YASKAWA F7 Programming Manual page 55

Torque Limit Operation Examples
Operation examples will be described separately for winding operation, in which the speed and motor torque are in the same
directions, and rewinding operation, in the which the speed and motor torque are in opposite directions.
Winding Operation
In a winding operation, the line (speed) and torque generated by the motor are in the same direction. For the winding operation, both
the speed limit and the torque reference input are positive. The motor will accelerate when the torque reference input is larger than the
load and will decelerate when it is smaller than the load. If the motor turns faster than the speed limit, a negative compensation value is
output from the speed limiter circuit. When the speed then drops below the speed limit, a positive compensation value is output. The
torque compensation is proportional to the ASR proportional gain. When the sum of the torque reference and the torque compensation
output by the speed limiter is the same as the actual load, the motor will stop accelerating and run at a constant speed.
Rewinding Operation
In a rewinding operation, the line (speed) and torque generated by the motor are in the opposite directions. (In this example, it
is assumed that the line speed is positive and the torque reference input is negative.) For the rewinding operation, the speed
limit is positive and the torque reference input is negative. If the motor turns faster than the speed limit, a negative
compensation value is output. If the speed is zero or is below the speed limit, a zero compensation value is output. In this way,
the output from the speed limiter is used to maintain the motor speed between zero and the speed limit. When the sum of the
torque reference and the torque compensation output by the speed limiter is the same as the actual load, the motor will stop
accelerating and run at a constant speed.
Configuration
Direction of Motor Rotation
Torque Reference (TREF)
Reference
Polarity
Speed Limit (NLIM)
Torque Profile
Table 7 Torque Control Example
Winding Operation
Line Direction
M
Forward
+
+
Torque
Torque Torque
DeltaN
Limit Limit
TREF
NLIM
0
Speed
NLIM
d5-05
TREF
Torque
DeltaN
Limit
DeltaN(%)=TREF(%)/C5-01 DeltaN(%)=TREF(%)/C5-01
Programming 47
N T
T
N
Motor
Reverse Forward
- -
- +
Torque Torque
Torque
Limit
d5-05
d5-05
0
0
Speed
TREF
DeltaN
Smaller of
DeltaN(%)=TREF(%)/C5-01
=TREF(%)/d5-05(%)
Rewinding Operation
Line Direction
M
Motor
Reverse
+
-
Torque
Torque
Limit
TREF
NLIM
0
Speed Speed
DeltaN
d5-05
NLIM
Torque
Torque
Limit
Limit
Smaller of
DeltaN(%)=TREF(%)/C5-01
=TREF(%)/d5-05(%)