6 Interfaces 6.1 Binary inputs
6.6 Ramp-function generator (RFG) and limiting stage in front of the ramp-function generator
A detailed description as supplement to the „Function diagrams, setpoint channel CU“, Chapter 10
6.6.1 Ramp-function generator, RFG
SDS 2, 3, 4
T ram p-u p fsys. rated
OFF2 OFF1without rounding off
foff T d e la y T d e la y t3 t1 t [s] without rounding-off OFF1 with rounding off f [Hz] with rounding-off F in a l rounding-off Initial rounding of F in a l rounding-off Initial rounding-off OFF3 1
Ramp down time for an OFF1 command: t = T f - f
f + T
1 OFF1-ramp down set off
Anl-rated
delay
×
Ramp down time for an OFF3 command: t = T f - f
f + T
3 OFF3-ramp down set off
Anl-rated
delay
×
Fig. 6.10 Ramp-function generator
For a detailed description of the OFF1-, OFF2- and OFF3 commands, refer to Section 5.1.2 „Control word 1“
Parameters for setting the acceleration time
P420 Rated system frequency (frated system) 1.00 Hz to 600.00 Hz
P462 Acceleration time (Tacceleration) i001: SDS1 to i004: SDS4 0.0 to 999.9 (Units: + P463) Acceleration time from standstill up to rated system frequency, (P420)
P463 Units, acceleration time i001: SDS1
to i004: SDS4
0: seconds 1: minutes 2: hours
P464 Deceleration time (Tdecelerate) i001: SDS1 to i004: SDS4 0.0 to 999.9 (Units: + P465) Deceleration time from the rated system frequency (P420) down to standstill
P465 Units, deceleration time i001: SDS1
to i004: SDS4
0: seconds 1: minutes 2: hours Time units for the acceleration time (P464)
P466 OFF3 deceleration time (TOFF3 deceleration) 0.0 s to 999.9 s
Deceleration time for an OFF3 command (if DC braking, P372 is not selected) in s from the rated system frequency (P420) down to standstill.
Rounding-off (P469 and P470) is de-activated.
P467 Protective ramp-up Kp i001: SDS1
to i004: SDS4
1.0 to 100.0
♦ Closed-loop V/f control (P163 = 0, 1, 2)
Factor from 1.0 to 100.0 referred to the acceleration time, P462, to enter a protective ramp-up time.
This is only effective, if seconds are selected as the ramp-up time units: P463 = 0
Using the protective ramp-up, the acceleration time up to 15% of the rated motor frequency (P107) can be extended (+ Fig. 6.11 „Protective ramp-up“)
Protective ramp-up is not activated for 1.0.
The total acceleration time can be calculated according to:
(
)
total run - up P462 P462 x 15 100 x P107 P420x P467 1 = + − T 1 5 % P 1 0 7 P420 P107 f [Hz] t [s] T a cce l. 15 % P107 P467 = 2 P462 2 T 1 5 % P 1 07 (P 46 7 = 2 )Fig. 6.11 Protective ramp-up
♦ Closed-loop frequency control (P163 = 3)
The protective ramp-function generator is effective up to 110% of the changeover frequency to the EMF model (P284). Ramp-up is also influenced by the current input (P202, P203 and P204) if the EMF model is inactive (P284 = 0).
♦ Closed-loop speed/torque control (P163 = 4. 5) The protective ramp-function generator is ineffective
P469 Initial rounding-off i001: SDS1
to i004: SDS4
0 % to 50 %
Initial rounding-off in % referred to the acceleration time, P462, when accelerating or the deceleration time, P464, when decelerating.
When accelerating, this is only effective, if seconds are selected for the acceleration time units: P463 = 0 When decelerating, this is only effective, if seconds are selected for the deceleration time units: P465 = 0
♦ Example:Acceleration time P462 = 10 s, rounding-off = 10 %. Thus, the acceleration time is extended by 1 s.
When accelerating from standstill up to the rated system frequency (P420), the effective acceleration time is increased to: P462 x ( 1+ P469/100 % + P470/100 % )
P470 Final rounding-off i001: SDS1 to i004: SDS4
0 % to 50 %
Final rounding-off in % referred to the acceleration time, P462, when accelerating, or the deceleration time, P464, when decelerating.
When accelerating, this is only effective, if seconds are selected for the acceleration time units: P463 = 0 When decelerating, this is only effective, if seconds are selected for the deceleration time units: P465 = 0
♦ Example:Acceleration time P462 = 10 s, rounding-off = 10 %. Thus, the acceleration time is extended by 1 s.
When accelerating from standstill up to the rated system frequency (P420), the effective acceleration time is increased to: P462 x ( 1+ P469/100 % + P470/100 % )
The same is valid for the deceleration time.
♦ If the motorized potentiometer is active (control word bits 13 and 14 set; + Section 5.1), there is no rounding-off
P475 RFG tracking 0.0 % to 50.0 %
Only effective, if P163 (open-/closed-loop control type) = 4 (closed-loop speed control)
For setpoint changes, and when the torque limits are reached (r235 „Mmax n/f control or r236 „Mmin n/f control“), the actual control error is sensed at the speed controller input (r224) (known here as: r224(limit)). If this value falls below r224 = r224(limit) + P475 x r224(limit), the ramp-function generator tracking is activated.
This means: The ramp-function generator output frequency is increased so fast, that the drive operates at the torque limit (the control error at the speed controller input (r224) is kept constant).
Thus, it is ensured that the ramp-function generator output frequency does not drift when the torque limits are reached, so that it can respond faster when the converter is powered-down or when setpoint changes are made.
Final rounding-off (P470) is not realized if the ramp-function generator tracking is activated. The ramp-function generator tracking is not activated for 0.0%.
P514 OFF shutdown frequency (foff) 0.00 Hz to 600.0 Hz
As soon as the „speed/frequency actual value“ r218 reaches the OFF shutdown frequency, P14 when the drive decelerates (OFF1 or OFF3 without DC braking, P372), then the OFF delay time P516, starts to run. After this, the inverter pulses are inhibited.
P516 OFF delay time (Tdelay) i001: SDS1
to i004: SDS4
0.0 s to 60.0 s
Delay time for OFF1 and OFF3 (if no DC braking, P372 is selected for OFF3) in s.
As soon as the „speed/frequency actual value“ (r218) reaches the OFF shutdown frequency (P514) when the drive decelerates, the OFF delay time starts to run. The inverter pulses are then inhibited.
6.6.2 Limit value stage in front of the ramp-function generator r45 1 RESV BASIC 1 0 0 P564.x S.setpoint enable Su m pt. 1 Setpoint enablei SDS / MDS 1 2,3,4 r460 R F G in pu t P455 , suppress. frequency P457 0 Hz - P457 min. frequency - P455 , suppress. frequency Suppression P456 P456 Suppression band band P 452, m a x. frq . (R D F ) P 453, m ax. frq. (L D F )
Fig. 6.12 Limit value stage before the ramp-function generator
P452 Max. frequency (RDF) Clockwise phase sequence
i001: MDS1
to i004: MDS4
0.0 Hz to 600.0 Hz
Max. setpoint frequency for a clockwise phase sequence
P453 Max. frequency (LDF) Counter-clockwise phase sequence i001: MDS1 to i004: MDS4 −600.0 Hz to 0.0 Hz
Max. setpoint frequency for a counter-clockwise phase sequence
P455 Suppression frequency i001: SDS1
to i004: SDS4
0.0 Hz to 600.0 Hz
Frequency suppression of ± ½ x P456 (suppression bandwidth) on each side of the parameterized suppression frequency (is valid for positive and negative setpoints), in order to prevent steady-state drive operation at possible resonant frequencies.
♦ Steady-state operation in a parameterized suppression bandwidth (P456) is therefore not possible; the range can only be run-through.
♦ For a setpoint at summation point 1 in front of the ramp-function generator, r451, which lies within the suppression bandwidth, the setpoint, increasing from below is held at the lower limit, and the setpoint decreasing from above is held at the upper limit.
P457 Min. frequency i001: SDS1 to i004: SDS4
−600.0 Hz to 600.0 Hz
≤ max. frequency LDF/RDF It is possible to realize a 0 Hz frequency suppression using the minimum frequency.
♦ Steady-state operation in the range 0 Hz ± minimum frequency is therefore not possible; the range can only be run-through.
♦ After the drive has been switched-on, and for a setpoint at summation point 1 in front of the ramp-function genertor, r451, in the range from 0 Hz up to the positive minimum frequency, the positive minimum frequency is approached, and in the range 0 Hz up to the negative minimum frequency, the negative minimum frequency.
♦ In operation, and for a setpoint at summation point 1 in front of the ramp-function generator, r451, in the suppression bandwidth (0 Hz ± minimum frequency), the setpoint increasing from below is held at the lower limit, and the setpoint decreasing from above, is held at the upper limit.
♦ The drive can be reversed by entering a reference frequency at summation point 1, which is outside the frequency suppression range.
A negative minimum frequency is only effective for closed-loop torque control and a selected slave drive (+ Chapter 10 „Function diagrams“)