Motor abnormality detecting apparatus

• US 20030179004A1
• Filed: 03/05/2003
• Published: 09/25/2003
• Est. Priority Date: 03/08/2002
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kifuku, Takayuki, Kurishige, Masahiko, Kawakami, Kenichi, Inoue, Noriyuki, Sakanishi, Seiji, Fukusumi, Kouji
• Granted Patent: US 6,831,477 B2
• Time in Patent Office: Days
• US Class Current: 324/713
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/343 in operation

Abstract

A judgment is made of an abnormal condition of a motor due to an influence of a disturbance voltage without addition of hardware by estimating the disturbance voltage on the basis of a target voltage and an actual current of the motor. An apparatus for detecting an abnormal condition of a motor for use in an electric power steering apparatus in which a steering torque generated in a handle shaft by an operation of a driver is assisted with a motor includes: a motor current detecting unit (9) for detecting an actual current flowing through the motor; a feedback controlling unit (3) for feedback-controlling a target voltage value that gives the motor a driving command in accordance with the deviation of the actual current from an inputted target current; an abnormal voltage estimating unit (16) for on the basis of the target voltage and the actual current, estimating an abnormal voltage estimation value corresponding to a voltage exhibiting an abnormal condition of the motor; and a motor abnormality judging unit (15) for judging the abnormality of the motor on the basis of comparison of the abnormal voltage estimation value with a predetermined abnormal voltage value previously stored.

Claims

1. An apparatus for detecting an abnormal condition of an electric motor, comprising:

motor current detecting means for detecting an actual current caused to flow through the motor;

feedback controlling means for feedback-controlling a target voltage value that gives the motor a driving command in accordance with the deviation of the actual current from an inputted target current;

abnormal voltage estimating means for on the basis of the target voltage and the actual current, estimating an abnormal voltage estimation value corresponding to a voltage exhibiting an abnormal condition caused in the motor;

commutation frequency arithmetically operating means for arithmetically operating a commutation frequency on the basis of a rotational speed of the motor, and the number of commutators and the number of brushes of the motor;

a filter device for changing a filter frequency in accordance with the commutation frequency to filter the abnormal voltage estimation value estimated by the abnormal voltage estimating means; and

motor abnormality judging means for judging an abnormal condition of the motor on the basis of the comparison of the abnormal voltage estimation value filtered by the filter device with a predetermined abnormal voltage value previously stored.

2. An apparatus for detecting an abnormal condition of an electric motor, comprising:

motor current detecting means for detecting an actual current caused to flow through the motor;

feedback controlling means for feedback-controlling a target voltage value that gives the motor a driving command in accordance with the deviation of the actual current from an inputted target current;

abnormal voltage estimating means for on the basis of the target voltage and the actual current, estimating an abnormal voltage estimation value corresponding to a voltage exhibiting an abnormal condition caused in the motor;

judgment value calculating means for obtaining a judgment value used to judge an abnormal condition of the motor on the basis of the abnormal voltage estimation value; and

motor abnormality judging means for judging an abnormal condition of the motor on the basis of a rotational frequency of the motor corresponding to a rotational speed of the motor, and the judgment value.

3. An apparatus for detecting an abnormal condition of an electric motor according to claim 2, wherein the judgment value calculating means is frequency analyzing means for carrying out frequency analysis with respect to the abnormal voltage estimation value to output information of a peak frequency on the basis of the result of the frequency analysis, and

the motor abnormality judging means judges an abnormal condition of the motor on the basis of the deviation of the peak frequency from a rotational frequency of the motor corresponding to a rotational speed of the motor.

4. An apparatus for detecting an abnormal condition of an electric motor according to claim 2, wherein:

the judgment value calculating means is time interval arithmetically operating means for arithmetically operating time intervals of generation of the abnormal voltages on the basis of the abnormal voltage estimation value; and

the motor abnormality judging means judges an abnormal condition of the motor on the basis of the time intervals of generation of the abnormal voltages arithmetically operated by the time interval arithmetically operating means, and the rotational frequency of the motor corresponding to the rotational speed of the motor.

5. An apparatus for detecting an abnormal condition of an electric motor according to claim 4, wherein the time interval arithmetically operating means comprises:

D.C. component removing means for removing a D.C. component of the abnormal voltage estimation value estimated by the abnormal voltage estimating means;

abnormal voltage generation judging means for judging generation of the abnormal voltage on the basis of the abnormal voltage estimation value from which the D.C. component is removed by the D.C. component removing means, and a predetermined abnormal voltage value previously stored; and

storage means for storing therein information of time intervals of generation of the abnormal voltage judged by the abnormal voltage generation judging means, and

wherein the motor abnormality judging means judges an abnormal condition of the motor on the basis of the time intervals of generation of the abnormal voltages the information of which is stored in the storage means, and the rotational frequency of the motor corresponding to the rotational speed of the motor.

6. An apparatus for detecting an abnormal condition of an electric motor, comprising:

motor current detecting means for detecting an actual current caused to flow through the motor;

feedback controlling means for feedback-controlling a target voltage value that gives the motor a driving command in accordance with the deviation of the actual current from an inputted target current;

abnormal voltage estimating means for on the basis of the target voltage and the actual current, estimating an abnormal voltage estimation value corresponding to a voltage exhibiting an abnormal condition caused in the motor;

first vibration component removing means for removing a vibration component of the abnormal voltage estimation value estimated by the abnormal voltage estimating means;

second vibration component removing means for removing a vibration component of the target voltage or a surveyed motor voltage; and

motor abnormality judging means for judging an abnormal condition of the motor on the basis of the abnormal voltage estimation value from which the vibration component is removed by the first vibration component removing means, and the target voltage or the surveyed motor voltage from which the vibration component is removed by the second vibration component removing means.

7. An apparatus for detecting an abnormal condition of an electric motor according to claim 6, wherein the motor abnormality judging means judges an abnormal condition of the motor on the basis of a preset voltage value instead of the target voltage or the surveyed motor voltage from which the vibration component is removed by the second vibration component removing means.

8. An apparatus for detecting an abnormal condition of an electric motor according to claim 6, further comprising:

arithmetically operating means for arithmetically operating the deviation of the target voltage or the surveyed motor voltage from which the vibration component is removed from the abnormal voltage estimation value from which the vibration component is removed;

cumulative arithmetically operating means for arithmetically operating the cumulative deviation obtained by accumulating the deviation arithmetically operated by the arithmetically operating means at predetermined time intervals; and

storage means for storing therein the past cumulative deviation obtained by the cumulative arithmetically operating means,

wherein the motor abnormality judging means judges an abnormal condition of the motor on the basis of the deviation of the current cumulative deviation obtained by the cumulative arithmetically operating means from the past cumulative deviation stored in the storage means.