Charging device and method for charging an electrical energy storage device

Abstract

The invention relates to a charging device (1) and a method for charging an electrical energy storage device (2), wherein the charging device (1) has a control unit (12) and a regulating unit (9), wherein the charging device (1) is designed to charge the electrical energy storage device (2) to a defined state of charge within a predefined charging time and to regulate the charging current and the secondary reaction current of the electrical energy storage device (2) for this purpose.

Description

Technical Field

[0001] The invention relates to a charging device and a method for charging an electrical energy storage device. Background Art

[0002] US 2014 / 0091772 A1 discloses a system for dynamically managing heat in a battery pack or supercapacitor in an electric vehicle.

[0003] WO 2012 / 0054864 A1 describes a device and a method for ultrafast charging of batteries.

[0004] US 2013 / 0179061 A1 describes a system for managing an electrical power grid having charging stations for electric vehicles.

[0005] The paper “Design of a Model-based Fractional-Order Controller for Optimal Charging of Batteries” (IFAC-Online Papers, Vol. 51, No. 28, pp. 97-102, 2018) describes a charging device for a battery that uses an electrothermal battery aging model.

[0006] The paper “A Fractional-Order Electro-Thermal Aging Model for Lifetime Enhancement of Lithium-ion Batteries” (IFAC-Online Papers, Vol. 51, No. 2, pp. 220-225, 2018) describes a battery model for simulating the voltage response to an input current. Summary of the invention

[0007] The core of the invention is a charging device for an electrical energy storage device, wherein the charging device has a control unit and a regulating unit, wherein the charging device is designed to charge the electrical energy storage device to a defined state of charge within a predetermined charging time and to regulate a charging current and a side reaction current of the electrical energy storage device for this purpose.

[0008] The invention is based on the fact that the control unit and the regulating unit can be operated simultaneously. The charging current is controlled by means of the control unit in such a way that the electrical energy storage device can be charged to a defined state of charge within a predefined charging time. At the same time, the regulating unit uses the current state parameters of the electrical energy storage device in order to regulate the charging current in such a way that the aging of the electrical energy storage device is minimized.

[0009] Advantageously, the charger can quickly adapt the charging current to the dynamic state changes of the electrical energy storage device, thereby shortening the charging time or rapidly charging the electrical energy storage device while reducing aging.

[0010] Further advantageous embodiments of the invention are the subject matter of the following.

[0011] According to an advantageous embodiment, the charging device has an evaluation unit having at least one connection for a sensor of the electrical energy storage device. As a result, a state parameter of the electrical energy storage device can be evaluated by the evaluation unit and can be adjusted by the charging device. Advantageously, the connection is suitable for a temperature sensor and / or a voltage sensor.

[0012] Advantageously, the evaluation unit is designed to determine at least the aging of the electrical energy storage device by means of a simplified linear electrothermal aging model of the electrical energy storage device, in particular by means of an aging model approximated using a Voltaic series. Such a model allows a rapid determination of the aging with good accuracy, so that the charging device can react quickly to changes in the state of the electrical energy storage device.

[0013] It is advantageous if the evaluation unit is connected to the control unit and / or the regulating unit in a signal-conducting manner so that the charge state and / or the aging state can be evaluated by the control unit and / or the regulating unit and the charging current can be matched or regulated to the current charge state or the current aging state.

[0014] Advantageously, the control unit is designed to control the first charging current and the first side reaction current in such a way that the electrical energy storage device is charged to a defined state of charge within a predefined charging time.

[0015] According to another advantageous embodiment, the control unit has an optimization device, in particular wherein the optimization device is designed to optimize a charge profile, in particular an affine charge profile or a polynomial charge profile, in particular by determining the minimum of a loss function of a parameter of the charge profile in a numerical manner, in particular by means of a gradient method. Advantageously, the charge profile has only a single parameter, which can be determined quickly by the optimization device by means of a numerical method, in particular a gradient method.

[0016] In this case, it is advantageous if the control unit has a charge control device, in particular if the charge control device is designed to control the first charging current according to an optimized charging profile.

[0017] In this case, it is advantageous if the regulating unit is designed to regulate the third charging current in such a way that the second secondary reaction current of the electrical energy store is minimized, thereby enabling aging of the electrical energy store to be reduced.

[0018] Furthermore, it is advantageous if the charging device has a summing device which is arranged between the control unit and the regulating unit on the one hand and the output connection of the charging device on the other hand, in particular wherein the summing device is designed to add the first charging current or the second charging current from the control unit to the third charging current from the regulating unit and to generate a fourth charging current as a sum. Thus, if only the first or the second charging current is available, it can be used for charging. If the third charging current is not equal to zero, the fourth charging current can be used for charging.

[0019] In this case, it is advantageous if the charging device has a low-pass filter which is arranged between the control unit and the summing device, in particular if the low-pass filter is designed to smooth the first charging current into the second charging current.

[0020] Advantageously, the charging device has a comparator device which is arranged between the control unit and the aging evaluation device on the one hand and the summing device on the other hand, in particular wherein the comparator device is designed to compare the first side reaction current with the second side reaction current. As a result, the side reaction current caused by the control unit can be compared with the current side reaction current in the electrical energy storage device, and the aging of the electrical energy storage device can be controlled by the control unit.

[0021] Advantageously, the comparator device is designed to determine a difference between the first side reaction current and the second side reaction current.

[0022] The core of the invention for a method for charging an electrical energy storage device, in particular with the aid of a charging device as described herein, is that the method comprises control method steps and regulation method steps which are carried out in parallel in time, wherein the electrical energy storage device is charged to a defined state of charge within a predetermined charging time and for this purpose the charging current and the side reaction current of the electrical energy storage device are regulated.

[0023] The invention is based on the fact that the regulation and control are carried out in a time-consistent manner, so that the charging process can be quickly adapted to the dynamic changes of the electrical energy storage device.

[0024] Advantageously, the charging time of the electrical energy storage device can be shortened while reducing aging or the electrical energy storage device can be charged more quickly.

[0025] According to an advantageous embodiment, the current state of charge and the current state of aging and / or the second side reaction current are determined from the sensor data of the electrical energy storage device, in particular by means of a simplified linear electrothermal aging model of the electrical energy storage device, in particular the linear electrothermal aging model is approximated by means of a Voltaic series. As a result, the current parameters of the electrical energy storage device can be determined quickly with little effort and good accuracy.

[0026] Furthermore, it is advantageous to optimize a charge profile, in particular an affine or polynomial charge profile, in particular by determining the minimum of a loss function of parameters of the charge profile in a numerical manner, in particular by means of a gradient method. The first charge current and the first side reaction current are controlled according to the optimized charge profile. It is advantageous that the charge profile has only a single parameter, which can be determined quickly and with good accuracy by means of a numerical method, in particular by means of a gradient method.

[0027] In this case, it is advantageous if the first side reaction current is compared with the second side reaction current and a third charging current is generated, in particular if the first side reaction current has the same value as the second side reaction current, the third charging current is equal to zero, and / or if the first side reaction current and the second side reaction current have different values, the third charging current is determined in such a way that the aging of the electrical energy storage device is minimized, wherein the third charging current is added to the second charging current and a fourth charging current is generated, in particular if the third charging current is equal to zero, the fourth charging current has the same value as the second charging current, wherein the electrical energy storage device is charged with the second charging current or the fourth charging current, in particular if no third charging current is available, the second charging current is used, and if the third charging current is available, the fourth charging current is used. In this case, it is advantageous if the second charging current is available as soon as the charging process is started. The third charging current is available only with a delay, because the regulation method step is more time-consuming than the control method step. As soon as the third charging current is available, the fourth charging current can be generated and the electrical energy storage device can be charged with the fourth charging current, so that the aging of the electrical energy storage device can be reduced.

[0028] The above-mentioned designs and improvements can be combined with each other as much as makes sense. Other possible designs, improvements and implementations of the present invention also include combinations of features described above or below with respect to the embodiments of the present invention that are not explicitly mentioned. In particular, those skilled in the art will also add individual aspects as improvements or supplements to the corresponding basic forms of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the following paragraphs, the invention is explained with the aid of exemplary embodiments, from which further inventive features emerge, but to which the invention is not restricted within its scope. The exemplary embodiments are shown in the drawings.

[0030] Figure 1 A schematic diagram of a method according to the invention for charging an electrical energy storage device 2 by means of a charging device 1 according to the invention is shown.

[0031] Figure 2 The affine charging profile for the current Ia is shown with the total charge Qc, the charging time tch and the starting current Iao as a function of the time t,

[0032] Figure 3 The polynomial charge profile for the current Ip is shown with the total charge Qc, the charging time tch and the starting current Ipo as a function of time t, and

[0033] Figure 4 The global loss function f of the polynomial charging profile is shown as a function of the optimization parameter d. DETAILED DESCRIPTION

[0034] exist Figure 1 Schematically, a charging device 1 and an electrical energy storage device 2 according to the invention are shown in FIG.

[0035] The charging device 1 comprises:

[0036] a control unit 12 having an optimization device 3 and a charge control device 11,

[0037] - Low pass filter 4,

[0038] - an evaluation unit 5, said evaluation unit having a charge state evaluation device 6 and an aging evaluation device 7,

[0039] - Total devices 8,

[0040] - regulating device 9 and

[0041] - Comparative device 10.

[0042] The evaluation unit 5 is connected to the electrical energy storage device 2 in a signal-conducting manner and is configured to receive sensor signals of sensors, in particular a temperature sensor and at least one cell voltage sensor, of the electrical energy storage device 2. The evaluation unit 5 is configured to evaluate the sensor signals, in particular the temperature T and at least one cell voltage Uc of the electrical energy storage device 2, and to determine therefrom a state parameter of the electrical energy storage device 2 by means of a fourth charging current I4. For this purpose, the evaluation unit 5 has at least one state of charge evaluation device 6 and an aging evaluation device 7.

[0043] Evaluation unit 7 is designed to determine, using the sensor signals, a state parameter of electrical energy storage device 2. Evaluation unit 7 uses a simplified linear electrothermal aging model of electrical energy storage device 2, which is approximated using a Voltaic series.

[0044] The state-of-charge evaluation device 6 is designed to determine the current state of charge of the electrical energy storage device 2. The state-of-charge evaluation device 6 is connected to the control unit 12 in a signal-conducting manner. The state-of-charge evaluation device 6 is designed to transmit the current state of charge to the control unit 12.

[0045] The aging evaluation device 7 is designed to determine the aging state of the electrical energy storage device 2 and the second secondary reaction current J2 generated therefrom. The aging evaluation device 7 is connected to the comparator device 10 in a signal-conducting manner. The aging evaluation device 7 is designed to transmit the second secondary reaction current J2 to the comparator device 10.

[0046] In this case, the side reaction current is a current which occurs during charging due to side reactions in the cells of the electrical energy storage device 2 , such as, for example, dendrite growth or separation of the electrolyte at the anode due to aging of the cells.

[0047] Control unit 12 is designed to control a first charging current I1 for charging electrical energy storage device 2 and a first side reaction current J1 generated therefrom, using the charge state of electrical energy storage device 2 .

[0048] For this purpose, the control unit 12 has an optimization device 3 and a charge control device 11 .

[0049] The optimization device 3 is designed to determine the charging parameters of the charging profile based on the current charge state of the electrical energy storage device 2 , the available charging time tch and a defined charge state achievable within the charging time tch by means of the total charge Qc.

[0050] In the first embodiment, as in Figure 2As shown in , the charge profile is made as an affine charge profile Ia(t). The affine charge profile is linear and has a slope α as the only parameter, which is calculated as follows:

[0051] (1)

[0052] In the second embodiment, as in Figure 3 As shown in , the charge profile is produced as a polynomial charge profile Ip(t). With the boundary conditions that the current is constant at time t=0 and at time t=tch, that is, the time derivative of the current is equal to zero at these times, the total charge Qc is predetermined, and the starting current Ipo is positive and limited by the cell capacitance of the electrical energy storage device 2, the polynomial charge profile Ip(t) can be described as follows:

[0053] (2)

[0054] The parameter d of the polynomial charge distribution Ip(t) has a loss function f(d) having a parabolic shape that opens upwards, as in Figure 4 The minimum value of the loss function f(d) corresponds to a value for the parameter d which produces a polynomial charge profile Ip(t) which leads to a minimum aging of the electrical energy storage device 2 .

[0055] The optimization device 3 is designed to determine the minimum value of the loss function f(d) in a numerically represented manner. For this purpose, a gradient method is used: First, the gradient of the loss function f(d) is determined at the outer limit values ​​dmin and dmax of the loss function f(d) and at the average value of the loss function f(d) halfway between the outer limit values ​​dmin and dmax. Thereafter, the following interval of the parameter d is selected in which the sign of the gradient is reversed and the approximation method is continued with the limit values ​​of this interval. Figure 4 In , this is the interval between the mean value dm and the upper limit value dmax, since the gradient for the values ​​dmin and dm is negative and the gradient for the value dmax is positive. As a result, the optimized parameter dopt is determined for which the loss function f(d) has a minimum value.

[0056] The optimization device 3 is designed to output the optimized parameter dopt to the charge control device 11 .

[0057] The charge control device 11 is designed to determine an optimized charge profile Ip(t) for the first current I1 and a first side reaction current J1 resulting therefrom by using an optimized parameter dopt and substituting it into formula (2).

[0058] The control unit 12 is electrically conductively connected to the low-pass filter 4 . The control unit is designed to conduct the first charging current I1 to the low-pass filter 4 .

[0059] The low-pass filter 4 electrically conductively connects the control unit 12 to the summing device 8 . The low-pass filter 4 is designed to smooth the first charging current I1 and to convert it into a second charging current I2 and to conduct the second charging current I2 to the summing device 8 .

[0060] The control unit 12 is connected to the comparator device 10 in a signal-conducting manner. The control unit 12 is designed to transmit the first side reaction current J1 to the comparator device 10 .

[0061] The comparison device 10 is arranged between the second control device 11 and the adjustment unit 9. The comparison device 10 is arranged between the aging evaluation device 7 and the adjustment unit 9. The comparison device 10 is configured to receive and compare the first side reaction current J1 and the second side reaction current, in particular to form a side reaction current difference, which is the difference between the first side reaction current J1 and the second side reaction current J2. The result of the comparison between the first side reaction current J1 and the second side reaction current J2 is sent to the adjustment unit 9.

[0062] The regulating unit 9 is arranged between the summing device 8 and the comparison device 10. The regulating unit 9 is designed to generate a third charging current I3 for charging the electrical energy store 2 based on the current second side reaction current J2 of the electrical energy store, the third charging current causing a side reaction current in the electrical energy store 2, which side reaction current corresponds to a minimum aging of the electrical energy store 2. The regulating unit 9 is electrically conductively connected to the summing device 8 and is designed to conduct the third charging current I3 to the summing device 8.

[0063] The control unit 9 uses a control method which is frequency-based and uses fractional difference orders as parameters, in particular the CRONE method. In this case, a numerically represented linear model of a nonlinear energy storage model is used.

[0064] The summing device 8 serves as a node between the low-pass filter 4 and the regulating unit 9 on the one hand and the electrical energy storage device 2 and the evaluation unit 5 on the other hand. The summing device 8 is designed to add the second charging current I2 and the third charging current I3 and to generate therefrom as a sum a fourth charging current which is used to charge the electrical energy storage device 2. For this purpose, the summing device 8 is electrically conductively connected to the electrical energy storage device 2. Furthermore, the summing device 8 is connected to the evaluation unit 5 in a signal-conducting manner in order to transmit the fourth charging current I4 to the evaluation unit 5.

[0065] The method according to the invention for charging electrical energy storage device 2 has control method steps and regulating method steps which are carried out simultaneously or in parallel at a certain time.

[0066] In a first method step, the current state of charge and the current state of aging of the electrical energy store 2 are determined, which causes a current second side reaction current J2 in the electrical energy store 2. In this case, a simplified linear electrothermal aging model of the electrical energy store 2 is used, which is approximated with the aid of a Voltaic series.

[0067] In a control method step, using the current state of charge, a defined state of charge achievable by means of charging and the available charging time tch, a first charging current I1 and a first side reaction current J1 of electrical energy storage device 2 are generated.

[0068] In a first control method step, the minimum value of the loss function f(d) of the parameter d of the polynomial charge profile Ip(t) is determined in a numerical manner. For this purpose, a gradient method is used: the gradient of the loss function f(d) is first determined at the outer limit values ​​dmin and dmax of the loss function f(d) and at the mean value dm of the loss function f(d) halfway between the outer limit values ​​dmin and dmax. Thereafter, an interval of the parameter d is selected in which the sign of the gradient is reversed and the approximation method is continued with the limit values ​​of this interval.

[0069] In a second control method step, a polynomial optimized charging profile Ip(t) for the first current I1 and the first side reaction current J1 resulting therefrom are determined by using the optimized parameters dopt and substituting them into formula (2).

[0070] In a third control method step, the first charging current I1 is smoothed into a second charging current I2.

[0071] In a first control method step, the first side reaction current J1 is compared with the second side reaction current J2 and a third charging current I3 is generated. If the first side reaction current J1 has the same value as the second side reaction current J2, the third charging current I3 is equal to zero. If the first side reaction current J1 and the second side reaction current J2 have different values, the third charging current is determined in such a way that the aging of the electrical energy storage device 2 is minimized.

[0072] In a second control method step, the third charging current I3 and the second charging current I2 are added and the sum results in a fourth charging current I4 , wherein if the third charging current I3 is equal to zero, the fourth charging current I4 has the same value as the second charging current I2 .

[0073] In a second method step, electrical energy storage device 2 is charged with second charging current I2 or fourth charging current I4 , wherein the second charging current is used if fourth charging current I4 is not available and the fourth charging current is used if fourth charging current I4 is available.

[0074] The method is then continued with the first method step.

[0075] An “electrical energy storage device” is understood here to mean a rechargeable energy storage device, in particular with electrochemical energy storage cells, and / or an energy storage module with at least one electrochemical energy storage cell and / or an energy storage pack with at least one energy storage module. The energy storage cells can be designed as lithium-based battery cells, in particular lithium-ion battery cells. As an alternative, the energy storage cells are designed as lithium polymer battery cells or nickel metal hydride battery cells or lead-acid battery cells or lithium-air battery cells or lithium-sulfur battery cells.

Claims

1. A charging device (1) for an electrical energy storage device (2), It is characterized in that The charging device (1) comprises a control unit (12) and a regulating unit (9). The charging device (1) is designed to charge the electrical energy storage device (2) to a defined state of charge within a predetermined charging time and to regulate the charging current and the secondary reaction current of the electrical energy storage device (2) for this purpose. wherein the control unit (12) is designed to control a first charging current (I1) for charging the electrical energy storage device (2) and a first side reaction current (J1) generated therefrom in such a way that the electrical energy storage device (2) is charged to a defined state of charge within a predetermined charging time, wherein the regulating unit (9) is designed to regulate a third charging current (I3) in such a way that a second side reaction current (J2) of the electrical energy storage device (2) is minimized, wherein the second side reaction current is obtained from sensor data of the electrical energy storage device (2), wherein the third charging current (I3) is generated by comparing the first side reaction current with the second side reaction current, And wherein the control unit and the regulating unit operate simultaneously.

2. The charging device (1) according to claim 1, It is characterized in that The charging device (1) has an evaluation unit (5) having at least one connection for a sensor of the electric energy storage device (2), wherein the evaluation unit (5) is designed to determine the aging of the electric energy storage device (2) by means of a simplified linear electrothermal aging model of the electric energy storage device (2).

3. The charging device (1) according to claim 2, characterized in that: The aging of the electrical energy storage device (2) is determined with the aid of an aging model approximated by a Voltaic series.

4. The charging device (1) according to claim 2, It is characterized in that The evaluation unit (5) is connected to the control unit (12) and / or the regulating unit in a signal-conducting manner.

5. The charging device (1) according to any one of claims 1 to 4, It is characterized in that The control unit (12) has an optimization device (3), wherein the optimization device (3) is designed to optimize a charging profile for a first charging current.

6. The charging device (1) according to claim 5, It is characterized in that The charge distribution is an affine charge distribution or a polynomial charge distribution.

7. The charging device (1) according to claim 5, It is characterized in that The optimization method is to determine the minimum value of the loss function of the parameter (d) of the charging distribution in a numerical manner.

8. The charging device (1) according to claim 5, It is characterized in that The optimization method is to determine the minimum of the loss function of the parameter (d) of the charging profile in a numerical manner by means of a gradient method.

9. The charging device (1) according to claim 5, It is characterized in that The control unit (12) has a charge control device (11), wherein the charge control device (11) is designed to control the first charging current (I1) according to an optimized charging profile.

10. The charging device (1) according to any one of claims 1 to 4, It is characterized in that The charging device (1) has a summing device (8) which is arranged between the control unit (12) and the regulating unit (9) on the one hand and an output connection (13) of the charging device (1) on the other hand, wherein the summing device (8) is designed to add a first charging current (I1) or a second charging current (I2) from the control unit (12) and a third charging current (I3) from the regulating unit (9) and to generate a fourth charging current (I4).

11. The charging device (1) according to claim 10, It is characterized in that The charging device (1) has a low-pass filter (4) which is arranged between the control unit (12) and the summing device (8), wherein the low-pass filter (4) is designed to smooth the first charging current (I1) into a second charging current (I2).

12. The charging device (1) according to claim 10, It is characterized in that The charging device (1) has a comparison device (10), which is arranged between the control unit (12) and the aging evaluation device (7) on the one hand and the summing device (8) on the other hand, wherein the comparison device (10) is designed to compare the first side reaction current (J1) with the second side reaction current (J2).

13. Method for charging an electrical energy storage device (2) by means of a charging device (1) according to any one of claims 1 to 12, It is characterized in that The method comprises a control method step and a regulation method step which are carried out simultaneously. wherein the electrical energy storage device (2) is charged to a defined state of charge within a predetermined charging time and for this purpose the charging current and the secondary reaction current of the electrical energy storage device (2) are adjusted, wherein, in the control method step, a first charging current (I1) for charging the electrical energy storage device (2) and a first side reaction current (J1) generated therefrom are controlled so that the electrical energy storage device (2) is charged to a defined charge state within a predetermined charging time; In the regulation method step, a third charging current (I3) is regulated so as to minimize a second side reaction current (J2) of the electrical energy accumulator (2), wherein the second side reaction current is obtained from sensor data of the electrical energy accumulator (2), wherein the first side reaction current (J1) is compared with the second side reaction current (J2) and the third charging current (I3) is generated.

14. The method (100) according to claim 13, It is characterized in that The current state of charge and / or the current state of aging are determined from sensor data of the electrical energy storage device (2).

15. The method (100) according to claim 14, It is characterized in that The current state of charge and / or the current state of aging is determined with the aid of a simplified linear electrothermal aging model of the electrical energy storage device (2).

16. The method (100) according to any one of claims 13 or 14, It is characterized in that Optimizing a charging profile for a first charging current by determining a minimum value of a loss function of a parameter (d) of the charging profile in a digital representation, The first charging current (I1) and the first side reaction current (J1) are controlled according to the optimized charging distribution.

17. The method (100) according to claim 13, It is characterized in that comparing the first side reaction current (J1) with the second side reaction current (J2) and generating a third charging current (I3), wherein the third charging current (I3) is added to the second charging current (I2) and a fourth charging current (I4) is generated, wherein the second charging current (I2) is formed by smoothing the first charging current (I1), In this case, the electrical energy storage device (2) is charged with the fourth charging current (I4).

18. The method (100) according to claim 17, It is characterized in that If the first side reaction current (J1) has the same value as the second side reaction current (J2), the third charging current (I3) is equal to zero, and / or if the first side reaction current (J1) and the second side reaction current (J2) have different values, the third charging current (I3) is determined in such a way that aging of the electrical energy storage device (2) is minimized.

19. The method (100) according to claim 17, It is characterized in that If the third charging current (I3) is equal to zero, the fourth charging current (I4) has the same value as the second charging current (I2).

Images