Difference between revisions of "Configuring VSD-E/XE for velocity mode"

Revision as of 22:29, 17 April 2012

Additional tips for VSD-E and VSD-XE in velocity mode.

When to use velocity mode

• If speed control only is needed (such as spindle, feeders etc)
• If position loop is closed externally (such as EMC2 Controller)

How to interface with controller

Suitable reference signal types to be used with velocity control:

• PWM, gives high accuracy, low offset and low noise
• Analog reference, easy to interface but comes with some noise and offset (drifting at 0V signal)
• Pulse and direction train. Pulse frequency will determine the speed.

Tips for tuning VSD drive for velocity control

Useful GDtool settings:

• Choose None/Indexer as input source during tuning (so no drifting occurs during tuning).
• Check that you have chosen correct encoder resolution and Trajectory planner settings have realistic veloicty limit setting. I.e. if you set limit to 2000 rpm, then +10V input will turn motor 2000 rpm and -10V turns 2000r pm in another direction.
• Check that Trajectory planner multiplier and divider settings have equal values (i.e. 50:50) to get behavior described above
• If motor has limited travel and axis reaches end of travel during tuning, just use negative value in "Step response amplitude" spinbox to reverse direction.

Adjusting offset in analog input mode

PWM/Analog offset parameter helps to zero the offset & drifting present in PWM and analog input reference modes.

In GDtool 2.5.1 there is a bug that prevents adjusting "PWM/Analog offset" spinbox whenever analog has been selected from drop down box. To workaround this, temporarily choose PWM from drop box and adjust the offset value. After value changed, switch back to "Analog in" mode. Press Set after offset value is changed and mode is set back to Analog in (no need to press during adjustment).