POWER CONTROL DEVICE FOR CONTROLLING THE ELECTRIC CHARGING POWER OF AN ENERGY SOURCE

Description

[0001] The invention relates to a power control device for controlling an electrical charging power of an energy source which serves to charge an electrical energy storage device.

[0002] If energy storage devices, in particular batteries, of vehicles such as rail vehicles are charged while driving, for example by means of a fuel cell or via an external energy supply network, it should be taken into account that the energy storage devices always have a charge level that is, on the one hand, small enough for the energy storage devices to absorb any braking power while driving, and, on the other hand, large enough for the energy storage devices to provide the energy required with sufficient buffer and power reserve, for example during longer uphill journeys without an external energy supply.If charging is carried out using fuel cells, for example, it must be taken into account with regard to the latter uphill journeys that the drive power of the vehicles can often significantly exceed the maximum fuel cell power of the fuel cells when driving uphill, so that the energy storage devices must provide the difference between the required drive power and the maximum fuel cell power in such a case.

[0003] Furthermore, the service life of the energy storage devices should be considered. For example, the maximum possible charge level or even a completely empty charge level should be avoided too frequently.

[0004] Document US 8 204 416 B2 discloses a method and a device for controlling the operating point of a battery, in particular for a secondary battery of a vehicle. A battery state of charge is detected and a current operating point is set using a continuously adjusted setpoint for the state of charge, which is dependent on a temperature and / or an aging state. Document US 2012 / 109443 A1 discloses a control system for a hybrid vehicle with a battery. Document EP 1 087 877 B1 discloses a control system for a hybrid system comprising at least one energy storage device and one energy source.

[0005] The invention is based on the object of specifying a particularly suitable power control device with regard to the boundary conditions described above.

[0006] This object is achieved according to the invention by a power control device, a vehicle, and a method having the respective features of the independent patent claims. Respective embodiments are specified in the dependent patent claims.

[0007] A first aspect of the invention relates to a power control device for controlling an electrical charging power of an energy source used to charge an electrical energy storage device. Characteristically, the power control device comprises a specification change device configured to change a target charging power specification depending on the respective state of charge of the energy storage device, forming a corrected charging power specification when an actual state of charge value indicating the state of charge approaches an upper or lower range limit of a predetermined target range.

[0008] A significant advantage of the power control device according to the invention is the subsequent modification or correction of a target charging power specification when the actual state of charge value approaches the upper or lower range limit, whereby overcharging or excessive discharging of the energy storage device can be avoided.

[0009] According to a further development of the power control device according to the invention, the specification change device corrects the target charging power specification in such a way that the degree of correction increases disproportionately as the actual state of charge value approaches the range limits. This disproportionate correction advantageously achieves particularly rapid and decisive countermeasures when the actual state of charge value approaches one of the range limits.

[0010] According to the invention, the specification change device carries out the change by reducing the target charging power specification disproportionately to the exceeding of the upper correction start value for actual state of charge values ​​above a predetermined upper correction start value which is smaller than the upper range limit, and by increasing the target charging power specification disproportionately to the falling below of the lower correction start value for actual state of charge values ​​below a predetermined lower correction start value which is greater than the lower range limit.

[0011] According to the invention, the power control device comprises a power reduction device, a power increase device and an output device.

[0012] With regard to the power reduction, the power reduction device according to the invention is designed to determine a power reduction end value as a function of the actual state of charge value and the upper correction start value, wherein for actual state of charge values ​​above the upper correction start value it increases the power reduction end values ​​disproportionately to the difference between the actual state of charge value and the upper correction start value.

[0013] With regard to a power increase, the power increase device according to the invention is designed to determine a power increase end value as a function of the actual state of charge value and the lower correction start value, wherein for actual state of charge values ​​below the lower correction start value, it increases the power increase end values ​​disproportionately to the difference between the lower correction start value and the actual state of charge value.

[0014] The output device is further configured according to the invention to form the corrected charging power specification by subtracting the respective power reduction final value from the target charging power specification and adding the respective power increase final value to the target charging power specification.

[0015] According to a further development based on the above development, the power reduction device has an upper reduction intermediate module which determines an upper difference value by subtracting the upper correction start value from the actual state of charge value and generates an upper reduction intermediate value with the upper difference value using an upper reduction function which assigns an upper reduction intermediate value to each upper difference value, wherein the upper reduction intermediate values ​​increase proportionally or disproportionately with increasing upper difference values.

[0016] According to a further development based on the above development, the power reduction device has an upper PI controller into which the respective upper intermediate reduction value is fed on the input side and which generates the final power reduction value on the output side, wherein the maximum output value of the upper PI controller is limited to a maximum value which corresponds to the maximum output power of the energy source.

[0017] According to a further development, the power increase device has a lower reduction intermediate module which determines a lower difference value by subtracting the actual state of charge value from the lower correction start value and generates a lower reduction intermediate value with the lower difference value using a lower reduction function which assigns a lower reduction intermediate value to each lower difference value, wherein the lower reduction intermediate values ​​increase proportionally or disproportionately with increasing lower difference values.

[0018] According to a further development based on the above development, the power increase device has a lower PI controller into which the respective lower intermediate reduction value is fed on the input side and which generates the final power increase value on the output side, wherein the maximum output value of the lower PI controller is limited to a maximum value which corresponds to the difference between the maximum output power of the energy source and the target charging power specification.

[0019] According to a further development, the upper reduction function and / or the lower reduction function are continuous and differentiable, at least piecewise differentiable, and the intermediate reduction values ​​are always greater than zero.

[0020] According to a further development, the following applies to the upper reduction function and / or the lower reduction function as a whole or to at least one of its sections: df / dx > 0 and / or d 2 f / dx 2 > 0 where f denotes the upper and lower reduction functions respectively.

[0021] The power control device is preferably used in vehicles, especially rail vehicles. In rail vehicles, the power or energy required to operate the rail vehicle, including the propulsion and other auxiliary systems, can be predicted relatively well, so that a suitable target power specification is generally easy to predict, and correction of the target power specification by the power control device rarely requires intervention.

[0022] According to an advantageous further development, the energy source is a fuel cell and the said energy storage device is a vehicle battery, wherein the power of the fuel cell is controlled by the power control device.

[0023] The target range, the upper range limit, and / or the lower range limit are defined, for example, based on time and / or location or route, in order to adapt the operating range to the respective requirements during a vehicle or rail vehicle journey. For example, the upper and lower range limits can be raised if uphill sections are imminent. Furthermore, the upper and lower range limits can be lowered if downhill sections are imminent and braking energy is likely to be available.

[0024] The upper correction start value and the lower correction start value are adjusted, for example, to the upper and lower range limits, for example, raised when the respective assigned range limit is raised and lowered when the respective assigned range limit is lowered.

[0025] The power control device can have a setting device which calculates a time- and / or distance-dependent setpoint power as the setpoint charging power.

[0026] The specification device can calculate the target performance specification, for example on the basis of route and / or timetable data, in a time-related manner over the travel time and / or in a route-related manner over the respective route location for the route section currently traveled or to be traveled next by the vehicle.

[0027] When calculating the target charging power specification, the specification device preferably takes into account that the target charging power specification is dimensioned such that the energy storage device has a state of charge which, on the one hand, is so small in certain route sections that the energy storage device can absorb braking power, and, on the other hand, is so high in other route sections that the energy storage device can provide the high output power required for this, for example on longer uphill journeys, with sufficient buffer and power reserve.

[0028] A second aspect of the invention relates to a vehicle which is equipped with at least one power control device according to the invention.

[0029] The vehicle is preferably designed as a rail vehicle, in particular as a locomotive or a multiple unit for regional and long-distance transport.

[0030] According to a further development of the vehicle according to the invention, the power control device has a specification device which calculates the target charging power specification as a function of route data of at least one route section ahead of the rail vehicle and / or as a function of time.

[0031] Finally, a third aspect of the invention relates to a method for controlling the electrical charging power of an energy source used to charge an electrical energy storage device. Characteristically, a target charging power specification is changed depending on a respective state of charge of the energy storage device, forming a corrected charging power specification when an actual state of charge value indicating the state of charge approaches an upper or lower range limit of a predetermined target range. The change is carried out by the specification change device by reducing the target charging power specification disproportionately to the exceeding of the upper correction start value for actual state of charge values ​​above a predetermined upper correction start value that is smaller than the upper range limit, and by reducing the target charging power specification disproportionately to the exceeding of the upper correction start value for actual state of charge values ​​below a predetermined lower correction start value that is greater than the lower range limit.the target charging power specification is increased disproportionately to the undershoot of the lower correction start value, and the power control device has a power reduction device, a power increase device and an output device, wherein the power reduction device determines a power reduction end value as a function of the actual state of charge value and the upper correction start value, wherein for actual state of charge values ​​above the upper correction start value, it increases the power reduction end values ​​disproportionately to the difference between the actual state of charge value and the upper correction start value, the power increase device determines a power increase end value as a function of the actual state of charge value and the lower correction start value, wherein for actual state of charge values ​​below the lower correction start value, it increases the power increase end values ​​disproportionately to the difference between the lower correction start value and the actual state of charge value,and the output device forms the corrected charging power specification by subtracting the respective power reduction final value from the target charging power specification and adding the respective power increase final value to the target charging power specification.

[0032] The method is preferably carried out with the power control device described above and preferably in a vehicle, in particular a rail vehicle.

[0033] The invention is explained in more detail below using exemplary embodiments. In the following: Figure 1 shows an embodiment of a rail vehicle according to the invention, Figure 2 shows a profile of a target band over the route of a route section to be traveled, Figure 3 shows an embodiment of a specification change device for the rail vehicle according to Figure 1 , Figure 4 shows a further embodiment of a specification change device for the rail vehicle according to Figure 1, and Figure 5 shows, by way of example, the course of reduction functions and the courses of upper and lower intermediate reduction values ​​as a function of actual state of charge values.

[0034] For the sake of clarity, the same reference numerals are used in the figures for identical or comparable components.

[0035] The Figure 1 shows components of an exemplary embodiment of a vehicle 10 according to the invention, which is preferably a rail vehicle, since the driving behavior of rail vehicles is comparatively easy to predict. The vehicle 10 is equipped with an exemplary embodiment of a power control device 20 according to the invention.

[0036] The power control device 20 serves to control the electrical charging power Pb of an energy source in the form of a fuel cell 30, which in turn serves to charge an electrical energy storage device in the form of a vehicle battery 40.

[0037] The vehicle battery 40 can be connected via a converter or DC voltage controller 50 to an internal vehicle power supply network, which can include, for example, a DC voltage intermediate circuit 60 or the like. The internal vehicle power supply network and other components of the vehicle 10 connected thereto, such as drive motors, additional converters, etc., are generally known and therefore, for reasons of clarity, are described in the Figure 1 not further shown.

[0038] The power control device 20 comprises a specification device 21 which, on the basis of route and / or timetable data, calculates a target charging power specification Ps based on time over the travel time and / or distance over the respective route location X for the route section 70 currently being traveled or the one to be traveled next, or in which the target charging power specification Ps based on travel time and / or distance is at least stored, for example, over the respective route location X. In the latter variant, the calculation of the target charging power specification Ps can also take place or have already taken place at another location, for example outside the vehicle 10.

[0039] When calculating the target charging power specification Ps, it is preferably taken into account that the fuel cell power Pb is set such that the vehicle battery 40 has a state of charge that, on the one hand, is low enough in certain route sections for the vehicle battery 40 to absorb braking power, and, on the other hand, is high enough in other route sections for the vehicle battery 40 to provide the high output power required for this, for example, during longer uphill journeys, with sufficient buffer and power reserve. With regard to the latter aspect, it must be taken into account that the drive power of the vehicle 10 can often significantly exceed the maximum fuel cell power Pb of the fuel cell 30 during uphill journeys, so that the vehicle battery 40 must be able to provide the difference between the required drive power and the maximum fuel cell power Pb in such a case.

[0040] In order to achieve the stated objectives, the target charging power Ps for the fuel cell 30 is initially calculated without feedback or without monitoring, preferably using timetable data and route data with elevation profiles, since the latter data allow the expected power requirements to be estimated relatively accurately.

[0041] Furthermore, when calculating the target charging power Ps, the battery's service life is preferably taken into account, and the battery's state of charge is selected accordingly. For example, it is beneficial for battery service life if the state of charge remains within certain limits or within a specified target range SB, and the maximum possible state of charge or an empty state of charge occurs as rarely as possible.

[0042] The Figure 2shows an example of a target range SB suitable for a route section 70 to be traveled, within which the actual state of charge values ​​SoC should be during the journey depending on the respective location X in order to achieve the longest possible battery life. The target range SB is defined in Figure 2 limited or defined by an upper range limit SoCmax and a lower range limit SoCmin. It is clear that the range limits SoCmax and SoCmin do not have to be constant; rather, they are preferably adapted to the route profile to be traveled and to specified travel times, so that the range limits SoCmax and SoCmin and the target range SB are therefore preferably time- and / or route-dependent.

[0043] Theoretically, it would be possible for the setting device 21 of the power control device 20 to perform the power control of the fuel cell 30 entirely on its own, i.e., the control takes place without feedback or monitoring. The curve K1 in Figure 2 shows, by way of example, the course of the actual state of charge values ​​SoC within the target range SB in the event that the vehicle 10 drives exactly as described or is actually controlled by the driver in such a way that the assumptions underlying the calculation of the target charging power specification Ps actually occur.

[0044] In reality, however, curve K1 is often deviated from because the vehicle 10 is or must be operated differently than assumed when calculating the target charging power Ps. This can lead to the actual state of charge being outside the desired limits or even the battery being completely discharged, as curves K2 and K3 exemplify.

[0045] In order to ensure a state of charge curve (SoC curve) that lies within the desired target range SB even in the case of an actual driving profile that does not match the target charging power specification Ps, it is provided that the power control device 20 additionally has a specification changing device 22 that is designed to correct the target charging power specification Ps of the specification device 21 as a function of the respective state of charge of the vehicle battery 40, forming a corrected charging power specification Psk when the actual state of charge value SoC approaches the upper or lower range limit SoCmax or SoCmin of the target range SB.

[0046] In the embodiment according to Figure 1the specification changing device 22 will carry out the correction of the target charging power specification Ps in such a way that the degree of correction increases disproportionately to the approach of the actual state of charge value SoC to the range limits SoCmax, SoCmin. The specification changing device 22 preferably achieves such a disproportionate correction by reducing the target charging power specification Ps disproportionately to the exceeding of the upper correction start value Kmax for actual state of charge values ​​SoC above a predetermined upper correction start value Kmax that is smaller than the upper range limit SoCmax. For actual state of charge values ​​SoC below a predetermined lower correction start value Kmin that is larger than the lower range limit SoCmin, it increases the target charging power specification Ps disproportionately to the falling below the lower correction start value Kmin. The correction start values ​​Kmax and Kmin can be fixed constants.Alternatively, they can be calculated by the specification changing device 22 as a function of the range limits SoCmax and SoCmin, for example according to: . Kmax = SoCmax − Q and Kmin = SoCmin + Q and where Q can be a constant. Alternatively, Q can also depend on the difference between SoCmax and SoCmin, for example, be proportional to this difference.

[0047] The Figure 3 shows in more detail a first embodiment of a specification change device 22, which in the power control device 20 according to Figure 1 The specification change device 22 according to Figure 3 is formed by a computing device 100 and a memory 110. A software program SW is stored in the memory 110, which, when executed by the computing device 100, determines the mode of operation of the specification changing device 22.

[0048] In the exemplary embodiment, the software program SW comprises a power reduction module SW200, which forms a power reduction device when executed by the computing device 100, a power increase module SW300, which forms a power increase device when executed by the computing device 100, and an output module SW400, which forms an output device when executed by the computing device 100.

[0049] The power reduction module SW200 determines a power reduction end value RW depending on the respective actual state of charge value SoC and the respective upper correction start value Kmax, whereby for actual state of charge values ​​SoC above the upper correction start value Kmax, it increases the power reduction end values ​​RW disproportionately to the difference between the respective actual state of charge value SoC and the upper correction start value Kmax, for example according to the following equation: RW = SoC − Kmax 3 f ü r Kmax < SoC ≤ 1 0 f ü r 0 ≤ SoC ≤ Kmax

[0050] The power increase module SW300 determines a power increase final value EW depending on the actual state of charge value SoC and the lower correction start value Kmin, whereby for actual state of charge values ​​SoC below the lower correction start value Kmin, it increases the power increase final values ​​EW disproportionately to the difference between the lower correction start value Kmin and the actual state of charge value SoC, for example according to the following equation: EW = Kmin − SoC 3 f ü r 0 ≤ SoC < Kmin 0 f ü r 1 ≥ SoC ≥ Kmin

[0051] The output module SW400 forms the corrected charging power specification Psk by subtracting the respective power reduction final value RW from the target charging power specification Ps and adding the respective power increase final value EW to the target charging power specification Ps, i.e. preferably according to Psk = Ps + EW − RW

[0052] The above-specified final power increase value EW and / or the above-specified lower final power reduction value RW can also be calculated differently, but it is advantageous if the calculation functions used are continuous and differentiable, at least sectionally differentiable, and if the final power increase values ​​EW and the final power reduction values ​​RW do not fall below zero.

[0053] The computing device 100 and the memory 110 can also form the specification device 21 and thus the entire power control device 20 if, for example, a further software program SW2 is stored in the memory 110, which takes over the function of the specification device 21 when executed by the computing device 100.

[0054] The Figure 4 shows a second embodiment of a default change device 22, which in the power control device 20 according to Figure 1can be used, in more detail. The specification change device 22 comprises a power reduction device 200, a power increase device 300 and an output device 400, which - analogously to the first embodiment according to the Figure 3 - can be implemented as software modules that are executed by a computing device 100, as in Figure 3 shown, executed.

[0055] The power reduction device 200 has an upper intermediate reduction module 210, which determines an upper difference value Do by subtracting the upper correction start value Kmax from the actual state of charge value SoC using a difference former 211 and generates an upper intermediate reduction value Zo with the upper difference value Do using an intermediate reduction block 212. This is done using an upper reduction function that assigns an upper intermediate reduction value Zo to each upper difference value Do, with the upper intermediate reduction values ​​Zo increasing proportionally or disproportionately with increasing upper difference values ​​Zo. The upper intermediate reduction values ​​Zo are preferably calculated as follows: Zo = SoC − Kmax 2 f ü r Kmax < SoC ≤ 1 0 f ü r 0 ≤ SoC ≤ Kmax

[0056] In addition, the power reduction device 200 has an upper PI controller 220, into which the respective upper intermediate reduction value Zo is fed on the input side and which generates the final power reduction value RW on the output side. The maximum output value of the upper PI controller 220 is limited to a maximum value max, which corresponds to the maximum output power Pbmax of the fuel cell 30. The minimum output value of the lower PI controller 220 is limited to a minimum value min of zero.

[0057] The power increase device 300 has in the embodiment according to Figure 4a lower intermediate reduction module 310, which determines a lower difference value Du by subtracting the actual state of charge value SoC from the lower correction start value Kmin using a difference former 311 and generates a lower intermediate reduction value Zu with the lower difference value Du using an intermediate increase block 312, specifically using a lower reduction function that assigns a lower intermediate reduction value Zu to each lower difference value Du, wherein the lower intermediate reduction values ​​Zu increase proportionally or disproportionately with increasing lower difference values ​​Du. The lower intermediate reduction values ​​Zu are preferably calculated as follows: Zu = Kmin − SoC 2 f ü r 0 ≤ SoC < Kmin 0 f ü r 1 ≥ SoC ≥ Kmin

[0058] In addition, the power boost device 300 includes a lower PI controller 320, into which the respective lower intermediate reduction value Zu is fed on the input side and which generates the final power boost value EW on the output side. The maximum output value of the lower PI controller 320 is limited to a maximum value max, which corresponds to the difference between the maximum output power of the energy source and the target charging power specification Ps. The minimum output value of the lower PI controller 320 is limited to a minimum value min of zero.

[0059] The Figure 5 shows, as an example, the course of the reduction functions and the courses of the upper and lower intermediate reduction values ​​Zo and Zu depending on the respective actual state of charge values ​​SoC.

[0060] The upper reduction function and / or the lower reduction function specified above can also look different. However, it is advantageous if the reduction functions are continuous and differentiable, at least piecewise differentiable, and the intermediate reduction values ​​Zo and Zu are always greater than zero.

[0061] It is particularly advantageous if the following applies to the upper reduction function and / or the lower reduction function as a whole or to at least one of its sections: df / dx > 0 and / or d 2 f / dx 2 > 0 where f denotes the upper and lower reduction functions.

[0062] Finally, it should be mentioned that the features of all embodiments described above can be combined with each other in any way to form further other embodiments of the invention.

[0063] All features of subclaims can also be combined individually with each of the independent claims, either individually or in any combination with one or other subclaims, in order to obtain further other embodiments.

Claims

1. Power control device (20) for controlling an electrical charging power (Pb) of a power source which serves for charging an electrical energy storage unit, wherein the power control device (20) has a specification amendment facility (22) which is designed to amend a target charging power specification (Ps) as a function of a respective state of charge of the energy storage unit by forming a corrected charging power specification (Psk), if an actual value of a state of charge SoC (SoC) which specifies the state of charge approaches an upper or lower range limit (SoCmax, SoCmin) of a predefined target band (SB), characterised in that the specification amendment facility (22) carries out the amendment in that it - reduces the target charging power specification (Ps) disproportionately relative to the exceeding of the upper correction starting value (Kmax) for actual values of a state of charge (SoC) above a predefined upper correction starting value (Kmax) which is smaller than the upper range limit (SoCmax) and - increases the target charging power specification (Ps) disproportionately relative to the undershooting of the lower correction starting value (Kmin) for actual values of a state of charge (SoC) below a predefined lower correction starting value (Kmin) which is larger than the lower range limit (SoCmin), the power control device (20) has a power-reducing facility (200), a power-increasing facility (300) and an output facility (400), wherein - the power-reducing facility (200) is designed to determine a power reduction end value (RW) as a function of the actual value of a state of charge (SoC) and the upper correction starting value (Kmax), wherein, for actual values of a state of charge (SoC) above the upper correction starting value Kmax (Kmax), the specification amendment facility increases the power reduction end value (RW) disproportionately relative to the difference between actual value of a state of charge (SoC) and upper correction starting value (Kmax), wherein, in particular, the following applies: RW = SoC − Kmax 3 for Kmax < SoC ≤ 1 0 for 0 ≤ SoC ≤ Kmax - the power-increasing facility (300) is designed to determine a power increase end value EW as a function of the actual value of a state of charge (SoC) and the lower correction starting value Kmin (Kmin), wherein, for actual values of a state of charge (SoC) below the lower correction starting value (Kmin), the specification amendment facility increases the power increase end values EW disproportionately relative to the difference between lower correction starting value (Kmin) and actual value of a state of charge (SoC), wherein, in particular, the following applies: EW = Kmin − SoC 3 for 0 ≤ SoC < Kmin 0 for 1 ≤ SoC ≤ Kmin - and the output facility (400) is designed to form the corrected charging power specification (Psk), in that it subtracts the respective power reduction end value (RW) from the target charging power specification (Ps) and adds the respective power increase end value EW to the target charging power specification (Ps).

2. Power control device (20) according to claim 1, characterised in that the specification amendment facility (22) carries out the correction of the target charging power specification (Ps) such that the degree of amendment increases disproportionately relative to the approaching of the actual value of a state of charge (SoC) to the range limits (SoCmax, SoCmin).

3. Power control device (20) according to claim 1, characterised in that the power-reducing facility (200) has an upper reduction intermediate module (210) which determines an upper difference value (Do) by subtracting the upper correction starting value (Kmax) from the actual value of a state of charge (SoC) and generates an upper reduction intermediate value Zo (Zo) with the upper difference value (Do) using an upper reduction function, which assigns an upper reduction intermediate value (Zo) to the respective upper difference value (Do), wherein the upper reduction intermediate values (Zo) increase proportionately or disproportionately with increasing upper difference values (Do), wherein, in particular, the following applies: Zo = SoC − Kmax 2 for Kmax < SoC ≤ 1 0 for 0 ≤ SoC ≤ Kmax 4. Power control device (20) according to claim 3, characterised in that the power-reducing facility (200) has an upper PI controller (220), into which the respective upper reduction intermediate value (Zo) is fed on the input side and which generates the power reduction end value (RW) on the output side, wherein the maximum output value of the upper PI controller (220) is limited to a maximum value which corresponds to the maximum output power of the power source.

5. Power control device (20) according to one of the preceding claims, characterised in that the power-increasing facility (300) has a lower reduction intermediate module (310) which determines a lower difference value (Du) by subtracting the actual value of a state of charge (SoC) from the lower correction starting value (Kmin) and which generates a lower reduction intermediate value (Zu) with the lower difference value (Du) using a lower reduction function which assigns a lower reduction intermediate value (Zu) to the respective lower difference value (Du), wherein the lower reduction intermediate values (Zu) increase proportionately or disproportionately with increasing lower difference values (Du), wherein, in particular, the following applies: Zu = Kmax − SoC 2 for 0 ≤ SoC ≤ Kmin 0 for 1 ≤ SoC ≤ Kmin 6. Power control device (20) according to claim 5, characterised in that the power-increasing facility (300) has a lower PI controller (320) into which the respective lower reduction intermediate value (Zu) is fed on the input side and which generates the power increase end value (EW) on the output side, wherein the maximum output value of the lower PI controller (320) is limited to a maximum value which corresponds to the difference between the maximum output power of the power source and the target charging power specification (Ps).

7. Power control device (20) according to claim 3, characterised in that the upper reduction function and / or the lower reduction function are continuous and can be differentiated, at least in part, and the reduction intermediate values (Zo, Zu) are always greater than zero.

8. Power control device (20) according to claim 3 or 7, characterised in that the following applies for the upper reduction function and / or the lower reduction function as a whole or for at least a part thereof: df / dx > 0 and / or d 2 f / dx 2 > 0 wherein f represents the upper or lower reduction function.

9. Power control device (20) according to one of the preceding claims, characterised in that the power source mentioned is a fuel cell (30) and the energy storage unit mentioned is a vehicle battery (40), wherein the power of the fuel cell (30) is controlled by way of the power control device (20).

10. Vehicle (10), characterised in that the vehicle (10) is equipped with at least one power control device (20) according to one of the preceding claims.

11. Vehicle (10) according to claim 10, characterised in that the power control device (20) has a specification facility (21) which calculates the target charging power specification (Ps) as a function of route data of at least a route section (70) lying ahead of the vehicle (10) and / or as a function of the time.

12. Method for controlling an electrical charging power (Pb) of a power source which serves for charging an electrical energy storage unit, wherein a target charging power specification (Ps) is amended independently of a respective state of charge of the energy storage unit by forming a corrected charging power specification (Psk), if an actual value of a state of charge SoC (SoC) which specifies the state of charge approaches an upper or lower range limit (SoCmax, SoCmin) of a predefined target band (SB), characterised in that the amendment is carried out by the specification amendment facility (22) in that it - reduces the target charging power specification (Ps) disproportionately relative to the exceeding of the upper correction starting value (Kmax) for actual values of a state of charge (SoC) above a predefined upper correction starting value (Kmax) which is smaller than the upper range limit (SoCmax) and - increases the target charging power specification (Ps) disproportionately relative to the undershooting of the lower correction starting value (Kmin) for actual values of a state of charge (SoC) below a predefined lower correction starting value (Kmin) which is larger than the lower range limit (SoCmin), the power control device (20) has a power-reducing facility (200), a power-increasing facility (300) and an output facility (400), wherein - the power-reducing facility (200) determines a power reduction end value (RW) as a function of the actual value of a state of charge (SoC) and the upper correction starting value (Kmax), wherein the specification amendment facility increases the power reduction end values RW (RW) disproportionately relative to the difference between actual value of a state of charge (SoC) and upper correction starting value (Kmax) for actual values of a state of charge (SoC) above the upper correction starting value (Kmax), wherein, in particular, the following applies: RW = SoC − Kmax 3 for Kmax < SoC ≤ 1 0 for 0 ≤ SoC ≤ Kmax - the power-increasing facility (300) determines a power increase end value EW as a function of the actual value of a state of charge (SoC) and the lower correction starting value Kmin (Kmin), wherein, for actual values of a state of charge (SoC) below the lower correction starting value (Kmin), the specification amendment facility increases the power increase end values EW disproportionately relative to the difference between lower correction starting value (Kmin) and actual value of a state of charge (SoC), wherein, in particular, the following applies: EW = Kmin − SoC 3 for 0 ≤ SoC < Kmin 0 for 1 ≤ SoC ≤ Kmin - and the output facility (400) forms the corrected charging power specification (Psk), in that it subtracts the respective power reduction end value (RW) from the target charging power specification (Ps) and adds the respective power increase end value EW to the target charging power specification (Ps).