7.1
Open-loop Vector Control
- 3
7.1.1 Torque Limit Function
With open-loop vector control, torque limits can be applied at an arbitrary value because the torque output
by the motor is calculated internally.
The torque limit function is useful when the load cannot sustain a torque above a certain level or to maintain
the regenerative torque above a certain level. The two ways to apply torque limits are listed below. (The
lower torque limit will be used if both of these methods are set.)
D
Setting a torque limit with the constants
D
Limiting torque with the analog inputs
The accuracy of the torque limit is
r
5% for output frequencies above 10 Hz, but the accuracy is lower for
output frequencies below 10 Hz. Use flux vector control if you want to apply a torque limit at low-speed (be-
low 10 Hz).
J
Torque Limits: L7-01 through L7-04
Torque limits can be set separately for the 4 ways that torque can be applied: forward torque, reverse torque,
forward regenerative torque, and reverse regenerative torque.
User
Change
during
Setting
Factory
Valid Access Levels
User
Constant
Number
Name
during
Opera-
tion
Setting
Range
Unit
Factory
Setting
Open Loop
Vector
Flux Vector
L7-01
Forward torque limit
0 to 300
%
200
B
B
L7-02
Reverse torque limit
0 to 300
%
200
B
B
L7-03
Forward regenerative
torque limit
0 to 300
%
200
B
B
L7-04
Reverse regenerative
torque limit
0 to 300
%
200
B
B
Figure 7.1 shows the relationship between each constant and the output torque.
When the torque limit function is used, the torque limits have priority and motor speed control and com-
pensation will be disregarded, so the acceleration/deceleration times might be lengthened and motor speed
might be reduced.
L7-04
L7-01
L7-02
L7-03
Output torque
Forward direction
Reverse direction
Motor speed
Reverse
Forward
Regenerative
torque
Regenerative
torque
Fig
7.1
Torque Limit Function
7
IMPORTANT
