Rockwell Automation 20P PowerFlex Digital DC Drive - Manual (Page 294)

294 Rockwell Automation Publication 20P-UM001I-EN-P - February 2013
Appendix C Application Notes
Speed Draw Example Configuration
Drive A:
• Set parameter 70 [Anlg In1 Sel] to 4 “Trim Speed”
Drive B:
• Set parameter 70 [Anlg In1 Sel] to 4 “Trim Speed”
• Set parameter 75 [Anlg In2 Sel] to 22 “Speed Ratio”
• Set parameter 1017 [Speed Ratio] to 10500
Drive C:
• Set parameter 70 [Anlg In1 Sel] to 4 “Trim Speed”
• Set parameter 75 [Anlg In2 Sel] to 22 “Speed Ratio”
• Set parameter 1017 [Speed Ratio] to 11000
Speed / Torque Mode
Selection Parameter 241 [Spd Trq Mode Sel] is used to choose whether the drive operates
as a speed regulator, a torque regulator, or a combination of the two. Each mode
is discussed in more detail below. See the “Torque Mode Selection” block
diagram on page
321 for more information.
Note: This function is only available for firmware version 3.001 and later.
Zero Torque Mode
Zero torque current is allowed when Par 241 [Spd Trq Mode Sel] is set to 0 “Zero
Trq Ref ”. Operation in zero torque mode allows the motor to be fully fluxed and
ready to rotate when a speed command or torque command is given. This mode
can be used for a cyclical application where throughput is a high priority. The
control logic can select zero torque during the “rest” portion of a machine cycle
instead of stopping the drive. When the cycle start occurs, instead of issuing a
start to the drive, a speed regulation mode can be selected. The drive will then
immediately accelerate the motor without the need for “flux up” time.
IMPORTANT Zero Torque may excessively heat the motor if operated in this mode for
extended periods of time. No load or flux current is still present when the drive
is operating in zero torque mode. A motor with an extended speed range or
separate cooling methods (blower) may be required.