Method for adapting the control parameters of an electric traction machine being a permanent magnetic synchronous motor

1. A method for adapting control parameters of an electric traction machine being a permanent magnetic synchronous motor, PMSM, the method comprising:

providing a flux linkage of permanent magnets (PM flux) in the PMSM by decoupling the PMSM from drive shaft and performing a first retardation test to measure the flux linkage of the permanent magnets (PM flux) in the PMSM;

performing a stand still characterisation of the PMSM to estimate linked magnetic flux as a function of current;

adding the PM flux to the estimated linked magnetic flux to provide a flux characteristic of the PMSM;

adapting the control parameters of the PMSM based on the flux characteristic.

2. The method according to claim 1 , wherein the adapted control parameters comprise current control.

3. The method according to claim 1 , wherein the adapted control parameters are adapted to increase the efficiency of the PMSM.

4. The method according to claim 1 , wherein for the stand still characterisation of the PMSM, the PMSM is locked to prevent rotation of a rotating shaft of the PMSM.

5. The method according to claim 1 , wherein the linked magnetic flux is estimated based on differential inductances and the current for various operating points.

6. The method according to claim 1 , comprising:

comparing the flux characteristic of the PMSM with reference data of known flux characteristic of a population of PMSMs, wherein the adaptation of the control parameters of the PMSM is based on the compared flux characteristic.

7. The method according to claim 1 , the PMSM being powered by a battery via an inverter, the method comprising:

performing a second retardation test in which the inverter is disconnected, to measure no-load power losses of the PMSM.

8. The method according to claim 1 , comprising:

correlating the PM flux with the no-load power losses in a health parameter of the PMSM, and comparing the health parameter with reference data of known health parameters of a population of PMSMs;

categorizing the performance of the PMSM based on the compared health parameter.

9. The method according to claim 1 , comprising

prior to the first retardation test, determining a steady state temperature for the permanent magnets in the PMSM.

10. The method according to claim 1 , wherein the PMSM is installed in a vehicle and the method is performed off-line, when the vehicle is at a standstill.

11. A computer program comprising program code means for performing the method of claim 1 , when the program is run on a computer.

12. The method according to claim 8 , wherein the adaptation of the control parameters of the PMSM is based on the categorization of the performance of the PMSM.

13. The method according to claim 8 , comprising:

determining whether or not the compared health parameter achieves a pre-set criteria, and categorizing the performance of the PMSM if the health parameter achieves the pre-set criteria, wherein the categorization is related to a reduced performance of the PMSM.

14. The method according to claim 9 , comprising:

measuring the temperature inside of the PMSM, e.g. in the stator windings of the PMSM, and the temperature outside of the PMSM, e.g. in the drive shaft or gearbox;

comparing the measured temperatures inside and outside of the PMSM by a compared temperature parameter,

determine a steady state temperature of the PMSM and the permanent magnets in the PMSM in response of determining that the compared temperature parameter is below a threshold temperature difference.

15. A controlling apparatus for controlling the operation of an electric traction machine being a permanent magnetic synchronous motor (PMSM) the controlling apparatus being configured to:

provide a flux linkage of permanent magnets (PM flux) in the PMSM, by that the controlling apparatus is configured to decouple the PMSM from drive shaft and to perform a first retardation test to measure the flux linkage of the permanent magnets (PM flux) in the PMSM;

perform a stand still characterisation of the PMSM to estimate linked magnetic flux as a function of current;

add the PM flux to the estimated linked magnetic flux to provide a flux characteristic of the PMSM;

adapt the control parameters of the PMSM based on the flux characteristic.

16. The controlling apparatus according to claim 15 , the PMSM being coupled to a drive shaft, and powered by a battery via an inverter, the controlling apparatus being further configured to:

perform a second retardation test in which the inverter is disconnected, to measure the no-load power losses of the PMSM;

correlate the PM flux with the no-load power losses in a health parameter of the PMSM, and comparing the health parameter with reference data of known health parameters of a population of PMSMs;

categorize the performance of the PMSM based on the compared health parameter.

17. An arrangement comprising:

an electric traction machine being a permanent magnetic synchronous motor, PMSM, the PMSM being connectable to a drive shaft of a vehicle, and configured to be powered by a battery via an inverter, and

a controlling apparatus according to claim 16 .

18. A vehicle comprising an arrangement according to claim 17 .