User manual

Controlinc Digital Futronic VIII User Manual

Model DF320A Version 1.0

(

2003-01-31

)

4. Application Tuning

The VFC controller was configured at the factory with settings that will satisfy most applications.

However,changes in the field may be required on some high performance applications.

4.1. Bandwidths

The speed bandwidth may need to be increased or decreased based on the amount of coast the

application has. Set the speed bandwidth just large enough so that the actuator slows to the slow

speed before moving into the Position Control Bandwidth.

4.2. Decel Rates

When the load comprises large masses the motor becomes a generator driven by the load when

decelerating. This generated energy can cause a VFC buss over-voltage. To prevent this, some

systems may require larger decel rates. If the buss over-voltage condition persists, it may be

necessary to add DC injection or dynamic brakes.

4.3. Speeds

As the frequency output of a VFC controller drops, the current increases and the torque decreases. If

the unit stalls at the slow speed it will jump to the normal speed after 5 seconds. If this happens, the

benefit of two speeds is not realized. Increase the slow speed until the unit does not stall.