US 8,148,926 B2 · Permanent magnet synchronization motor vector control device

Abstract

A vector control device for a permanent magnet synchronous motor drive by an inverter. The vector control device includes: a current command generation unit for generating a d-axis current command id* and q-axis current command iq* from a given torque command T*; and a current control unit operating so that the motor current coincides with the current command. The current command generation unit includes: d-axis basic current command id1* by using the torque command; a limiter unit for inputting the current command id1* and outputting a value limited to below zero as a second d-axis basic current command id2*; a d-axis current command compensation unit for outputting the current command id2* corrected in accordance with the d-axis current command compensation value dV as a d-axis current command id*; and a q-axis current command generation unit for generating a q-axis current command iq* from the d-axis current command id*.

A permanent magnet synchronization motor vector control device, applied to an electric vehicle control device, separating an electric current in a permanent magnet synchronization motor, driven by an inverter that converts a DC voltage into an arbitrary-frequency AC voltage and outputs the AC voltage, into a d-axis current id and a q-axis current iq that are quantities on a d axis and a q axis, respectively, and rotate in synchronization with a rotation electric angle of the permanent magnet synchronization motor, and controlling the d-axis current id and the q-axis current iq, the vector control device comprising:

a current command generation unit that generates a d-axis current command id* and a q-axis current command iq* from a given torque command;
and
a current control unit that operates in such a way that the currents in the motor coincide with the respective current commands,
wherein the current command generation unit is provided with a d-axis basic current command generation unit that utilizes the torque command so as to generate a first d-axis basic current command id1*;
a limiter unit that receives the first d-axis basic current command id1* and outputs a value obtained by limiting the first d-axis basic current command id1* to below zero, as a second d-axis basic current command id2*;
a d-axis current command compensation unit that receives the second d-axis basic current command id2* and outputs as the d-axis current command id* a value obtained by correcting the second d-axis basic current command id2* in accordance with a d-axis current command compensation value dV outputted from the current control unit;
and a q-axis current command generation unit that generates a q-axis current command iq* from the d-axis current command id*, and the current command generation unit generates the d-axis current command id* and the q-axis current command iq* capable of generating with minimum currents the torque corresponding to the torque command,
wherein the d-axis basic current command generation unit generates the first d-axis basic current command id1*, by obtaining an intersection point of an equation (3) below indicating the relationship among the torque T, the d-axis current id, and the q-axis current iq of the motor with a linear equation (4) below that is obtained by applying a linear approximation to a curve indicating a condition under which the motor can generate a given torque with minimum currents, over a range of the curve being substantially straight line and excluding a region where a magnitude of the d-axis current id and a magnitude of the q-axis current iq are small, and that has a gradient and an intercept that represent the relationship between the d-axis current and the q-axis current, and
wherein the first d-axis basic current command id1* is generated from a first equation (7) below:
i
q
=
T
P
n
⁢
{
φ
a
=
(
L
d
-
L
q
)
⁢
i
d
}
(
3
)
i
q
=
ai
d
+
b
(
4
)
i
d
⁢
⁢
1
*
=
-
{
(
aP
n
⁢
φ
a
)
+
bP
n
⁡
(
L
d
-
L
q
)
}
-
{
(
aP
n
⁢
φ
a
)
+
bP
n
⁡
(
L
d
-
L
q
)
}
2
-
4
⁢
{
aP
n
⁡
(
L
d
-
L
q
)
}
⁢
(
bP
n
⁢
φ
a
-
Tabs
*
)
2
⁢
{
aP
n
⁡
(
L
d
-
L
q
)
}
(
7
)
where Tabs* denotes the absolute value of the torque command;
Ld;
a d-axis inductance (H);
Lq, a q-axis inductance (H);
φa, permanent magnetic flux (Wb);
Pn, the number of pole pairs of the motor;
a, the gradient of the linear equation;
and b, the intercept of the linear equation.

142 more elements

Permanent magnet synchronization motor vector control device

Life of this patent

Permanent magnet synchronization motor vector control device

Life of this patent

Abstract

Claims9