Methods and apparatus for rotation detection of a brushed DC motor
AssigneeSemiconductor Components Industries, LLC
InventorTsutomu Murata
Life of this patent
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Abstract
Various embodiments of the present technology comprise a method and apparatus for rotation detection of a brushed DC motor. The method and apparatus may detect switching of the commutators and utilize signals indicative of switching to determine speed and/or rotation information of the motor. In one embodiment, the apparatus comprises an ADC, a difference circuit, an absolute value circuit, and a comparator connected in series with each other.
Claims20
A circuit configured to connect to a brushed DC motor, comprising:
- an amplifier configured to generate an analog signal that is proportional to a current of the DC motor;
- an analog-to-digital converter (ADC) connected to the amplifier and configured to convert the analog signal to a first digital signal;
- and
- a digital circuit, connected to the ADC, and configured to:
- compute a second digital signal according to the first digital signal and a previous-in-time first digital signal;
- compute an absolute value of the computed second digital signal;
- compare the computed absolute value with a predetermined threshold value;
- and
- generate a comparator output according to the comparison.
A circuit for detecting rotation information of a brushed DC motor having a plurality of commutators, comprising:
- an amplifier connected to the brushed DC motor at a first terminal and configured to generate a first signal that is proportional to a current of the DC motor;
- a signal converter connected to the amplifier and configured to convert the first signal to a second signal;
- a difference circuit connected to the signal converter and configured to compute a third signal according to the second signal and a fourth signal;
- an absolute value circuit connected to the difference circuit and configured to generate an absolute value of the third signal;
- and
- a comparator circuit connected to the absolute value circuit and configured to:
- compare the absolute value of the third signal with a predetermined threshold value;
- and
- generate a comparator output according to the comparison, wherein the comparator output represents rotation information of the brushed DC motor.
A brushed DC motor system, comprising:
- a drive circuit;
- a brushed DC motor connected to and controlled by the drive circuit, wherein the brushed DC motor comprises a plurality of commutators;
- a detection circuit connected to the brushed DC motor and configured to:
- to detect a current of the brushed DC motor;
- generating a first digital signal according to the detected current;
- compute a second digital signal the first digital signal and a previous first digital signal;
- compute an absolute value of the second digital signal;
- compare the computed absolute value with a predetermined threshold value;
- and
- generate a comparator output according to the comparison;
- and
- a microcontroller connected to the detection circuit and configured to analyze the comparator output to determine rotation information of the brushed DC motor.
Dependencies are inferred from the claim text.