METHOD FOR OPERATING AN ELECTRICAL SYSTEM, AND APPARATUS FOR CONTROLLING AN ELECTRICAL SYSTEM

• US 20140152093A1
• Filed: 07/04/2012
• Published: 06/05/2014
• Est. Priority Date: 07/21/2011
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wald, Klaus-Juergen, Wirth, Martin
• Granted Patent: US 9,186,998 B2
• Time in Patent Office: Days
• US Class Current: 307/10.1
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/427 Voltage
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• CPC Class Codes: B60L 50/15 with additional electric power supply with capacitors charged by engine-driven generators B60L50/40; with batteries charged by engine-driven generators B60L50/61
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

The present invention relates to a method (50) for operating an electrical system (44), particularly in a motor vehicle (10), wherein the electrical system (44) has at least two electrical machines (14, 34) which are connected to the electrical system (44) via one controllable inverter (32, 42) each, wherein a regulated generator mode for a first instance of the electrical machines (14, 34) is initiated (60), characterized in that a first step (54) involves detection of a drop below a first prescribable voltage value for the electrical voltage available in the electrical system (44), and then a second step (56), on the basis of an induced freewheeling voltage that is to be expected for one of the electrical machines (14, 32), involves one of the inverters (32, 42) being selected, which is associated with an electrical machine (14, 32), and being actuated such that the electrical machine (14, 34) connected thereto is operated in electrical freewheel, with the result that the rotation of said machine causes it to induce a freewheeling voltage which is applied in the electrical system (44), and then a third step (58) involves detection of the rise above a second prescribable voltage value for the induced electrical freewheeling voltage available in the electrical system (44), and then a fourth step (60) involves the inverter (32, 42) of the first electrical machine (14, 34) being actuated such that the first electrical machine (14, 34) connected thereto is operated in regulated generator mode.

Claims

1. A method (50) for operating an electrical system (44), wherein the electrical system (44) has at least two electrical machines (14, 34) which are connected to the electrical system (44) by a controllable inverter (32, 42) in each case, wherein a regulated generator mode of a first of the electrical machines (14, 34) is initiated (60), characterized in that, in a first step (54), detecting a situation of the electrical voltage which is available in the electrical system (44) falling below a first predefinable voltage value, and then, in a second step (56), depending on an expected induced freewheeling voltage of one of the electrical machines (14, 32), one of the inverters (32, 42), which is associated with one of the electrical machines (14, 32), is selected and is actuated such that the electrical machine (14, 34) which is connected to the selected and actuated one of the inverters (32, 42) is operated in electrical freewheel mode, so that said electrical machine, as a result of its rotation, induces a freewheeling voltage which is applied to the electrical system (44), and then, in a third step (58), detecting the situation of the induced electrical freewheeling voltage which is available in the electrical system (44) exceeding a second predefinable voltage value, and then, in a fourth step (60), the inverter (32, 42) of the first electrical machine (14, 34) is actuated such that the first electrical machine (14, 34) which is connected to it is operated in the regulated generator mode.

2. The method as claimed in claim 1, characterized in that the electrical system (44) has at least one electrical energy store (46), and in that a regulated generator mode of a first of the electrical machines (14, 34) is initiated during operation of the vehicle after disconnection (54) of the electrical energy store (46) from the electrical system (44), for the further supply of electrical energy to the electrical system (44).

3. The method as claimed in claim 1, characterized in that the electrical system (44) further has a voltage regulator (48) which regulates the induced generator voltage in the electrical system (44) in the regulated generator mode of the first electrical machine (14, 34).

4. The method as claimed in claim 1, wherein the first electrical machine (14) is connected to a crankshaft (20) of an internal combustion engine (16) of the motor vehicle (10), and the at least one further electrical machine (34) is connected to an axle of the motor vehicle (10).

5. The method as claimed in claim 1, wherein the first electrical machine (14) and the at least one further electrical machine (34) are operated at different rotation speeds.

6. The method as claimed in claim 1, wherein the first electrical machine (14) and the at least one further electrical machine (34) have different freewheeling characteristic curves.

7. The method as claimed in claim 1, wherein the expected induced freewheeling voltage of the respective electrical machine (14, 34) is determined on the basis of the respective rotation speed and the respective freewheeling characteristic curve.

8. The method as claimed in claim 7, wherein a regulated generator mode of a first of the electrical machines (14, 34) is initiated for generating a generator voltage in the electrical system (44) with a predefined generator voltage setpoint value, wherein the electrical machine (14, 34) selected for generating the freewheeling voltage in the electrical system (44) is that of which the expected induced freewheeling voltage deviates least from a predefined generator voltage setpoint value.

9. The method as claimed in claim 7, wherein that electrical machine of which the expected induced freewheeling voltage lies outside a permissible voltage range is precluded from being used as the electrical machine (14, 34) for generating the freewheeling voltage in the electrical system (44).

10. The method as claimed in claim 1, wherein the regulated generator mode of the first electrical machine is performed by a pulse-width-modulation method.

11. The method as claimed in claim 1, characterized in that the first and the second predefinable voltage values have the same magnitude.

12. An apparatus (48) for controlling an electrical system (44), comprising a voltage detector (49) configured to detect an electrical voltage in the electrical system (44), and a control unit (48) which is configured to execute the method (50) as claimed in claim 1.

13. An electrical system (44), comprising an electrical energy store (46), and at least two electrical machines (14, 34) which are connected to the electrical system (44) by a controllable inverter (32, 42) in each case, and comprising a control unit (48) as claimed in claim 12.

14. The method as claimed in claim 1, wherein the electrical system (44) is an electrical system of a motor vehicle (10).

15. The method as claimed in claim 1, wherein the least one electrical energy store (46), is an electrical high-voltage energy store (46).

16. The method as claimed in claim 1, wherein the first electrical machine (14) is connected to a crankshaft (20) of an internal combustion engine (16) of the motor vehicle (10), and the at least one further electrical machine (34) is connected to a wheel (40R, 40L) of the motor vehicle (10).

17. The method as claimed in claim 1, wherein the expected induced freewheeling voltage of the respective electrical machine (14, 34) is determined on the basis of the respective rotation speed.

18. The method as claimed in claim 1, wherein the expected induced freewheeling voltage of the respective electrical machine (14, 34) is determined on the basis of the respective freewheeling characteristic curve.

19. The apparatus (48) as claimed in claim 12, wherein the electrical system (44) is an electrical system (44) of a motor vehicle (10).

20. The electrical system (44), as claimed in claim 13, wherein the electrical system (44) is an electrical system (44) of a motor vehicle (10) and the electrical energy store (46) is an electrical high-voltage energy store (46).