Mitsubishi Electric FR-A700 Technical Manual page 208

(1) Optimum acceleration/deceleration mode
[Pr. 292 = 1, 11]
common
This function automatically
deceleration speed so as to achieve shortest time of
acceleration/deceleration with using stall prevention
function of the inverter.
Set [Pr. 292 Automatic acceleration/deceleration = 1] to use
Shortest acceleration/deceleration. Set [Pr. 292 = 11]
when using built-in brake resistor, high-duty brake
resistor and brake unit.
Note that when proper values are set in [Pr. 7 Acceleration
time] and [Pr. 8 Deceleration time], acceleration/
deceleration time may be shorter than selecting shortest
acceleration/deceleration mode.
1) Control method
Inverter regards that the shortest acceleration/
deceleration time (0s) is set, and accelerates/
decelerates with changing frequency with using stall
prevention operation. Since accelerating/decelerating
with using stall prevention function, acceleration/
deceleration speed varies depending on load
condition. (The setting values of [Pr. 7, 8] are not
changed)
Settings of [Pr. 7 Acceleration time], [Pr. 8 Deceleration
time], and [Pr. 22 Stall prevention operation level] are
ignored. When the stall prevention operation level in
[Pr. 61 to 63] are smaller than [Pr. 22], the setting of [Pr.
22] is valid. [Pr. 22] is valid when constant speed.
2) Applications
Appropriate application
• To make acceleration/deceleration in a shorter
time for a machine tool etc. but the design values
of machine constants are unknown.
• To exhibit the best performance of the inverter
and motor performance.
• To accelerate/decelerate in constant torque.
Inappropriate application
• Machine with a large inertia (more than 10 times)
such as a fan. Since current limit function will be
activated for a long time, this type of machine
may be brought to a fault due to motor
overloading, etc.
• To perform operation always with a constant
acceleration/deceleration time.
controls acceleration/
242
3) Setting of dedicated parameters
By setting the dedicated
application range can be made wider.
In the initial setting, the current limit function is
activated at the 150% value of the rated inverter
current.
Adjustment with [Pr. 61 to 63] is unavailable under
real sensorless vector control and vector control.
Operating with [Pr. 22] limit.
Since the [Pr. 61 to 63] settings automatically
return to the initial value (9999) if the [Pr. 292]
setting is changed, set [Pr. 292] first when you
need to set [Pr. 61 to 63].
[Pr.61]: Set the current value (A) that is referenced
for stall prevention operation level. When
the motor and inverter are different in
capacity, for example, and it is desired to
define the motor rating as reference, set
the reference
parameter.
[Pr. 62]:Set the stall prevention operation level (%)
for acceleration. Set to change the limit for
acceleration/deceleration.
[Pr. 63]:Set the stall prevention operation level (%)
for deceleration. Set to change the limit for
acceleration/deceleration.
[Pr. 293]: Set to select the Shortest acceleration/
deceleration operation for only when
accelerating or decelerating.
PARAMETER
parameters, the
current value in this