Method and device for determining a rotation variable

Patent metadata

Field	Value
Publication number	US-11290035-B2
Application number	US-201816753502-A
Country	US
Kind code	B2
Filing date	Sep 25, 2018
Priority date	Oct 4, 2017
Publication date	Mar 29, 2022
Grant date	Mar 29, 2022

Abstract

A method for determining a rotation variable of a rotatably mounted rotor of a mechanically commutated electric motor, having a motor current path formed between two brush elements of the electric motor, and leading via the commutator bars contacted by the brush elements, and via coil windings of the rotor electrically connected to said commutator bars, wherein an oscillating input signal is fed into the motor current path and the rotation variable is determined with the aid of a ripple of a resultant output signal, said ripple being due to the mechanical commutation of the motor current path.

First claim

The invention claimed is:

1. A method of determining a rotation variable of a rotatably mounted rotor of an electric motor, wherein the electric motor is mechanically commutated, the method comprising:
feeding an oscillating input signal through a motor current path formed between two brush elements of the electric motor, wherein the motor current path is guided via commutator segments, contacting the two brush elements, and coil windings of the rotor electrically and conductively connected to the commutator segments, and wherein the motor current path is arranged electrically parallel to a radio interference suppression path including a capacitor;
generating an output signal based on a current ripple created by mechanical commutation of the motor current path; and
establishing the rotation variable based on the output signal.

2. The method of claim 1 , wherein the feeding step includes generating the oscillating input signal at a measuring frequency, wherein the measuring frequency is selected based on an amplitude of a current ripple of the output signal being greatest.

3. The method of claim 2 , wherein the feeding step includes alternately switching the measuring frequency between a plurality of frequency values.

4. The method of claim 1 , wherein the input signal is generated as a sequence of measuring pulses.

5. The method of claim 1 , wherein the generating step includes guiding the output signal through an evaluation unit provided with high-pass filter and a digital pin.

6. A device configured to determine a rotation variable of a rotatably mounted rotor of a mechanically commutated electric motor, the device comprising:
a motor current path formed between two brush elements of the electric motor, wherein the motor current path is guided by commutator segments, contacted by the two brush elements, and rotor coil windings electrically and conductively connected to the commutator segments;
a radio interference suppression path provided with a capacitor connected in parallel to the motor current path; and
a measuring circuit provided with,
a signal generator capacitively coupled to one of the two brush elements and configured to generate an input signal,
an evaluation unit capacitively coupled to the other brush element and configured to evaluate an output signal.

7. The device of claim 6 ,
wherein the measuring circuit is decoupled in a signal-technical manner from a direct current circuit of the electric motor by utilizing a direct current decoupling, wherein the direct current circuit is guided to the brush elements.

8. The device of claim 7 ,
wherein the direct current decoupling has a longitudinal choke with a barrier effect in a range of a measuring frequency of the input signal.

9. The device of claim 6 ,
wherein the output signal is guided via a high-pass filter to a digital pin of the evaluation unit.

10. An adjustment drive a motor vehicle, comprising:
a motor current path formed between two brush elements of an electric motor, wherein the motor current path is guided by one or more commutator segments, contacted by the two brush elements, and rotor coil windings electrically and conductively connected to the commutator segments;
a radio interference suppression path provided with a capacitor configured to reduce interference, wherein the radio interference suppression path is connected in parallel to the motor current path;
a measuring circuit that includes a controller and a signal generator capacitively coupled to one of the two brush elements and configured to generate an input signal; and
a microcontroller capacitively coupled to the other brush element and configured to evaluate an output signal, wherein a rotational variable is determined in response to a current ripple of the output signal.

11. The adjustment drive of claim 10 , wherein the controller is an application-specific circuit.

12. The adjustment drive of claim 10 , wherein the output signal is guided via a high-pass filter to the microcontroller.

13. The adjustment drive of claim 10 , wherein a load current or motor current is not utilized to determine the rotational variable.

14. The adjustment drive of claim 10 , wherein the input signal is fed into the motor current path as an armature current signal.

15. The adjustment drive of claim 10 , wherein the input signal is generated as a result of a sequence of measuring pulses.

16. The adjustment drive of claim 10 , wherein the adjustment drive includes two or more digital pins interconnected to form a resistor ladder network.

17. The adjustment drive of claim 10 , wherein an alternating current path of the input signal or output signal is decoupled from a load current or motor current.

18. A method of determining a rotation variable a rotatably mounted rotor disposed in a mechanically commutated electric motor, the method comprising:
feeding an oscillating input signal through a motor current path formed between two brush elements of the electric motor, wherein the motor current path is guided via commutator segments, contacting the two brush elements, and coil windings of the rotor electrically and conductively connected to the commutator segments;
generating an output signal based on a current ripple created by mechanical commutation of the motor current path;
selecting a measurement frequency based on a peak amplitude of the current ripple; and
alternately switching the measuring frequency between a plurality of frequency values.

19. The method of claim 18 , wherein the feeding step includes generating a first measurement pulse and a second measurement pulse, the selecting step includes selecting a first measurement frequency, based on first peak amplitude of a current ripple of the first measurement pulse, and a second measurement frequency based on second peak amplitude of a current ripple of the second measurement pulse, and the feeding step further includes switching between the first measurement frequency and the second measurement frequency.

Assignees

• Brose Fahrzeugteile Se & Co Kg Bamberg

Inventors

• Thomann Christian
• Russ Detlef
• Naumann Guido
• Brand Christoph

Classifications

• H02P2203/03

  Determination of the rotor position, e.g. initial rotor position, during standstill or low speed operation · CPC title

• H02P6/007 Primary

  wherein the position is detected using the ripple of the current caused by the commutation · CPC title

• H02P7/0094 Primary

  wherein the position is detected using the ripple of the current caused by the commutator · CPC title

• H02P2203/11

  Determination or estimation of the rotor position or other motor parameters based on the analysis of high-frequency signals · CPC title