PowerFlex Digital DC Drive User Manual -
Publication 20P-UM001C-EN-P - July 2008
C-4
Application Notes
Current / Speed Curve
The current/speed curve function allows you to establish a current limit
lower than the standard current limits of the drive (specified in parameters 8
[Current Lim Pos] and 9 [Current Lim Neg]) and reduce the output current
(torque) of the drive through a defined curve of five equally divided set
points as the speed increases based on a threshold speed, effectively
reducing torque.
•
Enable the current/speed curve function by setting parameter 750
[TrqTpr_Enable] to 1 “Enabled”.
•
Set the current limit (for both directions of rotation in four quadrant
drives) in parameter 751 [TrqTpr_Lim0]. The value specified in this
parameter overrides the value of parameters 8 [Current Lim Pos] and 9
[Current Lim Neg].
•
Set the threshold speed at which current (torque) reduction begins in
parameter 756 [TrqTpr_Spd].
•
Set the first reduced current limit in parameter 752 [TrqTpr_Lim1]. The
value defined in this parameter must be less than the value in parameter
751 [TrqTpr_Lim0] and greater than the values in parameters 753
[TrqTpr_Lim2], 754 [TrqTpr_Lim3] and 755 [TrqTpr_Lim4].
•
Set the second, third and final reduced current limits in parameters 753
[TrqTpr_Lim2], 754 [TrqTpr_Lim3] and 755 [TrqTpr_Lim4],
respectively. The value of each subsequent parameter must be less than
the previous parameter’s value. The drive will maintain the value
specified in parameter 755 [TrqTpr_Lim4] up to the value set in
parameter 162 [Max Feedback Spd].
P
a
r 10 [C
u
r Lim Po
s
O
u
t]
or
P
a
r 11 [C
u
r Lim Neg O
u
t]
P
a
r 751 [Tr
q
Tpr_Lim0]
C
u
rrent/
S
peed
P
a
r 162 [M
a
x Feed
ba
ck
S
pd]
P
a
r 752 [Tr
q
Tpr_Lim1]
P
a
r 75
3
[Tr
q
Tpr_Lim2]
P
a
r 754 [Tr
q
Tpr_Lim
3
]
P
a
r 755 [Tr
q
Tpr_Lim4]
P
a
r 756 [Tr
q
Tpr_
S
pd]
