Motor control device and current ripple detection method for DC motor

Patent metadata

Field	Value
Publication number	US-10693399-B2
Application number	US-201716338642-A
Country	US
Kind code	B2
Filing date	Sep 15, 2017
Priority date	Oct 25, 2016
Publication date	Jun 23, 2020
Grant date	Jun 23, 2020

Abstract

A ripple detection device 10 includes: a current detection part 11 that outputs a variation in an armature current as a voltage variation signal; a first smoothing circuit block 12 that extracts a current ripple component and a noise component from the voltage variation signal and outputs a first smoothing signal S 1 ; a gain adjustment part 13 that adjusts the amplitude of the first smoothing signal S 1 and outputs an adjustment signal VCA; a second smoothing circuit block 14 that corrects distortion of the adjustment signal VCA and outputs a second smoothing signal S 2 ; a ripple detection part 15 that extracts only the current ripple component from the second smoothing signal S 2 by removing the noise component therefrom and outputs a ripple component signal S 0 ; and a digital signal conversion part 16 that converts the ripple component signal S 0 into a digital signal.

First claim

The invention claimed is:

1. A motor control device comprising a ripple detection device that detects a current ripple contained in an armature current of a DC motor and outputs the current ripple as a rectangular wave signal, wherein
the ripple detection device includes:
a current detection part that detects the armature current and outputs a variation in the armature current as a voltage variation signal;
a first smoothing part that extracts a current ripple component and a noise component from the voltage variation signal and outputs a first smoothing signal S 1 composed of the current ripple component and noise component;
a ripple detection part that extracts only the current ripple component from the first smoothing signal S 1 by removing the noise component therefrom and outputs a ripple component signal S 0 ; and
a digital signal conversion part that converts the ripple component signal S 0 into a digital signal.

2. The motor control device according to claim 1 , wherein
the first smoothing part includes:
a first control voltage generation circuit that extracts a center value of the current ripple component from the voltage variation signal as a variation component of the armature current and outputs the extracted center value as a first control voltage CV 1 ; and
a first fluctuation component smoothing circuit that calculates a difference between the voltage variation signal and the first control voltage CV 1 to remove a variation component of the armature current from the voltage variation signal and extract the current ripple component and noise component so as to form the first smoothing signal S 1 .

3. The motor control device according to claim 1 , wherein
the ripple detection part includes:
a high-pass filter that extracts the noise component from the first smoothing signal S 1 or second smoothing signal S 2 ; and
a differential amplification circuit that is input with the first smoothing signal S 1 or the second smoothing signal S 2 and a signal obtained by inverting a waveform of the noise component extracted by the high-pass filter, extracts only the current ripple component from the first smoothing signal S 1 or the second smoothing signal S 2 , and outputs the ripple component signal S 0 .

4. The motor control device according to claim 1 , wherein
the digital signal conversion part includes:
a phase shift part that generates a shift signal S 0 ′ by slightly shifting a phase of the ripple component signal S 0 ; and
a comparator that is input with the shift signal S 0 ′ and the ripple component signal S 0 and converts the ripple component signal S 0 into a digital signal based on a magnitude relation between the signals S 0 and S 0 ′.

5. A motor control device comprising a ripple detection device that detects a current ripple contained in an armature current of a DC motor and outputs the current ripple as a rectangular wave signal, wherein
the ripple detection device includes:
a current detection part that detects the armature current and outputs a variation in the armature current as a voltage variation signal;
a first smoothing part that extracts a current ripple component and a noise component from the voltage variation signal and outputs a first smoothing signal S 1 composed of the current ripple component and noise component;
a gain adjustment part that adjusts an amplitude of the first smoothing signal S 1 and outputs an adjustment signal VCA whose amplitude is made uniform;
a second smoothing part that corrects distortion of the adjustment signal VCA and outputs a second smoothing signal S 2 with a uniform amplitude having a constant center value;
a ripple detection part that extracts only the current ripple component from the second smoothing signal S 2 by removing the noise component therefrom and outputs a ripple component signal S 0 ; and
a digital signal conversion part that converts the ripple component signal S 0 into a digital signal.

6. The motor control device according to claim 5 , wherein
the first smoothing part includes:
a first control voltage generation circuit that extracts a center value of the current ripple component from the voltage variation signal as a variation component of the armature current and outputs the extracted center value as a first control voltage CV 1 ; and
a first fluctuation component smoothing circuit that calculates a difference between the voltage variation signal and the first control voltage CV 1 to remove a variation component of the armature current from the voltage variation signal and extract the current ripple component and noise component so as to form the first smoothing signal S 1 , and
the gain adjustment part includes:
a control voltage inversion circuit that inverts a waveform of the first control voltage CV 1 and outputs an inverted first control voltage CV 1 ′; and
a gain adjustment circuit that uses the inverted first control voltage CV 1 ′ to make the amplitude of the first smoothing signal S 1 uniform.

7. The motor control device according to claim 5 , wherein
the second smoothing part includes:
a second control voltage generation circuit that extracts a center value of the adjustment signal VCA and outputs the extracted center value as a second control voltage CV 2 ; and
a second fluctuation component smoothing circuit that calculates a difference between the adjustment signal VCA and the second control voltage CV 2 to remove a variation component of the adjustment signal VCA from the adjustment signal VCA so as to form the second smoothing signal S 2 .

8. A current ripple detection method for a DC motor that detects a current ripple contained in an armature current of the DC motor and outputs the current ripple as a rectangular wave signal, the method comprising:
detecting the armature current and outputting a variation in the armature current as a voltage variation signal;
extracting a current ripple component and a noise component from the voltage variation signal and outputting a first smoothing signal S 1 composed of the current ripple component and noise component;
extracting only the current ripple component from the first smoothing signal S 1 by removing the noise component therefrom and outputting a ripple component signal S 0 ; and
converting the ripple component signal S 0 into a digital signal.

9. The current ripple detection method according to claim 8 , comprising:
extracting a center value of the current ripple component from the voltage variation signal as a variation component of the armature current and outputting the extracted center value as a first control voltage CV 1 ; and
calculating a difference between the voltage variation signal and the first control voltage CV 1 to remove a variation component of the armature current from the voltage variation signal and extract the current ripple component and the noise component so as to form the first smoothing signal S 1 .

10. The current ripple detection method according to claim 8 , comprising:
extracting the noise component from the first smoothing signal S 1 or the second smoothing signal S 2 using a high-pass filter; and
synthesizing the first smoothing signal S 1 or the second smoothing signal S 2 and a signal obtained by inverting a waveform of the noise component extracted by the high-pass filter to extract only the current ripple component from the first smoothing signal S 1 or the second smoothing signal S 2 and outputting the ripple component signal S 0 .

11. The current ripple detection method according to claim 8 , comprising:
generating a shift signal S 0 ′ by slightly shifting a phase of the ripple component signal S 0 ; and
converting the ripple com

Assignees

• Mitsuba Corp

Inventors

• Yanagita Yuichi

Classifications

• H02P6/16

  Circuit arrangements for detecting position · CPC title

• H02P7/06 Primary

  for regulating or controlling an individual DC dynamo-electric motor by varying field or armature current · CPC title

• H02K13/10

  Arrangements of brushes or commutators specially adapted for improving commutation · CPC title

• H02P2203/09

  Motor speed determination based on the current and/or voltage without using a tachogenerator or a physical encoder · CPC title

• H02P7/0094 Primary

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