Mitsubishi Electric FR-A700 Series, Техническое руководство

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480
SELECTION
Since the current control loop is configured same as the
vector control with encoder, necessary excitation current
(current required to generate magnetic flux) and torque
current (current proportional to the load torque) can be
calculated separately by using the speed estimated value
found by the motor current and output voltage as the speed
feedback value.
[Speed control]
[Torque current control]
[Magnetic flux control]
[Excitation current control]
[Output frequency calculation]
The above results are used to make PWM modulation and
run the motor.
Block diagram of Real sensorless vector control
Speed control operation is performed to zero the
difference between the speed command
* and speed
estimated value FB. At this time, the motor load is
found and its result is transferred to the torque current
controller as a torque current command iq
* .
A voltage (Vq) is calculated for the current (iq) to flow
identical to the torque current command (iq*) found by
the speed controller.
The magnetic flux 2 of the motor is derived from the
excitation current id. An excitation current command
(id*) is calculated for the motor magnetic flux 2 to be
the predetermined magnetic flux.
PWM
modulation
Output
voltage
conversion
Torque
current
control
Speed
control
Slip
calculation
Current
conversion
Excitation
current
control
Magnetic
flux
control
ω
*
ω
FB
-
+
+
-
iq
*
id
Vq
Vd
ω
0
ω
s
iq
φ
2
id
φ
2 id *
IM
ω
FB
+
-
iq
ω
0
+
+
iq
id
Speed estimation
calculation
flux
Magnetic
iq
Vd
Vq
˜
A voltage (Vd) is calculated to flow a current id
*
which is
identical to the excitation current command (id*) found
by magnetic flux control.
Motor slip s is calculated on the basis of the torque
current value iq and magnetic flux 2. Output frequency
0 is found by adding the slip amount s to the speed
estimated value FB.