Method for determining a power limiting value for an electric machine in a vehicle, computer program and control unit for controlling an electric machine in a vehicle

• US 8,851,218 B2
• Filed: 02/25/2011
• Issued: 10/07/2014
• Est. Priority Date: 04/08/2010
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wirth, Martin, Raichle, Daniel, Scheidle, Alexander, Eisenhardt, Martin
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): GOLDMAN, RICHARD A
• Application Number:
  US13/639,425
• Publication Number:
  US 20130085635A1
• Time in Patent Office: 1,320 Days
• Field of Search: None
• US Class Current: 180/65.285
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 50/50 using propulsion power supplied by batteries or fuel cells
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2510/242 for electrical energy
• CPC Class Codes: B60W 2710/086 Power
• CPC Class Codes: G01R 31/3647 for determining the ability of a battery to perform a critical function, e.g. cranking
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• 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 10/72 Electric energy management in electromobility
• CPC Class Codes: Y10S 903/906 Motor or generator
• CPC Class Codes: Y10S 903/907 Electricity storage, e.g. battery, capacitor

Abstract

In a method for determining a power limiting value for an electric machine in a vehicle, the electric machine being assigned an energy storage device, an intermediate power value is calculated from a maximally allowable current of the energy storage device and an instantaneous voltage. A corrected intermediate power value is determined by adding at least one power loss to the intermediate power value. A first correction value is determined for reducing the absolute value of the corrected intermediate power value if an instantaneous power of the energy storage device is greater than the absolute value of the calculated intermediate power value. The power limiting value is determined by superimposing the first correction value on the corrected intermediate power value.

Claims

1. A method for controlling an electric machine in a vehicle, wherein the electric machine is assigned an energy storage device, and wherein the electric machine is supplied with power from the energy storage device in a motor mode and energy is stored in the energy storage device in a generator mode of the electric machine, the method comprising:

determining a power limiting value for the electric machine, wherein the determining of the power limiting value includes;

calculating an intermediate power value from a maximally allowable current of the energy storage device and an instantaneous voltage;

determining a corrected intermediate power value by a pilot control unit in the vehicle by adding at least one power loss value to the calculated intermediate power value;

determining a first correction value by a second control unit in the vehicle for reducing the absolute value of the corrected intermediate power value if the absolute value of an instantaneous power of the energy storage device is greater than the calculated intermediate power value; and

determining the power limiting value by superimposing, one of additively or multiplicatively, the first correction value on the corrected intermediate power value.

2. The method as recited in claim 1, wherein the second control unit is a proportional-integral controller.

3. The method as recited in claim 2, wherein the power loss value is determined as a function of the calculated intermediate power value and an instantaneous rotational speed of the electric machine.

4. The method as recited in claim 2, wherein the power loss value is read from a characteristics map.

5. The method as recited in claim 2, wherein the corrected intermediate power value is determined by superimposing, one of additively or multiplicatively, a second correction value, which compensates for inaccuracies when determining the power loss, on the sum of the power loss value and the calculated intermediate power value.

6. A non-transitory computer-readable data storage medium storing a computer program having program codes which, when executed on a computer, performs a method for controlling an electric machine in a vehicle, wherein the electric machine is assigned an energy storage device, and wherein the electric machine is supplied with power from the energy storage device in a motor mode and energy is stored in the energy storage device in a generator mode of the electric machine, the method comprising:

determining a power limiting value for the electric machine, wherein the determining of the power limiting value includes;

calculating an intermediate power value from a maximally allowable current of the energy storage device and an instantaneous voltage;

determining a corrected intermediate power value by a pilot control unit in the vehicle by adding at least one power loss value to the calculated intermediate power value;

determining a first correction value by a second control unit in the vehicle for reducing the absolute value of the corrected intermediate power value if the absolute value of an instantaneous power of the energy storage device is greater than the calculated intermediate power value; and

determining the power limiting value by superimposing, one of additively or multiplicatively, the first correction value on the corrected intermediate power value.

7. A controller in a vehicle for controlling an electric machine in the vehicle, wherein the electric machine is assigned an energy storage device, and wherein the electric machine is supplied with power from the energy storage device in a motor mode and energy is stored in the energy storage device in a generator mode of the electric machine, the method comprising:

determining a power limiting value for the electric machine, wherein the determining of the power limiting value includes;

calculating an intermediate power value from a maximally allowable current of the energy storage device and an instantaneous voltage;

determining a corrected intermediate power value by a pilot control unit in the vehicle by adding at least one power loss value to the calculated intermediate power value;

determining a first correction value by a second control unit in the vehicle for reducing the absolute value of the corrected intermediate power value if the absolute value of an instantaneous power of the energy storage device is greater than the calculated intermediate power value; and

determining the power limiting value by superimposing, one of additively or multiplicatively, the first correction value on the corrected intermediate power value.