Optimizations for resolver-to-digital converters

Patent metadata

Field	Value
Publication number	US-2025080133-A1
Application number	US-202418637102-A
Country	US
Kind code	A1
Filing date	Apr 16, 2024
Priority date	Aug 29, 2023
Publication date	Mar 6, 2025
Grant date	—

Abstract

In general, techniques are described for optimizations to resolver-to-digital signal converters. Processing circuitry comprising a delta-sigma analog-to-digital converter and a fixed-point signal processor may perform the techniques. The delta-sigma analog-to-digital converter may be communicatively coupled to a fixed-point digital signal processor and electrically coupled to a resolver sensor attached to a rotating element controlled by the processing circuitry, where the delta-sigma analog-to-digital converter is configured to obtain, based on electrical interactions with the resolver sensor, a digital cosine value for an indirectly sensed angle of the rotating element and a digital sine value for the indirectly sensed angle of the rotating element. The fixed-point digital signal processor may be configured to implement a fixed-point Luenberger Observer resolver-to-digital converter configured to obtain, based on the digital sine value and the digital cosine value, via fixed-point mathematical operations, an approximate angle of the rotating element.

First claim

What is claimed is:

1 . Processing circuitry comprising:
a delta-sigma analog-to-digital converter communicatively coupled to a fixed-point digital signal processor and electrically coupled to a resolver sensor attached to a rotating element controlled by the processing circuitry, the delta-sigma analog-to-digital converter configured to obtain, based on electrical interactions with the resolver sensor, a digital cosine value for an indirectly sensed angle of the rotating element and a digital sine value for the indirectly sensed angle of the rotating element; and a fixed-point digital signal processor configured to implement a fixed-point Luenberger Observer resolver-to-digital converter that obtains, based on the digital sine value and the digital cosine value, via fixed-point mathematical operations, an approximate angle of the rotating element.

2 . The processing circuitry of claim 1 ,
wherein the fixed-point Luenberger Observer resolver-to-digital converter is further configured to: apply a configurable wrap gain to an unwrapped approximate angle to obtain a gain adjusted unwrapped approximate angle.

3 . The processing circuitry of claim 2 ,
wherein the configurable wrap gain is configured based on a configurable step size of a lookup table, wherein the configurable step size identifies a difference between two or more adjacent cosine values of the cosine values or adjacent sine values of the sine values stored to two entries of the lookup table entries, and wherein the fixed-point Luenberger Observer resolver-to-digital converter is further configured to apply a wrap function to the gain adjusted unwrapped approximate angle to obtain the approximate angle of the rotating element.

4 . The processing circuitry of claim 3 ,
wherein the fixed-point digital signal processor includes a fixed-size lookup table having a fixed number of lookup table entries that store discrete cosine values over a set of stepped angles and discrete sine values over the set of stepped angles, and wherein the fixed-point Luenberger Observer resolver-to-digital converter is further configured to: access, based on the approximate angle, the fixed-size lookup table to obtain a discrete cosine value for the approximate angle stored to a first lookup table entry of the lookup table entries and a discrete sine value for the approximate angle stored to a second lookup table entry of the lookup table entries; multiply the discrete cosine value by the digital sine value to obtain a first version of the approximate angle; multiply the discrete sine value by a digital cosine value to obtain a second version of the approximate angle; and subtract the second version of the approximate angle from the first version of the approximate angle to obtain an approximate angle error.

5 . The processing circuitry of claim 4 , wherein the fixed-point Luenberger Observer resolver-to-digital converter is further configured to:
determine, based on an acceleration signal for controlling a speed of rotation of the rotating element, a velocity of the rotating element; apply a gain adjustment to the approximate angle error to obtain a gain adjusted approximate angle error; and add the velocity to the gain adjusted approximate angle to obtain the unwrapped approximate angle.

6 . The processing circuitry of claim 5 ,
wherein the gain-adjusted approximate angle error is weighted by: a first weight to calculate the approximate velocity; and a second weight to calculate the approximate angle; and wherein the sum of the approximate velocity and approximate angle error weighted by the second weight is further weighted by: a third weight; and wherein the sum weighted by a third weight and being the sum of the approximate velocity and approximate angle error weighted by the second weight is further weighted by: a fourth weight; and the first weight, third weight, and fourth weight accounting for the sampling period; and the third weight and fourth weight accounting for the configurable wrap gain.

7 . The processing circuitry of claim 4 ,
wherein the fixed number of lookup table entries store the discrete cosine values over the set of stepped angles for defining one of a quarter cosine wave, a half cosine wave, or a whole cosine wave, or wherein the fixed number of lookup table entries store the discrete sine values over the set of stepped angles for defining one of a quarter sine wave, a half sine wave, or a whole sine wave.

8 . The processing circuitry of claim 1 , wherein the resolver sensor includes:
a rotor; an excitation stator configured to electromagnetically interact with the rotor displaced collinearly with the rotation element; a cosine stator configured to electromagnetically interact with the rotor; and a sine stator configured to electromagnetically interact with the rotor, the sine stator mechanically disposed ninety degrees relative to the cosine stator.

9 . The processing circuitry of claim 8 , wherein the delta-sigma analog-to-digital converter is configured to:
output a carrier signal to the excitation stator to electromagnetically induce a current in the rotor such that the rotor generates a magnetic field to induce one or more of a cosine current in the cosine stator and a sine current in the sine stator; receive, via the cosine stator, an analog representation of the digital cosine signal as the cosine current; receive, via the sine stator, an analog representation of the digital sine signal as the sine current; perform delta-sigma analog-to-digital conversion with respect to the cosine current to obtain the digital cosine value; and perform the delta-sigma analog-to-digital conversion with respect to the sine current to obtain the digital sine value.

10 . The processing circuitry of claim 1 , wherein the delta-sigma analog-to-digital converter is configured to obtain, based on electrical interactions with the resolver sensor and without adjusting one or more of the digital sine value and the digital cosine value to account for resolver amplitude modulation, the digital sine signal and the digital cosine signal.

11 . The processing circuitry of claim 1 , wherein the delta-sigma analog-to-digital converter is configured to amplify each of the digital cosine value and the digital sine value by a configurable analog-to-digital gain having a power of two.

12 . A method comprising:
obtaining, by a delta-sigma analog-to-digital converter of a microcontroller, and based on electrical interactions with a resolver sensor, a digital cosine value for an indirectly sensed angle of a rotating element and a digital sine value for the indirectly sensed angle of the rotating element; obtaining, by a fixed-point Luenberger Observer resolver-to-digital converter implemented by a fixed-point digital signal processor of the microprocessor, and based on the digital sine value and the digital cosine value, via the fixed-point mathematical operations, an approximate angle of the rotating element; and outputting, by the fixed-point Luenberger Observer resolver-to-digital converter, the approximate angle to facilitate control of the rotating element.

13 . The method of claim 12 , further comprising:
applying a configurable wrap gain to an unwrapped approximate angle to obtain a gain adjusted unwrapped approximate angle, and applying a wrap function to the gain adjusted unwrapped approximate angle to obtain the approximate angle of the rotating element.

14 . The method of claim 13 ,
wherein the configurable wrap gain is configured based on a configurable step size of a lookup table, wherein the configurable step

Assignees

• Infineon Technologies Ag

Inventors

• Kussian Reinhard

Classifications

• G01D5/20

  by varying inductance, e.g. by a movable armature · CPC title

• H03M3/458

  Analogue/digital converters using delta-sigma modulation as an intermediate step · CPC title

• H03M3/388 Primary

  by storing corrected or correction values in one or more digital look-up tables · CPC title

• G01B7/30 Primary

  for measuring angles or tapers; for testing the alignment of axes · CPC title