Detection of demagnetization in a motor in an electric or partially electric motor vehicle
AssigneeFord Global Technologies, LLC
InventorsAbbas Raftari, Patrick J. Curran, Vijay K Garg
Life of this patent
Estimating the term…
Abstract
In an electric or hybrid electric vehicle, a voltage monitor (102) is directly coupled to a traction motor (38) and/or generator motor (30) to detect a permanent magnet induced voltage within the motor at a predetermined speed and no load condition. A controller (100) compares the detected permanent magnet induced voltage with an expected reference voltage that represents an expected permanent magnet induced voltage at full magnetization and the predetermined speed. The comparison includes identifying points of synchronization and using those points to determine a difference in the detected permanent magnet induced voltage that is caused by a faulty component.
Claims22
A device for detecting permanent magnet demagnetization in a motor in a vehicle comprising:
- a permanent magnet induced voltage monitor that measures a detected permanent magnet induced voltage of the motor at a predetermined speed, wherein the permanent magnet induced voltage monitor has
- a sensor coil wrapped around a plurality of teeth in a plurality of slots of a stator of the motor adjacent to a rotor of the motor at an edge closest to a gap between the stator and the rotor of the motor, and wherein the sensor coil is not related to a plurality of windings of the motor, and
- a voltmeter disposed in the vehicle coupled to the sensor coil of the motor, wherein the voltmeter periodically monitors of the state of magnetism of the permanent magnets in the motor during no load conditions to provide the detected permanent magnet induced voltage to a processor;
- a predetermined irregularity in the motor that cooperates with the sensor coil to locate a position of each of a plurality of permanent magnets in the motor;
- and a processor that:
- compares the detected permanent magnet induced voltage with a reference voltage that reflects a permanent magnet induced voltage of the motor with a fully magnetized permanent magnet at the predetermined speed;
- and
- analyzes the detected permanent magnet induced voltage with reference to the reference voltage to determine whether a characteristic of the detected permanent magnet induced voltage indicates a demagnetized permanent magnet of the motor.
A method for identifying a component that is causing permanent magnet demagnetization in a motor of a vehicle, the method comprising the steps of:
- providing a sensor coil wrapped around a plurality of teeth in a plurality of slots of a stator of the motor adjacent to a rotor of the motor at an edge closest to a gap between the stator and the rotor of the motor, wherein the sensor coil is not related to a plurality of windings of the motor;
- using the sensor coil to sense permanent magnet induced voltage in the motor;
- providing a voltmeter disposed in the vehicle coupled to the sensor coil of the motor;
- using the voltmeter to periodically monitor the state of magnetism sensed by the sensor coil of each of the plurality of permanent magnets in the motor during no load conditions;
- providing a predetermined irregularity in the motor that cooperates with the sensor coil to locate a position of each of a plurality of permanent magnets in the motor;
- detecting a first signal from the voltmeter that is a function of permanent magnetization of a plurality of permanent magnets in the motor;
- comparing the first signal with a reference signal that represents a function of permanent magnetization of the plurality of magnets in the motor, wherein the reference signal reflects a level of magnetization that is expected where the plurality of permanent magnets in the motor are fully magnetized;
- and
- analyzing a difference between the first signal and the reference signal to determine a demagnetized permanent magnet selected from the plurality of permanent magnets that is likely causing the difference.
The method of claim, 11 wherein the first signal is detected by inducing a voltage in the sensor coil .
A device for identifying a permanent magnet that is demagnetized in a motor of vehicle, the device comprising:
- a sensor coil wrapped around a plurality of teeth in a plurality of slots of a stator of the motor adjacent to a rotor of the motor at an edge closest to a gap between the stator and the rotor of the motor that operates to sense permanent magnet induced voltage in the motor, and wherein the sensor coil is not related to a plurality of windings of the motor;
- a voltmeter disposed in the vehicle coupled to the sensor coil of the motor, wherein the voltmeter periodically monitors of the state of magnetism of the permanent magnets in the motor during no load conditions to provide the detected permanent magnet induced voltage to a processor;
- a predetermined irregularity in the motor that cooperates with both the sensor coil and the processor to locate a position of each of the plurality of permanent magnets in the motor;
- and
- a processor that:
- receives a first signal that is a function of permanent magnetization of a plurality of permanent magnets in the motor;
- compares the first signal with a reference signal that represents a function of permanent magnetization of the plurality of magnets in the motor, wherein the reference signal reflects a level of magnetization that is expected where the plurality of permanent magnets in the motor are fully magnetized;
- analyzes a difference between the first signal and the reference signal to determine a demagnetized permanent magnet selected from the plurality of permanent magnets in the motor that is likely causing the difference.
Dependencies are inferred from the claim text.