Function Application
‑585‑
3. Setting the frequency upper limit in torque control (A0‑05, A0‑09, A0‑10, and A0‑11)
In torque control mode, the frequency upper limit can be set through A0‑05 or the
frequency source, depending on the value of A0‑09.
4. Setting the frequency upper limit acceleration time (A0‑12) and deceleration time
(A0‑13)
In torque control mode, if the load torque is lower than the motor output torque,
the motor speed keeps increasing. To prevent runaway or other incidents of the
mechanical system, limit the maximum motor speed in torque control mode. That
is, set the frequency upper limit in torque control.
5. Setting the torque acceleration/deceleration time (A0‑07, A0‑08)
In torque control, the difference between the motor output torque and the load
torque determines the speed change rate of the motor and load. Therefore, the
motor rotational speed may change sharply, resulting in noise or excessive
mechanical stress. Setting an appropriate torque acceleration/deceleration time
can ensure stable change of the motor rotational speed. The torque acceleration
time is the time required for the output torque to increase from 0 to A0‑03, and the
torque deceleration time is the time required for the output torque to decrease
from A0‑03 to 0.
For torque control with low startup torque, do not set the torque acceleration/
deceleration time. In a scenario requiring fast torque change, set the torque
acceleration/deceleration time to 0.00s.
For example, assume that one load is driven by two motors. To balance the load of
the two motors, set one drive as the master in speed control and set the other one
as the slave in torque control. The slave will follow the output torque of the master
as its torque reference, which requires quick response to the master output torque.
In this case, set acceleration/deceleration time of the slave in torque control to
0.00s.
Table 3–25 Speed limit/Speed limit offset
Item
Operating Condition
Command Forward Forward Forward Forward
Torque
reference
direction
+ ‑ ‑ +
Speed limit
direction
+ ‑ + ‑
Normal
operation
direction
Forward
Reverse
Forward
Reverse
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