SINCOS encoder interface

Patent metadata

Field	Value
Publication number	US-11740106-B2
Application number	US-202218054949-A
Country	US
Kind code	B2
Filing date	Nov 14, 2022
Priority date	Dec 6, 2018
Publication date	Aug 29, 2023
Grant date	Aug 29, 2023

Abstract

In an example, a circuit includes a first comparator, a second comparator, a pulse counter, a processor, a first ADC, and a second ADC. The first comparator has a first input coupled to a first node, a second input, and an output. The second comparator has a first input coupled to a second node, a second input, and an output. A first DAC is coupled to the second input of the first comparator. A second DAC is coupled to the second input of the second comparator. The pulse counter has a first input coupled to the output of the first comparator and a second input coupled to the output of the second comparator. The first ADC has an input coupled to the first node and an output coupled to the processor. The second ADC has an input coupled to the second node and an output coupled to the processor.

First claim

What is claimed is:

1. A system, comprising:
a rotary shaft;
a motor coupled to the rotary shaft;
a controller coupled to the motor;
an encoder coupled to the motor and to the controller, the encoder comprising:
a first comparator having a first input, a second input, and an output;
a second comparator having a first input, a second input, and an output;
a first digital-to-analog converter (DAC) coupled to the first input of the first comparator;
a second DAC coupled to the first input of the second comparator;
a pulse counter coupled to the output of the first comparator and to the output of the second comparator;
a processor having a first input and a second input;
a first analog-to-digital converter (ADC) coupled to the first input of the processor and to the second input of the first comparator; and
a second ADC coupled to the second input of the processor and to the second input of the second comparator.

2. The system of claim 1 , wherein a first sine wave is received at the first input of the first comparator and at an input of the first ADC;
wherein a first cosine wave is received at the first input of the second comparator and at an input of the second ADC;
wherein the first comparator is configured to convert the first sine wave into a first square wave, and the second comparator is configured to convert the first cosine wave into a second square wave;
wherein the first ADC is configured to convert the first sine wave into a first digital value; and
wherein the second ADC is configured to convert the first cosine wave to a second digital value.

3. The system of claim 2 , wherein the pulse counter is configured to count a number of rising edges of the first square wave and the second square wave to determine coarse position information, and wherein the processor is configured to generate fine position information based at least partially on the first digital value and the second digital value.

4. The system of claim 1 , further comprising:
a third comparator having a first input, a second input, and an output coupled to a third input of the pulse counter; and
a third DAC having an output coupled to the second input of the third comparator.

5. The system of claim 4 , wherein the first DAC, the second DAC, and the third DAC are configured to receive separate digital values configured to compensate for direct current (DC) bias.

6. The system of claim 4 , wherein the third comparator is configured to:
receive an index signal at the first input of the third comparator; and
convert the index signal to a third square wave,
wherein the pulse counter is configured to reset a count each time a rising edge of the third square wave is received.

7. The system of claim 1 , further comprising:
a third ADC coupled to the processor; and
a fourth ADC coupled to the processor.

8. The system of claim 7 , wherein the third ADC is configured to receive a second sine wave and to convert the second sine wave to a third digital value, and wherein the fourth ADC is configured to receive a second cosine wave and to convert the second cosine wave to a fourth digital value.

9. The system of claim 8 , wherein the processor is configured to generate absolute position information based at least partially on the third digital value and the fourth digital value.

10. A method, comprising:
receiving a plurality of signals, including a first sine wave and a first cosine wave;
processing the plurality of signals by:
providing the first sine wave to a first input of a first comparator and to a first analog-to-digital converter (ADC), the first comparator having a second input coupled to a first digital-to-analog converter (DAC);
providing the first cosine wave to a first input of a second comparator and to a second ADC, the second comparator having a second input coupled to a second DAC;
generating a first square wave based on the first sine wave;
sampling the first sine wave to generate a first digital value;
generating a second square wave based on the first cosine wave; and
sampling the first cosine wave to generate a second digital value;

generating position information based on the plurality of signals by:
determining a number of pulses present at an output of the first comparator and at an output of the second comparator; and
performing a first arctangent computation by dividing the first digital value by the second digital value; and
transmitting the generated position information to a controller configured to control operation of a motor.

11. The method of claim 10 , wherein the plurality of signals further comprising: a second sine wave and a second cosine wave.

12. The method of claim 11 , wherein the second sine wave and the second cosine wave indicate an absolute rotation of a rotary shaft coupled to the motor.

13. The method of claim 11 , further comprising:
providing the second sine wave to a third ADC;
providing the second cosine wave to a fourth ADC;

sampling the second sine wave to generate a third digital value; and
sampling the second cosine wave to generate a fourth digital value.

14. The method of claim 13 , wherein generating position information based on the plurality of signals further comprising performing a second arctangent computation by dividing the third digital value by the fourth digital value to generate absolute position information.

15. The method of claim 10 , wherein receiving the plurality of signals comprises receiving the plurality of signals from one or more sensors configured and positioned to monitor rotation of a rotary shaft coupled to the motor.

16. The method of claim 10 , wherein the first sine wave and the first cosine wave comprise a period determined according a speed of rotation of a rotary shaft coupled to the motor.

17. The method of claim 10 , further comprising:
providing an index signal to a third comparator, wherein the plurality of signals further includes the index signal; and
generating a third square wave based on the index signal.

18. The method of claim 17 , wherein generating the position information comprises:
resetting a count of pulses present at the output of the first comparator and at the output of the second comparator each time a pulse is received at the output of the third comparator.

19. The method of claim 17 , wherein determining a number of pulses present at an output of the first comparator and at an output of the second comparator generates coarse position information;
wherein the coarse position information is relative to a first position of a rotary shaft coupled to the motor until a first pulse at the output of the third comparator; and
wherein the coarse position information is relative to a second position of the rotary shaft after the first pulse.

20. The method of claim 10 , wherein determining a number of pulses present at an output of the first comparator and at an output of the second comparator generates coarse position information, and the coarse position information is relative to a position of a rotary shaft coupled to the motor.

Assignees

• Texas Instruments Inc

Inventors

• Poley Richard Mark
• Chakravarthy Srinivasa

Classifications

• G01D5/245 Primary

  using a variable number of pulses in a train · CPC title

• H02K11/21

  Devices for sensing speed or position, or actuated thereby (specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14) · CPC title

• H03M1/12

  Analogue/digital converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title

• H03M1/66

  Digital/analogue converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title

• G01D5/02

  using mechanical means · CPC title