Traction battery self-heating control method and device

1. A traction battery self-heating control method, comprising:

acquiring a second temperature of a rotor according to system parameters and a first temperature of a rotor of a permanent magnet motor; wherein the system parameters comprise: a material specific heat capacity of the rotor, a mass of the rotor and a power for heating the rotor in a sampling time interval, the first temperature is a temperature of the rotor at a first sampling time, the second temperature is a temperature of the rotor at a second sampling time, the second sampling time is a current sampling time, and the first sampling time is a previous sampling time of the second sampling time;

estimating a third temperature of the rotor according to the first temperature and the second temperature, wherein the third temperature is a temperature of the rotor at a third sampling time, and the third sampling time is a next sampling time of the second sampling time; and

stopping self-heating of the traction battery when the third temperature reaches a demagnetization temperature of the rotor.

2. The method according to claim 1 , wherein the method further comprises:

collecting a cell temperature of a cell of the traction battery at the second sampling time; and

stopping the self-heating of the traction battery when the cell temperature reaches a specified temperature of the cell.

3. The method according to claim 2 , wherein estimating the third temperature of the rotor according to the first temperature and the second temperature, specifically comprises:

determining a rotor temperature change amount according to the first temperature and the second temperature; and

estimating the third temperature according to the second temperature and the rotor temperature change amount.

4. The method according to claim 1 , wherein acquiring the second temperature of the rotor according to the system parameters and the first temperature of the rotor, specifically comprises:

determining a rotor temperature change amount in the sampling time interval according to the system parameters; and

determining the second temperature according to the first temperature and the rotor temperature change amount.

5. The method according to claim 4 , wherein determining the rotor temperature change amount in the sampling time interval according to the system parameters, specifically comprises:

determining the rotor temperature change amount according to a first formula, wherein the first formula is:

Δ

⁢

T

R

=

Δ

⁢

P

1

·

Δτ

C

R

⁢

M

R

wherein ΔT R denotes the rotor temperature change amount, Δτ denotes the sampling time interval, C R denotes the material specific heat capacity of the rotor, M R denotes the mass of the rotor, and ΔP 1 denotes the power for heating the rotor.

6. The method according to claim 1 , wherein estimating the third temperature of the rotor according to the first temperature and the second temperature, specifically comprises:

determining a rotor temperature change amount according to the first temperature and the second temperature; and

estimating the third temperature according to the second temperature and the rotor temperature change amount.

7. The method according to claim 1 , wherein the method further comprises:

determining a heating power of the permanent magnet motor according to a loss and a heat dissipation power of the permanent magnet motor;

acquiring a heating power of a stator core and a heating power of a stator winding of the permanent magnet motor; and

determining the power for heating the rotor according to the heating power of the permanent magnet motor, the heating power of the stator winding and the heating power of the stator core.

8. The method according to claim 7 , wherein before determining the heating power of the permanent magnet motor according to the loss and the heat dissipation power of the permanent magnet motor, the method further comprises

calculating the loss of the permanent magnet motor according to a stator core loss, a stator winding loss and an eddy current loss of the rotor.

9. The method according to claim 7 , wherein acquiring the heating power of the stator core and the heating power of the stator winding of the permanent magnet motor, specifically comprises

acquiring a temperature change amount of the stator core and a temperature change amount of the stator winding in the sampling time interval;

determining the heating power of the stator core according to the temperature change amount of the stator core, a mass of the stator core and a material specific heat capacity of the stator core; and

determining the heating power of the stator winding according to the temperature change amount of the stator winding, a mass of the stator winding and a material specific heat capacity of the stator winding.

10. The method according to claim 1 , wherein the method further comprises:

determining an eddy current loss of the rotor according to a second formula, wherein the second formula is:

P R =K r f 2 B s 2

wherein P R is the eddy current loss of the rotor, K r is an eddy current loss coefficient of the rotor, B s is a magnetic flux density amplitude of the rotor, and f denotes an electrification frequency of the stator winding.

11. A motor controller, comprising:

a memory, is configured to storing computer-executed instructions;

a processor, is configured to acquire a second temperature of a rotor according to system parameters and a first temperature of a rotor of a permanent magnet motor; wherein the system parameters comprise: a material specific heat capacity of the rotor, a mass of the rotor, and a power for heating the rotor in a sampling time interval, the first temperature is a temperature of the rotor at a first sampling time, the second temperature is a temperature of the rotor at a second sampling time, the second sampling time is a current sampling time, and the first sampling time is a previous sampling time of the second sampling time;

the processor is configured to estimate a third temperature of the rotor according to the first temperature and the second temperature, wherein the third temperature is a temperature of the rotor at a third sampling time, and the third sampling time is a next sampling time of the second sampling time; and

the processor is configured to stop self-heating of the traction battery when the third temperature reaches a demagnetization temperature of the rotor.

12. The motor controller according to claim 11 , wherein the processor is configured to collect a cell temperature of a cell of the traction battery at the second sampling time; and

the processor is further configured to stop the self-heating of the traction battery when the cell temperature reaches a specified temperature of the cell.

13. The motor controller according to claim 11 , wherein the processor is specifically configured to:

determine a rotor temperature change amount in the sampling time interval according to the system parameters; and

determine the second temperature according to the first temperature and the rotor temperature change amount.

14. The motor controller according to claim 13 , wherein the processor is specifically configured to:

determine the rotor temperature change amount according to a first formula, wherein the first formula is:

Δ

⁢

T

R

=

Δ

⁢

P

1

·

Δτ

C

R

⁢

M

R

wherein ΔT R denotes the rotor temperature change amount, Δτ denotes the sampling time interval, C R denotes the material specific heat capacity of the rotor, M R denotes the mass of the rotor, and ΔP 1 denotes the power for heating the rotor.

15. The motor controller according to claim 11 , wherein the processor is specifically configured to:

determine the rotor temperature change amount according to the first temperature and the second temperature; and

estimate the third temperature according to the second temperature and the rotor temperature change amount.

16. The motor controller according to claim 11 , wherein the processor is further configured to:

determine a heating power of the permanent magnet motor according to a loss and a heat dissipation power of the permanent magnet motor;

acquire a heating power of a stator core and a heating power of a stator winding of the permanent magnet motor; and

determine the power for heating the rotor according to the heating power of the permanent magnet motor, the heating power of the stator winding and the heating power of the stator core.

17. The motor controller according to claim 16 , wherein the processor is further configured to:

calculate the loss of the permanent magnet motor according to a stator core loss, a stator winding loss and an eddy current loss of the rotor.

18. The motor controller according to claim 16 , wherein the processor is specifically configured to:

acquire a temperature change amount of the stator core and a temperature change amount of the stator winding in the sampling time interval;

determine the heating power of the stator core according to the temperature change amount of the stator core, a mass of the stator core and a material specific heat capacity of the stator core; and

determine the heating power of the stator winding according to a temperature change amount of the stator winding, a mass of the stator winding and a material specific heat capacity of the stator winding.

19. The motor controller according to claim 11 , wherein the processor is further configured to:

determine an eddy current loss of the rotor according to a second formula, wherein the second formula is:

P R =K r f 2 B s 2

wherein P R is the eddy current loss of the rotor, K r is an eddy current loss coefficient of the rotor, B s is a magnetic flux density amplitude of the rotor, and f denotes an electrification frequency of the stator winding.

20. A power system, comprising: a permanent motor, a traction battery, an inverter, and the motor controller of claim 11 .