Electronic Gear Setting - Mitsubishi Electric FR-A820-00046 Instruction Manual

Parameters
5.5.7

Electronic gear setting

Set the gear ratio between the machine gear and motor gear.
Pr.
420
B001
421
B002
424
B005
Gear ratio calculation (Pr. 420, Pr. 421)
The position resolution (travel distance per pulse Δl [mm]) is the travel distance per motor rotation Δs
[mm] and the feedback pulse of the detector.
It is determined by Pf [pulse/rev] and represented with the following formula.
Δs
Δl =
Pf
Δl:
Δs:
Pf:
The travel distance in 1 command pulse can be separately specified with a parameter and so an in-
teger can be set as the travel distance in 1 command pulse.
Δs
Δl =
Pf
The following formula shows the relationship between the motor speed and internal command pulse
frequency.
Pr. 420
fo ×
Pr. 421
fo:
No:
NOTE Set the electronic gear ratio in the range of 1/50 to 20. Note that, if the setting value is too small,
the speed command will also be too small; while if it is too large, the speed ripple will be too large.
FR-A800
Position control under vector control and PM sensorless vector control
Vector Vector Vector
Name
Command pulse scaling
factor numerator
(electronic gear
numerator)
Command pulse
multiplication
denominator (electronic
gear denominator)
Position command
acceleration/deceleration
time constant
Travel distance per pulse [mm]
Travel distance in one motor rotation [mm]
Number of feedback pulses [pulse/rev] (the number of pulses after the number encoder
pulses is quadruplicated)
Pr. 420
×
Pr. 421
No
= Pf ×
60
Internal command pulse frequency [pps]
Motor rotation speed [r/min]
PM PM PM
Initial Setting
Description
value range
1 1 to 32767
Set the electronic gear.
Pr. 420 is the numerator and Pr. 421 is the
denominator.
1 1 to 32767
Use it when the rotation is not smooth because the
0 s 0 to 50 s electronic gear ratio is large (10 times or larger) and
the rotation speed is slow.
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