Mitsubishi Electric FR-A820-00046 Instruction Manual page 421

Parameters
S-pattern acceleration/deceleration A (Pr. 29 = "1")
● Use this when acceleration/deceleration is required for a short time until a high-speed area equal
to or higher than the base frequency, such as for the main shaft of the machine.
● The acceleration/deceleration pattern has the Pr. 3 "Base frequency" (Pr. 84 "Rated motor frequen-
cy" under PM sensorless vector control) (fb) as the point of inflection in an S-pattern curve, and
the acceleration/deceleration time can be set to be suitable for the motor torque reduction in the
constant-power operation range at the base frequency (fb) or more.
● Acceleration/deceleration time calculation method when the set frequency is equal to or higher
than the base frequency
Acceleration time t = (4/9) × (T/fb²) × f² + (5/9) × T
T: acceleration/deceleration time (s)
f: set frequency (Hz)
fb: base frequency (rated motor frequency)
● Reference (0 Hz to set frequency) of acceleration/deceleration time when Pr. 3 = "60 Hz"
Tab. 5-95:
NOTE For the acceleration/deceleration time setting of the S-pattern acceleration/deceleration A, set the
time to Pr. 3 (Pr. 84 under PM sensorless vector control) instead of Pr. 20 "Acceleration/decelera-
tion reference frequency".
S-pattern acceleration/deceleration B (Pr. 29 = "2")
● This is useful for preventing collapsing stacks such as on a conveyor. S-pattern acceleration/
deceleration B can reduce the impact during acceleration/deceleration by accelerating/deceler-
ating while maintaining an S-pattern from the present frequency (f2) to the target frequency (f1).
FR-A800
(F) Setting of acceleration/deceleration time and acceleration/deceleration pattern
[S-pattern acceleration/
deceleration A]
fb
Time
Acceleration/deceleration time (s)
5
15
Acceleration/deceleration times when Pr. 3 = 60 Hz
[S-pattern acceleration/
deceleration B]
f1
f2
Time
Fig. 5-90:
Characteristic for parameter 29 = 1
Set frequency (Hz)
60 120
5 12
15 35
Fig. 5-91:
Characteristic for parameter 29 = 2
I002557E_B
200 400
27 102
82 305
I002558E_B
5 - 241