Motor vehicle electric system

• US 20040112320A1
• Filed: 08/05/2003
• Published: 06/17/2004
• Est. Priority Date: 02/16/2001
• Status: Active Grant

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Bolz, Stephan, Knorr, Rainer
• Granted Patent: US 6,919,648 B2
• Time in Patent Office: Days
• US Class Current: 123/179.28
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: F02N 11/04 the motors being associated with current generators
• CPC Class Codes: F02N 11/0866 comprising several power sources, e.g. battery and capacitor or two batteries
• CPC Class Codes: F02N 2011/0885 Capacitors, e.g. for additional power supply
• CPC Class Codes: F02N 2011/0888 DC/DC converters
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 7/1423 with multiple batteries
• CPC Class Codes: H02J 7/1446 in response to parameters of a vehicle
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02P 2101/45 for motor vehicles, e.g. car alternators
• CPC Class Codes: H02P 9/307 more than one voltage output
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A starter-generator (ISG) is mechanically connected to an internal combustion engine (BKM), comprises a bi-directional AC/DC converter (1), and can be connected to an accumulator (B1) by means of a first switch (S1), and connected to a double layer capacitor (DLC) by means of a second switch (S2). The accumulator (B1) is either connected to the double layer capacitor (DLC) by means of a control circuit (PWM), or the accumulator (B1) and the double layer capacitor (DLC) are connected to a bidirectional DC/DC converter (3) and to a second accumulator (B2) by means of a third switch (S3) and a fourth switch (S4).

Claims

1. Motor vehicle electric system comprising an internal combustion engine and, mechanically connected thereto, an integrated starter-generator that charges a double layer capacitor and a battery to a first voltage via a bi-directional AC/DC converter in generator mode and is driven by the energy stored in the double layer capacitor or in the battery in motor mode, wherein an intermediate circuit capacitor is arranged between the positive and negative direct voltage terminals of the bi-directional AC/DC converter, a first switch is provided via which the positive direct voltage terminal of the bi-directional AC/DC converter can be connected to the plus pole of the battery, the minus pole of which is grounded, and a second switch is provided via which the positive direct voltage terminal of the bi-directional AC/DC converter can be connected to the positive terminal of the double layer capacitor, the negative terminal of which is grounded.

2. Motor vehicle electric system according to claim 1, wherein the first and second switches are interlinked in such a way that they cannot both be in the conducting position at the same time.

3. Motor vehicle electric system according to claim 1, wherein the intermediate circuit capacitor can be charged from the AC/DC converter to a voltage value corresponding to the voltage at the double layer capacitor or the battery before the first or second switch is switched to the conducting position.

4. Motor vehicle electric system according to claim 1, wherein the flow of current into the AC/DC converter or out of the AC/DC converter can be reduced to a minimal value before the first or second switch is switched to the non-conducting position.

5. Motor vehicle electric system according to claim 1, wherein a regulator circuit is provided by means of which the double layer capacitor can be recharged from the battery.

6. Motor vehicle electric system according to claim 1, wherein the double layer capacitor is charged to an elevated voltage higher than the voltage of the battery.

7. Motor vehicle electric system according to claim 1, comprising an additional battery to supply additional loads with a second voltage, which additional battery is charged via a bi-directional DC/DC converter by the battery, wherein a third switch is provided via which the plus pole of the first battery can be connected to a positive terminal of the bi-directional DC/DC converter, and a fourth switch is provided via which the positive terminal of the double layer capacitor can be connected with the same positive terminal of the bi-directional DC/DC converter.

8. Motor vehicle electric system according to claim 7, wherein the third and fourth switches are interlinked in such a way that they cannot both be in the conducting position at the same time.

9. Motor vehicle electric system according to claim 1, comprising a control/regulation circuit for controlling/regulating operations from the group of

charging the intermediate circuit capacitor via the AC/DC converter to a voltage value corresponding to the voltage at the double layer capacitor or the 36 V battery,

determining the working direction of the converters (step-up or step-down), and

controlling the positions of switches S1 to S4.

10. Motor vehicle electric system according to claim 1, wherein

when the integrated starter-generator is in generator mode:

the intermediate circuit capacitor is charged to a predefinable voltage when the switches are non-conducting,

the battery is charged when the first switch is conducting and

the double layer capacitor is charged when the second switch is conducting and

when the integrated starter-generator is in motor mode;

the starter-generator is driven with energy from the battery when the first switch is conducting and

the starter-generator is driven with energy from the double layer capacitor when the second switch is conducting.

11. Motor vehicle electric system according to claim 7, wherein

the battery charges or is charged by the additional battery when the third switch is conducting and

the double layer capacitor charges or is charged by the additional battery when the fourth switch is conducting.

12. Motor vehicle electric system according to claim 8, wherein

the battery charges or is charged by the additional battery when the third switch is conducting and

the double layer capacitor charges or is charged by the additional battery when the fourth switch is conducting.

13. Method of operating a motor vehicle electric system comprising an integrated starter-generator comprising the steps of:

charging a double layer capacitor and a battery to a first voltage via a bi-directional AC/DC converter in a generator mode,

driving the starter-generator by the energy stored in the double layer capacitor or in the battery in a motor mode,

arranging an intermediate circuit capacitor between the positive and negative direct voltage terminals of the bi-directional AC/DC converter,

providing a first switch via which the positive direct voltage terminal of the bi-directional AC/DC converter can be connected to the plus pole of the battery, the minus pole of which is grounded, and

providing a second switch via which the positive direct voltage terminal of the bi-directional AC/DC converter can be connected to the positive terminal of the double layer capacitor, the negative terminal of which is grounded.

14. Method according to claim 13, further comprising the step of interlinking the first and second switches in such a way that they cannot both be in the conducting position at the same time.

15. Method according to claim 13, further comprising the step of charging the intermediate circuit capacitor from the AC/DC converter to a voltage value corresponding to the voltage at the double layer capacitor or the battery before the first or second switch is switched to the conducting position.

16. Method according to claim 13, further comprising the step of reducing the flow of current into the AC/DC converter or out of the AC/DC converter to a minimal value before the first or second switch is switched to the non-conducting position.

17. Method according to claim 13, further comprising the step of recharging the double layer capacitor from the battery by a regulator circuit.

18. Method according to claim 13, further comprising the step of charging the double layer capacitor to an elevated voltage higher than the voltage of the battery.

19. Method according to claim 13, further comprising the steps of:

charging an additional battery via a bi-directional DC/DC converter by the battery,

providing a third switch via which the plus pole of the first battery can be connected to a positive terminal of the bi-directional DC/DC converter, and

providing a fourth switch via which the positive terminal of the double layer capacitor can be connected with the same positive terminal of the bi-directional DC/DC converter.

20. Method according to claim 19, further comprising the step of interlinking the third and fourth switches in such a way that they cannot both be in the conducting position at the same time.

21. Method according to claim 13, further comprising the step of controlling/regulating operations from the group of:

charging the intermediate circuit capacitor via the AC/DC converter to a voltage value corresponding to the voltage at the double layer capacitor or the 36 V battery,

determining the working direction of the converters (step-up or step-down), and

controlling the positions of switches S1 to S4.

22. Method according to claim 13, further comprising the steps of

when the integrated starter-generator is in generator mode:

charging the intermediate circuit capacitor to a predefinable voltage when the switches are non-conducting,

charging the battery when the first switch is conducting and

charging the double layer capacitor when the second switch is conducting and

when the integrated starter-generator is in motor mode;

driving the starter-generator with energy from the battery when the first switch is conducting and

driving the starter-generator with energy from the double layer capacitor when the second switch is conducting.

23. Method according to claim 19, further comprising the step of

the battery charges or is charged by the additional battery when the third switch is conducting and

the double layer capacitor charges or is charged by the additional battery when the fourth switch is conducting.

24. Method according to claim 20, further comprising the step of

the battery charges or is charged by the additional battery when the third switch is conducting and

the double layer capacitor charges or is charged by the additional battery when the fourth switch is conducting.