CN114552039A - Control method for battery constant-charge self-maintenance and constant-charge self-maintenance battery - Google Patents
Control method for battery constant-charge self-maintenance and constant-charge self-maintenance battery Download PDFInfo
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Abstract
The invention relates to a control method for constant-power self-maintenance of a battery and the battery with constant-power self-maintenance. The invention discloses a control method for constant-power-on self-maintenance of a battery, which comprises the following steps of: s10: after the electric quantity of the battery at least reaches the target electric quantity and has no discharge to the outside for a period of time, charging the battery to the target electric quantity, and calculating the current self-consumption rate according to the charging quantity; s20: under the condition that the battery does not discharge outwards, calculating the actual residual electric quantity of the battery in real time according to the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply; or S30: and under the condition that the battery is discharged outwards, calculating the actual residual electric quantity of the battery in real time by an ampere-hour metering method and the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply. The control method can accurately estimate the actual residual capacity of the battery and realize the functions of regular charging maintenance and automatic maintenance.
Description
Technical Field
The invention relates to the technical field of mobile energy storage batteries, in particular to a control method for battery constant-power self-maintenance and a battery with constant-power self-maintenance.
Background
With the development of electric vehicles, Battery Management Systems (BMS) have been widely used. The battery state of charge (SOC) is the ratio of the current remaining capacity of the battery to the actual available capacity of the battery, and is used as a main parameter of the BMS, so that the power performance of the battery system can be fully exerted, the safety of the battery in use is improved, and the battery is prevented from being overcharged and overdischarged, so that the service life of the battery is prolonged, the battery life is guaranteed, and the accurate estimation is the premise that the main functions of the BMS are realized.
In the prior art, the remaining capacity estimation methods include the following methods: an ampere-hour measuring method relying on current integration, an open-circuit voltage method and an electromotive force method by measuring terminal voltage, a neural network method based on multiple sample raw data and a neural network model, a Kalman filtering method based on a battery state space model and a recursion formula, and the like. Compared with other residual electricity quantity estimation methods, the ampere-hour metering method is simple in principle, stable in work, easy to implement, low in equipment cost, high in reliability and economy and widely applied to actual engineering. However, the accuracy of the traditional ampere-hour integration method depends on the estimation accuracy of the initial residual capacity, and along with the increase of the service time of the battery, an accumulated integration error also exists in the current time integration process, the whole estimation accuracy of the residual capacity gradually decreases along with the time, and the problems of gradual accumulation of the estimation error of the residual capacity, continuous decrease of the accuracy and the like occur. And wrong residual capacity estimation result can lead to BMS to overcharge and overdischarge the battery, influences battery energy storage system's safe operation, shortens the life of battery electricity core greatly, can cause the explosion that generates heat when serious.
On the other hand, after the mobile energy storage battery is fully charged, the charging system can be automatically disconnected to complete charging, but both the battery pack module and the BMS module in the battery have static loss, the battery can automatically power down after long standing time, the actual residual electric quantity of the battery is continuously reduced, even an over-discharge phenomenon is generated, and irreversible serious loss is caused to the battery. The ampere-hour metering method does not consider the influence of the self-power consumption of the battery when estimating the residual electric quantity, and the battery can always display the residual electric quantity in the final use state, namely when the battery is fully charged and no external load exists, the residual electric quantity can always be displayed as 100 percent. At the moment, even if the battery is connected with an external power supply, the battery cannot be charged, the mobile energy storage battery is in an insufficient or no-electricity state for a long time, and cannot provide enough electric energy or even cannot be used in emergency or outdoor application, so that the due energy storage function and the emergency function in an emergency state cannot be realized. Therefore, the current mobile energy storage batteries need to be charged and maintained regularly, namely, the batteries are charged after being placed for a long time.
Disclosure of Invention
Based on this, the invention aims to provide a control method for battery constant-power-on self-maintenance, which combines an ampere-hour metering method and a self-power consumption rate, can accurately estimate the actual residual capacity of a battery, and realizes the functions of periodic charging maintenance and automatic maintenance, thereby improving the application reliability and the service life of an energy storage battery, and has the advantages of simple principle, easy realization and high accuracy.
The invention is realized by the following technical scheme:
a method for controlling the constant-power self-maintenance of a battery comprises the following steps:
s10: after the electric quantity of the battery at least reaches the target electric quantity and has no discharge to the outside for a period of time, charging the battery to the target electric quantity, and calculating the current self-consumption rate according to the charging quantity;
s20: under the condition that the battery does not discharge outwards, calculating the actual residual electric quantity of the battery in real time according to the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply; or S30: and under the condition that the battery is discharged outwards, calculating the actual residual electric quantity of the battery in real time by an ampere-hour metering method and the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply.
According to the control method for the constant-power-on self-maintenance of the battery, the actual residual capacity of the battery is accurately estimated in real time through the self-power consumption rate on the basis of an ampere-hour metering method, the function of automatic power supplement at regular intervals is realized, and the limitation that the battery is overcharged and overdischarged and cannot exert an emergency function due to the fact that the residual capacity is estimated incorrectly is avoided, so that the application reliability and the service life of the energy storage battery are improved, and the control method has the advantages of being simple in algorithm, economical, practical and strong in reliability.
Further, the method also comprises the following steps:
fully charging the battery after the battery is completely discharged, and recording an OCV-SOC curve when the battery is charged; setting a target electric quantity, and reading a target voltage corresponding to the target electric quantity on the OCV-SOC curve; the battery is not discharged to the outside for a certain period of time.
Further, step S20 is specifically:
under the condition that the battery does not discharge outwards, calculating the actual residual electric quantity of the battery in real time according to the current self-power consumption rate; recording the time length of electricity to be supplemented; and when the time length of the electricity to be supplemented is more than or equal to the preset electricity supplementing time limit and the battery is connected with the external power supply, charging the battery to the target electric quantity.
Further, the calculation formula of the current power consumption rate is as follows:
wherein a represents the current power consumption rate, Q represents the charge amount, T0Indicating a preset power supply time limit.
Further, the calculation formula of the actual remaining capacity is: SOC ═ X0-a×t (4)
In the formula, SOC represents the actual remaining capacity of the battery at time t, and X0T represents the target electric quantity, and the value range of T is more than or equal to 0 and less than or equal to T0。
Further, step S30 is specifically:
under the state that the battery is discharged outwards, calculating the residual electric quantity of the battery after the battery is discharged outwards according to the ampere-hour metering method; correcting the residual electric quantity in real time according to the current power consumption rate to obtain the actual residual electric quantity; and when the battery is connected with an external power supply, charging the battery to the target electric quantity.
Further, when the charging voltage of the battery is equal to the target voltage, the battery is charged to the target electric quantity;
alternatively, the first and second electrodes may be,
calculating the amount of charge to be compensated of the battery according to the actual residual electric quantity of the battery; when the charging quantity of the battery is equal to the to-be-compensated charging quantity, the battery is charged to the target electric quantity.
Further, the method also comprises the following steps:
and when the actual residual electric quantity of the battery is reduced to be lower than the early warning electric quantity and is not connected with the external power supply, sending an early warning signal.
Based on the control method, the invention also provides a normally-charged self-maintenance battery, which comprises a battery unit and a BMS unit, wherein the battery unit comprises at least 1 battery pack capable of performing multiple charging and discharging cycles, and the BMS unit comprises a control module, a recording module, a detection module, a current self-power consumption rate calculation module, an actual residual power first calculation module, a time calculation module, an actual residual power first judgment module and an actual residual power second calculation module;
the control module enables the battery to be fully charged under a preset charging rate after the battery is completely discharged; the recording module records an OCV-SOC curve when the battery is charged in the process of fully discharging and fully charging the battery; the recording module also sets a preset power supplementing period and a target electric quantity, and reads a target voltage in the OCV-SOC curve; the control module enables the battery to be charged to the target electric quantity after the battery is placed for a period of time in a state that the battery is not discharged outwards; the recording module is also used for recording the charging amount in the battery charging process; the current power consumption rate calculation module calculates the current power consumption rate of the battery according to the charging amount; the detection module judges whether the battery is discharged outwards;
the actual residual electric quantity first calculation module calculates the actual residual electric quantity of the battery in real time according to the current self-power consumption rate when the battery does not discharge outwards; when the battery does not discharge outwards, the time calculation module records the power supplementing duration and judges whether the power supplementing duration is greater than or equal to the preset power supplementing time limit; the detection module also judges whether the battery is connected with an external power supply; the control module also enables the battery to be automatically charged when the power supplementing duration is greater than or equal to the preset power supplementing duration and the battery is connected with an external power supply; the actual residual electric quantity first judging module judges whether the battery is charged to the target electric quantity; the control module also enables the battery to finish automatic charging after the battery is charged to the target electric quantity; the detection module also judges whether the battery is discharged outwards before automatic charging;
and the actual residual electric quantity second calculation module calculates the actual residual voltage of the battery in real time according to an ampere-hour metering method and the current self-power consumption rate when the battery is discharged outwards.
Further, the battery also comprises an early warning unit;
the BMS unit further comprises an actual residual electric quantity second judgment module and a complete discharge judgment module;
the actual residual electric quantity second judgment module judges whether the actual residual electric quantity of the battery is reduced below the early warning electric quantity when the battery is not connected with an external power supply;
the complete discharge judgment module judges whether the battery is completely discharged;
and the early warning unit sends an early warning signal when the actual residual electric quantity of the battery is reduced to be lower than the early warning electric quantity.
Compared with the prior art, the control method for the normally charged self-maintenance of the battery and the normally charged self-maintenance battery provided by the invention have the advantages that the self-consumption rate is introduced to accurately estimate the actual residual electric quantity of the battery, the functions of periodic charging maintenance, automatic maintenance and low-power early warning are realized, the phenomena of power shortage and power shortage or overcharge and over-discharge during emergency use are avoided, the application reliability and the service life of the energy storage battery are improved, and the control method has the advantages of simple principle, easiness in realization and strong stability.
For a better understanding and practice, the invention is described in detail below with reference to the accompanying drawings.
Drawings
Fig. 1 is a flowchart illustrating steps of a method for controlling a battery during a normal-power self-maintenance operation according to an embodiment of the present invention;
fig. 2 is a LiFePO according to an embodiment of the present invention4The OCV-SOC curve diagram of the battery when the battery is charged under different charging rates;
fig. 3 shows LiMn provided in an embodiment of the present invention2O4Battery and LiFePO4And the OCV-SOC curve of the battery when the battery is charged under the same charging rate is shown.
Fig. 4 is a schematic diagram illustrating an OCV-SOC curve of a ternary lithium battery according to an embodiment of the present invention during charging and discharging;
fig. 5 is a flowchart illustrating steps of a method for controlling a battery during a normal-power self-maintenance operation according to an embodiment of the present invention;
fig. 6 is a flowchart illustrating a method for controlling self-maintenance of a battery in a normally-charged state according to an embodiment of the present invention.
Detailed Description
The mobile energy storage battery (battery for short) comprises a Lithium Ion battery (Lithium Ion Batteries for short), a lead-acid storage battery and a vanadium flow battery. Wherein the lithium ion battery comprises lithium cobaltate (LiCoO)2) Battery and lithium manganate (LiMn)2O4) Batteries, nickel-cobalt-manganese-lithium batteries (i.e., ternary lithium batteries, Li (NiCoMn) O)2NMC) and lithium iron phosphate (LiFePO)4) A battery. In the prior art, the self-consumption of the battery is not considered in the residual electric quantity estimation method, so that the estimation of the residual electric quantity of the battery is inaccurate, and the overcharge and over-discharge of the battery are easily caused, thereby affecting the performance and the service life of the battery. The invention introduces the power consumption rate to correct the residual electric quantity, realizes the real-time accurate estimation of the actual residual electric quantity of the battery, and realizes the functions of automatic charging and regular maintenance, and the control method of the constant-power self-maintenance comprises the following steps:
fully charging the battery after the battery is completely discharged, and recording an OCV-SOC curve when the battery is charged; setting a target electric quantity, and reading a target voltage corresponding to the target electric quantity in an OCV-SOC curve; the battery is not discharged for a period of time, then the battery is charged to the target electric quantity, and the current self-consumption rate of the battery is calculated according to the charging quantity;
or after the electric quantity of the battery reaches the target electric quantity and no external discharge exists for a period of time, the battery is charged to the target electric quantity, and the current self-consumption rate of the battery is calculated according to the charging quantity.
Under the condition that the battery does not discharge outwards, calculating the actual residual electric quantity of the battery in real time according to the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply;
and under the condition that the battery is discharged outwards, calculating the actual residual electric quantity of the battery in real time by an ampere-hour metering method and the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is made with reference to specific examples.
Example 1
Please refer to fig. 1, which is a flowchart illustrating a method for controlling a self-maintenance operation of a battery in a constant power state according to an embodiment of the present invention. The control method comprises the following steps:
s1: after the battery is completely discharged, fully charging the battery at a preset charging rate, and recording a charging Voltage (or Open Circuit Voltage, OCV) -remaining capacity (or state of Charge, SOC) curve when the battery is charged;
s2: setting a target electric quantity, and reading a target voltage corresponding to the target electric quantity in an OCV-SOC curve;
s3: after the battery is placed for a period of time in a state that the battery is not discharged outwards, the battery is charged to the target electric quantity;
s4: recording the charging amount of the charging process;
s5: calculating the current self-consumption rate of the battery according to the charging amount;
s6: and judging whether the battery is discharged to the outside.
In step S1, the battery may be completely discharged when the battery is first used, or when the battery is used for a long timeNot used, from power consumption to complete discharge; the charge rate is a current value required for the battery to be fully charged to its rated capacity within a predetermined time, for example, rated capacity C0The battery with 1 a.h is charged with a charging rate of 1C, and reaches a full-charge state after 1 hour, and the charging current is constant with I1A, that is, the battery is charged in a constant-current charging mode. In this embodiment, a preset charge rate is set, after the battery is completely discharged, the battery is fully charged at the preset charge rate, and an OCV-SOC curve is recorded.
The preset charging multiplying power comprises a fast charging multiplying power and a slow charging multiplying power, wherein the slow charging multiplying power is the preset charging multiplying power when the preset charging multiplying power is less than or equal to 0.3C, and the fast charging multiplying power is the preset charging multiplying power when the preset charging multiplying power is greater than 0.3C. The battery can generate heat during the charging process, so that the temperature is increased, and the voltage and the capacity of the battery are influenced; when the charging multiplying power is within a certain range, the heat generated in the charging process is very small, and the influence of the temperature on the voltage and the electric quantity can be ignored; on the other hand, increasing the charge rate accelerates the increase in the internal resistance of the battery and the capacity fade. Therefore, in this embodiment, it is preferable to charge the mobile energy storage battery with a slow charging rate, so as to generate an OCV-SOC curve when the battery is charged, and in the practical application process, the user may reset the charging rate.
Wherein, the remaining capacity in the OCV-SOC curve is calculated based on an ampere-hour method, which is defined as a ratio of the remaining capacity of the battery to the rated capacity of the battery, and the calculation formula is as follows:
in the formula, C0Indicating the rated capacity of the battery, CtIndicating the residual capacity of the battery at the time t; the value range of the residual capacity is 0-100%, when the SOC is 0%, the battery is completely discharged, and when the SOC is 100%, the battery is fully charged.
In practical applications, the battery capacity cannot always maintain the rated capacity, so the remaining capacity is redefined as the ratio of the remaining capacity to the actual maximum capacity, and the expression is as follows:
in the formula, CmaxRepresenting the actual maximum capacity updated each time the battery is fully charged.
Preferably, each time the battery is completely discharged (i.e., SOC ═ 0%), it is necessary to re-record the OCV-SOC curve of the battery at a preset charge rate to improve the accuracy of the remaining capacity estimation.
In step S2, the target amount of power X0The value range of (A) is 30%<X0Less than or equal to 95 percent, the numerical value can be set according to the actual requirement of a user, and preferably, the target electric quantity X0＝90％。
In step S3, T is left in a state where the battery is not discharged to the outside0After a day, charging the battery to the target electric quantity; wherein, T0The preset electricity supplementing time limit is a time interval at which the battery needs to be periodically maintained and automatically supplemented under the condition of no charging and discharging, and the numerical value can be set according to the actual needs of a user.
In the state that the battery is not discharged externally, because no charging and discharging current exists, the traditional ampere-hour measuring method is adopted to estimate the residual capacity, and T is placed0The remaining capacity of the battery still shows 100% after the day, and the battery is not automatically charged. However, the self-consumption of the battery can cause the actual remaining capacity of the battery to be less than 100%, and the voltage across the battery is reduced along with the continuous reduction of the time. Therefore, in the present embodiment, T is placed in a state where the battery is not discharged to the outside0After the day, the battery is charged, and the charging voltage of the battery is recorded, and when the charging voltage is equal to the target voltage, the battery is charged to the target electric quantity.
In step S4, calculating the charging amount of the battery in real time through an ampere-hour meter, and recording the charging amount of the battery in the whole charging process when the battery is charged to the target electric quantity, wherein the charging amount is the self-consumption electric quantity of the battery when the battery is discharged without external discharge, and is used for calculating the subsequent self-consumption rate.
In step S5, the calculation formula of the power consumption rate is:
where a represents the current power consumption rate of the battery, and Q represents the amount of charge during charging of the battery, and is equal in value to the power consumption of the battery during the leaving.
In step S6, it is necessary to first determine whether the battery has been discharged, and then calculate the actual remaining capacity of the battery in different manners according to the determination result.
When the judgment result of the step S6 is that the battery is not discharged to the outside, the control method further includes the steps of:
s11: under the condition that the battery does not discharge outwards, calculating the actual residual electric quantity of the battery in real time according to the current self-power consumption rate, and recording the time length to be supplemented;
s12: judging whether the time length of the power to be supplemented is greater than or equal to a preset power supplementing time limit or not;
s13: judging whether the battery is connected with an external power supply or not;
s14: automatically charging the battery; s15: judging whether the battery reaches the target electric quantity in real time;
s16: finishing the automatic charging;
s17: and judging whether the battery is discharged before automatic charging.
In step S11, since the battery is not discharged to the outside and the actual remaining capacity is only affected by the internal power consumption, the actual remaining capacity of the battery can be calculated in real time according to the power consumption rate calculated in step S5, and the calculation formula is:
SOC＝X0-a×t (4)
in the formula, SOC represents the actual residual capacity of the battery at the time T, and the value range of T is more than or equal to 0 and less than or equal to T0。
When the actual residual capacity is calculated in real time, the time length (represented by symbol T) to be compensated needs to be recorded, and the time length is used for judging whether the battery needs to be automatically compensated. The time length to be supplemented refers to the time elapsed after the charging of the battery is finished or the time elapsed after the battery is charged to the target electric quantity; the automatic power supply or self-maintenance refers to the behavior of automatic charging after a period of time without external discharge.
In step S12, it is determined whether the time period for power supply is greater than or equal to the preset power supply time period, and then:
when T is<T0Then, step S11 is executed, that is, the actual remaining capacity is continuously calculated in real time according to the current power consumption rate;
when T is more than or equal to T0If it is indicated that the battery needs to be automatically charged, step S13 is executed.
In step S13, when T ≧ T0Judging whether the battery is connected with an external power supply, namely detecting whether the battery can be automatically supplied with power; when the battery is connected to the external power source, step S14 is executed.
In step S14, when T ≧ T0When the battery is connected with the external power supply, the battery is automatically supplemented, so that the use reliability of the battery is ensured, and the performance damage and the service life reduction of the battery due to over discharge are avoided.
In step S15, it is determined whether the battery has been automatically charged to the target charge amount, which may be determined by the following two methods:
voltage method:recording the charging voltage of the battery in the automatic charging state, and judging whether the charging voltage reaches the target voltage read in the step S2; when V is equal to V0When it is greater than X, then represent SOC ═ X0。
Electric quantity method:calculating the amount Q' of charge to be compensated in the automatic power compensation state according to the actual remaining power amount calculated in step S11, wherein the calculation formula is as follows: q' ═ X0-an SOC; recording the charging amount of the battery in an automatic power compensation state, and judging whether the charging amount reaches the charging amount to be compensated or not; when Q is Q', it represents SOC is X0。
When the actual remaining capacity is equal to or greater than the target capacity (i.e., SOC ═ X)0) Or SOC is more than or equal to X0If so, executing step S16, namely ending the automatic power supply;
when SOC is reached<X0If the battery still needs to be automatically recharged, step S14 is executed.
In step S17, after the automatic charging is finished, it is determined whether the battery has been discharged before the automatic charging, or whether the automatic charging process of the battery is an automatic power supply process.
When the battery is not discharged to the outside before the automatic charging or the battery is automatically replenished, step S4 is executed again. That is, each time the automatic power supply is performed, the charging amount of the charging process is recorded, and the current power consumption rate of the battery is calculated according to the charging amount, and the current power consumption rate is only used for calculating the actual remaining power before the automatic power supply is completed to the next automatic power supply, so as to improve the accuracy of estimating the remaining power.
It should be noted that, in the present invention, when the battery records the OCV-SOC curve in the charging state and performs automatic power supply, the battery cannot have an external load, that is, the battery cannot be charged and discharged simultaneously, otherwise, the estimation of the remaining power will have a large error.
Two examples are provided below to illustrate in detail the specific application of the control method.
Example a:
please refer to fig. 2, which shows LiFePO provided in this embodiment4The battery was charged at different charging rates with the recorded OCV-SOC curves. As can be seen from FIG. 2, LiFePO4The OCV-SOC curve of the battery comprises a first identification region (>85 percent), a voltage flat area (30 to 85 percent) and a second identification area (less than or equal to 85 percent). The charging voltage of the first identification area and the charging voltage of the second identification area are changed greatly, and the charging voltage of the voltage flat area is changed insignificantly. If the target electric quantity is in the voltage flat area, it is difficult to judge whether the battery is charged to the target electric quantity through a voltage method, and a large error also exists in an estimation result. Meanwhile, in order to prevent the battery from having a bad influence on the capacity and the life of the battery when the battery is in the extreme operating condition, the battery should be controlled not to operate at both ends of the OCV-SOC curve, and the remaining capacity should not be corrected when the battery is at both ends of the OCV-SOC curve.
If the value range of the target electric quantity is 30 percent<X0When the charging voltage is less than or equal to 85% (namely the voltage flat area), because the charging voltage changes very little, the voltage method is used for judging whether the battery is charged to the target electric quantity, so that a large error is easily caused. Thus, for LiFePO4The target electric quantity is arranged in the voltage flat area, and whether the battery is charged to the target electric quantity can be judged only by adopting an electric quantity method.
Then, for step S15, at T ≧ T0And when the battery is connected with the external power supply, the battery is automatically supplemented, and the battery is judged to be charged to the target electric quantity in real time through an electric quantity method. Specifically, according to the current power consumption rate calculated in step S5, the amount Q' of charge to be compensated in the automatic power compensation state is calculated according to the calculation formula: q' ═ X0-an SOC; recording the charging amount of the battery in an automatic power compensation state, and judging whether the charging amount reaches the charging amount to be compensated or not; when Q is Q', it represents SOC is X0And ending the automatic power supply.
After the automatic power supply is finished, step S4 is executed again, and the charging amount Q ═ Q' ═ a × T in the charging process0The current power consumption rate calculated by the formula (3) is not changed. That is, when the determination is made by the coulometry method, the current power consumption rate is calibrated only when the battery is automatically replenished for the first time, and thus, after the automatic replenishment is finished, step S5 may be directly performed.
If the value range of the target electric quantity is 85 percent<X0When the battery capacity is less than or equal to 95% (namely the first identification area), the voltage method or the electric quantity method can be adopted to judge whether the battery is charged to the target electric quantity. The current self-consumption rate can be calibrated again by the voltage method during each automatic power supplement, and the current self-consumption rate is calibrated by the electric quantity method only during the first automatic power supplement, so that the LiFePO is calibrated4When the target electric quantity is set in the voltage flat region, the battery is preferably judged by a voltage method so as to improve the estimation precision of the residual electric quantity.
Example B:
referring to fig. 3 to 4, fig. 3 is a LiMn provided in this embodiment2O4Battery and LiFePO4FIG. 4 is a graph comparing OCV-SOC curves of a battery charged at the same charging rate, and FIG. 4 is a graph of the present embodimentThe OCV-SOC curve of the ternary lithium battery during charging and discharging is provided. As can be seen, LiMn is present during charging2O4The battery and the ternary lithium battery are not like LiFePO4The battery has a voltage flat area, and the charging voltage of the battery is greatly changed in the whole value range of the residual capacity. Thus, for removing LiFePO4When the value range of the target electric quantity of the mobile energy storage battery except the battery is 30-95%, whether the battery is charged to the target electric quantity or not is judged by adopting a voltage method, and in other embodiments, the battery can also be judged by adopting an electric quantity method.
Compared with the prior art, the control method for the constant-power-on self-maintenance of the battery provided by the embodiment can accurately estimate the actual residual capacity of the battery when the battery is not discharged externally in real time by calculating the self-power consumption rate of the battery, realize the function of regular automatic power supply maintenance, prevent the battery from being in a low-power or non-power state due to long-time idling, avoid the phenomenon of overcharge and overdischarge of the battery, ensure the reliability of the battery, and prolong the service life of the battery.
Example 2
Compared with embodiment 1, the present embodiment further includes method steps in a state where the battery has been discharged to the outside and in a state where the battery is not connected to an external power source.
Please refer to fig. 5, which is a flowchart illustrating a method for controlling a self-maintenance operation of a battery in a constant power-on state according to the present embodiment. The control method further comprises the following steps:
s21: after the battery is discharged, calculating the residual electric quantity of the battery according to an ampere-hour metering method;
s22: correcting the residual electric quantity in real time according to the current power consumption rate to obtain the actual residual electric quantity;
S23/S13: judging whether the battery is connected with an external power supply or not;
s24: when the battery is not connected with the external power supply, the actual residual capacity of the battery is continuously calculated in real time;
s25: judging whether the actual residual electric quantity is reduced below the early warning electric quantity or not;
s26: and sending an early warning signal.
In step S6, it is determined whether the battery has been discharged to the outside, and if the battery has not been discharged to the outside, the steps S11 to S17 described in embodiment 1 are performed; if the battery has been discharged, step S21 is executed.
In step S21, the ampere-hour meter obtains the remaining capacity of the battery by continuously detecting and integrating the charge/discharge current to obtain the amount of power released or absorbed by the battery, and the formula is:
in the formula, SOCτRepresenting the residual capacity of the battery at the time tau in an external discharge state; i represents a discharge current of the battery; τ represents the duration of the external discharge state of the cell.
In step S22, when the battery is not discharged externally, because there is no discharging current, the actual remaining capacity of the battery under the self-power consumption condition cannot be obtained by the ampere-hour meter method, so the present embodiment introduces the current self-power consumption rate to correct the remaining capacity in real time, so as to obtain the actual remaining capacity of the battery, and the calculation formula is as follows:
SOC＝SOCτ-a×t (6)
in step S23 (actually, step S13), since the battery has been discharged to the outside, the battery has a low electric quantity, and needs to be charged urgently, at this time, it is not necessary to determine whether the time length to be charged is greater than or equal to the preset charging time limit, and it is directly determined whether the battery is connected to the external power supply;
when the battery is connected to the external power source, steps S14 to S17 described in embodiment 1 are performed, but in this process, there are two differences between this embodiment and embodiment 1: firstly, the battery is automatically charged in step S14, and since the battery is discharged, it is only called automatic charging, and it cannot be called automatic power supplement; secondly, if the battery is discharged before the automatic charging or the battery is not automatically recharged as a result of the determination in the step S17, the power consumption rate cannot be calculated from the charged amount in the automatic charging process, so the next step cannot be executed as the step S4, and the step S6 should be executed.
When the battery is not connected with the external power supply, the battery continuously consumes power, the actual residual capacity is continuously reduced, and the over-discharge occurs even, so that a low-power early warning function is set, namely, the steps S24-25 are executed.
In step S24, when the battery is not connected to the external power source, the actual remaining capacity of the battery is continuously calculated in real time according to the formula (4) or the formula (6);
optionally, when the battery is not connected to the external power supply, the current power consumption used for calculating the actual remaining power may be the current power consumption calibrated in the last automatic power supplement, or the maximum power consumption obtained after multiple automatic power supplements.
In step S25, it is determined whether the actual remaining capacity of the battery falls below the warning capacity; wherein, the early warning electric quantity XaHas a value range of X a30% or less, preferably, X a30 percent; in the practical application process, the user can reset the early warning electric quantity according to the requirement of the user.
When SOC is reached>XaIf the low-power early warning function is not triggered, continuing to execute the step S25;
when SOC is equal to XaOr SOC is less than or equal to XaIf the battery power is low, step S26 is executed, i.e. an early warning signal is sent.
Optionally, when SOC is less than or equal to XaAnd when the actual residual capacity of the battery is reduced by 5%, an early warning signal is sent once.
Compared with the prior art, the control method for the constant-power self-maintenance of the battery provided by the embodiment combines the self-consumption rate of the battery on the basis of an ampere-hour metering method, can accurately estimate the actual residual capacity of the battery in real time no matter whether the battery is discharged outwards, realizes the functions of automatic charging and low-power early warning, and ensures the use reliability of the battery.
Example 3
In contrast to example 2, this example also includes the method steps in a state where the battery is fully discharged.
Please refer to fig. 6, which is a flowchart illustrating a method for controlling self-maintenance of a battery in a normal charging state according to the present embodiment. As can be seen, after step S17 is executed, step S4 or step S6 may be executed again, that is, the OCV-SOC curve recorded after the battery is completely discharged once may be used for multiple automatic power supply/charging cycles. In step S26, even if the warning signal is sent, the battery may not be charged and is continuously discharged from the power consumption to the complete discharge, and the control method further includes the step of
S27: after the early warning signal is sent, whether the battery is completely discharged is judged;
when the battery is not completely discharged, executing step S13, and determining whether the battery is connected to the external power supply again;
when the battery is completely discharged, step S1 is executed to record the OCV-SOC curve of the battery again at the preset charging rate, and a new automatic power supply/charging cycle is started using the updated OCV-SOC curve.
The performance of the battery changes along with the increase of the cycle number of charging and discharging, so that the latest recorded parameters and curves are preferably adopted for estimating the actual residual capacity of the battery, so that the estimation accuracy of the state of the battery is improved, the use stability and reliability of the battery are improved, and the service life of the battery is effectively prolonged.
Example 4
Based on the control method for battery constant-power self-maintenance described in embodiment 3, this embodiment further provides a battery with constant-power self-maintenance. The battery includes a battery unit, a BMS unit, and an early warning unit.
The battery unit includes at least 1 battery pack that can be subjected to a plurality of charge and discharge cycles.
The BMS unit comprises a control module, a recording module, a detection module, a current power consumption calculation module, an actual residual electric quantity first calculation module, a time calculation module, an actual residual electric quantity first judgment module, an actual residual electric quantity second calculation module, an actual residual electric quantity second judgment module and a complete discharge judgment module.
After the battery is completely discharged, the control module enables the battery to be fully charged under a preset charging rate; the recording module records an OCV-SOC curve when the battery is charged in the process of fully discharging and fully charging the battery; the recording module also sets a preset power supplementing period and a target electric quantity, and reads a target voltage in an OCV-SOC curve; the control module enables the battery to be charged to the target electric quantity after the battery is placed for a period of time in a state that the battery is not discharged outwards; the recording module also records the charging amount in the charging process of the battery; the current power consumption rate calculation module calculates the current power consumption rate of the battery according to the charging amount; the detection module judges whether the battery is discharged outwards.
The actual residual electric quantity first calculation module calculates the actual residual electric quantity of the battery in real time according to the current self-consumption rate when the battery does not discharge outwards; the time calculation module records the time length to be supplemented when the battery does not discharge outwards, and judges whether the time length to be supplemented is greater than or equal to a preset power supplementing time limit; the detection module also judges whether the battery is connected with an external power supply; the control module also enables the battery to be automatically charged when the time length of the power to be supplemented is more than or equal to a preset power supplementing time limit and the battery is connected with an external power supply; the actual residual electric quantity first judgment module judges whether the battery is charged to the target electric quantity; the control module also enables the battery to finish automatic charging after the battery is charged to the target electric quantity; the detection module also judges whether the battery is discharged before being automatically charged.
The actual residual electric quantity second calculation module calculates the actual residual voltage of the battery in real time according to an ampere-hour metering method and the current self-power consumption rate when the battery is discharged outwards; the actual residual electric quantity second judgment module judges whether the actual residual electric quantity of the battery is reduced below the early warning electric quantity when the battery is not connected with the external power supply; the complete discharge judgment module judges whether the battery is completely discharged.
The early warning unit sends an early warning signal when the actual residual capacity of the battery is reduced to be lower than the early warning capacity.
Compared with the prior art, the battery with constant power and self-maintenance provided by the embodiment has the advantages that on the basis of an ampere-hour metering method, the self-power consumption rate is introduced to calculate and correct the SOC, the accurate estimation of the SOC can be carried out in real time, the functions of automatic charging, regular maintenance and low-power early warning are realized, the phenomena of power shortage and power shortage or overcharge and over-discharge during emergency use are avoided, the whole structure is simple, the realization is easy, the reliability is high, and the service life is long.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (10)
1. A method for controlling self-maintenance of a battery in a normally-charged state is characterized by comprising the following steps:
s10: after the electric quantity of the battery at least reaches the target electric quantity and has no discharge to the outside for a period of time, charging the battery to the target electric quantity, and calculating the current self-consumption rate according to the charging quantity;
s20: under the condition that the battery does not discharge outwards, calculating the actual residual electric quantity of the battery in real time according to the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply; or S30: and under the condition that the battery is discharged outwards, calculating the actual residual electric quantity of the battery in real time by an ampere-hour metering method and the current self-consumption rate, and charging the battery to the target electric quantity when the battery is connected with an external power supply.
2. The method for controlling the constant-power self-maintenance of the battery according to claim 1, further comprising the steps of:
fully charging the battery after the battery is completely discharged, and recording an OCV-SOC curve when the battery is charged; setting a target electric quantity, and reading a target voltage corresponding to the target electric quantity on the OCV-SOC curve; the battery is not discharged to the outside for a certain period of time.
3. The method for controlling the constant-power self-maintenance of the battery according to claim 1 or 2, wherein the step S20 is specifically as follows:
under the condition that the battery does not discharge outwards, calculating the actual residual electric quantity of the battery in real time according to the current self-power consumption rate; recording the time length of electricity to be supplemented; and when the time length of the electricity to be supplemented is more than or equal to the preset electricity supplementing time limit and the battery is connected with the external power supply, charging the battery to the target electric quantity.
4. A method for controlling a constant-power self-maintenance battery according to claim 3, wherein:
the current power consumption rate calculation formula is as follows:
wherein a represents the current power consumption rate, Q represents the charge amount, T0Indicating a preset power supply time limit.
5. The method for controlling the constant-power self-maintenance of the battery according to claim 4, wherein:
the calculation formula of the actual residual capacity is as follows: SOC ═ X0-a×t (4)
In the formula, SOC represents the actual remaining capacity of the battery at time t, and X0The value range of T is more than or equal to 0 and less than or equal to T0。
6. The method for controlling the constant-power self-maintenance of the battery according to claim 4 or 5, wherein the step S30 is specifically as follows:
under the state that the battery is discharged outwards, calculating the residual electric quantity of the battery after the battery is discharged outwards according to the ampere-hour metering method; correcting the residual electric quantity in real time according to the current power consumption rate to obtain the actual residual electric quantity; and when the battery is connected with an external power supply, charging the battery to the target electric quantity.
7. The method for controlling the constant-power self-maintenance of the battery according to claim 6, wherein:
when the charging voltage of the battery is equal to the target voltage, the battery is charged to the target electric quantity;
alternatively, the first and second electrodes may be,
calculating the amount of charge to be compensated of the battery according to the actual residual electric quantity of the battery; when the charging amount of the battery is equal to the amount to be compensated, the battery is charged to the target electric quantity.
8. The method for controlling the constant-power self-maintenance of the battery according to claim 7, further comprising the steps of:
and when the actual residual electric quantity of the battery is reduced to be lower than the early warning electric quantity and is not connected with the external power supply, sending an early warning signal.
9. A battery of constant-live self-maintenance, characterized in that:
the battery unit comprises at least 1 battery pack capable of performing multiple charging and discharging cycles, and the BMS unit comprises a control module, a recording module, a detection module, a current self-power consumption rate calculation module, an actual residual electric quantity first calculation module, a time calculation module, an actual residual electric quantity first judgment module and an actual residual electric quantity second calculation module;
the control module enables the battery to be fully charged under a preset charging rate after the battery is completely discharged; the recording module records an OCV-SOC curve when the battery is charged in the process of fully discharging and fully charging the battery; the recording module also sets a preset power supplementing period and a target electric quantity, and reads a target voltage in the OCV-SOC curve; the control module enables the battery to be charged to the target electric quantity after the battery is placed for a period of time in a state that the battery is not discharged outwards; the recording module is also used for recording the charging amount in the battery charging process; the current power consumption rate calculation module calculates the current power consumption rate of the battery according to the charging amount; the detection module judges whether the battery is discharged outwards;
the actual residual electric quantity first calculation module calculates the actual residual electric quantity of the battery in real time according to the current self-power consumption rate when the battery does not discharge outwards; the time calculation module records the power supplementing duration when the battery does not discharge externally, and judges whether the power supplementing duration is greater than or equal to the preset power supplementing time limit; the detection module also judges whether the battery is connected with an external power supply; the control module also enables the battery to be automatically charged when the power supplementing duration is longer than or equal to the preset power supplementing duration and the battery is connected with an external power supply; the actual residual electric quantity first judging module judges whether the battery is charged to the target electric quantity; the control module also enables the battery to finish automatic charging after the battery is charged to the target electric quantity; the detection module also judges whether the battery is discharged outwards before automatic charging;
and the actual residual electric quantity second calculation module calculates the actual residual voltage of the battery in real time according to an ampere-hour metering method and the current self-power consumption rate when the battery is discharged outwards.
10. A normally charged self-service battery according to claim 9, wherein:
the battery also comprises an early warning unit;
the BMS unit further comprises an actual residual electric quantity second judgment module and a complete discharge judgment module;
the actual residual electric quantity second judgment module judges whether the actual residual electric quantity of the battery is reduced below the early warning electric quantity when the battery is not connected with an external power supply;
the complete discharge judgment module judges whether the battery is completely discharged;
and the early warning unit sends an early warning signal when the actual residual electric quantity of the battery is reduced to be lower than the early warning electric quantity.
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| CN202210176117.XA CN114552039A (en) | 2022-02-24 | 2022-02-24 | Control method for battery constant-charge self-maintenance and constant-charge self-maintenance battery |
| PCT/CN2022/082537 WO2023159708A1 (en) | 2022-02-24 | 2022-03-23 | Control method for normally-electrically charged self-maintenance of battery, and normally-electrically charged self-maintenance battery |
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| CN117458010A (en) * | 2023-12-20 | 2024-01-26 | 超耐斯(深圳)新能源集团有限公司 | Lithium battery energy storage monitoring system based on data analysis |
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