Function Applications
-490-
Figure 4-43 Torque control system diagram
1. Selecting speed/torque control mode (A0-00)
The speed or torque control mode is defined by A0-00.
The AC drive has two digital input functions related to torque control: "torque control disable"
(function 35) and "switchover between speed control and torque control" (function 36). The two DI
terminals work with A0-00 to implement switchover between speed control and torque control.
When the terminal assigned with function 36 (switchover between speed control and torque control)
is inactive, the control mode is determined by A0-00; when it is active, the control mode is reverse to
A0-00.
When the terminal assigned with function 35 (torque control disable) is active, the AC drive always
runs in speed control mode.
2. Setting torque reference in torque control (A0-01, A0-03)
A0-01 defines the torque reference source. There are a total of eight torque reference sources
available.
The torque reference is a relative value. 100.0% corresponds to the rated motor torque. (The output
torque of the motor can be viewed by using U0-06, where the value 100% corresponds to the rated
torque of the motor.) The value range is –200.0% to +200.0%, indicating that the maximum torque of
the AC drive is twice the rated torque of the motor.
3. Setting the frequency upper limit in torque control (A0-05, A0-09, A0-10, A0-11)
In torque control mode, the frequency upper limit can be set by A0-05 or the frequency source and
switched by A0-09.
4. Setting the acceleration/deceleration time for the frequency upper limit in A0-12 (acceleration
time)/A0-13 (deceleration time)
In torque control mode, if the load torque is smaller than the output torque of the motor, the motor
speed keeps rising. Therefore, to prevent accidents such as runaway in the mechanical system, the
motor speed must be controlled within a proper range. That is, the frequency upper limit must be
set in torque control mode.
5. Setting torque acceleration/deceleration time in torque control (A0-07, A0-08)
In torque control mode, the difference between the output torque of the motor and the torque of the
load determines the speed change rate of the motor and load. The motor speed may change quickly,
To Next Page
Loading...
