Advanced commissioning
6.13 Setpoint calculation
Converter with the control units CU240D-2
182
Operating Instructions, 04/2018, FW V4.9 SP10, A5E34262100B AF
6.13.6
Ramp-function generator
The ramp-function generator in the setpoint channel limits the rate change of the speed
setpoint (acceleration). A reduced acceleration reduces the accelerating torque of the motor.
In this case, the motor reduces the load on the mechanical system of the driven machine.
You can select between two different ramp-function generator types:
●
Extended ramp-function generator
The expanded ramp-function generator limits not only the acceleration but also the
change in acceleration (jerk) by rounding the setpoint. In this case, the torque does not
rise suddenly in the motor.
●
Basic ramp-function generator
The basic ramp-function generator limits the acceleration, however not the rate the
acceleration changes (jerk).
If you use a 1FK7 encoderless synchronous motor, we recommend using an extended ramp-
function generator with an initial rounding of at least 0.1 s.
Extended ramp-function generator
The ramp-up and ramp-down times of the extended ramp-function generator can be set
independently of each other. The optimum times that you select depend on your particular
application in question and can range from just a few 100 ms (e.g. for belt conveyor drives)
to several minutes (e.g. for centrifuges).
Initial and final rounding permit smooth, jerk-free acceleration and braking.
The ramp-up and ramp-down times of the motor are increased by the rounding times:
●
Effective ramp-up time = p1120 + 0.5 × (p1130 + p1131).
●
Effective ramp-down time = p1121 + 0.5 × (p1130 + p1131).
