Fuji Electric FRENIC-Ace series - V;F Control with Slip Compensation Active for IM; V;F Control with Speed Sensor for IM; V;F Control with Speed Sensor with Auto Torque Boost for IM; Vector Control with Speed Sensor for IM

4.6 Selecting a Desired Motor Drive Control
4-9
TEST RUN PROCEDURE
Chap 4
4.6.3 V/f control with slip compensation active for IM
Applying any load to an induction motor causes a rotational slip due to the motor characteristics, decreasing the
motor rotation. The inverter’s slip compensation function first presumes the slip value of the motor based on the
motor torque generated and raises the output frequency to compensate for the decrease in motor rotation. This
prevents the motor from decreasing the rotation due to the slip.
That is, this function is effective for improving the motor speed control accuracy.
The compensation value is specified by combination of function codes P12
*
(Rated slip frequency), P09
*
(Slip
compensation gain for driving) and P11
*
(Slip compensation gain for braking).
H68
*
enables or disables the slip compensation function according to the motor driving conditions.
H68* data
Motor driving conditions Motor driving frequency zone
Accl/Decel Constant speed
Base frequency or
below
Above the base
frequency
0 Enable Enable Enable Enable
1 Disable Enable Enable Enable
2 Enable Enable Enable Disable
3 Disable Enable Enable Disable
4.6.4 V/f Control with speed sensor for IM
This control requires an optional PG (pulse generator) and an optional PG interface card to be mounted on a motor
shaft and on the inverter, respectively. Applying any load to an induction motor causes a rotational slip due to the
motor characteristics, decreasing the motor rotation.
Under V/f control with speed sensor, the inverter detects the motor rotation using the encoder mounted on the motor
shaft and compensates for the decrease in slip frequency by the PI control to match the motor rotation with the
commanded speed. This improves the motor speed control accuracy.
4.6.5 V/f Control with speed sensor with Auto Torque Boost for IM
The difference from the "V/f control with speed sensor" stated above is that this method calculates the motor torque
for the load applied and uses the calculated torque to optimize the output voltage and current vectors for getting the
maximal torque out of a motor.
This control is effective for improving the system response to external disturbances such as load fluctuations, and
for improving the motor speed control accuracy.
4.6.6 Vector Control with speed sensor for IM
This control requires an optional PG (pulse generator) and an optional PG interface card to be mounted on a motor
shaft and on the inverter, respectively. The inverter detects the motor's rotational position and speed from PG
feedback signals and uses them in the control. In addition, it decomposes the motor drive current into the exciting
and torque current components, and controls each of components in vector.
The desired response can be obtained by adjusting the control constants (PI constants) and using the speed
regulator (PI controller). This control enables the speed control with higher accuracy and quicker response than the
vector control without speed sensor.
• Since vector control with speed sensor use motor parameters, the following conditions should be
satisfied; otherwise, full control performance may not be obtained.
•
A single motor should be controlled per inverter.
•
Motor parameters P02*, P03*, P06* to P13*,P16* to P20*,P53*,
P55* and P56* should be properly
configured or auto-tuning (P04*) should be performed.
•
The capacity of the motor to be controlled should not
be two or more ranks lower than that of the inverter
under vector control with speed sensor
; it should be the same as that of the inverter under the vector
control with speed sensor. Otherwise, the inverter may not contro
l the motor due to decrease of the
current detection resolution.
•
The wiring distance between the inverter and motor should be 50 m or less. If it is longer, the inverter
may not control the motor due to leakage current flowing through stray capacitance t
o the ground or
between wires.Especially, small capacity inverters whose rated current is also small may be unable to
control the motor correctly
even when the wiring is less than 50 m. In that case, make the wiring length
as short as possible or use a wire with small stray capacitance (e.g., loosely-
bundled cable) to minimize
the stray capacitance.