Rockwell Automation FlexPak 3000 Digital DC Drive Version 4.3 - Manual (Page 65)

Configuring the Speed/Voltage Loop 5-17
5.6 Configuring the Speed Loop PI Block
The proportional-integral transfer function is:
where:
• K
p
= SPD LOOP PI PROP GAIN (P.211)
• ω
ld = SPD LOOP PI LEAD FREQ (P.212)
When CONTROL SOURCE SELECT is set to NETWORK , you can reset and assign initial
values to the speed loop PI block. This allows you to switch between current and
speed regulation without stopping the drive.
The PI block is reset when SPD LOOP PI RESET is asserted. The PI block is also held in
reset when the drive is stopped. While reset is asserted, the output of the PI block is
the initial value.
The initial value is determined by SPD LOOP PI INIT SEL and SPD LOOP PI INIT VAL .
If CONTROL SOURCE SELECT is not set to NETWORK , the block uses an initial value of
zero ( SPD LOOP PI INIT SEL set to ZERO .)
When the PI block reset is used, the system must be set to minimize the error between
the actual reference and the commanded reference when changing regulation
schemes to minimize bumps in regulation. For example, when changing from speed to
current regulation, the speed loop
PI block’s initial value should be updated with the
actual armature current feedback just before the change is made. The speed
reference should be set to speed feedback before changing from current to speed
regulation.
You can pretorque the speed regulator by setting the speed loop PI block’s initial value
to the desired starting torque value and releasing the block from reset after starting
the drive. The initial torque will be the initial value as the drive begins to ramp to the
reference speed.
POSITIVE CURRENT LIM
(P.005)
Sets the highest
amount of current (%
full load amps) for the
forward bridge. Used
as a high limit for the
speed loop
PI block
when POS CURRENT
LIM SEL (P.223) is set
to REGISTER .
Parameter Range: 0 to MAXIMUM CURRENT (% FLA )
Default Setting: 150 % FLA
Parameter Type: Tunable
OIM Menu Path(s): Speed/Voltage Loop ( SPD ) - Speed/Voltage Loop
( SPD ) Tuning
Current Minor Loop ( CML ) - CML Tuning
Quick Start
K
p
s
ω
ld +
s
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