METHOD FOR OPERATING AN ELECTRIC VEHICLE AND ELECTRIC VEHICLE

Abstract

In a method for operating an electric vehicle and an electric vehicle, including an electric traction drive device for driving vehicle, a control device for controlling the driving, a first energy storage device, for supplying the control device using a first DC voltage, a second energy storage device, for supplying the traction drive device using a second DC voltage, and an energy supply unit for providing an output DC voltage, the first energy storage device is connected to the second energy storage device via a converter device, the first energy storage device is connected to the energy supply unit, the converter device converts the first DC voltage into the second DC voltage, and a power flow from the second energy storage device to the first energy storage device is prevented.

Claims

1-15. (canceled)

16. A method for operating an electric vehicle including an electric traction drive device adapted to drive the vehicle, a control device adapted to control driving movement of the vehicle, a first energy storage device adapted to supply the control device with a first DC voltage, a second energy storage device adapted to supply the traction drive device with a second DC voltage, and an energy supply unit adapted to provide an output DC voltage, the first energy storage device being connected to the second energy storage device via a converter device, the first energy storage device being connected to the energy supply unit, the converter device adapted to convert the first DC voltage into the second DC voltage, comprising: preventing a power flow from the second energy storage device.

17. The method according to claim 16, wherein the vehicle is arranged as a driverless mobile assistance system of an intralogistics application, the driving movement includes traction of the vehicle, the first energy storage device includes a rechargeable battery storage device, the second energy storage device includes a double-layer capacitor device and/or is chargeable and dischargeable more rapidly than the first energy storage device, the energy supply unit is adapted to provide the output DC voltage periodically, the first energy storage device is electrically connected to the second energy storage device via the converter device, the first energy storage device is electrically connected to the energy supply unit such, the output DC voltage substantially equals the first DC voltage, the first DC voltage is lower than the second DC voltage and/or is an extra-low voltage, and the power flow from the second energy storage device to the first energy storage device is prevented at any time.

18. The method according to claim 16, wherein the converter device includes a unidirectional DC/DC converter, a step-up converter, and/or a flyback converter adapted to prevent the power flow from the second energy storage device to the first energy storage device.

19. The method according to claim 16, wherein the vehicle includes an energy storage control device, the method further comprising: detecting a state value of the first energy storage device; and transmitting the state value to the energy storage control device.

20. The method according to claim 19, wherein the state value includes a voltage applied to the first energy storage device, a current flowing through the first energy storage device, and/or a temperature prevailing in the first energy storage device.

21. The method according to claim 19, wherein an output current provided by the energy supply unit is regulated and/or controlled by the energy storage control device as a function of the state value.

22. The method according to claim 21, wherein a value for the output current is specified as a setpoint value.

23. The method according to claim 19, further comprising determining, by the energy storage control device, an application parameter from the state value.

24. The method according to claim 23, further comprising transmitting the application parameter to the control device.

25. The method according to claim 23, wherein the application parameter includes a value of a maximum current dischargeable by first energy storage device, a state of charge of the first energy storage device, and/or an aging state of the first energy storage device.

26. The method according to claim 16, further comprising preventing a power flow to the first energy storage device and/or from the energy supply unit to the first energy storage device in response to a voltage applied at the first energy storage device exceeding a predefined maximum voltage, a current flowing through the first energy storage device exceeds a predefined maximum current, and/or a temperature prevailing in the first energy storage device exceeds a predefined maximum temperature.

27. The method according to claim 16, further comprising preventing a power flow from the first energy storage device and/or to the second energy storage device from the first energy storage device in response to a voltage applied at the first energy storage device falling below a predefined minimum voltage, a current flowing through the first energy storage device falling below a predefined minimum current, and/or a temperature prevailing in the first energy storage device exceeding a predefined maximum temperature.

28. The method according to claim 26, wherein the power flow to the first energy storage device is prevented by a bidirectional switch and/or by activating the bidirectional switch by the energy storage control device.

29. The method according to claim 27, wherein the power flow from the first energy storage device is prevented by a bidirectional switch and/or by activating the bidirectional switch by the energy storage control device.

30. The method according to claim 16, wherein energy is supplied to the energy supply unit with or without contact and/or in certain time intervals while driving.

31. A device for supplying a first consumer of an electric vehicle using a first DC voltage and a second consumer using a second DC voltage, including a first energy storage device, a second energy storage device, an energy supply unit adapted to provide an output DC voltage, the first energy storage device adapted to supply the first DC voltage, the second energy storage device adapted to supply the second DC voltage, the first energy storage device being connected to the second energy storage device via a converter device, the first energy storage device being connected to the energy supply unit, the converter device adapted to convert the first DC voltage into the second DC voltage, wherein the device is configured to prevent a power flow from the second energy storage device to the first energy storage device.

32. The device according to claim 31, wherein the vehicle includes a driverless, mobile assistance system of an intralogistics application, the first energy storage device includes a rechargeable battery storage device, the second energy storage device includes a double-layer capacitor and/or is chargeable and dischargeable more rapidly than the first energy storage device, the energy supply unit is adapted to provide the output DC voltage periodically, the first energy storage device is electrically connected to the second energy storage device via the converter device, the converter device includes a unidirectional DC/DC converter, a step-up converter, and/or a flyback converter, the first energy storage device is electrically connected to the energy supply unit, the output DC voltage substantially equals the first DC voltage, the first DC voltage is less than the second DC voltage and/or is an extra-low voltage, and the device is adapted to prevent to the power flow from the second energy storage device to the first energy storage device at any time.

33. The device according to claim 31, further comprising an energy storage control device, the device being adapted to detect and transmit to the energy storage control device a state variable.

34. The device according to claim 33, wherein the state variable includes a voltage applied at the first energy storage device, a current flowing through the first energy storage device, and/or a temperature prevailing in the first energy storage device.

35. The device according to claim 33, wherein the energy supply unit is adapted to regulate and/or control an output current provided by the energy supply unit as a function of the state value.

36. The device according to claim 35, wherein a value for the output current is predeterminable as a setpoint value.

37. The device according to claim 31, further comprising a bidirectional switch adapted to prevent a power flow from and to the first energy storage device.

38. The device according to claim 37, wherein the bidirectional switch is adapted to prevent the power flow from and to the first energy storage device in certain time intervals and/or the energy storage control unit is adapted to activate the bidirectional switch.

39. The device according to claim 37, wherein the first energy storage device, an energy storage control device, and the bidirectional switch are combined in one structural unit.

40. The device according to claim 39, wherein the structural unit is separable from the device and is replaceable.

41. An electric vehicle, comprising: a first consumer adapted to use a first DC voltage; a second consumer using a second DC voltage; a first energy storage device; a second energy storage device; an energy supply unit adapted to provide an output DC voltage; and a device adapted to prevent a power flow from the second energy storage device to the first energy storage device; wherein the first energy storage device is adapted to supply the first DC voltage, the second energy storage device is adapted to supply the second DC voltage, the first energy storage device is connected to the second energy storage device via a converter device, the first energy storage device is connected to the energy supply unit, and the converter device is adapted to convert the first DC voltage into the second DC voltage; and wherein the first consumer includes a control device adapted to control a driving movement of the vehicle and the second consumer includes an electric traction drive device adapted to drive the vehicle, a lifting device, and/or a handling device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] A device for the voltage supply of two consumers of a mobile assistance system according to an example embodiment of the present invention is schematically illustrated in FIG. 1.

[0048] The mobile assistance system is also referred to as MAS.

[0049] A mobile assistance system having two consumers is schematically illustrated in FIG. 2.

[0050] A mobile assistance system having two consumers and an intelligent battery is schematically illustrated in FIG. 3.

[0051] FIG. 4 schematically illustrates an intelligent battery illustrated in FIG. 3 in detail.

DETAILED DESCRIPTION

[0052] FIG. 1 illustrates a device for the voltage supply of two consumers using the DC voltages U.sub.1 and U.sub.2. For this purpose, the device has a first DC voltage connection 1 and a second DC voltage connection 2, at which the DC voltages U.sub.1 and U.sub.2 are applied, as illustrated. For the energy supply, the device has an energy supply unit 3 which, for example, includes a regulator 4 and a variable current source 5. The energy supply unit can also be designated as a charger 3. The regulator regulates the output current I.sub.0 of the charger 3 and thus controls the output DC voltage U.sub.0. The charger 3 is connected to the first DC voltage connection 1 without a voltage converter. For example, the output DC voltage U.sub.0 substantially corresponds to the first DC voltage U.sub.1, since no consumer is connected in series between the charger 3 and the first DC voltage connection 1.

[0053] The first DC voltage U.sub.1 at the first DC voltage connection differs from the second DC voltage U.sub.2. DC voltages U.sub.2 in the range of low voltages, e.g., in the range between 120 V and 600 V, e.g., 300 V, and DC voltages U.sub.1 in the range of extra-low voltages, e.g., 12 V, 24 V, 48 V, or 96 V, may be provided for the use of the device in a MAS.

[0054] In order to convert the first DC voltage U.sub.1 into the higher second DC voltage U.sub.2, a converter device 8 is present between the charger and the second DC voltage connection 2. The converter device 8 is connected in parallel to the first DC voltage connection 1, so that the converter device 8 also uses the output DC voltage U.sub.0 as the input voltage.

[0055] The device has two energy stores 6, 7 for buffering and energy storage. For example, the first energy store 6 is in the form of a battery store and is arranged, for example, as a secondary electrochemical element. For example, the second energy store 7 is arranged as a double-layer capacitor. In the illustrated exemplary embodiment, only a first and a second energy store are illustrated, for example. However, modularly constructed energy storage devices are also possible, which each include multiple identical or different energy stores.

[0056] Each energy store is supplied with energy by the charger. This energy can be stored and made available to a corresponding consumer. The double-layer capacitor 7 exclusively provides the energy for those consumers that can be supplied with the second DC voltage U.sub.2. The converter device 8 prevents transfer charging from the double-layer capacitor 7 to the battery store 6. In the exemplary embodiment illustrated in FIG. 1, the converter device 8 is arranged as a flyback converter. The flyback converter is a potential-isolated unidirectional DC/DC converter. Due to the construction, it has a diode 9, through which a power flow or energy flow from the double-layer capacitor to the battery store is prevented at any point in time, i.e., at all times. This provides for the double-layer capacitor to be configured deliberately to meet the needs of the consumer connected to it.

[0057] FIG. 2 schematically illustrates an application of the device for the voltage supply of two consumers in a MAS. In this example, the converter device 8 is arranged as a step-up converter, which is an example of a non-potentially-isolated DC/DC converter. A power flow from the double-layer capacitor 7 to the battery store 6 is thus prevented here as well.

[0058] In the illustrated exemplary embodiment, the first consumer 10 is in the form of a vehicle controller. Among other things, this controls the driving movement of the MAS. The controller is supplied with the first DC voltage U.sub.1, which is, for example, 12V, 24V, 48V, or 96V. Other consumers, which can generally be designated as vehicle electronics, can also be supplied with this DC voltage U.sub.1, for example, safety sensors such as laser scanners and corresponding evaluation electronics.

[0059] For the driving movement, the MAS has a drive device 11, which can be implemented, for example, as a 3-phase AC motor having an upstream 3-phase inverter. The inverter converts the second DC voltage U.sub.2 into a 3-phase AC voltage, using which the three-phase AC motor, for example, a squirrel-cage rotor, is operated. The drive device 11 can also have multiple motors, each of which is operable by its own inverter. In addition, the inverter can also be provided with feedback capability, so that it is possible to charge the double-layer capacitor 7 when the drive motors are operated in generator mode. In addition to drive devices for traction of the MAS, other consumers for the second DC voltage U.sub.2 are also possible, such as lifting devices for picking up a load or handling devices for moving an object, for example, a robot arm. These loads 11 are supplied using the second DC voltage U.sub.2 in the range from 120V to 600V.

[0060] For example, transfer charging from the battery store 6 to the double-layer capacitor 7 is possible. This is considered advantageous if the double-layer capacitor is drained due to an unforeseen disturbance, i.e., in an emergency. For example, it is possible that the battery store also provides energy for driving the vehicle. Another example for the transfer charging of energy from the first to the second energy store is switching the vehicle back on after a long break without the charger having to supply energy. Even if all consumers 10 and 11 are switched off when the vehicle is stationary, for example, when parking, the energy content of the two energy storage devices decreases due to self-discharge. In a double-layer capacitor, this self-discharge is many times greater than in a battery store. The second energy store can therefore be drained after a break of just a few hours or a few days, despite the consumers 11 being switched off. By transfer charging energy from the first to the second store, the MAS can be put back into a ready-to-drive state even after a longer break, without the charger 3 having to provide energy. In other words, the MAS does not have to be placed or parked in a place where an external power supply is available.

[0061] The charger 3 for the vehicle can be configured in different manners. For example, a charger having a plug contact is implementable, so that the MAS can be supplied with energy by contact at specific charging stations. Likewise, a contact-based energy supply is implementable during the journey of the MAS, for example, by conductor lines. Alternatively, a contactless energy supply is implementable, for example, an inductive energy supply. This can take place through coupled primary and secondary inductances. A supply at stationary charging stations and also a supply during driving of the MAS are both also possible, for example, through primary conductors laid in or on the whole floor. Such a primary conductor is, for example, a line conductor or a coil.

[0062] The energy stores are primarily adapted to supply the MAS with energy during operating phases in which the MAS does not have an external energy supply as described above. These can be journeys between stationary charging stations or journeys away from the primary conductor or conductor lines. In the normal case, the double-layer capacitor 7 supplies the drives of the MAS. Their consumption is approximately dependent on the distance traveled without an external energy supply, which should be planned well in advance, since the spatial arrangement of the charging infrastructure is known.

[0063] In the exemplary embodiments illustrated in FIG. 1 and FIG. 2, the charger 3 regulates the output current I.sub.0 of the variable current source 5 itself by its regulator 4. This output current I.sub.0 is divided into the current I.sub.1 that flows through the battery store, i.e., the charging current of the battery store, and the current I.sub.2, which flows into the converter device 8. In order to prevent the battery store from being destroyed, for example, due to overcharging, certain measures are, for example, taken to ensure that the battery store is charged correctly. For this purpose, the electric vehicle in the exemplary embodiment illustrated in FIG. 3 has a so-called intelligent battery 14, the detailed structure of which is illustrated again in FIG. 4.

[0064] The exemplary embodiment illustrated in FIG. 3 differs from that illustrated in FIG. 2 on the one hand in that a converter device 8 is present, which is schematically illustrated as the DC/DC converter 15 having downstream diode 9. This representation is intended to express that the converter device 8 is a unidirectional DC/DC converter, which permits a power or energy flow only from the charger 3 to the double-layer capacitor 7. A power or energy flow from the double-layer capacitor 7 to the battery store 6 is prevented by the converter device 8. Specific configurations of the converter device are illustrated in FIGS. 1 and 2. However, other specific configurations are also possible, as long as unidirectionality is provided.

[0065] Another difference is that the vehicle has an intelligent battery 14 in the exemplary embodiment illustrated in FIG. 3. As schematically illustrated in FIG. 4, this intelligent battery 14 includes a battery management system 12, a battery store 6, and a bidirectional switch 13. The bidirectional switch 13 is optional. The battery management system 12 can also be designated as an energy storage control device.

[0066] In the present exemplary embodiment, characteristic variables of the battery store 6 are measured and thus detected, for example, by sensors arranged in the battery store 6. These variables characterize the state of the battery store 6 and are, for example, the voltage U.sub.1 applied to the battery store 6, the current I.sub.1 flowing through the battery store 6, and the temperature T.sub.1 prevailing in the battery store 6. It is also possible that, for example, only the voltage U.sub.1 is detected. The detected state values are made available to the battery management system 12 and the battery management system 12 controls or regulates the output current I.sub.0 of the charger 3 depending on at least one of these state values. For this purpose, the battery management system 12 specifies a setpoint value for regulation or control to the charger 3. In the exemplary embodiment illustrated in FIG. 3, this setpoint value I.sub.0,soll is a setpoint value for the output current I.sub.0. A value for the charging current I.sub.1 flowing through the battery store 6 can be set via this setpoint value I.sub.0,soll. This ensures that the battery store 6 is always charged using a permissible charging current I.sub.1. It is therefore protected from destruction or misuse. The regulation or control of the charging process is specified by the intelligent battery 14, so that the charger 3 can be configured in a simple manner. In this case, only one variable current source 5 is necessary, so that the output current I.sub.0 is influenceable by the battery management system 12. With this method, it is permissible for the charger 3 to set a lower current than the setpoint value I.sub.1,soll. This is the case, for example, when the capacity of the charger is too low for the current I.sub.0,soll specified by the intelligent battery 14. It is important that the current I.sub.1 flowing through the battery store cannot be greater than permitted, so that the battery is protected against overloading. The setpoint value I.sub.0,soll therefore represents a maximum upper limit, which is dynamically adjustable.

[0067] For example, the intelligent battery 14 includes a bidirectional switch 13, using which it is possible to prevent the flow of power or energy to and from the battery store 6 independently of one another. For example, the bidirectional switch includes, as schematically illustrated in FIG. 4, two parallel current branches, each having an activatable switch and a diode, and the diodes are connected in antiparallel. In this manner, overcurrent and/or overvoltage and/or overtemperature protection is implementable in that the battery management system 12 interrupts the energy supply or discharge of the battery store 6 depending on the state variables.

[0068] For example, the intelligent battery 14 is a separate structural unit, so that all components are integrated in one housing and a replacement of the intelligent battery 14 is thus provided. This also makes it possible to refit the electric vehicle depending on the logistical application. The regulation or control of the battery charging current I1 is always taken over by the intelligent battery 14 itself, so that the same charger 3 and the same converter device 8 are always usable for different battery stores 6 having different parameters.

[0069] The battery management system 12 is, for example, connected to the vehicle controller 10 via a communication link 16. Various application parameters are transmittable via this communication link 16. For example, it is possible for the battery management system 12 to communicate the maximum possible discharge current I.sub.1,min to the vehicle controller 10. Another application parameter can be, for example, the state of charge (SOC) or an aging state of the battery store 6. In this manner, the vehicle controller 10 is always informed about the present status of the battery store 6.

LIST OF REFERENCE NUMERALS

[0070] 1 first DC connection [0071] 2 second DC connection [0072] 3 energy supply unit [0073] 4 regulator [0074] 5 variable power source [0075] 6 first energy storage device [0076] 7 second energy storage device [0077] 8 converter device [0078] 9 diode [0079] 10 first consumer [0080] 11 second consumer [0081] 12 energy storage control device [0082] 13 bidirectional switch [0083] 14 intelligent battery [0084] 15 DC/DC converter [0085] 16 communication link