Setting Of The Electronic Gear (Pr. 420, Pr. 421, Pr. 424) - Mitsubishi Electric FR-A700 Instruction Manual

Parameter
6.5.4

Setting of the electronic gear (Pr. 420, Pr. 421, Pr. 424)

Set the ratio of the machine side gear and the motor side gear.
Pr.
Name
No.
Command pulse scal-
420
ing factor numerator
Command pulse scal-
421
ing factor denominator
Position command
424
acceleration/decelera-
tion time constant
The above parameters can be set when the FR-A7AP (option) is mounted.
When the operation panel (FR-DU07) is used, the maximum setting is 9999. When a
parameter unit is used, up to the maximum value within the setting range can be set.
Calculation of the gear ratio (Pr. 420, Pr. 421)
The position resolution (travel per pulse
Δ
s [mm] and the feedback pulses Pf [pulse/rev] of the detector, and is represented by the fol-
lowing expression.
Δs
Δl
=
------ -
Pf
Δ
l:travel per pulse [mm]
Δ
s:travel per motor rotation [mm]
Pf:number of feedback pulses [pulse/rev] (number of pulses after multipling the
number of encoder pulses by four)
Using the parameters, the travel per command pulse can be set separately to set the travel per
command pulse without a fraction.
Δs
Δl
------ -
=
Pf
In addition, the relationship between the motor speed and internal command pulse frequency is
as follows:
Pr. 420
×
------------------ -
fo
Pr. 421
fo
:Internal command pulse frequency [pps]
No
:Motor speed [r/min]
NOTE
Set the electronic gear in the range of 1/50 to 20. Note that too small a value will decrease
the speed command and too large a value will increase the speed ripples.
FR-A700 EC
Initial
Setting Range
Value
1
0–32767
1
0–32767
0s 0–50 s
Pr. 420
×
------------------ -
Pr. 421
No
×
------ -
= Pf
60
Description
Set the electric gear.
Pr. 420 is a numerator and Pr. 421
is a denominator.
Used when rotation has become
unsmooth at a large electronic gear
ratio (about 10 times or more) and
low speed.
Δ
l [mm]) is determined by the travel per motor revolution
Position control by vector control
Vector Vector Vector
Parameters referred to
422 Position loop gain
Refer to
Section
6.5.6
6 - 137