CN110854460A - Battery cell discharging method, and battery full-life-cycle discharging method and system - Google Patents
Battery cell discharging method, and battery full-life-cycle discharging method and system Download PDFInfo
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/44—Methods for charging or discharging
- H01M10/441—Methods for charging or discharging for several batteries or cells simultaneously or sequentially
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0063—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
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Abstract
A battery cell discharging method, a battery full life cycle discharging method and a battery full life cycle discharging system belong to the field of battery management. The battery cell discharging method comprises the steps of carrying out pulse-form discharging on a load, and forming a current waveform required by the load by current filtering of a discharging pulse; the pulse amplitude of the discharge pulse is the discharge current of the battery core, the pulse width of the discharge pulse is not more than the recovery time tc, and the pulse gap of the discharge pulse is not less than the relaxation time tr; the recovery time is the longest continuous discharge time of the battery core, and the electrode structure distortion caused in the recovery time can be eliminated in the subsequent relaxation time. The invention is suitable for the discharge intelligent control of various electrochemical batteries, so that the load (working condition), discharge and battery management are fully matched and optimized, each battery cell works in a healthy operation area, and the service life of the battery is prolonged.
Description
Technical Field
The invention relates to the technical field of battery management, in particular to a battery cell discharging method, a battery full-life-cycle discharging method and a battery full-life-cycle discharging system.
Background
The electrochemical energy storage technology is the mainstream technology of distributed energy storage at present and is a guarantee for using renewable energy in a large proportion. The electrochemical energy storage construction period and the investment return period are short, the requirement on the environment is low, the electrochemical energy storage can be constructed in a distributed mode, and the electrochemical energy storage system is suitable for distributed renewable energy storage. The battery is the core of electrochemical energy storage and is also the core component of the electric automobile. A safe, economical, environment-friendly and reproducible battery system is the core of electrochemical energy storage. Because the battery products have vivid vital characteristics, the battery system for healthy and safe use needs to be subjected to full-life cycle control management, wherein the discharge technology is one of the keys of the battery system for healthy and safe use.
An unreasonable discharging method, especially a frequent overdischarge, may greatly shorten the battery life, and may even cause a safety hazard. The spontaneous combustion of the lithium battery electric automobile and the detonation accident of the energy storage power station which are frequently happened recently are partially directly related to the long-term overdischarge of the battery cell. For lead acid batteries, frequent overdischarging can accelerate battery vulcanization, thereby severely shortening battery life. For a large battery system, a plurality of battery cells are generally connected in parallel. Although the consistency of the new cells can be ensured when the cells are grouped, the consistency is deteriorated along with the aging of the battery, and thus some cells are inevitably over-discharged in the discharging process, so that the battery system is failed. Therefore, the discharging method for effectively delaying or controlling the failure of the battery system has great significance.
The complexity of discharge control comes from the uncontrollable nature of the discharge load, and with the wide use of the electric system, the discharge behavior depends greatly on the working condition and the load of the electric system, such as the use of an electric vehicle and the frequency modulation and peak shaving of a power grid system, and the load is determined by the external environment and the use working condition. When the electric and energy storage system is used, how to ensure the healthy discharge of each battery cell on the premise of not influencing the completion of a work task is a problem that an intelligent discharge control system must face.
The invention discloses a method for estimating the capacity and predicting the residual cycle life of a lithium ion battery, which is characterized in that the collected data of the number x of charge and discharge cycles of the battery, the discharge voltage and the battery capacity of each charge and discharge cycle and the a/N of the residual capacity data z of the battery after each charge and discharge and the residual (N-a)/N are used as test data, a segmented thrice Hermite interpolation method is used for expanding the training data, the training data of different interpolation points obtained after expansion are used for modeling, a GPR model with different parameters is used for extrapolation prediction, the residual capacity of the battery after the next charge and discharge cycle of the lithium battery is predicted, and the residual capacity of the battery after the N charge and discharge cycles is obtained. Although the method can solve the problem that the capacity estimation and the residual life prediction of the lithium battery cannot be realized, the method is based on the judgment of the post-event state of the battery. Under some load conditions, over-discharge already occurs, and long-term over-discharge may cause degradation of the state of health of the battery.
Disclosure of Invention
The invention provides a battery cell discharging method, a battery full life cycle discharging method and a battery full life cycle discharging system, which aim at the problems in the prior art, carry out full life cycle management on a battery, master the operation and health condition of each battery cell in the battery at any time, predict the inconsistent pressure of the battery discharging on each battery cell according to possible loads and working conditions, balance the charge state (SoC) and the power state (SoP) of each battery cell in advance, ensure that the battery cells are not over-discharged without being recovered under the complex loads and working conditions, thereby greatly improving the use safety of the battery and prolonging the service life of the battery.
The invention is realized by the following technical scheme:
a cell discharge method, comprising:
discharging the load in a pulse form, and filtering the discharge pulse by current to form a current waveform required by the load;
the pulse degree of the discharge pulse is the discharge current of the battery core, the pulse width of the discharge pulse is not more than the recovery time tc, and the pulse gap of the discharge pulse is not less than the relaxation time tr;
the recovery time is the longest continuous discharge time of the battery cell, and the electrode structure distortion caused in the time can be eliminated in the subsequent relaxation time;
the relaxation time is the time required for the electrode structure to distort and recover to the original state.
The invention provides a pulse type discharging method. After the end of a single pulse, there is a gap so that the accumulation of distortion during the pulse period can be reduced or eliminated, and the degree of aging can be reduced without doubt.
Preferably, the recovery time tc varies with the discharge current, the temperature, the state of health SOH, the state of charge SOC, and the depth of discharge DoD of the battery.
Preferably, the recovery time tc is inversely proportional to the discharge current of the battery core, and the recovery time tc is inversely proportional to the battery depth of discharge DoD.
Preferably, the relaxation time tr varies with the discharge current, the temperature, the state of health SOH, the state of charge SOC, and the depth of discharge DoD of the battery.
Preferably, the minimum value of the relaxation time tr is proportional to the cell discharge current.
Preferably, the method further comprises: and the discharging process is carried out until the load is charged or the battery cell is put into a cut-off state.
A battery full-life cycle discharge method, comprising:
monitoring battery real-time data and load real-time data discharged under the discharge pulse at the current moment;
calculating a discharge pulse at the next moment according to the load real-time data, the battery real-time data and the change information of the recovery time tc and the relaxation time tr;
forming the discharge pulse into a current waveform at the next moment required by the load by controlling current filtering;
discharging by adopting the calculated discharge pulse, charging the load by adopting the calculated current waveform, and discharging until the load is charged completely or the battery is put into a cut-off state;
the battery real-time data comprises voltage, current and temperature data of the battery; the load real-time data comprises voltage, current and temperature data of the load;
the recovery time is the longest continuous discharge time of the battery, and the electrode structure distortion caused in the recovery time can be eliminated in the subsequent relaxation time; the recovery time tc is changed along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the relaxation time tr is the time required for the distortion and the recovery of the electrode structure, and changes along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the discharge pulse comprises a discharge current, a recovery time tc and a relaxation time tr of the battery core.
The invention manages the whole life cycle of the battery, grasps the operation and health condition of each battery cell in the battery at any time, predicts the inconsistent pressure of the battery discharge to each battery cell according to the possible load and working condition, balances the charge state (SoC) and the power state (SoP) of each battery cell in advance, and ensures that the battery cell has no unrecoverable overdischarge under the complex load and working condition.
Preferably, the step of calculating the discharge pulse at the next time according to the load real-time data, the battery real-time data, and the change information of the recovery time tc and the relaxation time tr includes:
determining a predicted load curve according to the load real-time data;
according to the real-time data of the battery, determining the discharge pulse of each battery cell at the next moment by contrasting curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the battery health state SOH, the state of charge SOC and the battery discharge depth DoD of the battery cell and combining with a predicted load curve;
and taking the minimum value of the discharge current, the minimum value of the recovery time and the maximum value of the relaxation time in all the battery cores to form the battery discharge pulse at the next moment.
Preferably, when the battery includes a series battery cell, the step of calculating the discharge pulse at the next time according to the load real-time data, the battery real-time data, and the change information of the recovery time tc and the relaxation time tr further includes:
before the discharging pulse of each battery cell at the next moment is determined, if at least one battery cell in the plurality of battery cells is close to a discharging cut-off state, charging the battery cell close to the discharging cut-off state by using other battery cells;
and then, according to the real-time data of the battery, comparing curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the state of health (SOH) of the battery, the state of charge (SOC) of the battery and the discharge depth (DoD) of the battery, and combining the predicted load curves to determine the discharge pulse of each battery cell at the next moment.
Preferably, the step of forming the battery discharge pulse into a current waveform at a next time required by the load by controlling the current filtering includes:
and performing filtering calculation, and performing filtering processing to filter the discharge pulse to form a current waveform when the load curve obtained by calculation is consistent with the predicted load curve.
Preferably, the method for calculating the discharge pulse and the current waveform at the next time is applied to a battery formed by connecting a plurality of battery cells in series, a battery formed by connecting a plurality of battery cells in parallel, or a battery formed by connecting a plurality of battery cells in series and parallel.
Preferably, the method further comprises: and correcting the curve of each battery cell in real time according to the real-time data of the battery, the SOH (state of charge), the SOC (state of charge) and the DOD (depth of discharge).
Preferably, the method is suitable for discharging chemical batteries.
A battery full life cycle discharging system comprises a battery module, a detection protection module, a load detection module, a current filtering module, a database and a calculation control module; the database stores the change information of the recovery time tc and the relaxation time tr of the battery; the detection protection module is used for detecting the battery module in real time to obtain battery real-time data; the load detection module is used for detecting a load in real time to obtain load real-time data; the calculation control module calculates the discharge pulse at the next moment according to the load real-time data, the battery real-time data, the recovery time tc of the battery and the change information of the relaxation time tr; the battery module discharges according to the control signal of the calculation control module, and forms a current waveform required by a load by a discharge pulse through the current filtering module to charge the load until the load is charged or the battery core is put into a cut-off state;
the battery real-time data comprises voltage, current and temperature data of the battery; the load real-time data comprises voltage, current and temperature data of the load;
the recovery time tc is the longest continuous discharge time of the battery, and the electrode structure distortion caused in the recovery time tc can be eliminated in the subsequent relaxation time; the recovery time tc is changed along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the relaxation time tr is the time required for the distortion and the recovery of the electrode structure, and changes along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the discharge pulse comprises a discharge current, a recovery time tc and a relaxation time tr of the battery core.
Preferably, the calculation control module includes:
the load curve determining unit is used for determining a predicted load curve according to the load real-time data;
the battery cell discharge pulse calculation unit is used for contrasting curves of the recovery time tc and the relaxation time tr of each battery cell changing along with the discharge current, the temperature, the battery health state SOH, the charge state SOC and the battery discharge depth DoD of the battery cell according to the real-time data of the battery, and determining the discharge pulse of each battery cell at the next moment by combining the predicted load curve;
and the battery discharge pulse calculation unit is used for taking the minimum value of the discharge current, the minimum value of the recovery time and the maximum value of the relaxation time in all the battery cells to form the battery discharge pulse at the next moment.
Preferably, the calculation control module further includes: and the filtering calculation unit is used for carrying out filtering calculation on the battery discharging pulse, if the load curve obtained by calculation is consistent with the predicted load curve, the calculation control module sends a control instruction containing the battery discharging pulse to the battery module, and if not, the load curve determination unit, the battery cell discharging pulse calculation unit and the battery discharging pulse calculation unit recalculate the battery discharging pulse.
Preferably, the system further comprises a battery energy management module and a switch module which are arranged between the battery module and the current filtering module; the calculation control module further comprises a charging control unit, and the charging control unit is used for controlling the switch module to cut off a discharging path and control other battery cores to perform charging operation on the battery cores approaching the discharging cut-off state when the battery energy management module detects that at least one battery core of the plurality of battery cores approaches the discharging cut-off state, and then controlling the switch module to switch on the discharging path after charging is completed, and triggering the load curve determination unit, the battery core discharging pulse calculation unit and the battery discharging pulse calculation unit to work.
The invention has the following beneficial effects:
the cell discharging method, the battery full-life-cycle discharging method and the battery full-life-cycle discharging system are suitable for discharging intelligent control of various electrochemical batteries, so that load (working condition), discharging and battery management are fully matched and optimized, each cell works in a healthy operation area, and the service life of the battery is prolonged.
Drawings
FIG. 1a is a block diagram of a discharge configuration of a single cell battery;
FIG. 1b is a graph of the discharge curve (discharge current I-discharge time t) according to the structure of FIG. 1 a;
FIG. 2a is a block diagram of a discharge configuration for a multi-cell series cell;
FIG. 2b is a graph of the discharge curve (discharge current I-discharge time t) according to the structure of FIG. 2 a;
FIG. 3 is a graph of the trend of battery cycle life with discharge current and depth;
FIG. 4 is a schematic diagram of a battery discharge pulse;
FIG. 5a is a graph showing the recovery time tc versus the depth of discharge DoD;
FIG. 5b is a graph of the trend of recovery time versus depth of discharge DoD, wherein the change in discharge current also affects the curve;
FIG. 6 is a block diagram of a battery full-life cycle discharging method according to the present invention;
FIG. 7a is a cell structure formed by multiple cells connected in series;
FIG. 7b shows a cell structure in which multiple cells are connected in parallel;
fig. 7c is a schematic diagram of a battery formed by connecting multiple cells in series-parallel, in which the battery is formed by sequentially connecting multiple groups of cells in series after parallel connection;
fig. 7d is a schematic diagram of a battery formed by connecting multiple cells in series and parallel, in which the battery is formed by connecting multiple groups of cells connected in series in parallel;
FIG. 8 is a schematic diagram of a single cell battery full life discharge system;
fig. 9 is a schematic diagram of a full life cycle discharge system for a multi-cell battery.
Detailed Description
The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.
At present, battery discharge management focuses on the state of charge (SoC), the battery health condition (SoH), the internal resistance, the power condition (SoP) and the like, and rarely hooks with the load of a battery; due to the nonlinear relationship between SoC, SoP, SoH and internal resistance to load current/voltage height, it is difficult to predict the effect of load on battery state before complex load appears. Thus, the battery can be protected only by judging the state after the event. Under some load conditions, judgment is carried out after over-discharge occurs, if recovery is not timely, certain damage can be caused to the battery, and the health condition of the battery can be declined due to long-term over-discharge. Since batteries have significant life characteristics, the characteristic parameters of the batteries change as the batteries age. Therefore, the control method for battery discharge should perform adaptive discharge management according to its life characteristics, especially perform full-life management on the battery.
Fig. 1a, 1b are discharge diagrams of single cell batteries. The single-cell battery discharges, and the discharged electric quantity is supplied to the load for use. Current I required by loadloadAt charging time tchargeThe required electric quantity needs to be supplied by battery discharge, the current on the load side needs to be smooth, when the battery is discharged in a pulse form, filtering processing is needed, partial charge loss exists in the filtering processing, and the electric quantity discharged by the battery is at least Iload*tcharge/tdischarge. It follows that the cut-off voltage at which the discharge of the battery cell is completed is related to the load current of the discharge, whether it be a lithium battery, a lead-acid battery or other electrochemical battery.
Fig. 3 depicts the trend of cycle life as a function of discharge current and depth. The cycle life of the battery is in inverse proportion to the battery discharging depth DoD, and the deeper the discharging is, the shorter the cycle life is; the cycle life of the battery is inversely proportional to the discharge current (discharge rate), and the larger the discharge current is, the lower the cycle life is. Among them, the cycle life is the number of times that the battery can be repeatedly used while still maintaining 80% capacity. The capacity decline and aging of the battery is a gradual fading accumulation process, and the accumulation is the accumulation of the distortion of the electrode structure from the viewpoint of the microstructure. The aging of the battery is mostly caused by the distortion of an electrode structure in the charging and discharging processes; the discharge process is also critical to lead to cell aging. Taking a lithium battery as an example, the discharge process is a positive electrode lithium ion desorption and negative electrode lithium ion intercalation process, and during the process, positive and negative electrode structural distortion, lithium metal precipitation, dendrite growth, SEI film change and the like are causes of aging; experience has shown that a larger discharge current, longer discharge duration, accelerates cell aging. If the irreversible distortion in the current discharge can be eliminated in the period during each discharge, the distortion will not be accumulated. In practical applications, the battery may not be restored after discharging and then eliminating the distortion due to the complexity of the discharging condition, and the pulse discharging in a shorter time can reduce the distortion during the single pulse discharging and the distortion can be restored in the non-discharging state, so that the pause restoration is required during the discharging process.
It follows that deep discharge or large current discharge over a long period of time accelerates battery aging due to rapid accumulation of irreversible distortion of the electrode structure. If the battery is discharged in a pulse form, and the width of each discharge pulse is controlled within a certain time tx, so that the distortion of the electrode structure caused by the pulse discharge can be recovered after the pulse is ended; the maximum value of tx is defined as the maximum recoverable time tc; and ensuring that the irreversible distortion of the electrode structure can be eliminated within the gap time after each pulse, wherein the minimum value tr of the gap time is the relaxation time for the distortion recovery of the electrode structure. Electrode distortion of the battery caused by the pulse discharge width tc can be eliminated in the following relaxation time, and battery aging caused by discharge can be greatly reduced through the pulse form.
Based on this, as a general description, the pulse amplitude of the discharge pulse (as shown in fig. 4) is the discharge current of the battery, the pulse width of the discharge pulse is not greater than the recovery time tc, and the pulse gap of the discharge pulse is not less than the relaxation time tr. The recovery time is the longest continuous discharge time of the battery, and the electrode structure distortion caused in the recovery time can be eliminated in the subsequent relaxation time. The relaxation time is the time required for the electrode structure to distort and recover to the original state.
The recovery time tc varies with the discharge current, temperature, state of health SOH, state of charge SOC, and depth of discharge DoD of the battery. As in fig. 5a, the recovery time tc is different at different depth of discharge, e.g. when the depth of discharge Dx is smaller, the recovery time tcx is higher, the pulse starts at DoD = (Dx-delta) and ends at (Dx + delta); when the discharge depth D1 is large, the recovery time tc1 is small, and the discharge pulse starts from DoD = (D1-delta) to (D1+ delta) ends. Generally, as shown in fig. 5b, the recovery time tc is inversely proportional to the discharge current of the battery, and the recovery time tc is inversely proportional to the battery depth of discharge DoD.
The relaxation time tr varies with the discharge current, temperature, state of health SOH, state of charge SOC, and depth of discharge DoD of the battery. The minimum value of the relaxation time tr is proportional to the pulse current amplitude.
For the same discharge cycle, at the cut-off voltage (DoD =100%), the recovery time tc is the smallest and the relaxation time tr is the largest. Theoretically, the smaller the discharge pulse amplitude, the smaller the recovery time tc, and the larger the relaxation time tr, the less the battery is damaged by the discharge. However, due to the requirement of the load, the tc/tr ratio and the pulse amplitude in the discharge pulse need to be proper so as to ensure that the current waveform required by the load can be generated after the pulse passes through the filter.
From a safety point of view, the discharge current pulse amplitude should not be too large, otherwise the battery would be damaged by overheating. The maximum discharge pulse amplitude depends on the electrochemical performance of the various batteries, the heat dissipation of the battery system and the battery production process, and the state of charge and state of health of the battery. Taking a lithium ion battery as an example, precipitation of negative electrode lithium is easily caused by long-term large-current discharge, and thermal runaway is caused under certain conditions. Generally, the maximum discharge current of a new cell under the same condition is larger, and is generally provided by a production party, and as the battery is continuously aged, the maximum amplitude of the pulse is reduced. In order to ensure that the filtered current waveform meets the load requirement, under the condition that the current pulse amplitude is limited, matching between the filtered current and the load is realized by increasing the pulse duty ratio (tx/tr value).
Based on the above characteristics, the present invention provides a battery cell discharging method, including: and discharging the load in a pulse form, and filtering the discharge pulse by current to form a current waveform required by the load. The pulse amplitude of the discharge pulse is the discharge current of the battery core, the pulse width of the discharge pulse is not more than the recovery time tc, and the pulse gap of the discharge pulse is not less than the relaxation time tr. And the battery cell discharging process is carried out until the load charging is completed or the battery cell is put into a cut-off state.
Fig. 2a, 2b are discharge diagrams of multi-cell batteries. In a multi-cell series system, because the consistency of each cell is different and the aging of each cell is different, the parameter of each cell evolves along with the aging of the battery, and the overdischarge phenomenon of the weakened cell inevitably occurs when the system discharges; the existing battery control system has no management system for adjusting the over-discharge behavior of the battery core in real time. Furthermore, due to the consistency of the cells and the complexity of the load, it is important that the discharge system has the capability of predicting the discharge of each cell. The load prediction and the discharge capacity of each battery cell are balanced in advance, so that the battery system can support the load most durably while the battery cells are prevented from being over-discharged. The existing battery control system has poor over-discharge prevention performance on the battery, and meanwhile, the electric energy stored by each battery cell cannot be released to the maximum degree. In the past, the weaker the weak current core is, the capacity of the battery system is rapidly declined, and the aging of the battery system is accelerated.
As for the condition of a battery system with vital signs, a discharge curve and an overdischarge condition need to be determined in real time under the management of a full life cycle, so that the healthy operation of the battery system can be ensured. Therefore, the invention provides a battery full-life-cycle discharging method and system.
Referring to fig. 6, a method for discharging a battery in a full life cycle includes:
step S01, monitoring discharged battery real-time data and load real-time data under the discharge pulse at the current moment;
step S02, calculating the discharge pulse at the next moment according to the load real-time data, the battery real-time data and the change information of the recovery time tc and the relaxation time tr;
step S03, forming the discharging pulse into a current waveform of the next moment required by the load by controlling current filtering;
step S04, discharging by using the calculated discharge pulse, charging the load by using the calculated current waveform, and discharging until the load is charged or the battery is put to a cut-off state;
the battery real-time data comprises voltage, current and temperature data of the battery; the load real-time data comprises voltage, current and temperature data of the load;
the recovery time is the longest continuous discharge time of the battery, and the electrode structure distortion caused in the recovery time can be eliminated in the subsequent relaxation time; the recovery time tc is changed along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the relaxation time tr is the time required for the distortion and the recovery of the electrode structure, and changes along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the discharge pulse comprises a discharge current, a recovery time tc and a relaxation time tr of the battery core.
In step S02, since the recovery time tc and the relaxation time tr vary with the discharge current, the temperature, the state of health of the battery SOH, the state of charge SOC, and the depth of discharge of the battery DoD of the battery cell, for this reason, the variation information is recorded in the form of a recovery time tc-depth of discharge of the battery DoD curve (as shown in fig. 5 b) and a relaxation time tr-depth of discharge of the battery DoD curve. Wherein the minimum value of the relaxation time tr is proportional to the pulse current amplitude. The above curves are initially formed based on initial data provided by the battery manufacturer and are corrected in real time at a later stage by historical data during use, such as temperature, SOH, SOC, depth of discharge, discharge current, voltage data. Therefore, when the real-time data of the battery is compared with the change information, the comparison curve acquires a corresponding proper discharge pulse as the discharge at the next moment.
The method is suitable for various electrochemical batteries, such as lithium batteries, lead-acid batteries, super capacitors and the like. The battery referred to herein may be a single cell battery or a battery constructed with multiple cells.
When the single-cell battery is subjected to discharge management, firstly, the battery real-time data and the load real-time data discharged under the discharge pulse at the current moment are monitored. And determining the state of charge S0C and the state of health (SOH) of the battery according to the monitored real-time data of the battery, including temperature, current and voltage data. And predicting a load curve according to the monitored real-time data of the load, including voltage, current and temperature data of the load. And then, calculating the discharge pulse at the next moment according to the load real-time data, the battery real-time data and the change information of the recovery time tc and the relaxation time tr. And according to the real-time data of the battery, determining the discharge pulse of each battery cell at the next moment by comparing curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the battery health state SOH, the state of charge SOC and the battery discharge depth DoD of the battery cell and combining the predicted load curve.
When carrying out the discharge management to many electric cores battery, the battery structure that many electric cores constitute has multiple form, if many electric cores battery connect in series the battery that constitutes in proper order, if many electric cores battery connect in parallel the battery that constitutes each other again, if the battery that the electric core of multiunit after connecting in parallel connects in series the battery that constitutes in proper order again, if the battery that multiunit electric core after connecting in series connects in parallel each other and constitutes, etc.. The battery is not limited to the above structure, and may be any battery structure that meets the use requirements. Based on the management of the multi-cell battery, the step of calculating the discharge pulse is further refined as follows:
(a) determining a predicted load curve according to the load real-time data;
(b) according to the real-time data of the battery, determining the discharge pulse of each battery cell at the next moment by contrasting curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the battery health state SOH, the state of charge SOC and the battery discharge depth DoD of the battery cell and combining with a predicted load curve;
(c) and taking the minimum value of the discharge current, the minimum value of the recovery time and the maximum value of the relaxation time in all the battery cores to form the battery discharge pulse at the next moment.
And then, forming the discharge pulse into a current waveform required by the load at the next moment by controlling current filtering. Specifically, filtering calculation is performed, and when the load curve obtained by calculation is consistent with the predicted load curve, filtering processing is performed to filter the discharge pulse to form a current waveform. If the calculated load curve is compared with the predicted load curve and an error exists, the discharge pulse needs to be recalculated.
Taking the battery formed by sequentially connecting multiple electric cores in series as an example shown in fig. 7a, the real-time data of the battery includes the temperature 1 of the electric core 1, the discharge current 1, the discharge voltage 1, the discharge depth 1, the SOC1, and the SOH 1; the temperature 2, the discharge current 2, the discharge voltage 2, the discharge depth 2, the SOC2 and the SOH2 of the battery core 2; temperature 3 of the cell 3, discharge current 3, discharge voltage 3, depth of discharge 3, SOC3, SOH3, …, temperature n of the cell n, discharge current n, discharge voltage n, depth of discharge n, SOCn, SOHn. Each cell includes parameters of a discharge current I, a recovery time tc, and a relaxation time tr (see fig. 7 a). Firstly, the amplitude and the width of a discharge current pulse are measured and calculated by predicting a load curve, and then the pulse amplitude and the recovery time tc are determined according to the post-pulse relaxation time tr. The relaxation time tr is then determined based on the pulse amplitude (i.e., the discharge current) and the recovery time tc. This process is repeated until the calculated load curve is consistent with the predicted load curve, i.e., the optimal result is achieved. After the above steps are performed on the multiple battery cells, the battery discharge pulse at the next time which is finally and actually required is determined by using the step (c) mainly according to the principles of Min { tci }, Max { tri }, and Min { Ii }.
When a battery is provided with a plurality of cells which are connected in series, the discharge depth of each cell is inconsistent during discharge due to inevitable inconsistency of each cell, and over-discharge of part of the cells is caused under certain conditions; the long-term uncontrolled overdischarge of the cell can easily lead to accelerated aging and even thermal runaway, which is more obvious in the case of rapid discharge. In the existing battery management system (such as passive or active management of lithium battery), the balance of cells during discharging is not supported due to the limited balancing capability among cells. The imbalance of the cells can cause over-discharge of part of the cells or the discharge capacity of the battery to be greatly reduced. In order to ensure that the maximum value of the discharge capacity is reached under the health state of each battery cell, the battery cell balance is necessary when the battery discharges. The most appropriate value is re-determined as the next discharge pulse at each moment according to the real-time data of all the electric cores of the battery, so that the requirement on the consistency of all the electric cores in the battery structure with multiple serially connected electric cores can be reduced, the problem of charge balance of the battery is solved, and the capacity of the battery can be fully utilized.
Before the discharging pulse of each battery cell at the next moment is determined, if at least one battery cell in the plurality of battery cells is close to the discharging cut-off state, the battery cells close to the discharging cut-off state are charged by using other battery cells. And then, according to the real-time data of the battery, comparing curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the state of health (SOH) of the battery, the state of charge (SOC) of the battery and the discharge depth (DoD) of the battery, and combining the predicted load curves to determine the discharge pulse of each battery cell at the next moment.
The method for charging the battery cell close to the discharge cut-off state comprises the steps of charging the battery cell with one of other battery cells, such as the battery cell with the largest residual electric quantity of the battery cell, so that the electric quantity difference between the fully charged battery cell and the other battery cells is small; or, charging with a plurality of other cells, such as the cell with the most remaining cell capacity and the second most cell; or, charging with all other cells is included, such as uniform and equal charging. In the charging process, too large charging and too small charging are not needed, so that each charging is ensured, the electric quantity between the battery cores is almost the same, and the consistency of the battery cores is ensured.
Taking the battery formed by connecting multiple electric cores in parallel in sequence as shown in fig. 7b as an example, the real-time data of the battery includes the temperature 1 of the electric core 1, the discharge current 1, the discharge voltage 1, the discharge depth 1, the SOC1, and the SOH 1; the temperature 2, the discharge current 2, the discharge voltage 2, the discharge depth 2, the SOC2 and the SOH2 of the battery core 2; temperature 3 of the cell 3, discharge current 3, discharge voltage 3, depth of discharge 3, SOC3, SOH3, …, temperature n of the cell n, discharge current n, discharge voltage n, depth of discharge n, SOCn, SOHn. Each cell includes parameters of a discharge current I, a recovery time tc, and a relaxation time tr (see fig. 7 b). Firstly, the amplitude and the width of a discharge current pulse are measured and calculated by predicting a load curve, and then the pulse amplitude and the recovery time tc are determined according to the post-pulse relaxation time tr. The relaxation time tr is then determined based on the pulse amplitude (i.e., the discharge current) and the recovery time tc. This process is repeated until the calculated load curve is consistent with the predicted load curve, i.e., the optimal result is achieved. After the above steps are performed on the multiple battery cells, the battery discharge pulse at the next time which is finally and actually required is determined by using the step (c) mainly according to the principles of Min { tci }, Max { tri }, and Min { Ii }.
Due to the non-uniformity of the cells, there is a difference in the current through each cell at equal pressures. In order to ensure the health of each battery cell, the parameters of the discharge pulse are determined, and Min { Ii }, Min { tci }, and max { tri } determine the bias current problem of the discharge pulse of the system when each battery cell discharges under the intelligent pulse discharge.
Taking the battery formed by connecting multiple electric cores in series and parallel as an example shown in fig. 7c and 7d, the real-time data of the battery includes the temperature 1 of the electric core 1, the discharge current 1, the discharge voltage 1, the discharge depth 1, the SOC1, and the SOH 1; the temperature 2, the discharge current 2, the discharge voltage 2, the discharge depth 2, the SOC2 and the SOH2 of the battery core 2; temperature 3 of the cell 3, discharge current 3, discharge voltage 3, depth of discharge 3, SOC3, SOH3, …, temperature n of the cell n, discharge current n, discharge voltage n, depth of discharge n, SOCn, SOHn. Each cell includes parameters of a discharge current I, a recovery time tc, and a relaxation time tr (see fig. 7c and 7 d). Firstly, the amplitude and the width of a discharge current pulse are measured and calculated by predicting a load curve, and then the pulse amplitude and the recovery time tc are determined according to the post-pulse relaxation time tr. The relaxation time tr is then determined based on the pulse amplitude (i.e., the discharge current) and the recovery time tc. This process is repeated until the calculated load curve is consistent with the predicted load curve, i.e., the optimal result is achieved. After the above steps are performed on the multiple battery cells, the battery discharge pulse at the next time which is finally and actually required is determined by using the step (c) mainly according to the principles of Min { tci }, Max { tri }, and Min { Ii }.
For the serial portion, the charge imbalance of the battery is caused due to the spread of the aging characteristics of the serial battery during the normal operation and the difference in the self-discharge rate of the battery. For the parallel portion, due to the non-uniformity of the cells, the current passing through each cell is different at equal pressures, resulting in a bias current. For this reason, based on the difference of each cell and the cell health consideration, the entire battery is discharged with the minimum recovery time value among all cells, and is recovered with the maximum relaxation time value among all cells, and the minimum discharge current is used. The most appropriate value is re-determined as the next discharge pulse at each moment according to the real-time data of all the electric cores of the battery, so that the requirement on the consistency of all the electric cores in a multi-electric-core battery structure can be lowered, the problem of battery charge balance is solved, the battery capacity can be fully utilized, and the problem of discharge bias current of the electric cores is effectively inhibited.
For the part with the series connection in the battery cells, before the discharging pulse of each battery cell at the next moment is determined, if at least one battery cell in the plurality of battery cells is close to the discharging cut-off state, the battery cell close to the discharging cut-off state is charged by using other battery cells. And then, according to the real-time data of the battery, comparing curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the state of health (SOH) of the battery, the state of charge (SOC) of the battery and the discharge depth (DoD) of the battery, and combining the predicted load curves to determine the discharge pulse of each battery cell at the next moment.
The method for charging the battery cell close to the discharge cut-off state comprises the steps of charging the battery cell with one of other battery cells, such as the battery cell with the largest residual electric quantity of the battery cell, so that the electric quantity difference between the fully charged battery cell and the other battery cells is small; or, charging with a plurality of other cells, such as the cell with the most remaining cell capacity and the second most cell; or, charging with all other cells is included, such as uniform and equal charging. In the charging process, too large charging and too small charging are not needed, so that each charging is ensured, the electric quantity between the battery cores is almost the same, and the consistency of the battery cores is ensured.
Fig. 8 shows a discharge system. The system comprises a battery module, a detection protection module, a load detection module, a current filtering module, a database and a calculation control module. The database stores information on the change in the recovery time tc and the relaxation time tr of the battery. The recovery time tc is the longest continuous discharge time of the battery, and the electrode structure distortion caused in the recovery time tc can be eliminated in the subsequent relaxation time; the recovery time tc varies with the discharge current, temperature, state of health (SOH), state of charge (SOC), and depth of discharge (DoD) of the battery cell. The relaxation time tr is the time required for the distortion and the recovery of the electrode structure, and the relaxation time tr changes along with the discharge current, the temperature, the battery health state SOH, the charge state SOC and the battery discharge depth DoD of the battery core. The detection protection module is used for detecting the battery module in real time to obtain real-time data of the battery. The real-time battery data comprises voltage, current and temperature data of the battery. The load detection module is used for detecting the load in real time to obtain real-time load data. The load real-time data comprises voltage, current and temperature data of the load. And the calculation control module calculates a discharge pulse at the next moment according to the load real-time data, the battery real-time data, the recovery time tc of the battery and the change information of the relaxation time tr, wherein the discharge pulse comprises the discharge current, the recovery time tc and the relaxation time tr of the battery core. And the battery module discharges according to the control signal of the calculation control module, and forms a current waveform required by the load by the discharge pulse through the current filtering module to charge the load until the load is charged or the battery core is put into a cut-off state.
The system can track the aging condition of the battery and the change condition of (tc, tr) in the whole life cycle, and meanwhile, protective measures can be taken under extreme conditions to ensure that the battery core cannot be over-discharged.
The battery module is a single-cell battery, and the battery module may also be a multi-cell battery (see fig. 9). When the battery is a multi-cell battery, the battery structure may be formed by connecting multiple cells in series with each other (see fig. 9), or by connecting multiple cells in parallel with each other, or by connecting multiple cells in series and parallel.
The detection protection module comprises a detection circuit and a protection circuit. The detection circuit can adopt the existing detection circuit capable of detecting the voltage, the current and the temperature of the battery. The protection circuit can adopt common circuits for overcurrent, overheat and overvoltage protection of the battery. If protection is required, the protection function is immediately started.
The database comprises an initial database, a current database and a historical database, wherein the database stores a discharge curve, a load curve, an SOH, an SOC, an internal resistance, a recovery time tc, a relaxation time tr and a discharge depth DoD of the battery cell, and the recovery time tc and the relaxation time tr change along with the change information of the discharge current, the temperature, the SOC, the SOH and the discharge depth DoD. At the initial stage, the initial data of the initial database is provided by the battery manufacturer, such as a load curve, a discharge curve, SOH, SOC internal resistance, and is determined according to the provided initial information, such as a recovery time tc, a relaxation time tr, a recovery time tc, and change information of the relaxation time tr along with the change of discharge current, temperature, SOC, SOH, and discharge depth. The presence database stores the above information updated in real time during the discharge system use phase. The historical database stores the battery data at different stages. The presence database outputs the presence data to a history database. The historical database feeds back information to the current status database, each discharge cycle is corrected, and information in the database, such as recovery time tc and relaxation time tr, and change information of the recovery time and the relaxation time along with changes of discharge current, temperature, SOC, SOH and discharge depth, is corrected, so that the health and efficient discharge of the battery are guaranteed.
Specifically, for a battery composed of a single battery cell, the calculation control module includes a load curve determination unit and a battery cell discharge pulse calculation unit. And the load curve determining unit is used for determining a predicted load curve according to the real-time load data. And the battery cell discharge pulse calculation unit is used for contrasting curves of the recovery time tc and the relaxation time tr of each battery cell changing along with the discharge current, the temperature, the battery health state SOH, the charge state SOC and the battery discharge depth DoD of the battery cell according to the real-time data of the battery, and determining the discharge pulse of each battery cell at the next moment by combining the predicted load curve.
Specifically, for a battery composed of multiple cells, the calculation control module includes a load curve determination unit, a cell discharge pulse calculation unit, and a battery discharge pulse calculation unit. And the load curve determining unit is used for determining a predicted load curve according to the real-time load data. And the battery cell discharge pulse calculation unit is used for contrasting curves of the recovery time tc and the relaxation time tr of each battery cell changing along with the discharge current, the temperature, the battery health state SOH, the charge state SOC and the battery discharge depth DoD of the battery cell according to the real-time data of the battery, and determining the discharge pulse of each battery cell at the next moment by combining the predicted load curve. And the battery discharge pulse calculation unit is used for taking the minimum value of the discharge current, the minimum value of the recovery time and the maximum value of the relaxation time in all the battery cores to form the battery discharge pulse at the next moment.
The calculation control module further includes: and the filtering calculation unit is used for carrying out filtering calculation on the battery discharging pulse, if the load curve obtained by calculation is consistent with the predicted load curve, the calculation control module sends a control instruction containing the battery discharging pulse to the battery module, and if not, the load curve determination unit, the battery cell discharging pulse calculation unit and the battery discharging pulse calculation unit recalculate the battery discharging pulse.
Fig. 9 shows a discharge system for a multi-cell series-connected battery. Because of the inevitable inconsistency of each battery cell, the discharge depth of each battery cell is inconsistent during discharge, and over-discharge of part of the battery cells is caused under certain conditions; the long-term uncontrolled overdischarge of the cell can easily lead to accelerated aging and even thermal runaway, which is more obvious in the case of rapid discharge. The discharge system can solve the problems by monitoring and managing the whole life cycle of the battery. The system comprises a battery module, a detection protection module, a load detection module, a current filtering module, a database, a calculation control module, a battery energy management module and a switch module.
The detection protection module 100 is used for detecting the current, voltage, and temperature of each battery cell of the battery in real time, protecting the battery in an extreme case, balancing the battery cells simply, and managing the energy among the battery cells. The load monitoring module 102 is used to monitor the load 101, the switching module may be a power switch 103 for generating a pulsed discharge current, and the current filtering module 104 is used to filter the pulsed current to generate a desired load current waveform. The database 106 is composed of a local database and a cloud database.
The database 106 and the calculation control module 107 receive the battery detection and load detection information and then calculate and generate a control signal to control the power switch and the current filtering module. Firstly, inputting initial battery parameters, algorithms of a battery SoC, SoH, internal resistance and the like, and a change curve of a battery cell pulse amplitude Ii, tci, tri along with temperature, SoC and SoH in a database; data tested by the detection protection module 100 is input into a database in real time, curves of tci and tri of each battery cell at the time are corrected through calculation (a calculation control module 107), minimum min { tci }, maximum max { tri }, and minimum min { Ii } of a battery system are calculated, discharge current pulses are generated, and a load current curve is generated through a filtering module. Meanwhile, the calculation module grasps the unbalance information of each battery cell by calculating the DoD of each battery cell, and balances the battery cells through the detection protection module 100 in the pulse gap min { tri }, so that the DoD of each battery cell approaches. The detection protection module 100 continuously detects each electric core and behavior of the battery system in real time, and generates a subsequent pulse sequence until a load is received or the battery is put into a cut-off state.
The battery energy management module (not shown) and the switch module are disposed between the battery module and the current filtering module. The calculation control module further comprises a charging control unit, and the charging control unit is used for controlling the switch module to cut off a discharging path and control other battery cores to perform charging operation on the battery cores approaching the discharging cut-off state when the battery energy management module detects that at least one battery core of the plurality of battery cores approaches the discharging cut-off state, and then controlling the switch module to switch on the discharging path after charging is completed, and triggering the load curve determination unit, the battery core discharging pulse calculation unit and the battery discharging pulse calculation unit to work.
It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the present invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.
Claims (17)
1. A cell discharge method, comprising:
discharging the load in a pulse form, and filtering the discharge pulse by current to form a current waveform required by the load;
the pulse amplitude of the discharge pulse is the discharge current of the battery core, the pulse width of the discharge pulse is not more than the recovery time tc, and the pulse gap of the discharge pulse is not less than the relaxation time tr;
the recovery time is the longest continuous discharge time of the battery cell, and the electrode structure distortion caused in the time can be eliminated in the subsequent relaxation time;
the relaxation time is the time required for the electrode structure to distort and recover to the original state.
2. The cell discharging method according to claim 1, wherein the recovery time tc varies with the discharging current, the temperature, the state of health (SOH), the state of charge (SOC), and the depth of discharge (DoD) of the cell.
3. The cell discharging method according to claim 1, wherein the recovery time tc is inversely proportional to a discharge current of the cell, and the recovery time tc is inversely proportional to a battery depth of discharge DoD.
4. The cell discharging method according to claim 1, wherein the relaxation time tr varies with a discharge current, a temperature, a state of health (SOH), a state of charge (SOC), and a depth of discharge (DoD) of the cell.
5. The cell discharge method according to claim 1, wherein the minimum value of the relaxation time tr is proportional to the cell discharge current.
6. The cell discharging method according to claim 1, further comprising: and the discharging process is carried out until the load is charged or the battery cell is put into a cut-off state.
7. A method for full-life discharge of a battery, comprising:
monitoring battery real-time data and load real-time data discharged under the discharge pulse at the current moment;
calculating a discharge pulse at the next moment according to the load real-time data, the battery real-time data and the change information of the recovery time tc and the relaxation time tr;
forming the discharge pulse into a current waveform at the next moment required by the load by controlling current filtering;
discharging by adopting the calculated discharge pulse, charging the load by adopting the calculated current waveform, and discharging until the load is charged completely or the battery is put into a cut-off state;
the battery real-time data comprises voltage, current and temperature data of the battery; the load real-time data comprises voltage, current and temperature data of the load;
the recovery time is the longest continuous discharge time of the battery, and the electrode structure distortion caused in the recovery time can be eliminated in the subsequent relaxation time; the recovery time tc is changed along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the relaxation time tr is the time required for the distortion and the recovery of the electrode structure, and changes along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the discharge pulse comprises a discharge current, a recovery time tc and a relaxation time tr of the battery core.
8. The method as claimed in claim 7, wherein the step of calculating the discharging pulse at the next time according to the load real-time data, the battery real-time data, and the change information of the recovery time tc and the relaxation time tr comprises:
determining a predicted load curve according to the load real-time data;
according to the real-time data of the battery, determining the discharge pulse of each battery cell at the next moment by contrasting curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the battery health state SOH, the state of charge SOC and the battery discharge depth DoD of the battery cell and combining with a predicted load curve;
and taking the minimum value of the discharge current, the minimum value of the recovery time and the maximum value of the relaxation time in all the battery cores to form the battery discharge pulse at the next moment.
9. The battery full-life-cycle discharging method according to claim 8, wherein when the battery includes series cells, the step of calculating the discharging pulse at the next time according to the load real-time data, the battery real-time data, and the change information of the recovery time tc and the relaxation time tr further includes:
before the discharging pulse of each battery cell at the next moment is determined, if at least one battery cell in the plurality of battery cells is close to a discharging cut-off state, charging the battery cell close to the discharging cut-off state by using other battery cells;
and then, according to the real-time data of the battery, comparing curves of the recovery time tc and the relaxation time tr of each battery cell, which are changed along with the discharge current, the temperature, the state of health (SOH) of the battery, the state of charge (SOC) of the battery and the discharge depth (DoD) of the battery, and combining the predicted load curves to determine the discharge pulse of each battery cell at the next moment.
10. The method of claim 8, wherein the step of forming the battery discharge pulse into the current waveform at the next moment required by the load by controlling the current filtering comprises:
and performing filtering calculation, and performing filtering processing to filter the discharge pulse to form a current waveform when the load curve obtained by calculation is consistent with the predicted load curve.
11. The battery full-life-cycle discharging method according to claim 7, wherein the method for calculating the discharging pulse and the current waveform at the next moment is suitable for a battery formed by connecting a plurality of cells in series, or a battery formed by connecting a plurality of cells in parallel, or a battery formed by connecting a plurality of cells in series and in parallel.
12. The battery full-life cycle discharging method of claim 8, further comprising: and correcting the curve of each battery cell in real time according to the real-time data of the battery, the SOH (state of charge), the SOC (state of charge) and the DOD (depth of discharge).
13. The battery full-life-cycle discharging method as claimed in claim 7, wherein the method is suitable for discharging chemical batteries.
14. A battery full life cycle discharging system is characterized by comprising a battery module, a detection protection module, a load detection module, a current filtering module, a database and a calculation control module; the database stores the change information of the recovery time tc and the relaxation time tr of the battery; the detection protection module is used for detecting the battery module in real time to obtain battery real-time data; the load detection module is used for detecting a load in real time to obtain load real-time data; the calculation control module calculates the discharge pulse at the next moment according to the load real-time data, the battery real-time data, the recovery time tc of the battery and the change information of the relaxation time tr; the battery module discharges according to the control signal of the calculation control module, and forms a current waveform required by a load by a discharge pulse through the current filtering module to charge the load until the load is charged or the battery core is put into a cut-off state;
the battery real-time data comprises voltage, current and temperature data of the battery; the load real-time data comprises voltage, current and temperature data of the load;
the recovery time tc is the longest continuous discharge time of the battery, and the electrode structure distortion caused in the recovery time tc can be eliminated in the subsequent relaxation time; the recovery time tc is changed along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the relaxation time tr is the time required for the distortion and the recovery of the electrode structure, and changes along with the discharge current, the temperature, the SOH (state of health), the SOC (state of charge) and the DOD (depth of discharge) of the battery cell;
the discharge pulse comprises a discharge current, a recovery time tc and a relaxation time tr of the battery core.
15. The battery full-life cycle discharge system of claim 14, wherein the calculation control module comprises:
the load curve determining unit is used for determining a predicted load curve according to the load real-time data;
the battery cell discharge pulse calculation unit is used for contrasting curves of the recovery time tc and the relaxation time tr of each battery cell changing along with the discharge current, the temperature, the battery health state SOH, the charge state SOC and the battery discharge depth DoD of the battery cell according to the real-time data of the battery, and determining the discharge pulse of each battery cell at the next moment by combining the predicted load curve;
and the battery discharge pulse calculation unit is used for taking the minimum value of the discharge current, the minimum value of the recovery time and the maximum value of the relaxation time in all the battery cells to form the battery discharge pulse at the next moment.
16. The battery full-life cycle discharge system of claim 15, wherein said calculation control module further comprises: and the filtering calculation unit is used for carrying out filtering calculation on the battery discharging pulse, if the load curve obtained by calculation is consistent with the predicted load curve, the calculation control module sends a control instruction containing the battery discharging pulse to the battery module, and if not, the load curve determination unit, the battery cell discharging pulse calculation unit and the battery discharging pulse calculation unit recalculate the battery discharging pulse.
17. The battery full-life cycle discharge system of claim 15, further comprising a battery energy management module and a switch module disposed between the battery module and the current filtering module; the calculation control module further comprises a charging control unit, and the charging control unit is used for controlling the switch module to cut off a discharging path and control other battery cores to perform charging operation on the battery cores approaching the discharging cut-off state when the battery energy management module detects that at least one battery core of the plurality of battery cores approaches the discharging cut-off state, and then controlling the switch module to switch on the discharging path after charging is completed, and triggering the load curve determination unit, the battery core discharging pulse calculation unit and the battery discharging pulse calculation unit to work.
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