WEG CFW700, Programming And Troubleshooting Manual

Page: 117 / 223

Functions Common to all the Control Modes
12
CFW700 | 12-9
12.5.1 V/f or V VW Flying Start
In the V/f or VVW modes, the inverter imposes a fixed frequency at the start, defined by the speed reference, and
applies a voltage ramp defined at the parameter P0331. The Flying Start function will be activated after the time
adjusted in P0332 elapses (to allow the motor demagnetization), every time a “Run” command is driven.
12.5.2 Vector Flying Start
12.5.2.1 P0202=4
The behavior of the Flying Start function (FS) in the sensorless mode during acceleration and reacceleration can
be understood from the figure 12.4 .
The figure 12.4 (b) shows the behavior of the speed reference when the FS function is started with stopped motor
shaft and small P0329 value (not optimized).
Operation analysis:
1. The frequency correspondent to the P0134 adjustment is applied, with approximately the motor nominal current
(I/f control).
2. The frequency is reduced down to zero using the ramp given by: P0329 x P0412.
3. If the speed is not found during this frequency scan, a new scan in the opposite speed direction is initiated, in
which the frequency goes from -P0134 to zero. After this second scan the FS is finished and the control mode
changes to vector sensorless.
The figure 12.4
(c)
shows the speed reference when the FS function is initiated with the motor shaft already running
in the desired direction, or with stopped shaft and an already optimized P0329.
Operation analysis:
1. The frequency correspondent to the P0134 adjustment is applied, with approximately the motor nominal current.
2. The frequency is reduced using the ramp given by: P0329 x P0412 until reaching the motor speed.
3. In this moment the control mode changes to vector sensorless.
NOTE!
In order that the motor speed is found in the first scan, proceed with the P0329 setting in the following
manner:
1. Increase P0329 using 1.0 steps.
2. Enable the inverter and observe the motor shaft movement during the FS process.
3. If the shaft rotates in both directions, stop the motor and repeat the steps 1 and 2.
NOTE!
The used parameters are P0327 to P0329 and the not used ones are P0182, P0331 and P0332.
NOTE!
When the general enable command is activated, the motor magnetization will not occur.
NOTE!
For a better performance of the function, the activation of the braking without losses is recommended
by setting the parameter P0185 according to the
table 11.8 .