Electronically commutated electric motor comprising rotor position detection with interference field compensation

Patent metadata

Field	Value
Publication number	US-9438152-B2
Application number	US-201214110889-A
Country	US
Kind code	B2
Filing date	Apr 11, 2012
Priority date	Apr 11, 2011
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

An electronically commutated electric motor includes a stator and a rotor formed as a permanent magnet. A control unit is connected to the stator and configured to energize the stator to produce a rotating magnetic field. The electric motor further includes at least one Hall sensor configured to detect at least a magnitude of a sensor magnetic field produced by a sensor magnet connected to the rotor. The electric motor also includes at least one magneto resistive sensor configured to detect an alignment of a total magnetic field during a rotor revolution of the rotor and to generate a rotor position signal representing this alignment. The total magnetic field includes the sensor magnetic field and an interference magnetic field superimposed thereon. The control unit is further configured to determine the rotor position of the rotor at least depending on the alignment of the total magnetic field.

First claim

The invention claimed is:

1. An electronically commutated electric motor comprising:
a rotor;
a stator;
a control unit connected to the stator and configured to energize the stator so as to generate a rotating magnetic field;
at least one Hall sensor configured to (i) ascertain at least one magnitude of a magnetic field that is generated by a sensor magnet connected to the rotor and (ii) generate a rotor position signal that represents the magnetic field; and
at least one magnetoresistive sensor configured to (i) ascertain an alignment of a total magnetic field during a rotor revolution of the rotor and (ii) generate a rotor position signal that represents said alignment,
wherein the total magnetic field comprises the sensor magnetic field and an interference magnetic field that is superimposed on said sensor magnetic field and is generated by at least electrical components of the electric motor, and
wherein the control unit is connected at the input side to the rotor position sensors and is configured to ascertain the rotor position of the rotor in dependence upon the alignment of the total magnetic field, at least of a previously stored magnitude of the sensor magnetic field and a magnitude and an alignment of the interference magnetic field.

2. The electric motor as claimed in claim 1 , wherein the electric motor comprises at least a further Hall sensor configured to ascertain the sensor magnetic field and generate a further rotor position signal that represents the rotor position, and wherein the Hall sensor and the further Hall sensor are arranged offset with respect to each other in the direction of the rotor revolution.

3. The electric motor as claimed in claim 2 , in that wherein the Hall sensor and the further Hall sensor are arranged in an orthogonally offset manner with respect to each other in the direction of the rotor revolution.

4. The electric motor as claimed in claim 2 , wherein one or more of the Hall sensor and the further Hall sensor is a temperature-compensated Hall sensor configured to generate a digital Hall sensor signal independently of a temperature of the temperature-compensated Hall sensor.

5. The electric motor as claimed in claim 4 , wherein the temperature-compensated Hall sensor comprises an operating voltage that corresponds to an operating voltage of the control unit.

6. The electric motor as claimed in claim 2 , wherein the control unit is configured to generate a total Hall sensor signal from the rotor position signals of the Hall sensor and of the further Hall sensor and ascertain the sensor magnetic field in dependence upon the total Hall sensor signal.

7. The electric motor as claimed in claim 6 , wherein the total Hall sensor signal is configured as a quadrature signal.

8. The electric motor as claimed in claim 6 , wherein the control unit is configured to ascertain the magnitude and alignment of the sensor magnetic field in dependence upon the total Hall sensor signal.

9. The electric motor as claimed in claim 2 , wherein the control unit is configured to ascertain an alignment or in addition the magnitude of the total magnetic field in dependence upon the total Hall sensor signal.

10. The electric motor as claimed in claim 9 , wherein the control unit is configured to ascertain the alignment or in addition the magnitude of the total magnetic field in dependence upon a quadrature signal.

11. A method for operating an electronic commutated electric motor including a rotor, a stator, and a control unit connected to the stator and configured to energize the stator so as to generate a rotating magnetic field, the method comprising:
ascertaining via a Hall sensor and storing at least a magnitude of a sensor magnetic field that is generated by a sensor magnet connected to the rotor;
ascertaining an alignment of a total magnetic field during a rotor revolution of the rotor by a magnetoresistive sensor and generating a rotor position signal that represents the alignment, the total magnetic field comprising the sensor magnetic field and an interference magnetic field that is superimposed on said sensor magnetic field and is generated at least by electrical components of the electric motor, and
ascertaining an alignment of the sensor magnetic field by a vector calculation in dependence upon the ascertained alignment of the total magnetic field, the previously stored magnitude of the sensor magnetic field and a magnitude and an alignment of the interference magnetic field.

12. The method as claimed in claim 11 , further comprising:
ascertaining via a further Hall sensor the sensor magnetic field;
generating a further Hall sensor signal; and
forming a total Hall sensor signal from the Hall sensor signal and the further Hall sensor signal, the total Hall sensor signal representing the sensor magnetic field.

13. The method as claimed in claim 12 , wherein the total Hall sensor signal is a quadrature signal.

14. The electric motor as claimed in claim 1 , wherein the rotor is configured as a permanent magnet rotor.

15. The method as claimed in claim 11 , wherein the magnitude of the sensor magnetic field is ascertained and stored in a currentless state of the stator.

Assignees

• Chabaud Antoine
• Frey Martin
• Finke Sven
• Sader Frank
• Vogel Markus
• Bosch Gmbh Robert

Inventors

• Chabaud Antoine
• Frey Martin
• Finke Sven
• Sader Frank
• Vogel Markus

Classifications

• H02K11/25

  Devices for sensing temperature, or actuated thereby · CPC title

• H02P6/16 Primary

  Circuit arrangements for detecting position · CPC title

• H02K29/08

  using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) · CPC title