Apparatus and method for estimating motor RPM in electronic brake system

Patent metadata

Field	Value
Publication number	US-11519931-B2
Application number	US-202016850453-A
Country	US
Kind code	B2
Filing date	Apr 16, 2020
Priority date	Apr 18, 2019
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

An apparatus for estimating a motor RPM in an electronic brake system may include: a current signal amplifier configured to amplify a voltage applied across a motor driver by a current which flows while the motor driver is turned on, the motor driver being included in a motor driving circuit configured to apply motor driving power to a motor or remove the motor driving power according to a switch-on/off of the motor driver; and a controller configured to detect a waveform with a one-period time from periodically repeated waveforms by processing the signal waveform amplified by the current signal amplifier, calculate a one-rotation time based on the one-period time and the number of commutators of the motor, and calculate a motor RPM using the one-rotation time.

First claim

What is claimed is:

1. An apparatus for estimating a motor rotation per minute (RPM) in an electronic brake system, comprising:
a current signal amplifier configured to amplify a signal waveform of a voltage applied across a motor driver by a current which flows while the motor driver is turned on, the motor driver being included in a motor driving circuit configured to apply motor driving power to a motor or remove the motor driving power according to a switch-on/off of the motor driver; and
a controller configured to detect a waveform with a one-period time from periodically repeated waveforms by processing the signal waveform amplified by the current signal amplifier, calculate a one-rotation time based on the one-period time and a number of commutators of the motor, and calculate a motor RPM using the one-rotation time.

2. The apparatus of claim 1 , wherein the voltage applied across the motor driver is a voltage corresponding to (motor current*resistance of motor driver).

3. The apparatus of claim 1 , wherein the number of the periodically repeated waveforms corresponds to the number of commutators of the motor.

4. The apparatus of claim 1 , wherein the controller is configured to:
sample signal waveforms which are generated during rotation of a motor as sampling data;
detect slopes using differences between adjacent sampling data;
determine a maximum peak and a minimum peak using slope changes based on differences between the sampling data and an accumulated number of slopes; and
calculate the one-period time using a sampling speed and a number of sampling data accumulated between the maximum peak and the minimum peak.

5. The apparatus of claim 4 , wherein the controller is configured to:
accumulate positive slopes between adjacent sampling data;
maintain a predetermined number or more of positive slopes;
determine a point where the slope changes to a negative slope as the maximum peak;
accumulate negative slopes between adjacent sampling data;
maintain a predetermined number or more of negative slopes; and
determine a point where the slope changes to a positive slope as the minimum peak.

6. The apparatus of claim 5 , wherein the predetermined number of accumulated slopes is designated according to a specification of the motor and the sampling speed.

7. The apparatus of claim 4 , wherein the controller is configured to:
continuously accumulate the number of slopes between the sampling data until a peak designated for period determination is determined; and
determine that a portion where a slope characteristic changes while the number of accumulated slopes having a same characteristic does not reach a predetermined number is a noise signal, and filter the noise signal.

8. The apparatus of claim 4 , wherein the sampling speed or interval of sampling is set in consideration of influence on a load factor or a computation performance or of the controller.

9. The apparatus of claim 1 , wherein the controller is configured to
apply a moving average method to the motor RPM calculated for each of the waveforms;
ignore a motor RPM which is less than or more than a minimum/maximum value of a physical variation in the motor RPM; and
additionally perform RPM calculation data processing to correct an error of the calculated motor RPM.

10. A method for estimating a motor rotation per minute (RPM) in an electronic brake system, comprising:
detecting and amplifying, by a current signal amplifier, a signal waveform of a voltage applied across a motor driver by a current which flows while the motor driver is turned on, the motor driver being included in a motor driving circuit configured to apply motor driving power to a motor or remove the motor driving power according to a switch-on/off of the motor driver;
detecting, by a controller, a waveform with a one-period time from periodically repeated waveforms by processing the signal waveform amplified by the current signal amplifier;
calculating, by the controller, a one-rotation time by multiplying the one-period time by a number of commutators of the motor; and
calculating, by the controller, a motor RPM using the one-rotation time.

11. The method of claim 10 , wherein in order to calculate the one-period time of the waveform, the controller samples signal waveforms which are generated during rotation of a motor, detects slopes using differences between adjacent sampling data, determines a maximum peak and a minimum peak using slope changes based on the differences between the sampling data and an accumulated number of slopes, and calculates the one-period time using sampling speed and a number of sampling data accumulated between the maximum peak and the minimum peak.

12. The method of claim 10 , wherein the voltage applied across the motor driver is a voltage corresponding to (motor current*resistance of motor driver).

13. The method of claim 10 , wherein a number of the periodically repeated waveforms corresponds to the number of commutators of the motor.

14. The method of claim 11 , wherein the controller accumulates positive slopes between adjacent sampling data, maintains a predetermined number or more of positive slopes, and then determines a point where the slope changes to a negative slope as the maximum peak, and
wherein the controller accumulates negative slopes between adjacent sampling data, maintains a predetermined number or more of negative slopes, and determines a point where the slope changes to a positive slope as the minimum peak.

15. The method of claim 14 , wherein while continuously accumulating the number of slopes between the sampling data until a designated peak is determined, the controller determines that a portion where a slope characteristic changes while the number of accumulated slopes having a same characteristic does not reach a predetermined number is a noise signal, and filters the noise signal.

16. The method of claim 10 , further comprising applying, by the controller, a moving average method to the motor RPM calculated for each of the waveforms, ignoring a motor RPM which is less than or more than a minimum/maximum value of a physical variation in the motor RPM, and performing RPM calculation data processing to correct an error of the calculated motor RPM, after the calculating of the motor RPM.

Assignees

• Hyundai Mobis Co Ltd

Inventors

• Kim Jung Hoon
• Ahn Bong Ju

Classifications

• G01D5/24495

  using previous values · CPC title

• H02P7/0094

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

• H02P6/007

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

• H02P23/14

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• H02P6/182

  using back-emf in windings · CPC title