On-line minimum copper loss control of interior permanent-magnet synchronous machine for automotive applications
View Patent ↗A system and method for controlling an IPM synchronous machine in a vehicle that calculates an operating trajectory of the machine on-line. The system defines three operating ranges of the machine based on voltage magnitude, where a first operating range is controlled by a current limit of the machine and second and third operating regions are controlled by a voltage limit of the machine. The system calculates d- and q-axis current reference signals in the reference rotor frame for each of the three regions. The system determines which set of current reference signals will be used to control the machine based on the operating region. The third operating region is used during over-modulation of the machine.
1. A method for calculating current control signals for controlling a machine, said machine being in a vehicle, said method comprising:
determining an operating range of the machine based on the voltage limit of an inverter in the machine;
calculating a current reference signal for controlling the torque of the machine based on the determined operating range, wherein calculating the current reference signal includes using one of a plurality of equations that optimize the current reference signal based on the determined operating range; and
applying the current control signals to the machine based on the calculated current reference signal.
2. The method according to claim 1 wherein determining an operating range of the machine includes determining a first operating range of the machine at relatively low vehicle speeds and determining a second operating range of the machine at relatively high vehicle speeds, wherein the first operating range is controlled by a current limit and the second operating range is controlled by a voltage limit.
3. The method according to claim 2 wherein determining an operating range of the vehicle includes determining a third operating range of the machine at relatively high vehicle speeds, wherein the third operating range of the machine is controlled by the voltage limit and the machine being in an over-modulation operation.
4. The method according to claim 3 wherein calculating a current reference signal includes calculating a d-axis current reference signal and a q-axis current reference signal in a rotor reference frame, and calculating a current reference signal for the third operating range as:
[
i
d
r
*
i
q
r
*
]
=
[
L
ds
0
0
L
qs
]
-
1
{
[
τ
e
*
2
T
e
2
0
0
τ
e
*
T
e
]
(
[
L
ds
0
0
L
qs
]
[
I
d
r
I
q
r
]
+
[
Λ
m
0
]
)
-
[
Λ
m
0
]
}
where i d r* is the d-axis current reference signal, i q r* is the q-axis current reference signal, L ds is the d-axis static inductance of the machine, L qs is the q-axis static inductance of the machine, Λ m is the permanent-magnet flux linkage and I d r is the d-axis current signal, I q r is the q-axis current reference signal to produce the maximum torque with linear voltage limit.
5. The method according to claim 2 wherein calculating a current reference signal includes calculating a d-axis current reference signal and a q-axis current reference signal in the rotor reference frame.
6. The method according to claim 5 wherein calculating a current reference signal includes calculating the current reference signal for the first operating range as:
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
λ
d
r
λ
d
r
λ
q
r
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
or
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
L
dd
i
q
r
-
λ
d
r
+
L
i
d
r
λ
d
r
+
(
L
dd
-
2
L
)
i
d
r
λ
q
r
+
(
L
-
2
L
dd
)
i
q
r
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
where i d r* is the d-axis current reference signal, i q r* is the q-axis current reference signal, L dd is the d-axis dynamic inductance of the machine, L qq is the q-axis dynamic inductance of the machine, λ d r is the d-axis flux linkage, λ q r is the q-axis flux linkage of the machine and ƒ and g are non-linear functions.
7. The method according to claim 5 wherein calculating a current reference signal includes calculating the current reference signal for the second operating range as:
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
λ
d
r
ω
r
2
L
ds
λ
d
r
ω
r
2
L
qs
λ
q
r
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
or
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
L
dd
i
q
r
-
λ
d
r
+
L
i
d
r
ω
r
2
L
dd
λ
d
r
-
ω
r
R
s
(
λ
q
r
-
L
dd
i
q
r
)
ω
r
2
L
λ
q
r
+
ω
r
R
s
(
λ
d
r
-
L
i
d
r
)
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
where i d r* is the d-axis current reference signal, i q r* is the q-axis current reference signal, L dd is the d-axis dynamic inductance of the machine, L qq is the q-axis dynamic inductance of the machine, λ d r is the d-axis flux linkage, λ q r is the q-axis flux linkage of the machine and ƒ and g are non-linear functions and ω r is representative of the machine speed.
8. The method according to claim 5 wherein applying the current control signals to the machine includes using the calculated current reference signal for the first region if the voltage of the inverter has not exceeded a linear voltage limit.
9. The method according to claim 1 wherein calculating a current reference signal includes using a flux and inductance estimation of the machine for calculating the current reference signal.
10. The method according to claim 1 wherein calculating a current reference signal includes considering the saturation of the machine.
11. The method according to claim 1 wherein the machine is an interior permanent-magnet synchronous machine.
12. The method according to claim 11 wherein the machine includes a stator and a rotor, said stator including three coils receiving current signals and said rotor including a permanent magnet.
13. A system for calculating current control signals for controlling a machine, said machine being in a vehicle, said system comprising:
a command optimizer, said command optimizer determining an operating range of the machine based on the voltage of an inverter in the machine, said command optimizer calculating a current reference signal for controlling the torque of the machine based on its operating range, wherein calculating the current reference signal includes using one of a plurality of equations that optimize the current reference signal based on the determined operating range.
14. The system according to claim 13 further comprising a flux and inductance estimator, said flux and inductance estimator providing a machine flux and inductance signal to the command optimizer for calculating the current reference signal.
15. The system according to claim 13 further comprising a current controller for producing a voltage reference signal.
16. The system according to claim 13 wherein the command optimizer determines a first operating range of the machine at relatively low vehicle speeds and determines a second operating range of the machine at relatively high vehicle speeds, wherein the first operating range is controlled by a current limit and the second operating range is controlled by a voltage limit.
17. The system according to claim 16 wherein the command optimizer determines a third operating range of the machine at relatively high vehicle speeds, wherein the third operating range of the machine is controlled by the voltage limit and the machine being in an over-modulation operation.
18. The system according to claim 17 wherein the command optimizer calculates a d-axis current reference signal and a q-axis current reference signal in the rotor reference frame and calculates the current reference signal for the third operating range as:
where i d r* is the d-axis current reference signal, i q r* is the q-axis current reference signal, L ds is the d-axis static inductance of the machine, L qs is the q-axis static inductance of the machine, Λ m is the permanent-magnet flux linkage and I d r is the d-axis current signal, I q r is the q-axis current reference signal to produce the maximum torque with linear voltage limit.
19. The system according to claim 16 wherein the command optimizer calculates a d-axis current reference signal and a q-axis current reference signal in the rotor reference frame.
20. The system according to claim 19 wherein the command optimizer calculates the current reference signal for the first operating range as:
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
λ
d
r
λ
d
r
λ
q
r
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
or
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
L
dd
i
q
r
-
λ
d
r
+
L
i
d
r
λ
d
r
+
(
L
dd
-
2
L
)
i
d
r
λ
q
r
+
(
L
-
2
L
dd
)
i
q
r
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
where i d r* is the d-axis current reference signal, i q r* is the q-axis current reference signal, L dd is the d-axis dynamic inductance of the machine, L qq is the q-axis dynamic inductance of the machine, λ d r is the d-axis flux linkage, λ q r is the q-axis flux linkage of the machine and ƒ and g are non-linear functions.
21. The system according to claim 19 wherein the command optimizer calculates the current reference signal for the second operating range as:
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
λ
d
r
ω
r
s
L
ds
λ
d
r
ω
r
s
L
qs
λ
q
r
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
or
[
i
d
r
*
i
q
r
*
]
≈
[
i
d
r
i
q
r
]
-
[
λ
q
r
-
L
dd
i
q
r
-
λ
d
r
+
L
i
d
r
ω
r
2
L
dd
λ
d
r
-
ω
r
R
s
(
λ
q
r
-
L
dd
i
q
r
)
ω
r
2
L
λ
q
r
+
ω
r
R
s
(
λ
d
r
-
L
i
d
r
)
]
-
1
[
f
(
i
d
r
,
i
q
r
)
g
(
i
d
r
,
i
q
r
)
]
where i d r* is the d-axis current reference signal, i q r* is the q-axis current reference signal, L dd is the d-axis dynamic inductance of the machine, L qq is the q-axis dynamic inductance of the machine, λ d r is the d-axis flux linkage, λ q r is the q-axis flux linkage of the machine and ƒ and g are non-linear functions and ω r is representative of the machine speed.