PREDICTIVE BRUSH CONTROL FOR SEPARATELY EXCITED ELECTRIC MOTORS

Abstract

A device and a method for predictive brush control in separately excited electric motors.

Claims

1. A separately excited electric motor, comprising: a brush unit with partial brushes, each of which can be moved towards a commutator via an adjusting mechanism driven by an adjusting motor to reversibly establish an electrical contact between partial brush and commutator, or can be moved away from the commutator to reversibly interrupt an electrical contact between partial brush and commutator, wherein the brush unit is connected to a control unit which is set up to control the adjusting motors in such a way that only a minimum contact surface between the entirety of the partial brushes and the commutator is provided that is required to reach a predicted, imminent operating point of the electric motor.

2. The separately excited electric motor according to claim 1, wherein the brush unit comprises partial brushes of different widths.

3. The separately excited electric motor according to claim 1, which comprises means for detecting a length of the partial brushes.

4. The separately excited electric motor according to claim 3, wherein the means for detecting a length of the partial brushes are set up to transmit the length of the partial brushes to the control unit.

5. The separately excited electric motor according to claim 1, wherein the adjusting motors are linear motors.

6. The separately excited electric motor according to claim 1, wherein the control unit is connected to a computing unit set up to predict an imminent operating point of the separately excited electric motor.

7. The separately excited electric motor according to claim 6, wherein the computing unit is set up to receive and process real-time information with respect to the vehicle surroundings, route, and traffic data.

8. A method for operating a separately excited electric motor of a vehicle drive according to claim 1, wherein the control unit controls the adjusting motors of the brush unit, such that only a minimum contact surface between the entirety of the partial brushes and the commutator is provided that is required to achieve the predicted imminent operating point of the electric motor.

9. The method according to claim 8, wherein the lengths of the individual partial brushes are determined and taken into account in the control of the associated adjusting motors.

10. The method according to claim 8, wherein the imminent operating point of the electric motor is predicted by a computing unit on the basis of real-time information with respect to the vehicle surroundings, route, traffic data, and data on the current driving behavior of the driver of the vehicle.

11. The separately excited electric motor according to claim 2, which comprises means for detecting a length of the partial brushes.

12. The separately excited electric motor according to claim 2, wherein the adjusting motors are linear motors.

13. The separately excited electric motor according to claim 3, wherein the adjusting motors are linear motors.

14. The separately excited electric motor according to claim 4, wherein the adjusting motors are linear motors.

15. The separately excited electric motor according to claim 2, wherein the control unit is connected to a computing unit set up to predict an imminent operating point of the separately excited electric motor.

16. The separately excited electric motor according to claim 3, wherein the control unit is connected to a computing unit set up to predict an imminent operating point of the separately excited electric motor.

17. The separately excited electric motor according to claim 4, wherein the control unit is connected to a computing unit set up to predict an imminent operating point of the separately excited electric motor.

18. The separately excited electric motor according to claim 1, wherein the control unit is connected to a computing unit set up to predict an imminent operating point of the separately excited electric motor.

19. The method according to claim 9, wherein the imminent operating point of the electric motor is predicted by a computing unit on the basis of real-time information with respect to the vehicle surroundings, route, traffic data, and data on the current driving behavior of the driver of the vehicle.

Description

BRIEF DESCRIPTION OF THE FIGURE(S)

[0023] The invention is schematically illustrated in the drawing with the aid of embodiments and is described further with reference to the drawing. Wherein:

[0024] FIG. 1 shows a schematic representation of an embodiment of the brush unit according to the invention.

DETAILED DESCRIPTION

[0025] FIG. 1 shows a separately excited electric motor 10 with an embodiment of the brush unit 20 according to the invention. The separately excited electric motor 10 has a rotor 11 and a stator 12 in which the rotor 11 rotates when a current I flows through it. The rotor 11 is supplied with current via a commutator 13. The current I is fed to the commutator 13 via the brush unit 20.

[0026] The brush unit 20 comprises several (partial) brushes 21 (1 . . . n), which are each moved individually via an adjusting mechanism 22 and an adjusting motor 23 to the commutator 13 and can brought into electrically conductive contact with the commutator 13 or can be moved away therefrom, whereby the electrical contact is interrupted between the (partial) brush 21 and the commutator, and an air gap is formed. The (partial) brushes 21 have a vertical variability 24, which is indicated in the drawing by the arrow, i.e., they can each be moved up to a maximum distance from the surface of the commutator 13 and on the other hand in the direction of the surface of the commutator 13 are tracked in order to compensate for wear of the (partial) brush 21 due to abrasion. The individual (partial) brushes 21 are electrically isolated from one another. In the embodiment shown in the drawing, the (partial) brushes 21 have different brush widths (x, y) 25. The brush unit 20 has means 26 for detecting the length of the (partial) brushes 21. The measurement of the length of the (partial) brushes 21 enables, on the one hand, an exact setting of the position of the (partial) brushes 21, even if the length of the (partial) brushes 21 changes due to wear, and, on the other hand, it also enables the point in time at which replacement of a (partial) brush 21 is required.

[0027] A control unit, not shown in the FIGURE, controls the adjusting motors 23 of the individual (partial) brushes 21 to set the current flow through the commutator 13 required for the respective immediately following operating point. The control unit (or a central processing unit connected thereto) determines how much brush contact area is minimally required at the respective operating point and controls the individual (partial) brushes 21 accordingly.

[0028] In freewheeling mode, i.e., when no current has to flow, all (partial) brushes 21 can also be raised in order to achieve maximum efficiency at this operating point without friction losses. As soon as more output is requested again, the individual adjusting motors 23 are activated in such a way that a respective feed is generated, as a result of which the respective (partial) brushes 21 contact the commutator 13. The required brush contact area is calculated over the entire journey.

LIST OF REFERENCE NUMERALS

[0029] 10 separately excited electric motor [0030] 11 rotor [0031] 12 stator [0032] 13 commutator [0033] 20 brush unit [0034] 21 brushes [0035] 22 adjusting mechanism [0036] 23 adjusting motors [0037] 24 vertical variability [0038] 25 different brush widths [0039] 26 detection of the brush length