Methods and control devices for determining the amount of energy in a battery or cell.

Abstract

This invention relates to a method for determining the amount (20) of energy in a battery or cell, wherein an initial charging state (10) is received, a final charging state (11) is received, a load curve (12) between the initial charging state (10) and the final charging state (11) is received, an intermediate charging state (14) between the initial charging state (10) and the final charging state (11) and associated weighting coefficients (15) are determined, parameters (16) of an equivalent circuit model (30) of the battery or cell are estimated for each determined intermediate charging state (14), and the amount (20) of energy in the battery or cell between the initial charging state (10) and the final charging state (11) is determined based on the load curve (12), the weighting coefficients (15) and the parameters (16) and provided as an energy quantity signal (21). This invention also relates to a control device (1) for determining the amount (20) of energy in a battery or cell.

Description

[0001] This invention relates to a method and control device for determining the amount of energy in a battery or cell.

[0002] With the increasing electrification of transportation, batteries, especially lithium-ion batteries, are becoming increasingly important. A crucial parameter is the amount of energy, or energy quantity, that is gained or added during battery operation. This energy quantity determines remaining driving range, operating time, or the amount of energy required to fully charge the battery. The energy quantity can be determined in both the charging and discharging directions. Furthermore, it can be determined within the range of the battery's state of charge (SOC). Accurate determination of the energy quantity is essential for determining the battery's (current) state.

[0003] A recursive method for adaptive multiparameter regression is known from US7612532B2, which expands upon a forgetting factor and is unambiguous for each regression parameter. Applications of this method can include lead-acid batteries, nickel-metal hydride batteries, and lithium-ion batteries. A control method is introduced, which has an arbitrary number of model parameters, each with its own time-weighted coefficients. A method for determining the optimal values ​​for the time-weighted coefficients is included to give greater influence to the most recently obtained data used to determine the system state. A weighted recursive least squares method is used, where the time weighting corresponds to an exponential forgetting form. The results do not include matrix inversion, and the method is iterative, meaning each parameter is fed back individually at each time step.

[0004] The technical problem to be solved by the present invention is to implement a method and a control device for determining the amount of energy in a battery or cell, wherein the amount of energy can be reliably determined.

[0005] The aforementioned technical problem is solved according to the present invention by a method having the features of claim 1 and a control device having the features of claim 6. Advantageous embodiments of the invention are derived from the dependent claims.

[0006] In particular, a method is provided for determining the amount of energy in a battery or cell, wherein an initial state of charge is received, a final state of charge is received, a load curve between the initial and final states of charge is received, an intermediate state of charge and associated weighting coefficients are determined between the initial and final states of charge, parameters of an equivalent circuit model of the battery or cell are estimated for each determined intermediate state of charge, and the amount of energy in the battery or cell between the initial and final states of charge is determined based on the load curve, weighting coefficients, and parameters and provided as an energy quantity signal or energy quantity signal.

[0007] Furthermore, a control device for determining the amount of energy in a battery or cell is provided, wherein the control device is configured to: receive an initial charging state, receive a final charging state, receive a load curve between the initial charging state and the final charging state, determine an intermediate charging state and associated weighting coefficients between the initial charging state and the final charging state, estimate parameters of an equivalent circuit model of the battery or cell for each determined intermediate charging state, and determine the amount of energy in the battery or cell between the initial charging state and the final charging state based on the load curve, weighting coefficients, and parameters, and provide it as an energy quantity signal.

[0008] This method and control device enable a better determination of the amount of energy, particularly estimation or assessment of the amount of energy. To this end, it is stipulated that parameters of the equivalent circuit model of the battery or cell are estimated for intermediate charging states within the interval between the initial charging state and the final charging state. The parameters are estimated here, in particular, based on the intermediate charging states discussed separately. Furthermore, temperature or temperature dependence is particularly considered in estimating the parameters. Therefore, the parameters depend particularly on the corresponding intermediate charging state and the temperature present. The temperature can be detected, for example, by a temperature sensor on the battery or cell, or can be provided by other means, such as estimation. Based on the received load curve, weighting coefficients, and estimated parameters, the amount of energy of the battery or cell between the initial charging state and the final charging state is determined. The determined amount of energy is provided as an energy quantity signal. The energy quantity signal can be analog or digital. The energy quantity signal can be transmitted, for example, to a battery control device and / or a vehicle control device or charging infrastructure.

[0009] One advantage of this method and control device is that by considering parameters related to the state of charge and, in particular, temperature, losses occurring in the battery or cell can be better accounted for. Therefore, the amount of energy between the initial and final states of charge can be more accurately determined.

[0010] The initial state of charge and the final state of charge are particularly located between the minimum state of charge and the maximum state of charge of the battery or cell. The initial state of charge and the final state of charge are received, for example, as analog or digital initial state of charge signals and analog or digital final state of charge signals, such as from a battery control unit and / or a vehicle control unit. The initial state of charge and the final state of charge can also be queried at the battery control unit or the vehicle control unit.

[0011] Load profiles specifically relate to the current between the initial and final states of charge during charging and / or discharging. Load profiles can be based on detected sensor data (current measurements) or on predetermined data, such as simulated or estimated data. Load profiles can also be time-resolved.

[0012] The parameters of the equivalent circuit model can be determined empirically for different states of charge and temperatures of the battery. The determined parameters are then stored in memory, particularly the memory of the control device, and can be retrieved as needed, and interpolated if necessary when estimating parameters for intermediate states of charge. Alternatively, or additionally, the parameters can also be determined and / or estimated through simulation.

[0013] The determined intermediate charging states form control points, particularly in the numerical integration performed to determine the amount of energy. Specifically, the intermediate charging states between the initial and final charging states, along with the associated weighting coefficients, are determined as preset values ​​by a selected numerical integration method. In other words, the selected numerical integration method defines the intermediate charging states and associated weighting coefficients as control points. Thus, the amount of energy within any arbitrary charging state interval can be determined by integrating over the voltage of the battery or cell. For example, open or closed Newton-Cotes formulas can be chosen as the numerical integration method, using equally distributed control points. Even unequally distributed control points can be used via the Gauss-Legend integration method. The methods differ in the choice of control points, but the rest of the procedure is the same. In particular, the integration is always calculated as a weighted sum of voltages at the control points. However, other numerical integration methods can also be used in principle.

[0014] The control device can be designed individually or in combination as a combination of hardware and software, such as program code that executes on a microcontroller or microprocessor. However, it can be specified that parts are designed individually or in combination as application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs).

[0015] This method and control device are particularly applicable to vehicles, especially motor vehicles. However, the vehicles can also be other land, rail, water, air, or space vehicles, such as drones or air taxis. In principle, this method and control device can also be used for other mobile or stationary energy storage devices.

[0016] The amount of energy can generally be calculated as follows:

[0017]

[0018] In this Q Nominal It refers to the capacity of the battery or cell, measured in Ah (ampere-hours), or State of Charge (SOC). start It is the initial charging state, SOC. End The final state of charge (represented as a percentage or a value between 0 and 1, respectively), U is the voltage of the battery or cell, and SOC is the state of charge of the battery or cell.

[0019] The integral is solved using numerical integration methods, such as either an open-ended or closed-ended Newton-Cotes formula:

[0020]

[0021] Here w i This corresponds to the intermediate state of charge (SOC). i The weighting coefficients at control point i.

[0022] In one embodiment, the equivalent circuit model is specified to include at least one open-circuit voltage as a voltage source, at least one series resistor, and at least one RC element. This allows the main effects in the battery or cell to be taken into account, particularly time-related characteristics, which can be considered through at least one RC element. In particular, the equivalent circuit model has more than one RC element so that multiple time-related processes within the battery or cell can be considered.

[0023] In one implementation, to determine the amount of energy, for each intermediate state of charge, the total voltage of the battery or cell is determined at least by the open-circuit voltage, the voltage across the series resistor, and the voltage across at least one RC element. This allows for particularly efficient determination of the amount of energy. The RC elements are, in particular, connected in series.

[0024] The voltage of the battery or cell is:

[0025]

[0026] Here U ocv It is the open-circuit voltage, U R0 It is the voltage across the series resistor, U RC,n It is the voltage across the nth RC element. This applies to each intermediate state of charge (SOC). i :

[0027]

[0028] Open-circuit voltage U ocv Based on the intermediate state of charge (SOC) i It is estimated as a parameter of the equivalent circuit model.

[0029] This applies to the amount of energy E:

[0030]

[0031] In another embodiment, the load curve is received in the form of mean square current and average current, wherein, for intermediate charging states, the series resistor voltage across the series resistor is determined by the mean square current and the average current. This allows for reliable determination of the series resistor voltage, especially in cases where the current flow of the load curve is not constant.

[0032] For depending on the intermediate state of charge (SOC) iSeries resistor voltage U R0 :

[0033]

[0034] Here, R0 depends on the intermediate state of charge (SOC). i The series resistance, I RMS It is the root mean square value of the current, I Avg R0 is the average value of the current. R0 is a parameter that estimates the corresponding intermediate state of charge through an equivalent circuit model. The average value can also be the average value of multiple control points around the control point in question (e.g., in the form of a smoothed average value that takes into account a predetermined number of control points).

[0035] In another embodiment, to determine the RC element voltage on at least one RC element, the time from the initial charging state until reaching the corresponding intermediate charging state in question is determined, wherein the RC element voltage is determined based on the determined time and the time constant of at least one RC element. This allows for a better estimation of the RC element voltage of at least one RC element, and the result allows for a better determination of the total voltage.

[0036] For reaching the corresponding intermediate state of charge (SOC) discussed i Time t i :

[0037]

[0038] Depends on intermediate state of charge (SOC) i RC element voltage U RC,n :

[0039]

[0040] Here τ n This is the time constant for the nth RC element. The resistance R of the RC element... RC,n As a parameter, it is based on the intermediate state of charge (SOC). i Estimated using an equivalent circuit model.

[0041] To reduce the required computational power, in one implementation, the RC element can be considered saturated so that it can be replaced by a constant resistor. This approach is particularly feasible when there is a constant load (constant current in the load curve) and / or a large range between the initial and final charging states.

[0042] Further features related to the design of the control device are derived from the description of the method design. Here, the advantages of the control device are the same as those in the method design.

[0043] The present invention will now be further described with reference to the accompanying drawings and preferred embodiments. In the drawings:

[0044] Figure 1 A schematic diagram illustrating an embodiment of a control device for determining the amount of energy in a battery or cell;

[0045] Figure 2 A schematic diagram illustrating the process of handling in a control device according to an embodiment of this method is shown;

[0046] Figure 3 A schematic diagram of the equivalent circuit model is shown.

[0047] Figure 1 The diagram shows an embodiment of a control device 1 for determining the amount 20 of energy in a battery or cell.

[0048] Control device 1 includes computing device 2 and memory 3. Computing device 2 is, for example, a microprocessor or microcontroller, on which program code is executed to perform the methods described in this disclosure. Alternatively, fixed-wire hardware components may be specified, which partially or completely perform the methods. Control device 1 may be part of a battery control device.

[0049] The initial charging state 10, final charging state 11, and load curve 12 are transmitted to the control device 1. Additionally, the current temperature 13 of the battery or cell can be specified as input to the control device 1. The current temperature of the battery or cell can be detected and / or estimated, for example, by a temperature sensor 50. The control device 1 and the temperature sensor 50 can also be integrated into a single device. The initial charging state 10, final charging state 11, and load curve 12 are queried and / or provided, for example, from an energy management system (not shown) or a vehicle control device 51 of a vehicle (not shown). The initial charging state 10, final charging state 11, and load curve 12 are received by the control device 1 and processed by the computing device 2.

[0050] According to one embodiment of the method, the processing in the control device 1 is illustrated as a flowchart. Figure 2 The diagram shows the signal flow. Control device 1 sets up intermediate charging states 14 and associated weighting factors 15 between the initial charging state 11 and the final charging state 12. This is done in module 100. For each determined intermediate charging state 14, control device 1 estimates parameters 16 of the equivalent circuit model of the battery or cell in module 101. This is especially important considering temperature 13. For example, the estimation is based on empirically determined parameters from the equivalent circuit model. It can be specified here that the empirically determined parameters are interpolated. Alternatively, or additionally, it can be specified that the parameters are estimated based on simulation.

[0051] exist Figure 3An example equivalent circuit model is shown. In this example, the equivalent circuit model 30 is specified to include at least one open-circuit voltage U modeled in the form of a capacitor C. ocv The equivalent circuit model 30 consists of a voltage source, a series resistor R0, and two RC elements RC1 and RC2 with resistors R1 and R2 and capacitors C1 and C2. However, in principle, the equivalent circuit model 30 can also have more or fewer RC elements RC1 and RC2.

[0052] As parameter 16 ( Figure 2 Based on the corresponding intermediate charging state 14, the open-circuit voltage U is estimated in particular. ocv ( Figure 3 ), series resistor R0 ( Figure 3 ), RC components RC1, RC2 resistors R1, R2 ( Figure 3 The time constants of RC1 and RC2 are also estimated for the initial charging state 10.

[0053] Based on the load curve 12( particularly provided as the average current 12-1 and the mean square current 12-2), Figure 2 Using weighting coefficient 15 and parameter 16, module 102 determines the amount of energy 20 of the battery or cell between the initial charging state 10 and the final charging state 11. The determined amount of energy 20 is provided as an energy quantity signal 21.

[0054] To determine the amount of energy, it is specifically stipulated that for each intermediate charging state 14, it is at least determined by the open-circuit voltage U. ocv The series resistor voltage U across the series resistor R0 R0 And the voltage U of the RC elements RC1 and RC2 RC1 U RC2 Determine the total voltage U of the battery or cell. Figure 3 ).

[0055] It is specifically stipulated here that, for intermediate charging state 14, the mean square value of the current is 12-2 ( Figure 2 ) and the average value of the current 12-1 ( Figure 2 Determine the series resistor voltage U across the series resistor R0. R0 Furthermore, it is specifically stipulated that, in order to determine at least one RC element RC1, RC2 ( Figure 3 The voltage U of the RC element on the ) RC1 U RC2 The time from the initial charging state 10 until the corresponding intermediate charging state 14 is determined, wherein the RC element voltage U RC1 U RC2 The determination is based on the determined time and the time constant of at least one RC element RC1, RC2.

[0056] The total voltage U generated by the battery or cell is then numerically integrated over the interval between the initial charging state 10 and the final charging state 11 to obtain the energy quantity 20. This can be done, for example, using an open or closed Newton-Cotes formula. However, other numerical integration methods can also be used in principle. The obtained energy quantity 20 is then used to generate an energy quantity signal 21, which encodes the value of the energy quantity 20 in an appropriate form. The energy quantity signal 21 can be input, for example, to a battery control device 52 or a vehicle control device 51.

[0057] This method and control device are particularly effective at determining the amount of energy in a battery or cell. They can be advantageously used at different temperatures and within different states of charge ranges. Furthermore, non-constant load curves can be considered to better account for losses. Different charging histories can also be taken into account, as the current state of charge of the battery is always taken into account.

[0058] List of reference numerals

[0059] 1. Control equipment

[0060] 2. Computing device

[0061] 3. Memory

[0062] 10. Initial charging state

[0063] 11 Final charging status

[0064] 12 Load Curve

[0065] 12-1 Average Current

[0066] 12-2 Mean Square Current

[0067] 13 Temperature

[0068] 14. Intermediate charging state

[0069] 15 Weighting coefficients

[0070] 16 parameters

[0071] 20. Amount of energy

[0072] 21. Energy quantity signal

[0073] 30 Equivalent Circuit Model

[0074] 50 Temperature Sensor

[0075] 51 Vehicle control device

[0076] 52 Battery control device

[0077] Modules 100-102

[0078] Cx capacitor

[0079] C Capacitor (Open Circuit Voltage)

[0080] RCx RC components

[0081] Rx resistor

[0082] U Total Voltage

[0083] U ocv Open circuit voltage

[0084] R0 series resistor

[0085] U R0 Series resistor voltage

[0086] U RCX RC element voltage

Claims

1. A method for determining the amount of energy (20) in a battery or cell, in, Receive the initial charging status (10), Among them, receiving the final charging status (11), Among them, the load curve (12) between the initial charging state (10) and the final charging state (11) is received. Among them, the intermediate charging state (14) between the initial charging state (10) and the final charging state (11) and the relevant weighting coefficient (15) are determined. Specifically, for each determined intermediate charging state (14), the parameters (16) of the equivalent circuit model (30) of the battery or cell are estimated, and the amount of energy (20) of the battery or cell between the initial charging state (10) and the final charging state (11) is determined based on the load curve (12), weighting coefficients (15), and parameters (16) and provided as an energy quantity signal (21). The equivalent circuit model (30) includes at least one open-circuit voltage (U) as a voltage source. ocv ), at least one series resistor (R0) and at least one RC element (RCx), wherein the load curve (12) is received in the form of a current mean square value (12-2) and a current average value (12-1), wherein, for an intermediate charging state (14), the series resistor voltage (U) across the series resistor (R0) is determined by the current mean square value (12-2) and the current average value (12-1). R0 ).

2. The method according to claim 1, characterized in that, To determine the amount of energy (20), for each intermediate charging state (14), it is determined at least by the open-circuit voltage (U). ocv ), the series resistor voltage (U) across the series resistor (R0) R0 ) and the RC element voltage (U) on the at least one RC element (RCx). RCx Determine the total voltage U of the battery or cell.

3. The method according to claim 2, characterized in that, To determine the RC element voltage (U) on at least one RC element (RCx) RCx The time from the initial charging state (10) to the arrival of the corresponding intermediate charging state (14) is determined, wherein the RC element voltage (U) RCx The determination is based on the determined time and the time constant of at least one RC element (RCx).

4. A control device (1) for determining the amount (20) of energy in a battery or cell, wherein, The control device (1) is configured as follows: Receive the initial charging status (10), Receive final charging status (11), Receive the load curve (12) between the initial charging state (10) and the final charging state (11). Determine the intermediate charging states (14) between the initial charging state (10) and the final charging state (11) and the associated weighting coefficients (15). For each determined intermediate state of charge (14), the parameters (16) of the equivalent circuit model (30) of the battery or cell are estimated, and the amount of energy (20) of the battery or cell between the initial state of charge (10) and the final state of charge (11) is determined based on the load curve (12), weighting coefficients (15) and parameters (16) and provided as an energy quantity signal (21). The equivalent circuit model (30) includes at least one open-circuit voltage (U) as a voltage source. ocv The control device (1) includes at least one series resistor (R0) and at least one RC element (RCx), wherein the load curve (12) is received in the form of a current mean square value (12-2) and a current average value (12-1), wherein, for an intermediate charging state (14), the series resistor voltage (U) across the series resistor (R0) is determined by the current mean square value (12-2) and the current average value (12-1). R0 ).

5. The control device (1) according to claim 4, characterized in that, The control device (1) is configured such that, in order to determine the amount of energy (20), for each intermediate charging state (14), at least the open-circuit voltage (U) is used. ocv ), the series resistor voltage (U) across the series resistor (R0) R0 ) and the RC element voltage (U) on at least one RC element (RCx). RCx Determine the total voltage (U) of the battery or cell.

6. The control device (1) according to claim 5, characterized in that, The control device (1) is configured to determine the RC element voltage (U) on at least one RC element (RCx). RCx The time from the initial charging state (10) to the arrival of the respective intermediate charging state (14) is determined, and the RC element voltage (U) is determined based on the determined time and the time constant of at least one RC element (RCx). RCx ).

Images