring the working state information of the battery in real time and judging the working state of the battery according to the working state information;
the capacity parameter determination module 20 includes a first capacity determination unit 21 and a second capacity determination unit 22;
the first capacity determining unit 21 is configured to determine a real-time capacity of the battery according to the current, the auxiliary parameter, and the stored state of charge when the operating state is the charging state, and use the real-time capacity as a capacity parameter;
the second capacity determining unit 22 is configured to use the reserved capacity as a capacity parameter when the operating state is the discharging state;
the update module 50 is also configured to update the saved parameters according to the real-time capacity before triggering the acquisition module 10.
Further, the stored parameters further include a stored ohmic internal resistance and a stored polarization voltage;
the ohmic internal resistance parameter determining module 30 includes a first ohmic internal resistance determining unit 31 and a second ohmic internal resistance determining unit 32;
the first ohmic internal resistance determining unit 31 is configured to, when the working state is the charging state, use the stored ohmic internal resistance as an ohmic internal resistance parameter;
the second ohmic internal resistance determining unit 32 is configured to determine a real-time ohmic internal resistance of the battery according to the current, the voltage, the auxiliary parameter, the stored state of charge, the stored polarization voltage, and the stored capacity when the working state is the discharging state, and use the real-time ohmic internal resistance as an ohmic internal resistance parameter;
the state of charge determining module 40 further comprises a polarization voltage determining unit, wherein the polarization voltage determining unit is used for determining and storing the real-time polarization voltage of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
the updating module 50 is further configured to update the saved parameters according to the real-time ohmic internal resistance and the real-time polarization voltage before triggering the obtaining module 10.
Furthermore, the capacity parameter determining module 20 further includes a capacity delaying unit 23, where the capacity delaying unit 23 is configured to perform a delay processing on the real-time capacity determined by the first capacity determining unit 21; the ohmic internal resistance parameter determining module 30 further includes an ohmic internal resistance delay unit 33, and the ohmic internal resistance delay unit 33 is configured to perform delay processing on the real-time ohmic internal resistance determined by the second ohmic internal resistance determining unit 32.
The invention provides a method and a device for determining the state of charge of a battery, which are applied to state of charge estimation, can improve the estimation accuracy of the state of charge within the whole service life range, and can determine the capacity and the internal resistance for calculating the aging state of the battery.
In the present invention, the state of charge determination module 40 estimates the state of charge and the polarization voltage based on kalman filtering. When the battery is in a charging state, estimating real-time capacity as a capacity parameter in each period, and using the ohmic internal resistance calculated for the last time as an ohmic internal resistance parameter in each period, thereby determining the charging state according to the capacity parameter and the ohmic internal resistance parameter. And when the battery is in a discharging state, the capacity calculated for the last time is used as a capacity parameter in each period, and the real-time ohmic internal resistance is estimated as an ohmic internal resistance parameter in each period.
In the invention, an extended Kalman filtering algorithm is adopted to determine the state of charge, a Thevenin model is selected as a battery model, calibration values are used for open-circuit voltage, polarization internal resistance and polarization capacitance, a current voltage measurement value, an internal resistance estimation value and a capacity estimation value are input when the state of charge is determined, and the state of charge and the polarization voltage are output.
In the invention, the capacity and the ohmic internal resistance are respectively estimated in two steps or two modules, so that the estimation of the capacity and the ohmic internal resistance is isolated, and the condition that the capacity and the ohmic internal resistance are diffused simultaneously can not occur; the capacity is determined in real time only in the charging state of the battery, because the current of the battery is stable in the charging process, and the SOC estimation is relatively accurate, so the calculation precision of the capacity is higher; the internal resistance estimation is only carried out in the battery discharge state; the invention can also carry out smoothing treatment on the real-time capacity, the real-time ohmic internal resistance and the real-time charge state, remove noise and ensure that the result is more accurate.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method of determining a state of charge of a battery, comprising:
an acquisition step: acquiring current, voltage, auxiliary parameters and stored parameters of a battery, wherein the auxiliary parameters comprise open-circuit voltage, polarization internal resistance and polarization capacitance;
capacity parameter determination: determining and saving a capacity parameter of the battery according to the current, the auxiliary parameter and the saved parameter;
determining ohmic internal resistance parameters: determining and storing the ohm internal resistance parameters of the battery according to the current, the voltage, the auxiliary parameters and the stored parameters;
a state of charge determining step: determining and storing the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
an updating step: and updating the stored parameters according to the real-time state of charge, and returning to execute the acquiring step.
2. The method of determining battery state of charge of claim 1, in which the saved parameters comprise saved capacity;
a judging step is further included after the acquiring step and before the capacity parameter determining step, the working state information of the battery is acquired in real time, and the working state of the battery is judged according to the working state information;
the capacity parameter determining step includes: if the working state is a charging state, determining the real-time capacity of the battery according to the current, the auxiliary parameters and the stored state of charge, and taking the real-time capacity as the capacity parameter;
if the working state is a discharging state, taking the saved capacity as the capacity parameter;
in the updating step, before the obtaining step is executed, the stored parameters are updated according to the real-time capacity.
3. The method of determining battery state of charge of claim 2, wherein said saved parameters further comprise a saved ohmic internal resistance and a saved polarization voltage;
the ohmic internal resistance parameter determining step comprises the following steps: if the working state is a discharging state, determining the real-time ohmic internal resistance of the battery according to the current, the voltage, the auxiliary parameter, the stored state of charge, the stored polarization voltage and the stored capacity, and taking the real-time ohmic internal resistance as the ohmic internal resistance parameter;
if the working state is a charging state, taking the stored ohmic internal resistance as the ohmic internal resistance parameter;
in the charge state determining step, the real-time polarization voltage of the battery is determined and stored according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
in the updating step, before the obtaining step is executed, the stored parameters are updated according to the real-time ohmic internal resistance and the real-time polarization voltage.
4. The method of determining battery state of charge of claim 3, wherein said capacity parameter determining step further comprises, after determining said real-time capacity, performing a time delay on said real-time capacity;
the ohmic internal resistance parameter determining step further comprises the step of carrying out time delay processing on the real-time ohmic internal resistance after the real-time ohmic internal resistance is determined.
5. The method of determining the state of charge of a battery according to claim 3, wherein in the capacity parameter determining step, the real-time capacity is determined based on an extended Kalman filter method or a least square method;
in the step of determining the ohmic internal resistance parameters, the real-time ohmic internal resistance is determined based on a Kalman filtering method or a least square method;
in the charge state determining step, the real-time charge state is determined based on an extended Kalman filtering method or a least square method.
6. The method of determining battery state of charge of claim 3, wherein said capacity parameter determining step further comprises, after determining said real-time capacity, smoothing said real-time capacity based on a Kalman filtering method;
the ohmic internal resistance parameter determining step further comprises the step of smoothing the real-time ohmic internal resistance based on a Kalman filtering method after the real-time ohmic internal resistance is determined;
and the step of determining the state of charge further comprises the step of smoothing the real-time state of charge based on a Kalman filtering method after the real-time state of charge is determined.
7. An apparatus for determining a state of charge of a battery, the apparatus being configured to perform the method of any one of claims 1-6, comprising an acquisition module, a capacity parameter determination module, an ohmic internal resistance parameter determination module, a state of charge determination module, and an update module;
the acquisition module is used for acquiring current, voltage, auxiliary parameters and saved parameters of the battery, wherein the auxiliary parameters comprise open-circuit voltage, polarization internal resistance and polarization capacitance;
the capacity parameter determining module is used for determining and saving the capacity parameter of the battery according to the current, the auxiliary parameter and the saved parameter;
the ohmic internal resistance parameter determining module is used for determining and storing the ohmic internal resistance parameter of the battery according to the current, the voltage, the auxiliary parameter and the stored parameter;
the charge state determining module comprises a charge state determining unit and a triggering unit, and the charge state determining unit is used for determining and storing the real-time charge state of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
the updating module is used for updating the stored parameters according to the real-time charge state and triggering the acquiring module after updating.
8. The apparatus for determining battery state of charge of claim 7, wherein said saved parameters include saved capacity;
the device also comprises a judging module, wherein the judging module is used for acquiring the working state information of the battery in real time and judging the working state of the battery according to the working state information;
the capacity parameter determination module comprises a first capacity determination unit and a second capacity determination unit;
the first capacity determining unit is used for determining the real-time capacity of the battery according to the current, the auxiliary parameters and the stored charge state when the working state is a charging state, and taking the real-time capacity as the capacity parameter;
the second capacity determining unit is configured to use the stored capacity as the capacity parameter when the operating state is a discharge state;
the updating module is further configured to update the saved parameters according to the real-time capacity before triggering the obtaining module.
9. The apparatus for determining battery state of charge of claim 8, wherein said saved parameters further comprise a saved ohmic internal resistance and a saved polarization voltage;
the ohmic internal resistance parameter determining module comprises a first ohmic internal resistance determining unit and a second ohmic internal resistance determining unit;
the first ohmic internal resistance determining unit is used for taking the stored ohmic internal resistance as the ohmic internal resistance parameter when the working state is a charging state;
the second ohmic internal resistance determining unit is configured to determine a real-time ohmic internal resistance of the battery according to the current, the voltage, the auxiliary parameter, the stored state of charge, the stored polarization voltage, and the stored capacity when the operating state is a discharging state, and use the real-time ohmic internal resistance as the ohmic internal resistance parameter;
the state of charge determining module further comprises a polarization voltage determining unit, and the polarization voltage determining unit is used for determining and storing the real-time polarization voltage of the battery according to the capacity parameter, the ohmic internal resistance parameter and the auxiliary parameter;
the updating module is further configured to update the saved parameters according to the real-time ohmic internal resistance and the real-time polarization voltage before triggering the obtaining module.
10. The apparatus for determining battery state of charge of claim 9, wherein said capacity parameter determination module further comprises a capacity delay unit for delaying said real-time capacity determined by said first capacity determination unit;
the ohmic internal resistance parameter determining module further comprises an ohmic internal resistance delay unit, and the ohmic internal resistance delay unit is used for carrying out delay processing on the real-time ohmic internal resistance determined by the second ohmic internal resistance determining unit.
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