Apparatus and method for determining a rotation angle of a rotor

Patent metadata

Field	Value
Publication number	US-9746345-B2
Application number	US-201514886059-A
Country	US
Kind code	B2
Filing date	Oct 18, 2015
Priority date	Oct 17, 2014
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

A method and an apparatus for determining a rotation angle of a rotor in a motor with the aid of angle sensors by measurement of reference values and correction of the effected computations. The method is used, for example, in a synchronous motor.

First claim

What is claimed is:

1. A method for determining a rotation angle of a rotor with the aid of angle sensors in a motor, comprising:
capturing of reference values by reading signal values from the angle sensors after the rotor was brought to a predetermined rotor position;
measuring amplitude values of a magnetic field during at least one full revolution of the rotor;
computing offset values of the angle sensors by forming an average value of peak values of the magnetic field;
computing corrected amplitude values by subtraction of the offset values from the measured amplitude values;
computing amplitude difference values from the difference of the peak values of the magnetic field;
computing normalized/standardized amplitude values and of normalized/standardized reference values by division of the corrected amplitude values and the reference values with a divisor, corresponding to the half of the amplitude difference values;
computing a correction angle by computing the ATAN value of the normalized/standardized reference values; and
determining the rotation angle by computing the ATAN value of the normalized/standardized amplitude values in the X direction and in the Y direction and deduction of the correction angle.

2. The method according to claim 1 , wherein the predetermined rotor position is determined by using the magnetic field.

3. The method according to claim 1 , further comprising a constant measurement of the rotation angle.

4. The method according to claim 2 , further comprising a constant measurement of the rotation angle.

5. An apparatus for determining the rotor position of a motor, comprising:
at least one sensor for capturing a magnetic field value; and
a processor for computing the rotor position, wherein the processor is configured to:
capture of reference values by reading signal values from angle sensors after the rotor was brought to a predetermined rotor position;
measure amplitude values of a magnetic field during at least one full revolution of the rotor;
compute offset values of the angle sensors by forming an average value of peak values of the magnetic field;
compute corrected amplitude values by subtraction of the offset values from the measured amplitude values;
compute amplitude difference values from the difference of the peak values of the magnetic field;
compute normalized/standardized amplitude values and of normalized/standardized reference values by division of the corrected amplitude values and the reference values with a divisor, corresponding to the half of the amplitude difference values;
compute a correction angle by computing the ATAN value of the normalized/standardized reference values; and
determine the rotation angle by computing the ATAN value of the normalized/standardized amplitude values in the X direction and in the Y direction and deduction of the correction angle.

6. The apparatus according to claim 5 , wherein the processor is further configured to use a value of the magnetic field to determine the predetermined rotor position.

7. The apparatus according to claim 5 , wherein the processor is further configured to constantly measure the rotation angle.

8. The apparatus according to claim 6 , wherein the processor is further configured to constantly measure the rotation angle.

9. A synchronous motor, comprising:
a stator with a plurality of switchable coils;
a rotor rotatably held in the stator;
a permanent magnet mounted on an axle connected to the rotor; and
an apparatus for determining the rotor position of a motor, comprising:
at least one sensor for capturing a magnetic field value; and
a processor for computing the rotor position configured to:
capture of reference values by reading signal values from angle sensors after the rotor was brought to a predetermined rotor position;
measure amplitude values of a magnetic field during at least one full revolution of the rotor;
compute offset values of the angle sensors by forming an average value of peak values of the magnetic field;
compute corrected amplitude values by subtraction of the offset values from the measured amplitude values;
compute amplitude difference values from the difference of the peak values of the magnetic field;
compute normalized/standardized amplitude values and of normalized/standardized reference values by division of the corrected amplitude values and the reference values with a divisor, corresponding to the half of the amplitude difference values;
compute a correction angle by computing the ATAN value of the normalized/standardized reference values; and
determine the rotation angle by computing the ATAN value of the normalized/standardized amplitude values in the X direction and in the Y direction and deduction of the correction angle.

10. The synchronous motor according to claim 9 , further comprising an electronic circuit for switching the switchable coils on and off.

Assignees

• Micronas Gmbh
• Tdk-Micronas Gmbh

Inventors

• Baumann Marc
• Sadeq Redouane

Classifications

• G01D18/004

  Continuous recalibration · CPC title

• G01D5/2448

  Correction of gain, threshold, offset or phase control · CPC title

• G01D5/145 Primary

  influenced by the relative movement between the Hall device and magnetic fields (see G01R33/06) · CPC title