UNIFREM v.3.41x
10 May 2017
Page 131 from 180
This is applicable to drives, where you need to minimize jerk and torque shocks during Start or
Stop (e.g. passenger elevators, electric vehicles, etc.)
S-curve operation mode can be configured and modified using the parameter:
Parameter ID: 874
SETTINGS
–
> CONTROL AND REGULATION
–
> FREQUENCY RAMPS
–
> S-CURVE
–
>
S-curve mode
Enabling of the S-curve
enabling S-curves
S-krivka ramp-up +
ramp curve for positive ramp-up
S-curve ramp-down +
ramp curve for positive ramp-down
S-curve ramp-up -
ramp curve for negative ramp-up
S-curve ramp-down -
ramp curve for negative ramp-down
S splitting
zero crossing
Curve rate of the S-curve and its shape can be configured by using the parameter:
Parameter ID: 873
SETTINGS
–
> CONTROL AND REGULATION
–
> FREQUENCY RAMPS
–
> S-CURVE
–
>S-curve
curvature
8.3.2 V/f curve
The main feature of the V/f control is that with increasing frequency of the output voltage,
value of this voltage on the converter output increases proportionally until maximal value
limit (saturation) is reached.
The condition of induction motor constant flux is achieved by
maintaining a constant ratio of
V
(voltage) /
f
(frequency).
100%
dF(t)
dt
F(t)
50%
10%
