Position control under vector control and PM sensorless vector control
PARAMETERS
247
5
5.5.6 Electronic gear setting
Gear ratio calculation (Pr.420, Pr.421)
• The position resolution (travel distance per pulse [mm]) is the travel distance per motor rotation s [mm] and the
feedback pulse of the detector.
It is determined by Pf [pulse/rev] and represented with the following formula.
The travel distance in 1 command pulse can be separately specified with a parameter and so an integer can be set as the
travel distance in 1 command pulse.
The following formula shows the relationship between the motor speed and internal command pulse frequency.
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.
Set the gear ratio between the machine gear and motor gear.
Pr. Name Initial value Setting range Description
420
B001
Command pulse scaling factor
numerator (electronic gear
numerator)
1 1 to 32767
Set the electronic gear.
Pr.420 is the numerator and Pr.421 is the
denominator.
421
B002
Command pulse multiplication
denominator (electronic gear
denominator)
1 1 to 32767
424
B005
Position command
acceleration/deceleration time
constant
0 s 0 to 50 s
Use it when the rotation is not smooth because
the electronic gear ratio is large (10 times or
larger) and the rotation speed is slow.
: Travel distance per pulse [mm]
s: Travel distance in one motor rotation [mm]
pf: Number of feedback pulses [pulse/rev] (the number of pulses after the number encoder pulses is
quadruplicated)
=
s
Pf
=
s
Pr.420
Pf Pr.421
fo
Pr.420
=Pf
No. fo: internal command pulse frequency [pps]
No: motor rotation speed [r/min]
Pr.421 60
Vector
Vector
PM
PM
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