Diagnostic strategy for an electric motor using sensorless control and a position sensor

• US 6,750,626 B2
• Filed: 09/11/2002
• Issued: 06/15/2004
• Est. Priority Date: 09/11/2002
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Miller, John Michael, Leonardi, Franco, Degner, Michael W., Huang, Henry Heping
• Primary Examiner(s): DUDA, RINA I
• Application Number:
  US10/065,026
• Publication Number:
  US 20040046519A1
• Time in Patent Office: 643 Days
• Field of Search: 318/602, 318/603, 318/652, 318/653, 318/668, 318/721, 318/799, 318/432, 318/434, 324/207.11, 324/207.12, 324/207.14, 324/207.23
• US Class Current: 318/602
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 2220/18 Reluctance machines
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2510/0685 Engine crank angle
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 50/00 Details of control systems for road vehicle drive control not related to the control of a particular sub-unit , e.g. process diagnostic or vehicle driver interfaces
• CPC Class Codes: H02P 23/03 specially adapted for very low speeds
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position
• CPC Class Codes: H02P 6/18 without separate position detecting elements
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Abstract

A strategy to control and diagnose the operation of an electric motor using a sensorless control system augmented by feedback from a position and speed sensor is disclosed. The strategy can improve the robustness of operation and diagnose potential faults in electric motors. The present invention includes a method for diagnosing operation of an electric motor and a method and system for controlling an electric motor. In the diagnostic method, a sensorless system and a sensor based system are checked against each other to determine if either of the systems is faulted. In the control method, the sensor based control system is used when the motor speed is below a predetermined threshold and the sensorless system is used when the motor speed is above the predetermined threshold. The position sensor can be a low resolution position sensor, an engine crankshaft sensor, an engine camshaft sensor, or a transmission sensor.

Claims

1. A method for diagnosing operation of an electric motor, comprising:

determining a first shaft position using a sensorless control system;

determining a second shaft position using a position sensor; and

evaluating operation of said electric motor based at least in part on a comparison of said first shaft position to said second shaft position;

transmitting a modified shaft position to a torque controller from a position estimator based on said evaluation of said electric motor;

transmitting a voltage command from said torque controller to an inverter based at least in part on said modified shaft position unless the evaluation indicates inoperability of said position estimator, said torque controller calculating and transmitting said voltage command based on using the sensorless control system during inoperability of said position estimator.

2. The method according to claim 1, further comprising evaluating operation of said sensorless control scheme based on said second shaft position.

3. The method according to claim 1, further comprising evaluating operation of said position sensor based on said first shaft position.