Method and control unit for an electric motor or generator
A control unit for identifying a fault in an electric motor or generator, the control unit comprising means for measuring a value of a first parameter associated with the operation of the electric motor or generator; means for increasing a counter value if the difference between the measured first parameter value or a value derived from the measured value and a second value is greater than a first predetermined value; means for decreasing the counter value if the difference between the measured first parameter value and the second value is less than the first predetermined value; and means for generating a signal indicative of a fault if the counter value exceeds a second predetermined value.
1. A control unit for identifying a fault in an electric motor or generator, the control unit comprising means for measuring a value of a first parameter associated with the operation of the electric motor or generator; means for increasing a counter value if the difference between the measured first parameter value or a value derived from the measured value and a second value is greater than a first predetermined value; means for decreasing the counter value if the difference between the measured first parameter value and the second value is less than the first predetermined value; and means for generating a signal indicative of a fault if the counter value exceeds a second predetermined value.
2. A control unit according to claim 1 , further comprising means for calculating a value of the first parameter, wherein the second value is the calculated value of the first parameter.
3. A control unit according to claim 2 , wherein the means for calculating is arranged to calculate the value of the first parameter using a value of a second parameter associated with the operation of the electric motor or generator.
4. A control unit according to claim 3 , wherein the first parameter is a current generated in a coil winding of the electric motor or generator, and wherein the second parameter is a voltage.
5. A control unit according to claim 4 , wherein the second parameter is a component of voltage.
6. A control unit according to claim 5 , wherein the component of voltage is phase and/or amplitude or vd and/or vq.
7. A control unit according to claim 2 , further comprising means for comparing the calculated value of the first parameter and the measured value of the first parameter.
8. A control unit according to claim 1 , wherein the first parameter is a current generated in a coil winding of the electric motor or generator.
9. A control unit according to claim 8 , wherein the first parameter is a component of current.
10. A control unit according to claim 8 , wherein the value derived from the measured current is a value of id or iq.
11. A control unit according to claim 1 , wherein the first parameter is a voltage.
12. A control unit according to claim 11 , wherein the first parameter is a component of voltage.
13. A control unit according to claim 12 , wherein the component of voltage is phase and/or amplitude or vd and/or vq.
14. A control unit according to claim 1 , wherein the means for measuring is arranged to measure a value of a first parameter associated with the operation of a first sub motor of the electric motor, further comprising means for measuring a value of a first parameter associated with the operation of a second sub motor of the electric motor, wherein the second value is the measured value of the first parameter associated with the second sub motor.
15. A control unit according to claim 14 , wherein the first parameter is a voltage or current generated in a coil winding of the electric motor or generator.
16. A control unit according to claim 15 , wherein the first parameter is a component of voltage or current.
17. An electric motor system comprising an electric motor and a control unit, the control unit comprising means for measuring a value of a first parameter associated with the operation of the electric motor or generator; means for increasing a counter value if the difference between the measured first parameter value or a value derived from the measured value and a second value is greater than a first predetermined value; means for decreasing the counter value if the difference between the measured first parameter value and the second value is less than the first predetermined value; and means for generating a signal indicative of a fault if the counter value exceeds a second predetermined value.
18. An electric motor system according to claim 17 , wherein the electric motor is a permanent magnet synchronous electric motor.
19. A method for identifying a fault in an electric motor or generator, the method comprising measuring a value of a first parameter associated with the operation of the electric motor or generator; increasing a counter value if the difference between the measured first parameter value or a value derived from the measured value and a second value is greater than a first predetermined value; decreasing the counter value if the difference between the measured first parameter value and the second value is less than the first predetermined value; and generating a signal indicative of a fault if the counter value exceeds a second predetermined value.
20. A method according to claim 19 , further comprising calculating a value of the first parameter, wherein the second value is the calculated value of the first parameter.
21. A method according to claim 20 , wherein the value of the first parameter is calculated using a value of a second parameter associated with the operation of the electric motor or generator.
22. A method according to claim 19 , wherein the first parameter is a current generated in a coil winding of the electric motor or generator.
23. A method according to claim 22 , wherein the first parameter is a component of current.
24. A method according to claim 22 , wherein the value derived from the measured current is a value of id or iq.
25. A method according to claim 19 , wherein the first parameter is a current generated in a coil winding of the electric motor or generator, wherein the second parameter is a voltage.
26. A method according to claim 25 , wherein the second parameter is a component of voltage.
27. A method according to claim 26 , wherein the component of voltage is phase and/or amplitude or vd and/or vq.
28. A method according to claim 19 , wherein the first parameter is a voltage.
29. A method according to claim 19 , wherein measured value of a first parameter is a measured value of a first parameter associated with the operation of a first sub motor of the electric motor, further comprising measuring a value of a first parameter associated with the operation of a second sub motor of the electric motor, wherein the second value is the measured value of the first parameter associated with the second sub motor.