Integration of Starter Current Control Device and On-Board Electrical System Disconnecting Switch

Abstract

An integrated starter and on-board electrical system disconnecting module for connecting to a starter battery and to an on-board electrical system by a transducer is disclosed. A method for limiting the starting current in a motor vehicle and the use of the integrated starter and on-board electrical system disconnecting module in multi-voltage on-board electrical systems, in particular during a start-stop operation of plug-in hybrid vehicles and for hybrid on-board electrical systems, are also disclosed. The transducer can be connected to a starter circuit including the starter battery from an on-board electrical system side, via a starter control device and via an on-board electrical system disconnector. The on-board electrical system can be uncoupled from the starter circuit and the starter control device and the on-board electrical system disconnector are integrated in the module.

Claims

1.-10. (canceled)

11. A module for connecting to a starter battery and to an on-board electrical system by a transducer, comprising: a starter control device and an on-board electrical system disconnector, wherein the transducer is connected to a starter circuit including the starter battery from an on-board electrical system side via the starter control device and via the on-board electrical system disconnector; wherein the on-board electrical system is uncoupled from the starter circuit during a starting process and wherein the starter control device and the on-board electrical system disconnector are integrated in the module.

12. The module according to claim 11, wherein the starter control device comprises a starter switch that switches on a starter motor, wherein the starter motor is electrically coupled to the starter battery such that the starter motor and the starter battery can be disconnected from the on-board electrical system during a starting process.

13. The module according to claim 12, wherein the on-board electrical system disconnector comprises an on-board electrical system disconnecting switch, wherein the starter switch and the on-board electrical system disconnecting switch are formed as MOSFETs having intrinsic diodes.

14. The module according to claim 11, further comprising a first quasi-diode which is closed in a base state and wherein, during a starting process, the first quasi-diode is opened and a monitoring of a voltage relative to the on-board electrical system takes place.

15. The module according to claim 14, further comprising a control unit which is connected to the first quasi diode, wherein the control unit switches through the first quasi-diode and terminates the starting process in an event of falling below a predetermined voltage drop on the on-board electrical system side or in an event of a failure of the transducer.

16. The module according to claim 14: wherein the starter control device comprises a starter switch that switches on a starter motor, wherein the starter motor is electrically coupled to the starter battery such that the starter motor and the starter battery can be disconnected from the on-board electrical system during a starting process; and further comprising a series resistor that is switched in series with the starter switch, wherein the series resistor can be electrically connected to the first quasi-diode from a starter circuit side.

17. The module according to claim 14, further comprising a second quasi-diode that is switched in series with the first quasi-diode.

18. A method for limiting a starting current in a motor vehicle, wherein a transducer is connected from an on-board electrical system side to a starter circuit via a starter control device and via an on-board electrical system disconnector, comprising the step of: uncoupling an on-board electrical system from the starter circuit during a starting process, wherein the starter control device and the on-board electrical system disconnector are integrated in a module.

19. The method according to claim 18, wherein both the starter circuit and the on-board electrical system are supplied by the starter control device.

20. The method according to claim 18, wherein the motor vehicle is a plug-in hybrid motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 illustrates an integrated starter and on-board electrical system disconnecting module according to a first exemplary embodiment of the invention;

[0018] FIG. 2 illustrates an integrated starter and on-board electrical system disconnecting module according to a second exemplary embodiment of the invention;

[0019] FIG. 3 is a schematic depiction of the limitation of the start voltage failure with series resistor according to a third exemplary embodiment;

[0020] FIG. 4 illustrates an on-board electrical system disconnector and a start termination and an on-board electrical system support in the event of transducer failure according to a fourth exemplary embodiment of the invention; and

[0021] FIG. 5 illustrates a starter protection device with low-Ohm battery according to a fifth exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0022] As can be seen in FIG. 1, an integrated starter and on-board electrical system disconnecting module 13 having a connected starter battery 2 according to a first exemplary embodiment is depicted. The module 13 is connected on the on-board electrical system side by a transducer 4 that is located in the on-board electrical system 3. The transducer 4 can be connected to a starter circuit 5 including the starter battery 2 from the on-board electrical system side via the module 13. The connection takes place via a starter control device and via an on-board electrical system disconnector in the module 13. The on-board electrical system 3 can be uncoupled from starter circuit 5 and the starter control device and the on-board electrical system disconnector are integrated together in the module 13. Hybrid vehicles require a 12-volt start when travelling at high speeds. The voltage requirement of the steering and driving gear system requires uncoupling between the starter circuit 5 and the on-board electrical system 3.

[0023] In the event of the vehicle coming to a halt and operation of the vehicle without the starting process, uncoupling is not necessary. A quasi-diode 9 provided in the module 13 is closed in its base state. As soon as the vehicle picks up speed during the starting process, an uncoupling between the starter circuit 5 and the on-board electrical system 3 takes place. As a result, the quasi-diode switch 9 is opened. A voltage monitoring of the on-board electrical system 3 is active. The starter motor 7 is provided in the starter circuit 5 and the starter circuit 5 can be switched in series via a series resistor 12 by means of the quasi-diode 9. Here, a starter switch 6 is provided in the starter circuit 5 itself, the starter switch 6 being switched in series to the series resistor 12 and in parallel to an on-board electrical system disconnecting switch 8.

[0024] In the event of a voltage drop to a voltage less than 11 volts on the on-board electrical system side or in the event of a transducer failure, the start is terminated. The recovery time of the battery 2 to return to the nominal voltage of 12 volts is 20 ms with a switching time of less than 1 s in this exemplary embodiment. The maximum time below a voltage of 11 volts is less than 20 ms. This time can be supported in the vehicle systems.

[0025] FIG. 2 shows the module 13 according to a second exemplary embodiment of the invention. FIG. 2 differs from FIG. 1 by a control unit 11 further being provided which controls the first quasi-diode 9 and a second quasi-diode 10, wherein the two quasi-diodes 9, 10 are switched in series. In the event of falling below an on-board electrical system voltage limit, the control unit 11 switches through the quasi-diode 9 and terminates the start. By means of a corresponding software control device, a diagnosis and a status report take place in this second exemplary embodiment. Furthermore, the current usage of the two quasi-diodes 9, 10 is minimized by a corresponding controller, wherein the starter switch 6 and the on-board electrical system disconnecting switch 8 are formed as MOSFETs with intrinsic diodes. The whole system 1 of FIG. 2 thus differs from that of FIG. 1, in particular in the module 13.

[0026] FIG. 3 illustrates a limitation of the voltage drop with series resistors according to a third exemplary embodiment of the invention. Here, the voltage is applied to the on-board electrical system 3 via the time axis. When the two switches 6, 8 are open, the series resistor 12 is in neutral and the starter wire is potential-free. If the voltage drops below 11 volts in a time of 20 ms, the starter switch 6 is closed, such that the series resistor 12 is switched in series with the quasi-diode 9. The series resistor 12 is 8.5 m and is switched on until the on-board electrical system voltage remains safely above 9 V. Within a time of between 70 ms and 80 ms, wherein, in this third exemplary embodiment, the maximum time is 150 ms, the voltage increases again virtually exponentially, before the on-board electrical system disconnecting switch 8 is also closed and thus the series resistor 12 is bridged and the whole current flows. Then, a further voltage drop to virtually 9 volts takes place, wherein thereafter, the voltage continuously increases again until the nominal voltage is reached again, and the starter wire becomes potential-free. The start duration is 500 ms in this third exemplary embodiment.

[0027] FIG. 4 illustrates the on-board electrical system disconnector, a quick start termination and an on-board electrical system support in the event of transducer failure according to a fourth preferred exemplary embodiment. The transducer failure takes place where there is an arrow with the label DCDC in FIG. 4. Before this, the transducer supplies the on-board electrical system 3, and the quasi-diode 9 is closed and disconnects the starter circuit 5 from the on-board electrical system 3. After this, the quasi-diode 9 is switched and the starter battery 2 supplies the on-board electrical system 3. Furthermore, the diode function of the on-board electrical system disconnecting switch 8 is applied in a dashed manner in this diagram, wherein the voltage drop is applied over time. In the last section, the battery voltage recovers to a resulting load voltage within 15 ms.

[0028] FIG. 5 illustrates the starter protection device with a low-Ohm battery according to a fifth exemplary embodiment of the invention. FIG. 5 does not differ at all from FIG. 3 in terms of the three time sections, yet in this fifth exemplary embodiment, a lithium starter battery is used and, at the end of the first time section, this low-Ohm battery is recognized. As a result, the resistor remains switched until the resistor becomes too hot. Furthermore, the course between the second and the third time section differs, such that, in FIG. 5, there is no abrupt voltage drop to be seen at the end of the second time section. During the second time section, the current switches through and an emergency switching can take place in the event of exceeding the temperature limit of the resistor.