Parasitic pulse cancelation circuit

Patent metadata

Field	Value
Publication number	US-11923850-B2
Application number	US-202217715223-A
Country	US
Kind code	B2
Filing date	Apr 7, 2022
Priority date	Apr 9, 2021
Publication date	Mar 5, 2024
Grant date	Mar 5, 2024

Abstract

A motor control system includes a DC motor and a ripple count circuit. The DC motor includes a rotor that rotates in response to a drive current. The rotation of the rotor generates a mechanical force that drives a component. The ripple count circuit includes an active filter circuit and a parasitic pulse cancellation circuit. The active filter circuit is configured to filter the drive current and to generate a pulsed signal. The parasitic pulse cancelation circuit is in signal communication with the ripple count circuit to receive the pulsed signal and generates a ripple count signal that excludes parasitic pulses included in the pulsed signal having a parasitic voltage level that exceeds a voltage level of a voltage threshold. The parasitic pulse cancelation circuit actively adjusts the voltage level of the voltage threshold based at least in part on a rotational direction of the rotor.

First claim

What is claimed is:

1. A motor control system comprising:
a direct current (DC) motor including a rotor induced to rotate in response to a drive current generated by a supply voltage, the rotation of the rotor generating a mechanical force that drives a component;
a ripple count circuit including an active filter circuit and a parasitic pulse cancellation circuit; and
a pulse width modulation, “PWM” circuit in signal communication with the parasitic pulse cancelation circuit, the PWM circuit configured to generate a PWM signal based on the rotational direction of the rotor,
wherein the active filter circuit is configured to filter the drive current and to generate a pulsed signal,
wherein the parasitic pulse cancelation circuit is in signal communication with the ripple count circuit to receive the pulsed signal and generates a ripple count signal that excludes parasitic pulses included in the pulsed signal having a parasitic voltage level that exceeds a voltage level of a voltage threshold,
wherein the parasitic pulse cancelation circuit actively adjusts the voltage level of the voltage threshold based at least in part on a rotational direction of the rotor, and
wherein the parasitic pulse cancelation circuit actively adjusts the voltage level of the voltage threshold based at least in part on the PWM signal.

2. The motor control system of claim 1 , wherein the parasitic pulses have a first parasitic voltage in response to rotating the rotor in a first direction and have a second parasitic voltage different than the first parasitic voltage in response to rotating the rotor in a second direction opposite the first direction.

3. The motor control system of claim 2 , wherein the voltage threshold is set to a first voltage level (Vt 1 ) that is less than the first parasitic voltage in response to rotating the rotor in a clockwise direction, and wherein the voltage threshold is set to a second voltage level (Vt 2 ) that is less than the second parasitic voltage in response to rotating the rotor in a counter-clockwise direction.

4. The motor control system of claim 1 , wherein the PWM signal is generated having a first frequency in response to rotating the rotor in the clockwise direction so as to set the first voltage level (Vt 1 ) of the voltage threshold, and wherein the PWM signal is generated having a second frequency less than the first frequency in response to rotating the rotor in the counter-clockwise direction so as to set the second voltage level (Vt 2 ) of the voltage threshold.

5. The motor control system of claim 1 , wherein the parasitic pulse cancelation circuit further comprises an operational amplifier, “op amp” that compares the parasitic voltage of the parasitic pulses to the voltage threshold, outputs the ripple count signal having a logic “1” state in response to the parasitic voltage exceeding the voltage threshold, and outputs the ripple count signal having a logic “0” state in response to the parasitic voltage being less than or equal to the voltage threshold.

6. The motor control system of claim 5 , wherein the op amp comprises:
a non-inverting input (+) configured to receive the pulsed signal; and
an inverting input (−) configured to receive the PWM signal,
wherein varying the frequency of the PWM signal actively adjusts the voltage level of the voltage threshold.

7. A method of controlling a motor control system, the method comprising:
generating a drive current using a supply voltage and delivering the drive current to a direct current (DC) motor;
rotating a rotor of the motor in response to the drive current;
generating a mechanical force in response to rotating the rotor to drive a component;
filtering the drive current using an active filter circuit and generating a pulsed signal based on the filtered drive current;
generating a pulse width modulation, (PWM) control signal indicative of a rotational direction of the rotor, and delivering the PWM signal to a PWM circuit included in a parasitic pulse cancelation circuit;
generating a PWM signal using the PWM circuit, wherein the PWM signal is generated based at least in part on the rotational direction of the rotor;
comparing, by the parasitic pulse cancelation circuit, a parasitic voltage level of the pulsed signal to a voltage level of a voltage threshold;
actively adjusting the voltage level of the voltage threshold using the parasitic pulse cancelation circuit based at least in part on the PWM signal; and
delivering the pulsed signal to the parasitic pulse cancelation circuit and generating a ripple count signal that excludes parasitic pulses included in the pulsed signal that have the parasitic voltage level that exceeds the voltage level of the voltage threshold.

8. The method of claim 7 , wherein the parasitic pulses have a first parasitic voltage in response to rotating the rotor in a first direction and have a second parasitic voltage different than the first parasitic voltage in response to rotating the rotor in a second direction opposite the first direction.

9. The method of claim 8 , further comprising setting the voltage threshold to a first voltage level (Vt 1 ) that is less than the first parasitic voltage in response to rotating the rotor in a clockwise direction, and setting the voltage threshold is a second voltage level (Vt 2 ) that is less than the second parasitic voltage in response to rotating the rotor in a counter-clockwise direction.

10. The method of claim 7 , further comprising:
generating the PWM signal having a first frequency in response to rotating the rotor in the clockwise direction so as to set the first voltage level (Vt 1 ) of the voltage threshold; and
generating the PWM signal having a second frequency that is less than the first frequency in response to rotating the rotor in the counter-clockwise direction so as to set the second voltage level (Vt 2 ) of the voltage threshold.

11. The method of claim 7 , further comprising:
comparing, using an operational amplifier, “op amp” set with the voltage threshold, the parasitic voltage of the parasitic pulses included in the pulsed signal to the voltage threshold;
outputting from the op amp the ripple count signal having a logic “1” state in response to the parasitic voltage exceeding the voltage threshold; and
outputting from the op amp the ripple count signal having a logic “0” state in response to the parasitic voltage being less than or equal to the voltage threshold.

12. The method of claim 11 , further comprising:
delivering the pulsed signal to a non-inverting input (+) of the op amp;
delivering the PWM signal to an inverting input (−) of the op amp; and
actively adjusting the voltage threshold of the op amp in response to varying the frequency of the PWM signal.

Assignees

• Inteva Products Llc

Inventors

• Breynaert François

Classifications

• H03K23/58 Primary

  Gating or clocking signals not applied to all stages, i.e. asynchronous counters (H03K23/74 - H03K23/84 take precedence) · CPC title

• H02P7/0094 Primary

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

• H02P7/18

  by master control with auxiliary power · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H03K5/1252

  Suppression or limitation of noise or interference (specially adapted for transmission systems H04B15/00, H04L25/08) · CPC title