Sensorless induction motor system and control method thereof

Patent metadata

Field	Value
Publication number	US-12184207-B2
Application number	US-202217980893-A
Country	US
Kind code	B2
Filing date	Nov 4, 2022
Priority date	Jun 14, 2022
Publication date	Dec 31, 2024
Grant date	Dec 31, 2024

Abstract

A sensorless induction motor system includes a control unit which applies a plurality of sampling pulse voltages to phases of the stator, estimates the position of a rotor through a first rotor position vector having the greatest deviation in an induced current, compares an induced current deviation of a second rotor position vector having a second greatest deviation of deviation of the induced current with that of a first rotor position vector, and determines whether or not permanent magnets are demagnetized; and a method of controlling the sensorless induction motor system.

First claim

What is claimed is:

1. A sensorless induction motor system comprising:
an electric motor including a stator having windings forming a plurality of phases and a rotor having permanent magnets; and
a control unit configured to control driving of the electric motor by controlling a voltage applied in each phase of the stator, to apply a plurality of sampling pulse voltages to the phases of the stator, to estimate a position of the rotor through a first rotor position vector having a greatest deviation of an induced current, to compare induced current deviation of a second rotor position vector having a second greatest deviation of the induced current with induced current deviation of the first rotor position vector, and to determine whether or not the permanent magnets are demagnetized.

2. The sensorless induction motor system of claim 1 , wherein the control unit is configured to estimate the position of the rotor in a state in which starting is completed before driving of the electric motor, and to determine whether or not the permanent magnets are demagnetized.

3. The sensorless induction motor system of claim 1 , wherein, when applying the pulse voltages to the stator in each phase thereof, the control unit allows the pulse voltages to be alternately applied in directions in which magnetic fields are offset from each other.

4. The sensorless induction motor system of claim 1 , wherein, when the sampling pulse voltages are applied to the respective phases of the stator, the control unit is configured to apply a constant level of voltage in a plurality of times, to estimate the position of the rotor, and to determine whether or not the permanent magnets are demagnetized.

5. The sensorless induction motor system of claim 4 , wherein the control unit is configured to perform position estimation of the rotor a plurality of times, and to conclude that the permanent magnets are demagnetized when an average of difference values between the induced current deviation of the first rotor position vector derived whenever the position is estimated and the induced current deviation of the second rotor position vector.

6. The sensorless induction motor system of claim 5 , wherein the control unit is configured to apply secondary sampling pulse voltages after increasing a magnitude and frequency of the voltage applied when the permanent magnets are demagnetized.

7. The sensorless induction motor system of claim 6 , wherein, when the secondary sampling pulse voltages are applied and a rotor position vector having a greatest deviation of the induced current is equally detected, the position of the rotor is estimated by a corresponding position vector.

8. The sensorless induction motor system of claim 7 , wherein the controller is configured to output a failure signal when the secondary sampling pulse voltages are applied a plurality of times and when rotor position vectors in which the deviation of the induced current is greatest are not equally detected, the control unit outputs a failure signal.

9. A method of controlling a sensorless induction motor system including an electric motor, which includes a stator having windings forming a plurality of phases and a rotor having permanent magnets, and a control unit for controlling driving of the electric motor by controlling a voltage applied to the stator in each phase thereof, the method comprising:
applying, by the control unit, a plurality of sampling pulse voltages to the stator in respective phases thereof, and estimating a position of the rotor through a first rotor position vector having a greatest deviation of an induced current; and
comparing, by the control unit, an induced current deviation of a second rotor position vector having a second greatest deviation of the induced current with an induced current deviation of the first rotor position vector, and determining whether or not the permanent magnets are demagnetized.

10. The method of claim 9 , wherein the control unit alternately applies the pulse voltages to be in directions in which magnetic fields are offset from each other when the pulse voltages are applied to the stator in each phase thereof.

11. The method of claim 9 , wherein, in determining whether or not the permanent magnets are demagnetized, the control unit is configured to perform position estimation of the rotor in a plurality of times, and to determine that the permanent magnets are magnetized when an average of difference values between deviation of the induced current of the first rotor position vector and deviation of the induced current of the second rotor position vector is less than a reference value.

12. The method of claim 11 , further including, after determining whether or not the permanent magnets are demagnetized, increasing, with the control unit, a magnitude and a frequency of the voltage applied when the control unit concludes that the permanent magnet is demagnetized, and applying secondary sampling pulse voltages.

13. The method of claim 12 , further including: after applying the secondary sampling pulse voltages, estimating, by the control unit, the position of the rotor using a corresponding position vector when a rotor position vector having a greatest deviation of the induced current caused by the application of the secondary sampling pulse voltages in a plurality of times is equally detected.

14. The method of claim 13 , wherein the controller is configured to output a failure signal when the secondary sampling pulse voltages are applied the plurality of times and when rotor position vectors in which the deviation of the induced current is greatest are not equally detected, the control unit outputs a failure signal.

15. The method of claim 9 , wherein the control unit is configured to estimate the position of the rotor in a state in which starting is completed before driving of the electric motor, and to determine whether or not the permanent magnets are demagnetized.

16. The method of claim 9 , wherein, when the sampling pulse voltages are applied to the respective phases of the stator, the control unit is configured to apply a constant level of voltage in a plurality of times, to estimate the position of the rotor, and to determine whether or not the permanent magnets are demagnetized.

Assignees

• Hyundai Motor Co Ltd
• Kia Corp

Inventors

• Kim Sung Do
• You Chang Seok
• Lee Hyo Jeong
• Kang Min Su
• Kim Joo Yeon

Classifications

• H02K11/35

  Devices for recording or transmitting machine parameters, e.g. memory chips or radio transmitters for diagnosis · CPC title

• H02P25/026

  thereby detecting the rotor position · CPC title

• H02P21/28

  Stator flux based control · CPC title

• H02P21/18 Primary

  Estimation of position or speed · CPC title

• H02P6/185 Primary

  using inductance sensing, e.g. pulse excitation · CPC title