System and method for monitoring temperature of rotating electric machine

1. A system for monitoring temperature of a rotating electric machine, comprising:

a coil that has a strand for passing a current through the coil forming part of the rotating electric machine, and an insulating layer placed around the strand;

at least one in-coil temperature sensor that is placed within the coil;

a physical quantity sensor that is placed within the rotating electric machine and measures a physical quantity related to operation of the rotating electric machine;

a sensor data storage that stores values measured by the at least one in-coil temperature sensor and the physical quantity sensor;

an in-machine temperature predictor that predicts a temperature inside the rotating electric machine by use of the value measured by the physical quantity sensor and stored in the sensor data storage;

a strand temperature calculator that calculates a relationship between a temperature of the strand and a temperature measured by the at least one in-coil temperature sensor, on the basis of the temperature inside the rotating electric machine predicted by the in-machine temperature predictor; and

a strand temperature predictor that predicts a temperature of the strand from the value measured by the at least one in-coil temperature sensor and stored in the sensor data storage, and from the relationship between a temperature of the strand and a temperature measured by the at least one in-coil temperature sensor calculated by the strand temperature calculator.

2. The system for monitoring temperature of a rotating electric machine according to claim 1 , further comprising a display device that successively displays a relationship between a temperature measured by the at least one in-coil temperature sensor and a maximum temperature of the strand predicted by the strand temperature predictor.

3. The system for monitoring temperature of a rotating electric machine according to claim 1 ,

wherein the strand temperature calculator calculates a change over time in measured temperature measured by the at least one in-coil temperature sensor, and

the strand temperature predictor predicts a change over time in temperature of the strand on the basis of the change over time.

4. The system for monitoring temperature of a rotating electric machine according to claim 1 ,

wherein the at least one in-coil temperature sensor includes a plurality of in-coil temperature sensors placed within the coil,

the strand temperature calculator calculates a relationship between a temperature of the strand and a temperature measured by the at least one in-coil temperature sensor for each of the plurality of in-coil temperature sensors, and

the strand temperature predictor predicts a temperature of the strand from the relationship between a temperature of the strand and temperatures measured by each of the plurality of in-coil temperature sensors thus calculated by the strand temperature calculator, and the strand temperature predictor predicts a temperature distribution in the strand within the coil.

5. The system for monitoring temperature of a rotating electric machine according to claim 1 , wherein the at least one in-coil temperature sensor includes a plurality of in-coil temperature sensors arranged from a center of the coil toward an end portion of the coil along a radial direction of the coil.

6. The system for monitoring temperature of a rotating electric machine according to claim 1 ,

wherein the coil has the strand, a plurality of coil members including an insulating layer placed around the strand, and an intermediate layer placed between coil members of the plurality of coil members, and

the at least one in-coil temperature sensor is placed in the intermediate layer.

7. The system for monitoring temperature of a rotating electric machine according to claim 1 , wherein the physical quantity includes a current value of the coil and a value of a temperature of a cooling medium flowing through the rotating electric machine.

8. A method for monitoring temperature of a rotating electric machine, comprising the steps of:

measuring a temperature by at least one in-coil temperature sensor that is installed in a coil having a strand for passing a current through the coil forming part of the rotating electric machine, and an insulating layer placed around the strand;

measuring a physical quantity related to operation of the rotating electric machine, by a physical quantity sensor that is placed within the rotating electric machine;

predicting a temperature inside the rotating electric machine using a value measured by the physical quantity sensor;

calculating a relationship between a temperature of the strand and a temperature measured by the at least one in-coil temperature sensor, on the basis of the temperature inside the rotating electric machine predicted; and

predicting a temperature of the strand from the temperature measured by the at least one in-coil temperature sensor, and from the relationship between a temperature of the strand and a temperature measured by the at least one in-coil temperature sensor, the relationship being calculated.

9. The method for monitoring temperature of a rotating electric machine according to claim 8 , further comprising the step of successively displaying a relationship between a temperature measured by the at least one in-coil temperature sensor and a maximum temperature of the strand predicted.

10. The method for monitoring temperature of a rotating electric machine according to claim 8 ,

wherein when the relationship between a temperature of the strand and a temperature measured by the at least one in-coil temperature sensor is calculated on the basis of the temperature inside the rotating electric machine, a change over time in measured temperature measured by the at least one in-coil temperature sensor is calculated, and

a change over time in temperature of the strand is predicted on the basis of the change over time.

11. The method for monitoring temperature of a rotating electric machine according to claim 8 ,

wherein the at least one in-coil temperature sensor includes a plurality of in-coil temperature sensors placed within the coil,

a relationship between a temperature of the strand and a temperature measured by the at least one in-coil temperature sensor is calculated for each of the plurality of in-coil temperature sensors, and

a temperature of the strand is predicted from the relationship between a temperature of the strand and temperatures measured by each of the plurality of in-coil temperature sensors thus calculated, and a temperature distribution in the strand within the coil is predicted.

12. The method for monitoring temperature of a rotating electric machine according to claim 8 , wherein the at least one in-coil temperature sensor includes a plurality of in-coil temperature sensors arranged from a center of the coil toward an end portion of the coil along a radial direction of the coil.

13. The method for monitoring temperature of a rotating electric machine according to claim 8 ,

wherein the coil has the strand, a plurality of coil members including an insulating layer placed around the strand, and an intermediate layer placed between coil members of the plurality of coil members, and

the at least one in-coil temperature sensor is placed in the intermediate layer.

14. The method for monitoring temperature of a rotating electric machine according to claim 8 , wherein the physical quantity includes a current value of the coil and a value of a temperature of a cooling medium flowing through the rotating electric machine.