Torque obtaining method and device, motor controller, and readable storage medium
Embodiments of this application provide a torque obtaining method and device, a motor controller, and a readable storage medium. The torque obtaining method includes: obtaining a rotation speed of a motor; obtaining a current of the motor; obtaining a flux linkage of the motor; determining an electromagnetic torque of the motor based on the current and the flux linkage; and inputting the rotation speed and the electromagnetic torque into a preset status observer, and obtaining an observed value of an actual output torque of the motor, where the observed value is output by the status observer. The obtaining method is intended to obtain the actual output torque effectively, simply, and accurately.
1. A method for obtaining a torque of a motor, comprising:
obtaining a rotation speed of the motor;
obtaining a current of the motor, the current comprising a q-axis current and a d-axis current;
obtaining a flux linkage of the motor, the flux linkage comprising a q-axis flux linkage and a d-axis flux linkage, and obtaining the flux linkage of the motor comprising:
obtaining an internal resistance of a winding of the motor;
determining a q-axis voltage based on the q-axis current and a preset q-axis current, and determining a d-axis voltage based on the d-axis current and a preset d-axis current; and
determining the d-axis flux linkage based on the internal resistance of the winding, the rotation speed, and the q-axis voltage, and determining the q-axis flux linkage based on the internal resistance of the winding, the rotation speed, and the d-axis voltage;
determining an electromagnetic torque of the motor based on the current and the flux linkage; and
inputting the rotation speed and the electromagnetic torque into a preset status observer, and obtaining an observed value of an actual output torque of the motor, wherein the observed value is output by the status observer.
2. The method according to claim 1 , wherein the preset status observer outputs the observed value of the actual output torque of the motor based on the following calculation formula:
w
ˆ
.
m
=
1
J
*
(
T
elc
-
T
ˆ
load
-
B
*
w
ˆ
m
+
J
*
L
1
*
(
w
m
-
w
ˆ
m
)
)
,
T
ˆ
.
load
=
L
2
*
(
w
m
-
w
ˆ
m
)
,
wherein, w m is the rotation speed, T elc is the electromagnetic torque, ŵ m is an observed value of the rotation speed, B is a damping coefficient of the motor, J is a moment of inertia of the motor, {circumflex over ({dot over (w)})} m is a derivative of the observed value of the rotation speed, {circumflex over (T)} load is the observed value of the actual output torque, {circumflex over ({dot over (T)})} load is a derivative of the observed value of the actual output torque, L1 is a preset first control parameter, and L2 is a preset second control parameter; and
the observed value of the rotation speed is determined by integrating the derivative of the observed value of the rotation speed.
3. The method according to claim 1 , wherein determining the electromagnetic torque of the motor based on the current and the flux linkage comprises:
determining the electromagnetic torque of the motor based on the current, the flux linkage, and a preset electromagnetic torque calculation formula, wherein
the electromagnetic torque calculation formula is expressed as: T elc =1.5*Pn*(ψ d *iq−ψ q *id),
wherein, T elc is the electromagnetic torque, Pn is a number of pole pairs of the motor, iq is the q-axis current, id is the d-axis current, ψ q is the q-axis flux linkage, and ψ d is the d-axis flux linkage.
4. The method according to claim 1 , wherein the d-axis flux linkage is expressed as: ψ d =(uq−Rs*iq)/w m , and the q-axis flux linkage is expressed as: ψ q =(−ud+Rs*id)/w m ,
wherein, Rs is the internal resistance of the winding, w m is the rotation speed, uq is the q-axis voltage, and ud is the d-axis voltage.
5. The method according to claim 1 , wherein obtaining the current of the motor comprises:
obtaining a three-phase current of the motor and a rotor angle of the motor; and
determining a two-phase current of the motor based on the three-phase current, the rotor angle, and a preset coordinate transformation algorithm.
6. The method according to claim 1 , further comprising:
obtaining status information of the motor;
obtaining a wind friction force of the motor at the rotation speed; and
correcting the observed value of the actual output torque based on the status information and the wind friction force to obtain a corrected actual output torque.
7. The method according to claim 6 , wherein correcting the observed value of the actual output torque based on the status information and the wind friction force to obtain the corrected actual output torque comprises:
subtracting, when determining that the status information is that the motor is in an electromotive state and the motor is rotating forward, the wind friction force from the observed value of the actual output torque to obtain the corrected actual output torque.
8. The method according to claim 6 , wherein correcting the observed value of the actual output torque based on the status information and the wind friction force to obtain the corrected actual output torque comprises:
adding, when determining that the status information is that the motor is in an electromotive state and the motor is rotating reversely, the observed value of the actual output torque and the wind friction force to obtain the corrected actual output torque.
9. The method according to claim 1 , further comprising:
obtaining a temperature of the motor;
determining, based on the temperature and a preset correspondence, a deviation coefficient corresponding to the temperature, wherein the preset correspondence is a correspondence between the temperature and the deviation coefficient; and
correcting the observed value of the actual output torque based on the deviation coefficient corresponding to the temperature to obtain a corrected actual output torque.
10. The method according to claim 9 , wherein the corrected actual output torque is expressed as: T act =(1−K)×{circumflex over (T)} load ,
wherein, K is the deviation coefficient corresponding to the temperature, and {circumflex over (T)} load is the observed value of the actual output torque.
11. A motor controller, comprising a processor and a memory communicationally connected to the processor,
wherein, the memory stores an instruction executable by the processor, and the instruction is executed by the processor so that the processor is enabled to perform the torque obtaining method according to claim 1 .
12. A device for obtaining a torque of a motor, the device comprising:
an obtaining module, configured to:
obtain a rotation speed;
obtain a current of the motor, the current comprising a q-axis current and a d-axis current; and
obtain a flux linkage of the motor, the flux linkage comprising a q-axis flux linkage and a d-axis flux linkage, and obtaining the flux linkage of the motor comprising:
obtaining an internal resistance of a winding of the motor;
determining a q-axis voltage based on the q-axis current and a preset q-axis current, and determine a d-axis voltage based on the d-axis current and a preset d-axis current; and
determining the d-axis flux linkage based on the internal resistance of the winding, the rotation speed, and the q-axis voltage, and determine the q-axis flux linkage based on the internal resistance of the winding, the rotation speed, and the d-axis voltage; and
a processing module, configured to:
determine an electromagnetic torque of the motor based on the current and the flux linkage; and
input the rotation speed and the electromagnetic torque into a preset status observer, and obtain an observed value of an actual output torque of the motor, wherein the observed value is output by the status observer.
13. The device according to claim 12 , wherein the preset status observer outputs the observed value of the actual output torque of the motor based on the following calculation formula:
w
ˆ
.
m
=
1
J
*
(
T
elc
-
T
load
-
B
*
w
^
m
+
J
*
L
1
*
(
w
m
-
w
ˆ
m
)
)
,
T
ˆ
.
load
=
L
2
*
(
w
m
-
w
ˆ
m
)
,
wherein, w m is the rotation speed, T elc is the electromagnetic torque, ŵ m is an observed value of the rotation speed, B is a damping coefficient of the motor, J is a moment of inertia of the motor, {circumflex over ({dot over (w)})} m is a derivative of the observed value of the rotation speed, {circumflex over (T)} load is the observed value of the actual output torque, {circumflex over ({dot over (T)})} load is a derivative of the observed value of the actual output torque, L1 is a preset first control parameter, and L2 is a preset second control parameter; and
the observed value of the rotation speed is determined by integrating the derivative of the observed value of the rotation speed.
14. The device according to claim 12 , wherein the processing module is further configured to: determine an electromagnetic torque of the motor based on the current, the flux linkage, and a preset electromagnetic torque calculation formula, wherein
the electromagnetic torque calculation formula is expressed as: T elc =1.5*Pn*(ψ d *iq−ψ q *id),
wherein, T elc is the electromagnetic torque, Pn is a number of pole pairs of the motor, iq is the q-axis current, id is the d-axis current, ψ d is the q-axis flux linkage, and ψ d is the d-axis flux linkage.
15. The device according to claim 12 , wherein the d-axis flux linkage is expressed as: ψ d =(uq−Rs*iq)/w m , and the q-axis flux linkage is expressed as: ψ q =(−ud+Rs*id)/w m ,
wherein, Rs is the internal resistance of the winding, w m is the rotation speed, uq is the q-axis voltage, and ud is the d-axis voltage.
16. The device according to claim 12 , wherein the obtaining module is further configured to:
obtain a three-phase current of the motor and a rotor angle of the motor; and
determine a two-phase current of the motor based on the three-phase current, the rotor angle, and a preset coordinate transformation algorithm.
17. The device according to claim 12 , wherein;
the obtaining module is further configured to:
obtain status information of the motor; and
obtain a wind friction force of the motor at the rotation speed; and
the processing module is further configured to:
correct the observed value of the actual output torque based on the status information and the wind friction force to obtain a corrected actual output torque.
18. The device according to claim 12 , wherein:
the obtaining module is further configured to: obtain a temperature of the motor; and
the processing module is further configured to:
determine, based on the temperature and a preset correspondence, a deviation coefficient corresponding to the temperature, wherein the preset correspondence is a correspondence between the temperature and the deviation coefficient; and
correct the observed value of the actual output torque based on the deviation coefficient corresponding to the temperature to obtain a corrected actual output torque.