Dynamic regulation of an electric output

Abstract

The invention relates to a method for automatically regulating an electric output which is dispensed by a secondary battery that has at least two battery cells, wherein the charge states of all the battery cells are repeatedly detected at time intervals, an average charge state (SOC.sub.average) is ascertained per battery cell from the detected charge states of the battery cells, a deviation of at least one charge state of a battery cell from the average charge state (SOC.sub.average) is detected, and the average charge state (SOC.sub.average) and the deviation are taken into consideration during the automatic and dynamic regulation of the electric output dispensed by the secondary battery.

Claims

1. A method for automatically regulating an electric output which is dispensed by a secondary battery that has at least two battery cells, the method comprising: repeatedly detecting charge states of all the battery cells at time intervals, ascertaining an average charge state (SOC.sub.average) per battery cell from the detected charge states of the battery cells, ascertaining a difference between a charge state (SOC.sub.max) of a battery cell of the at least two battery cells having the highest charge and a charge state (SOC.sub.min) of a battery cell of the at least two battery cells having the lowest charge, and automatically and dynamically regulating the electric output of the secondary battery based on the average charge state (SOC.sub.average) and the difference.

2. The method according to claim 1, wherein the average charge state (SOC.sub.average) is multiplied by a function which depends on the difference, wherein a function value of the function for the difference is ascertained from a predefined relationship between the possible values of the difference and the possible function values.

3. The method according to claim 2, wherein the predefined relationship is defined by at least one characteristic curve.

4. The method according to claim 2, wherein the predefined relationship is defined by means of at least one proportional integral (PI) controller.

5. A system for automatically and dynamically regulating an electric output which is dispensed by a secondary battery that has at least two battery cells, comprising at least one electronic device that is configured to: repeatedly detect charge states of all the battery cells at time intervals, ascertain an average charge state (SOC.sub.average) per battery cell from the detected charge states, ascertain a difference between a charge state (SOC.sub.max) of a battery cell of the at least two battery cells having the highest charge and a charge state (SOC.sub.min) of a battery cell of the at least two battery cells having the lowest charge, and automatically and dynamically regulate the electric output dispensed by the secondary battery based upon the average charge state (SOC.sub.average) and the difference.

6. The system according to claim 5, wherein the electronic device is configured to multiply the average charge state (SOC.sub.average) by a function which depends on the ascertained difference and to ascertain a function value of the function for the difference from a predefined relationship between the possible values of the difference and the possible function values.

7. The system according to claim 6, wherein the predefined relationship is defined by at least one characteristic curve deposited in the electronic device or in a separate storage device.

8. The system according to claim 6, wherein the electronic device has at least one proportional integral (PI) controller, by means of which the predefined relationship is defined.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained below in an exemplary manner with reference to the attached figure using a preferred exemplary embodiment, wherein the features subsequently described can constitute an aspect of the invention when taken respectively by themselves as well as in different combinations with one another. In the drawing:

(2) FIG. 1: shows an exemplary embodiment of a method according to the invention.

DETAILED DESCRIPTION

(3) FIG. 1 shows an exemplary embodiment of a method according to the invention. In step 10, an electric output by means of an electric machine is accessed by a secondary battery. In step 11, an electronic device of the system according to the invention ascertains the charge states of all the battery cells and ascertains therefrom a charge state SOC.sub.max of a battery cell having the highest charge and a charge state SOC.sub.min of a battery cell having the lowest charge. In step 12, the electronic device ascertains an average charge state SOC.sub.average per battery cell from the ascertained charge states of the individual battery cells. In step 13, the electronic device of the system ascertains a difference between the charge state SOC.sub.max and the charge state SOC.sub.min. In step 14, the electronic device of the system limits the electric output dispensed by the secondary battery as a function of the difference ascertained in step 13. This can, for example, take place using a characteristic curve or a family of characteristic curves in combination with a multiplier function. After a predefinable time interval t, a check is made with the electronic device of the system in step 15 whether the charge state SOC.sub.max and/or the charge state SOC.sub.min has changed. If this is the case, the electronic device of the system goes to step 13 in order to be able to adjust and regulate the electric output dispensed by the secondary battery to the new conditions. If the charge state SOC.sub.max and/or the charge state SOC.sub.min have/has not changed, which was checked in step 15, the secondary battery can continue to be operated in step 16 with the previously ascertained specifications.