Propulsion system with rotor position estimation based on voltage signal

Patent metadata

Field	Value
Publication number	US-11872893-B2
Application number	US-202217719819-A
Country	US
Kind code	B2
Filing date	Apr 13, 2022
Priority date	Apr 13, 2022
Publication date	Jan 16, 2024
Grant date	Jan 16, 2024

Abstract

A propulsion system for a device includes an electric motor configured to generate torque to propel the device. A position sensor is adapted to determine a rotor position of the electric motor. The system includes a controller having instructions recorded for determining the rotor position when a sensor fault condition is detected. The controller is adapted to selectively command injection of a voltage signal in a direct magnetic axis in a synchronous reference frame when a motor speed of the electric motor is below a predefined motor speed threshold and the sensor fault condition is detected. The rotor position is estimated based in part on a motor current response to the voltage signal. The voltage signal is defined by an alternating periodic shape having respective constant segments in each of a plurality of control periods, the respective constant segments being discontinuous between the control periods.

First claim

What is claimed is:

1. A propulsion system for a device, comprising:
an electric motor configured to generate torque to propel the device, the electric motor including a stator and a rotor;
a position sensor adapted to determine a rotor position of the electric motor;
a controller having a processor and tangible, non-transitory memory on which instructions are recorded for determining the rotor position when a sensor fault condition in the position sensor is detected;
wherein the controller is adapted to:
determine a motor speed of the electric motor;
selectively command injection of a voltage signal in a direct magnetic axis in a synchronous reference frame when the motor speed is below a predefined motor speed threshold and the sensor fault condition is detected; and
estimate the rotor position based in part on a motor current response to the voltage signal;

wherein the voltage signal is defined by an alternating periodic shape with respective constant segments in each of a plurality of control periods, the respective constant segments being discontinuous between the plurality of control periods.

2. The propulsion system of claim 1 , wherein:
the voltage signal has a zero-magnitude signal in a quadrature magnetic axis in the synchronous reference frame; and
operation of the electric motor is controlled based in part on the rotor position.

3. The propulsion system of claim 1 , wherein the predefined motor speed threshold is between 10% and 20% of a maximum speed of the electric motor.

4. The propulsion system of claim 1 , wherein the predefined motor speed threshold is about 15% of a maximum speed of the electric motor.

5. The propulsion system of claim 1 , wherein the electric motor defines a switching frequency, and a maximum frequency of the voltage signal is one-sixth of the switching frequency.

6. The propulsion system of claim 1 , further comprising:
a current sensor in communication with the controller and adapted to measure the motor current response.

7. The propulsion system of claim 6 , wherein the controller is adapted to add a one-sample delay in pulse width modulation generation in the electric motor, thereby affecting the motor current response.

8. The propulsion system of claim 1 , wherein the alternating periodic shape of the voltage signal has a partially sinusoidal shape.

9. The propulsion system of claim 1 , further comprising:
a filter operatively connected to the electric motor and adapted to receive the motor current response, the filter being a band stop filter and/or a notch filter.

10. A method of operating a propulsion system in a device, the propulsion system having an electric motor with a stator, a rotor, a position sensor, and a controller having a processor and tangible, non-transitory memory, the method comprising:
determining if a sensor fault condition in the position sensor has been detected;
determining a motor speed of the electric motor;
commanding injection of a voltage signal in a direct magnetic axis of a synchronous reference frame, when the motor speed is below a predefined motor speed threshold and the sensor fault condition is detected;
selecting the voltage signal to have an alternating periodic shape with respective constant segments in each of a plurality of control periods, the respective constant segments being discontinuous between the plurality of control periods; and
estimating the rotor position based in part on a motor current response to the voltage signal.

11. The method of claim 10 , further comprising:
selecting the voltage signal to have a zero-magnitude signal in a quadrature magnetic axis in the synchronous reference frame.

12. The method of claim 10 , further comprising:
selecting the predefined motor speed threshold to be between 10% and 20% of a maximum speed of the electric motor.

13. The method of claim 10 , further comprising:
selecting the predefined motor speed threshold to be about 15% of a maximum speed of the electric motor.

14. The method of claim 10 , wherein the electric motor defines a switching frequency, further comprising:
selecting a maximum frequency of the voltage signal to be one-sixth of the switching frequency.

15. The method of claim 10 , further comprising:
measuring the motor current response via a current sensor in communication with the controller.

16. The method of claim 15 , further comprising:
adding a one-sample delay in pulse width modulation generation in the electric motor, thereby affecting the motor current response.

17. The method of claim 10 , further comprising:
selecting the voltage signal in the direct magnetic axis based in part on a FUNCTION (n) represented as: [1 (at n=6m), ½ (at n=6m+1), −½ (at n=6m+2), −1 (at n=6m+3), −½ (at n=6m+4), ½ (at n=6m+5), . . . ], where m represents a positive integer and/or zero and n represents each control period of the voltage signal.

18. The method of claim 10 , further comprising:
operatively connecting a filter to the electric motor, the filter being a band stop filter and/or a notch filter adapted to receive the motor current response.

19. A propulsion system for a device, comprising:
an electric motor configured to generate torque to propel the device, the electric motor including a stator and a rotor;
a position sensor adapted to determine a rotor position of the electric motor;
a controller having a processor and tangible, non-transitory memory on which instructions are recorded for determining the rotor position when a sensor fault condition is detected;
wherein the controller is adapted to:
determine a motor speed of the electric motor;
selectively command injection of a voltage signal in a direct magnetic axis in a synchronous reference frame when the motor speed is below a predefined motor speed threshold and the sensor fault condition is detected; and
estimate the rotor position based in part on a motor current response to the voltage signal;

wherein the voltage signal is defined by an alternating periodic shape with respective constant segments in each of a plurality of control periods, the voltage signal having a zero-magnitude signal in a quadrature magnetic axis in the synchronous reference frame; and
wherein the alternating periodic shape has a partially sinusoidal shape, the respective constant segments being discontinuous between the plurality of control periods.

Assignees

• Gm Global Tech Operations Llc
• Seoul National Univ
• Seoul Nathional Univ

Inventors

• Yoo Anno
• Sul Seung-Ki
• Cho Hyung-June

Classifications

• B60L15/20 Primary

  for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed · CPC title

• H02P23/14

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

• B60L3/0038 Primary

  relating to sensors · CPC title

• B60L15/025

  using field orientation; Vector control; Direct Torque Control [DTC] · CPC title

• B60L3/12

  Recording operating variables {; Monitoring of operating variables} · CPC title