Mitsubishi Electric FR-A800, Instruction Manual

Page: 235 / 1042

Parameters Control method
FR-A800 5 - 55
Speed control
Speed control operation is performed to zero the difference between the speed command (ω*) and
actual rotation value detected by encoder (ω
FB
). At this time, the motor load is found and its result is
transferred to the torque current controller as a torque current command (i
q
*).
Torque current control
A voltage (V
q
) is calculated to flow a current (i
q
) which is identical to the torque current command (i
q
*)
found by the speed controller.
Magnetic flux control
The magnetic flux (Ф2) of the motor is derived from the excitation current (id). The excitation current
command (i
d
*) is calculated to use that motor magnetic flux (Ф2) as a predetermined magnetic flux.
Excitation current control
A voltage (V
d
) is calculated to flow a current (i
d
) which is identical to the excitation current command
(i
d
*).
Output frequency calculation
Motor slip (ωs) is calculated on the basis of the torque current value (i
q
) and magnetic flux (Ф2). The
output frequency (ω
0
) is found by adding that slip (ωs) to the feedback (ω
FB
) found by a feedback from
the encoder.
The above results are used to make PWM modulation and run the motor.
I002503E
Fig. 5-5: Block diagram of Vector control
ω
ω
FB
-
+
+
-
iq
id
Vq
Vd
ω 0
ω
s
iq
φ
2
id
φ
2 id
ω
FB
+
-
iq
ω
0
+
+
iq
id
∗
∗
∗
Magnetic
flux
control
Speed
control
Slip
calculation
PWM
modulation
Pre-
excitation
current
control
Torque
current
control
Output
voltage
conversion
Current
conversion
Magnetic
flux
calculation
IM
Encoder