REDUCING SWITCHING-ON AND SWITCHING-OFF PROCESSES IN AN ELECTRIC DRIVETRAIN

Abstract

A method (100) for operating a vehicle (1) with an electric drive-train (2), wherein this electric drivetrain (2) is fed via a DC voltage source (3) and a converter (4) for converting the DC voltage into a single-phase or multiphase AC voltage, comprising the steps: —it is detected (110) that the vehicle (1) is stopped; — it is checked (120) on the basis of at least one specified criterion (10) whether the vehicle (1) is expected to be stopped only briefly; —in response to the fact that the vehicle (1) is expected to be stopped only briefly, the vehicle (1) is transferred (130) from the ready-to-drive state into a disabled state, wherein in this disabled state the vehicle (1) is protected against unauthorized use but the converter (4) continues to be supplied with the DC voltage from the DC voltage source (3); —in response to the fact that the vehicle (1) is not expected to be stopped only briefly, at least one functional test of the electric drivetrain (2), said test being provided for powering down the electric drivetrain (2), is performed (140), and after the termination of this functional test the vehicle (1) is transferred (150) into a switched-off state, in which the vehicle (1) is secured against unauthorized use and the supply of the converter (4) from the DC voltage source (3) is interrupted.

Claims

1. A method (100) for operating a vehicle (1) having an electric drivetrain (2), wherein this electric drivetrain (2) is fed via a DC-voltage source (3) and a converter (4) for converting the DC voltage into a single-phase or polyphase AC voltage, the method comprising the following steps: determining (110) that the vehicle (1) is parked; and ascertaining using at least one preset criterion (10) (120) whether the vehicle (1) is likely to be parked for only a short time; in response to the ascertaining that the vehicle (1) is likely to be parked for only a short time, shifting the vehicle (1) from a drive-ready state to a blocking state (130), wherein, in the blocking state, the vehicle (1) is protected from unauthorized use, and the converter (4) is supplied the DC voltage from the DC-voltage source (3); in response to ascertaining that the vehicle (1) is likely not to be parked for only a short time, performing at least one function check on the electric drivetrain (2) which is intended to ramp down the electric drivetrain (2) (140), and, once this function check has concluded, shifting the vehicle (1) to a switched-off state, in which the vehicle (1) is protected from unauthorized use and the supply to the converter (4) from the DC-voltage source (3) is interrupted.

2. The method (100) as claimed in claim 1, wherein the vehicle (1) is shifted to the drive-ready state starting from the blocking state, and/or from the switched-off state, (170) in response to authenticating a driver of the vehicle (1) with respect to the vehicle (1) (160).

3. The method (100) as claimed in claim 2, wherein different authentication criteria apply for the transition from the blocking state to the drive-ready state, on the one hand, and for the transition from the switched-off state to the drive-ready state, on the other hand, (161).

4. The method (100) as claimed in claim 1, wherein, in the blocking state, a check continues to be performed using at least one preset criterion (11) (180) to ascertain whether the vehicle (1) is likely to be parked for only a short time, and wherein the vehicle (1) is shifted to the switched-off state in response to ascertaining that, in accordance with this check, it is likely not to be parked for only a short time (190).

5. The method (100) as claimed in claim 1, wherein the preset criterion (10, 11) comprises: a comparison of the present position of the vehicle (1) with at least one geographical area which is associated with a short-term or non-short-term parking of the vehicle (1); a removal from the vehicle (1) of a mobile electronic device which is carried along in the vehicle (1) prior to the parking of the vehicle (1); and/or an input by the driver of the vehicle (1) in respect of whether short-term or non-short-term parking of the vehicle (1) is intended; (121, 181).

6. The method (100) as claimed in claim 5, wherein a mobile telephone, a tablet computer, a device for accepting card payments, a device for confirming the delivery of consignments and/or a vehicle key is selected as the mobile electronic device (121a, 181a).

7. The method (100) as claimed in claim 1, wherein, in response to the fact that a preset time span has elapsed since the transition from the drive-ready state to the blocking state (200); and/or the energy reserve of the DC-voltage source (3) falls below a preset threshold value (210); and/or an electrical or electronic fault is established in the drivetrain (2) (220), the vehicle (1) is shifted from the blocking state to the switched-off state (230).

8. The method (100) as claimed in claim 1, wherein the transition from the blocking state to the switched-off state includes switching off a switch (3a) in the form of a mechanical switch or in the form of a contactor for the supply to the converter (4) from the DC-voltage source (3) (151), and/or discharging a capacitor (4a) in the converter (4) which buffer-stores the DC voltage from the DC-voltage source (3) (152).

9. The method (100) as claimed in claim 1, wherein the vehicle comprises a utility vehicle intended for the delivery of items.

10. (canceled).

11. A non-transitory, computer-readable medium containing instructions that when executed by a computer cause the computer to operate a vehicle (1) having an electric drivetrain (2), wherein this electric drivetrain (2) is fed via a DC-voltage source (3) and a converter (4) for converting the DC voltage into a single-phase or polyphase AC voltage, by: determining (110) that the vehicle (1) is parked; and ascertaining using at least one preset criterion (10) (120) whether the vehicle (1) is likely to be parked for only a short time; in response to ascertaining that the vehicle (1) is likely to be parked for only a short time, shifting the vehicle (1) from a drive-ready state to a blocking state (130), wherein, in the blocking state, the vehicle (1) is protected from unauthorized use, and the converter (4) is supplied the DC voltage from the DC-voltage source (3); in response to ascertaining that the vehicle (1) is likely not to be parked for only a short time, performing at least one function check on the electric drivetrain (2) which is intended to ramp down the electric drivetrain (2) (140), and, once this function check has concluded, shifting the vehicle (1) to a switched-off state, in which the vehicle (1) is protected from unauthorized use and the supply to the converter (4) from the DC-voltage source (3) is interrupted.

12. (canceled).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further measures improving the invention will be illustrated in more detail below together with the description of the preferred exemplary embodiments of the invention with reference to the figures.

[0035] In the drawings:

[0036] FIG. 1 shows an exemplary embodiment of the method 100;

[0037] FIG. 2 shows an example of an electric drivetrain 2 for use of the method 100.

DETAILED DESCRIPTION

[0038] FIG. 1 shows a schematic flowchart of an exemplary embodiment of the method 100. In step 105, a utility vehicle intended for the delivery of goods, consignments of letters, consignments of packages and/or piece goods is selected as vehicle 1. In step 110, it is established that this vehicle 1 is parked.

[0039] In step 120, a check is now performed using the criterion 10 to ascertain whether the vehicle is likely to be parked for only a short time. If this is the case (probability value 1), the vehicle, in step 130, is shifted from the drive-ready state to the blocking state. Otherwise (probability value 0), in step 140, at least one function check of the electric drivetrain 2 is performed, which function check is intended for ramping down, and in step 150, the vehicle 1 is shifted to the switched-off state.

[0040] The shifting to the switched-off state, in accordance with block 151, can include switching off a switch 3a for the supply to the converter 4 in the drivetrain 2 from the DC source 3. Alternatively or else in combination therewith, according to block 152, a capacitor 4a in the converter 4 which buffer-stores the DC voltage from the DC-voltage source 3 can be discharged. The design of the drivetrain 2 is illustrated in more detail in FIG. 2.

[0041] In step 180, again a check can be performed in accordance with a preset criterion 11 to ascertain whether the vehicle 1 is still likely to be parked for a short time. If this is not the case (probability value 0), the vehicle 1 is shifted to the switched-off state in step 190.

[0042] In step 200, a check can be performed to ascertain whether a preset time span has elapsed since the transition from the drive-ready state to the blocking state. In step 210, a check can be performed to ascertain whether the energy reserve of the DC-voltage source 3 falls below a preset threshold value. In step 220, a check can be performed to ascertain whether an electrical or electronic fault is established in the drivetrain 2. If one of these conditions is met (i.e. if the respective probability value is 1), the vehicle 1 is shifted from the blocking state to the switched-off state in step 230.

[0043] In step 160, starting from the blocking state, and/or from the switched-off state, a check is performed to ascertain whether the driver of the vehicle 1 has been legitimized with respect to the vehicle 1. If this is the case (probability value 1), the vehicle 1 is shifted to the drive-ready state again, in step 170. In this case, in accordance with block 161, different legitimization criteria apply depending on whether the start point is the blocking state or the switched-off state.

[0044] In accordance with block 121 or 181, the preset criterion 10 or 11 can comprise [0045] a comparison of the present position of the vehicle 1 with at least one geographical area which is associated with a short-term or non-short-term parking of the vehicle 1; [0046] removal from the vehicle 1 of a mobile electronic device which is carried along in the vehicle 1 prior to parking of the vehicle 1; and/or [0047] an input by the driver of the vehicle 1 in respect of whether a short-term or non-short-term parking of the vehicle 1 is intended.

[0048] In accordance with block 121a or 181a, the mobile electronic device may be in particular a mobile telephone, a tablet computer, a device for accepting card payments, a device for confirming the delivery of consignments and/or a vehicle key.

[0049] FIG. 2 shows an exemplary electric drivetrain 2 for a vehicle 1. A DC-voltage source 3, for example a battery, feeds a converter 4 via a switch 3a, for example a contactor, which converter converts the DC voltage into an, in this example, three-phase AC voltage with the phases U, V and W and connects through to an electric motor 5. The converter 4 contains a capacitor 4a, which buffer-stores the DC voltage. The pre-charging circuit with resistor which prevents excessively quick and steep charging of the capacitor 4a is not illustrated in FIG. 2 for reasons of clarity. The basic functional principle does not change when the number of phases is increased to, for example, six or nine phases.