RECHARGEABLE BATTERY DISCHARGE DEVICE FOR DISCHARGING RECHARGEABLE BATTERIES, AND METHOD FOR DISCHARGING A PLURALITY OF RECHARGEABLE BATTERIES

Abstract

The invention relates to a rechargeable battery discharge device (10) for discharging rechargeable batteries (20) with (a) a first rechargeable battery connection (12.1) for connecting a first rechargeable battery (20.1), (b) a second rechargeable battery connection (12.2) for connecting a second rechargeable battery (20.2), (c) at least a third rechargeable battery connection (12.3) for connecting a third rechargeable battery (20.3) and (d) a load connection (14) for a load (16) for dissipating an electric output during discharging of the rechargeable batteries (20). The invention provides for (e) a discharge circuit (18) comprising (i) a first short circuit switch (24.1), (ii) a first voltmeter (22.1) that is arranged to measure a first rechargeable battery voltage (U.sub.20.1) dropped across the first rechargeable battery connection (12.1), (iii) a second short circuit switch (24.2), (iv) a second voltmeter (22.2) that is arranged to measure a second rechargeable battery voltage (U.sub.20.2) dropped across the second rechargeable battery connection (12.2), (v) a third short circuit switch (24.3), (vi) a third voltmeter (22.3) that is arranged to measure a third rechargeable battery voltage (U.sub.20.3) dropped across the third rechargeable battery connection (12.3), and (vii) a control unit (27), the control unit (27) being designed to automatically carry out a method comprising the steps: (i) for all voltmeters (22.i), detecting the respective rechargeable battery voltage (U.sub.20.i), (ii) when the respective rechargeable battery voltage (U.sub.20.i) exceeds a predetermined minimum voltage (U.sub.min), connecting the corresponding rechargeable battery (20.i) into a series circuit with at least one other rechargeable battery and (iii) when the respective rechargeable battery voltage (U.sub.20.i) does not exceed a minimum voltage (U.sub.min), removing the corresponding rechargeable battery (20.i) from the series circuit by means of the corresponding short circuit switch.

Claims

1. A rechargeable battery discharge device for discharging rechargeable batteries comprising a first rechargeable battery connection for connecting a first rechargeable battery, a second rechargeable battery connection for connecting a second rechargeable battery, at least a third rechargeable battery connection for connecting a third rechargeable battery, and a load connection for a load for dissipating an electric output during discharging of the rechargeable batteries, a discharge circuit comprising a first short circuit switch, a first voltmeter that is arranged to measure a first rechargeable battery voltage dropped across the first rechargeable battery connection, a second short circuit switch, a second voltmeter that is arranged to measure a second rechargeable battery voltage dropped across the second rechargeable battery connection, a third short circuit switch, a third voltmeter that is arranged to measure a third rechargeable battery voltage dropped across the third rechargeable battery connection, and a control unit, the control unit being configured to automatically carry out a method comprising the steps: for all of the first, second, and third voltmeters, detecting the respective first, second, or third rechargeable battery voltage, when the respective first, second, or third rechargeable battery voltage exceeds a predetermined minimum voltage, connecting the corresponding first, second, or third rechargeable battery into a series circuit with at least one other rechargeable battery and when the respective first, second, or third rechargeable battery voltage does not exceed the predetermined minimum voltage, removing the corresponding first, second, or third rechargeable battery from the series circuit by means of the corresponding first, second, or third short circuit switch.

2. The rechargeable battery discharge device according to claim 1, further comprising a load connected to the load connection in the form of an inverter for generating an AC voltage of a predetermined frequency and voltage and/or a DC voltage converter for generating a DC voltage of a predetermined voltage, from a DC voltage acting on the load connection.

3. The rechargeable battery discharge device according to claim 1, further comprising a display for displaying any of the first, second, and third rechargeable batteries whose respective first, second, or third rechargeable battery voltage falls below the minimum voltage and/or any of the first, second, and third rechargeable battery connections whose connection contacts are short-circuited.

4. The rechargeable battery discharge device according to claim 1, further comprising a polarity reversal protection circuit for automatically detecting a rechargeable battery connected with an incorrect polarity and emitting a polarity reversal warning and/or connecting an incorrectly connected rechargeable battery with a correct polarity.

5. The rechargeable battery discharge device according to claim 1, wherein the control unit is configured to automatically perform further steps of: (i) determining changes in the first, second, and third rechargeable battery voltages over time and (ii) bridging the corresponding first, second, or third rechargeable battery by means of the corresponding first, second, or third short circuit switch and/or emitting a voltage disconnection warning when a determined change in first, second, or third rechargeable battery voltage over time lies outside of a predetermined tolerance interval.

6. The rechargeable battery discharge device according to claim 1, wherein the control unit is configured to automatically perform a further step of: connecting some of the first, second, and third rechargeable batteries into the series circuit so that a sum of the corresponding first, second, or third rechargeable battery voltages lies within a predetermined target voltage interval, wherein a combination with a largest number of rechargeable battery voltages is selected when two or more combinations of rechargeable battery voltages lie within the target voltage interval.

7. The rechargeable battery discharge device according to claim 1, further comprising at least one heat sensor arranged to detect a temperature of at least one of the first, second, and third rechargeable batteries.

8. The rechargeable battery discharge device according to claim 1, wherein the control unit is configured to automatically perform further steps of: detecting a rechargeable battery among the first, second, and third rechargeable batteries that is connected to the respective first, second, or third rechargeable battery connection and does not exceed the minimum voltage, closing a first switch element of the short circuit switch of the respective first, second, or third rechargeable battery connection, or keeping said first switch element closed, closing a second switch element of the short circuit switch of the respective first, second, or third rechargeable battery connection, or keeping said second switch element closed, emitting a signal that encodes that the detected rechargeable battery can be removed, detecting that no rechargeable battery is connected to any rechargeable battery connection, opening the second switch element or keeping it open, then opening the first switch element or keeping it open, and then closing the second switch element.

9. The rechargeable battery discharge device according to claim 2, wherein the inverter is connected to a power grid to which electrical consumers) are connected, the control unit is configured to automatically perform further steps of: detecting a target power output of the rechargeable battery discharge device and reducing a discharge output of the first, second, and third rechargeable batteries when an actual power output exceeds the target power output.

10. The rechargeable battery discharge device according to claim 9, further comprising an electrical buffer store, wherein the control unit is configured to perform further steps of: detecting the target power output of the rechargeable battery discharge device (10) and loading the buffer store so that the actual power output does not exceed the target power output.

11. A method for discharging a plurality of rechargeable batteries comprising the automatically performed steps: continuously measuring one rechargeable battery voltage of a plurality of rechargeable batteries, connecting the rechargeable batteries whose rechargeable battery voltages do not fall below a predetermined minimum voltage into a series circuit so that the rechargeable batteries are discharged, and decontacting a rechargeable battery whose rechargeable battery voltage falls below the predetermined minimum voltage so that it is no longer connected in series.

12. The method according to claim 11, further comprising emitting a notification that encodes the rechargeable batteries whose respective rechargeable battery voltage falls below the minimum voltage and/or rechargeable battery connections whose connection contacts are short-circuited.

13. The method according to claim 11, further comprising detecting a rechargeable battery connected with an incorrect polarity and emitting a polarity reversal warning and/or connecting an incorrectly connected rechargeable battery with a correct polarity.

14. The rechargeable battery discharge device according to claim 7, wherein the at least one heat sensor is a thermal imaging camera.

15. The rechargeable battery discharge device according to claim 8, wherein the first switch element is a short circuit relay and the second switch element is a connecting relay.

Description

[0059] In the following, the invention will be explained in more detail with the aid of the accompanying drawing. It shows:

[0060] FIG. 1 a circuit diagram of a rechargeable battery discharge device according to the invention,

[0061] FIG. 2 a circuit diagram of a rechargeable battery discharge device according to the invention according to a second embodiment and

[0062] FIG. 3 an alternative embodiment of a rechargeable battery discharge device according to the invention.

[0063] FIG. 1 shows a rechargeable battery discharge device 10 according to the invention with rechargeable battery connections 12.i (i=1, 2, . . . , N; here: N=4). The rechargeable battery discharge device 10 also has a load connection 14 to which, in the present case, a load 16 in the form of an inverter 17 is connected. The inverter 17 has a voltage connection 18 to which an AC voltage U.sub.AC with a predetermined frequency f is applied, for example 50 Hertz or 60 Hertz. The AC voltage U.sub.AC is 230 Volt or 110 Volt, for example. However, other voltages are possible.

[0064] For each rechargeable battery connection 12.i, the discharge circuit 18 has a voltmeter 22.i for measuring a rechargeable battery voltage U.sub.20.i of the respective connected rechargeable battery 20.i. The discharge circuit 18 also has a short circuit switch 24.i for each rechargeable battery connection 12. The respective rechargeable battery connection 12.i can be short-circuited by means of each short circuit switch 24.i. In other words, respective connection contacts 26a.i of the rechargeable battery connection 12.i can be switched to the same potential. In this way, current no longer flows through the corresponding rechargeable battery 20.i.

[0065] The rechargeable battery discharge device 10 has a control unit 27 that is connected to all voltmeters 22.i, so that the control unit 27 detects all rechargeable battery voltages U.sub.20.i. The control unit 27 is also connected to all short circuit switches 24.i for control purposes. In other words, the control unit 27 can automatically close and open each short circuit switch 24.i.

[0066] The rechargeable battery discharge device 10 may have a display 28 that is connected to the control unit 27 by means of a conductor or via radio connection and designed to display the rechargeable battery connections 12.i to which a rechargeable battery voltage 20.i is applied that is smaller than a predetermined minimum voltage U.sub.min or the rechargeable battery connections 12.i where the respective short circuit switch 24.i is closed. An operator of the rechargeable battery discharge device 10 can then remove the corresponding rechargeable battery 12.i as it is discharged. For example, the minimum voltage is zero Volt.

[0067] It is also possible, but not essential, that the rechargeable battery discharge device comprises a polarity reversal protection circuit 30.i for at least one rechargeable battery connection, particularly for all rechargeable battery connections 12.i. If the voltmeter 22.i measures an incorrect polarity of the connected rechargeable battery, i.e. If the rechargeable battery is connected with the incorrect polarity, the control unit 27 controls the polarity reversal protection circuit 30.i in such a way that it reverses the polarity, so that the polarity reversal circuit connections 32a.1, 32b.1 are again connected with the right polarity.

[0068] The control unit 27 is configured in such a way that it automatically and continuously detects the rechargeable battery voltages U.sub.20.i. If a rechargeable battery voltage U.sub.20.i is greater than the minimum voltage U.sub.min, the control unit 27 keeps the respective short circuit switch 24.i open. If all rechargeable battery voltages 20.i are greater than the minimum voltage U.sub.min, all short circuit switches 24.i are closed and all rechargeable batteries 20.i are connected to one another in a series circuit. The rechargeable battery voltages U.sub.20.i thus add up to an output voltage U.sub.A, which is applied to the load connection 14 and corresponds to the sum of all rechargeable battery voltages U.sub.20.i when in the load-free state.

[0069] If the rechargeable battery voltage U.sub.20.i falls below the minimum voltage U.sub.min for one rechargeable battery 20.i, the control unit 27 closes the respective short circuit switch 24.i, so that the corresponding rechargeable battery 20.i is bridged. Current then no longer flows through the corresponding rechargeable battery 20.i. If the minimum voltage U.sub.min is not selected to be zero Volt, the discharge circuit 18 has an additional switch for each rechargeable battery connection 12.i, said switch separating one of the two connection contacts 26a.i or 26b.1 from the rest of the circuit.

[0070] To ensure that the output voltage U.sub.A always remains within a predetermined target voltage interval Z, the control unit 27 can be designed in such a way that it only connects some of the rechargeable batteries 20.i into series and bridges the remaining rechargeable batteries, so that the corresponding output voltage U.sub.A is reached.

[0071] The display 28 can be used to emit warnings, for example a polarity reversal warning or a voltage disconnection warning, if the control unit 27 detects that a change in the rechargeable battery voltage {dot over (U)} is too stark. The change in the rechargeable battery voltage {dot over (U)} is calculated by the control unit 27 by numerically deriving the respective rechargeable battery voltage U.sub.20.3.

[0072] The respective temperatures T.sub.i of the rechargeable batteries 20.i are monitored by means of a heat sensor 34, in the present case in the form of a thermal imaging camera 34 in whose field of view S the rechargeable batteries are located. The heat sensor 34 is connected to the control unit 27. If one of the temperatures T.sub.i exceeds a predetermined warning temperature T.sub.warn, the control unit 27 decontacts the corresponding rechargeable battery 20.i. According to a preferred embodiment, the control unit 27 reconnects the corresponding rechargeable battery 20.i into the series circuit after a predetermined waiting time. Alternatively to the thermal imaging camera, the heat sensor may also have thermocouples, for example.

[0073] FIG. 2 shows a circuit diagram of a rechargeable battery discharge device 10 according to the invention according to a second embodiment. In this embodiment, the short circuit switches 24.i have a first switch element 36a.i and a second switch element 36b.i. The switch elements 36a.i, 36b.i are, for example, relays. In this way, a rechargeable battery 20.i can be decontacted when its rechargeable battery voltage U.sub.20.i falls below the minimum voltage U.sub.min, wherein U.sub.min≠0 V applies for the minimum voltage.

[0074] The switch elements 36a.i can also be referred to as short circuit relays. The switch elements 36b.i can also be referred to as connecting relays. The connecting relay switches.

[0075] A target voltage interval Z is stored in the control unit 27. The control unit 27 automatically connects so many rechargeable batteries 20.i into series that the resulting sum voltage lies within the target voltage interval Z. The connection of a rechargeable battery 20.i is achieved by opening the corresponding short circuit relay 36a.i and closing the connecting relay 36b.i. As a result, the rechargeable battery releases electrical energy. This preferably, but not necessarily, occurs automatically, for example by means of the control unit 27.

[0076] The disconnection of a rechargeable battery 20.i is achieved by (a) closing the corresponding short circuit relay 36a.i or keeping it closed, and (b) opening the connecting relay 36b.i or keeping it open. After removing a rechargeable battery from its rechargeable battery connection 12.i., the connecting relay 36b.i is opened. A further rechargeable battery 20′.i is then connected to the rechargeable battery connection 12.i. If necessary, the corresponding short circuit relay 36a.i is then opened and the connecting relay 36b.i closed. This also preferably, but not necessarily, occurs automatically, for example by means of the control unit 27. The new rechargeable battery 20′.i is then connected.

[0077] The N number of rechargeable battery connections is preferably selected in such a way that not all rechargeable batteries have to be connected in series for the sum voltage to be within the target voltage interval Z. The number N is preferably selected in such a way that at most half, in particular at most one third, of the rechargeable battery connections have to be contacted for the sum voltage to lie within the target voltage interval Z.

[0078] If a rechargeable battery has reached or fallen below the minimum voltage U.sub.min, it is bridged, as described above. It is then advantageous, but not essential, for the control unit 27 to emit a signal that the corresponding rechargeable battery can be removed.

[0079] FIG. 3 depicts an alternative embodiment of a rechargeable battery discharge device 10 according to the invention, the inverter 17 of which is connected to a public power grid 38′ for feeding electrical energy back into it.

[0080] Alternatively or additionally, the inverter 17 is connected to a power grid 38 to which electrical consumers 40.j (j=1, 2, . . . J) are connected. The electrical power P.sub.40 of the electrical consumers 40.j can be measured as a function of time by means of a power meter 42.

[0081] The control unit 27 is designed to automatically detect the electric output P.sub.40, which represents a target power output P.sub.soll of the rechargeable battery discharge device 10. If the actual power output P.sub.ist of the rechargeable battery discharge device 10 falls below the target power output P.sub.soll, power is taken from the public power grid 38′. However, if the actual power output P.sub.ist exceeds the target power output P.sub.soll, the electric output is fed into the public grid 38′. To prevent this, the control unit can be designed to reduce the actual power output P.sub.ist by, for example, disconnecting one or multiple rechargeable batteries from the circuit.

[0082] Alternatively or additionally, the rechargeable battery discharge 10 may comprise an electrical buffer store 44. The buffer store 44 can be a rechargeable battery, for example. The buffer store 44 is connected in such a way that electrical energy, which is taken from the rechargeable batteries 20 by the rechargeable battery discharge device 10, can be stored at least partially and/or at least temporarily in the buffer store.

[0083] For example, the control unit 27 is designed in such a way that electric output is introduced into the buffer store 44 when the target power output P.sub.soll is smaller than the actual power output P.sub.ist. For example, so much electric output is introduced into the buffer store 40 that the electrical energy introduced into the public power grid 38′ is minimised.

REFERENCE LIST

[0084]

TABLE-US-00001 10 rechargeable battery discharge device 12 rechargeable battery connection 14 load connection 16 load 17 inverter 18 discharge circuit 20 rechargeable battery 22 voltmeter 24 short circuit switch 26 connection contacts 27 control unit 28 display 30 polarity reversal protection circuit 32 polarity reversal circuit connection 34 thermal imaging camera 36a first switch element, short circuit relay 36b second switch element, connecting relay 38 power grid 38′ public power grid 40 consumer 42 power meter 44 buffer store f frequency i running index of rechargeable battery connections j running index of consumers N number of rechargeable battery connections P.sub.soll target power output P.sub.ist actual power output S field of view Ti temperature of the i-th rechargeable battery T.sub.warn warning temperature U.sub.AC AC current U.sub.20.i rechargeable battery voltage U.sub.min minimum voltage U.sub.A output voltage {dot over (U)} change in rechargeable battery voltage Z target voltage interval