Counter electromotive force estimation
For counter electromotive force estimation, a disturbance estimator calculates an estimated disturbance as a control function of a quadrature axis current regulator output signal and a quadrature axis current feedback signal of a running permanent magnet motor. A calculator calculates an estimated counter electromotive force of the running permanent magnet motor as a function of the estimated disturbance, a control flux, and an angular velocity.
1. An apparatus comprising:
a disturbance estimator that calculates an estimated disturbance as a control function of a quadrature axis current regulator output signal (IqCurRegPIOut) and a quadrature axis current feedback signal (IqFdbk) of a running permanent magnet motor; and
a calculator that calculates an estimated counter electromotive force (CEMF) of the running permanent magnet motor as a function of the estimated disturbance, a control flux, and an angular velocity,
wherein at least a portion of the disturbance estimator and a calculator comprise one or more of hardware and executable code, the executable code stored on one or more computer readable storage media.
2. The apparatus of claim 1 , wherein the control function is a proportional integral (PI) control function driven by the error between the IqFdbk and an estimated quadrature axis current feedback signal (IqEst) calculated from a quadrature axis inductance model driven by the sum of the IqCurRegPIOut and the estimated disturbance.
3. The apparatus of claim 2 , wherein the PI control function is represented by
CF
=
K
P_Est
+
K
i_Est
s
,
wherein K P_Est and K i_Est are proportional and integrational gain respectively.
4. The apparatus of claim 2 , wherein the quadrature axis inductance model MM is
MM
=
1
L
q
S
,
wherein L q is a quadrature inductance of the permanent magnet motor and s is a frequency transform.
5. The apparatus of claim 1 , the apparatus further comprising a memory that stores the CEMF and provides the CEMF 135 during start of the permanent magnet motor as an initial value.
6. The apparatus of claim 1 , wherein the CEMF is calculated as
ψ
Est
=
D
Est
ω
-
ψ
Ctrl
,
wherein ψ Est is the estimated disturbance, ψ Ctrl is the control flux, and ω is the angular velocity.
7. The apparatus of claim 1 , wherein the CEMF adaptively modifies the calculation of a quadrature axis current reference (IqRef) and a direct axis current reference (IdRef) that drive a current regulator generating IqCurRegPIOut for the permanent magnet motor.
8. The apparatus of claim 7 , wherein the CEMF is continually updated.
9. The apparatus of claim 1 , wherein no rotation test is performed on the permanent magnet motor.
10. The apparatus of claim 1 , the apparatus further comprising the permanent magnet motor.
11. A method comprising:
calculating an estimated disturbance as a control function of a quadrature axis current regulator output signal (IqCurRegPIOut) and a quadrature axis current feedback signal (IqFdbk) of a running permanent magnet motor; and
calculating an estimated counter electromotive force (CEMF) of the running permanent magnet motor as a function of the estimated disturbance, a control flux, and an angular velocity.
12. The method of claim 11 , wherein the control function is a proportional integral (PI) control function driven by the error between the IqFdbk and an estimated quadrature axis current feedback signal (IqEst) calculated from a quadrature axis inductance model driven by the sum of the IqCurRegPIOut and the estimated disturbance.
13. The method of claim 12 , wherein the PI control function is represented by
CF
=
K
P_Est
+
K
i_Est
s
,
wherein K P_Est and K i_Est are proportional and integrational gain respectively.
14. The method of claim 12 , wherein the quadrature axis inductance model MM is
MM
=
1
L
q
S
,
wherein L q is a quadrature inductance of the permanent magnet motor and s is a frequency transform.
15. The method of claim 11 , the method further comprising storing the CEMF and providing the CEMF during start of the permanent magnet motor as an initial value.
16. The method of claim 11 , wherein the CEMF is calculated as
ψ
Est
=
D
Est
ω
-
ψ
Ctrl
,
wherein ψ Est is the estimated disturbance, ψ Ctrl is the control flux, and ω is the angular velocity.
17. The method of claim 11 , wherein the CEMF adaptively modifies the calculation of a quadrature axis current reference (IqRef) and a direct axis current reference (IdRef) that drive a current regulator generating IqCurRegPIOut for the permanent magnet motor.
18. The method of claim 17 , wherein the CEMF is continually updated.
19. The method of claim 11 , wherein no rotation test is performed on the permanent magnet motor.
20. A computer program product comprising a computer readable storage medium having program code embodied therein, the program code readable/executable by a processor to:
calculate an estimated disturbance as a control function of a quadrature axis current regulator output signal (IqCurRegPIOut) and a quadrature axis current feedback signal (IqFdbk) of a running permanent magnet motor; and
calculate an estimated counter electromotive force (CEMF) of the running permanent magnet motor as a function of the estimated disturbance, a control flux, and an angular velocity.