Systems and methods for calculating motor position, inertia and rest position in sensorless brushed DC motor control systems

Patent metadata

Field	Value
Publication number	US-10536100-B2
Application number	US-201715474580-A
Country	US
Kind code	B2
Filing date	Mar 30, 2017
Priority date	Apr 1, 2016
Publication date	Jan 14, 2020
Grant date	Jan 14, 2020

Abstract

A system according to the present disclosure includes a motor driver module and a motor position determination module. The motor driver module is configured to measure current supplied to a motor. The motor position determination module is configured to determine a first position of the motor at a first time when power supply to the motor is initially discontinued based on ripples in the current supplied to the motor during a first period before the first time. The motor position determination module is configured to determine a second position of the motor at a second time when the motor stops rotating after power supply to the motor is discontinued based on the first position of the motor and a rotational speed of the motor at the first time.

First claim

What is claimed is:

1. A system comprising:
a motor driver module configured to measure current supplied to a motor; and
a motor position determination module configured to:
detect ripples in the measurement of the current supplied to the motor;
determine a first position of the motor at a first time when power supply to the motor is initially discontinued based on the ripples in the current supplied to the motor during a first period before the first time;
determine a second position of the motor at a second time when the motor stops rotating after power supply to the motor is discontinued based on the first position of the motor and a rotational speed of the motor at the first time; and
determine the rotational speed of the motor during a second period between the first and second times based on the rotational speed of the motor at the first time and a decay factor.

2. The system of claim 1 wherein the motor position determination module is configured to determine the decay factor based on a first voltage supplied to the motor at the first time.

3. The system of claim 2 wherein the motor position determination module is configured to determine the decay factor based on a difference between (i) a frequency of the ripples in the current supplied to the motor during the first period and (ii) a reference ripple frequency of the motor corresponding to the first voltage supplied to the motor at the first time.

4. The system of claim 1 wherein the motor position determination module is configured to determine the first position of the motor based on a number of the ripples in the current supplied to the motor during the first period.

5. The system of claim 1 wherein the motor position determination module is configured to determine the first and second positions of the motor without using a motor position sensor.

6. A system comprising:
a motor driver module configured to measure current supplied to a motor;
a motor position determination module configured to:
detect ripples in the measurement of the current supplied to the motor;
determine a first position of the motor at a first time when power supply to the motor is initially discontinued based on the ripples in the current supplied to the motor during a first period before the first time;
determine a second position of the motor at a second time when the motor stops rotating after power supply to the motor is discontinued based on the first position of the motor and a rotational speed of the motor at the first time; and
predict the second position of the motor at a third time based on the first position of the motor and the rotational speed of the motor at the first time when power supply to the motor is initially discontinued, wherein the third time is earlier than the second time when the motor stops rotating; and

a target motor stop position module configured to determine when to discontinue power supply to the motor based on the second position and a target position.

7. The system of claim 6 further comprising a motor control module configured to discontinue power supply to the motor when the second position is one of equal to the target position and within a predetermined range of the target position.

8. A system comprising:
a motor driver module configured to:
measure current supplied to a motor; and
measure current induced by the motor after power supply to the motor is discontinued; and

a motor position determination module configured to:
detect ripples in the measurement of the current supplied to the motor;
determine a position of the motor when power is supplied to the motor based on the ripples in the current supplied to the motor;
detect ripples in the measurement of the current induced by the motor; and
determine the position of the motor after power supply to the motor is discontinued based on the ripples in the current induced by the motor after power supply to the motor is discontinued.

9. The system of claim 8 wherein the motor position determination module is configured to:
determine a distance by which the motor rotates during a period between a first time when power supply to the motor is initially discontinued and a second time after power supply to the motor is discontinued; and
determine the position of the motor at the second time based on the position of the motor at the first time and the rotational distance of the motor during the period between the first and second times.

10. The system of claim 9 wherein the motor position determination module is configured to determine the rotational distance of the motor during the period between the first and second times based on a rotational speed of the motor during the period and a duration of the period.

11. The system of claim 10 wherein the motor position determination module is configured to determine the rotational speed of the motor during the period between the first and second times based on a frequency of the ripples in the current induced by the motor during the period.

12. The system of claim 8 wherein the motor position determination module is configured to determine the position of the motor after power supply to the motor is discontinued based on a number of the ripples in the current induced by the motor.

13. The system of claim 8 further comprising:
a motor control module configured to:
rotate the motor in a first rotational direction by closing a first switch to allow current to flow through the motor in a first flow direction; and
rotate the motor in a second rotational direction by closing a second switch to allow current to flow the motor in a second flow direction;

a first motor driver module configured to control a first amount of current flowing in the first flow direction; and
a second motor driver module configured to control a second amount of current flowing in the second flow direction,
wherein the motor control module is configured to control the first and second switches to circulate current through both the first and second motor driver modules when the motor continues to rotate in either one of the first and second rotational directions after power supply to the motor is discontinued, and
wherein at least one of the first and second motor driver modules is configured to measure the current induced by the motor.

14. The system of claim 8 wherein the motor position determination module is configured to:
determine the position of the motor when power is supplied to the motor based on a number of the ripples in the current supplied to the motor; and
determine the position of the motor after power supply to the motor is discontinued based on a frequency of the ripples in the current induced by the motor.

15. The system of claim 8 wherein the motor position determination module is configured to determine the position of the motor without using a motor position sensor.

16. The system of claim 8 wherein the motor position determination module is configured to determine the position of the motor after power supply to the motor is discontinued based on a frequency of the ripples in the current induced by the motor after power supply to the motor is discontinued.

17. The system of claim 9 wherein the motor position determination module is configured to determine the rotational distance of the motor during the period between the first and second times based on a frequency of the ripples in the current induced by the motor after power supply to the motor is discontinued.

18. A system comprising:
a motor driver module configured to measure current supplied to a m

Assignees

• Gentherm Inc

Inventors

• Jordan Patrick
• Petrovski Dusko

Classifications

• H02P7/0094

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

• H02P6/18 Primary

  without separate position detecting elements · CPC title

• B60N2/12

  slidable and tiltable · CPC title

• B60N2/16

  height-adjustable · CPC title

• H02P23/14 Primary

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