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4.7 Encoder Feedback Control
Make sure that Pr. 80 "motor capacity", Pr. 81 "number of motor poles", Pr. 144 "speed setting change",
Pr. 359 "encoder rotation direction", Pr. 369 "number of encoder pulses" and Pr. 370 "control mode" values
are set properly. (Refer to page 39, 40.)
(1) Pr. 367 "speed feedback range". (factory setting: 9999)
This parameter is used to make the encoder feedback function valid.
Set the speed feedback control range.
(When Pr. 367 = 9999 (factory setting), the encoder feedback function is invalid.)
<Setting>
Define the upper and lower limits in reference to the set value (frequency at which the motor is to be
rotated at constant speed). Normally, set the frequency converted from the rated motor speed (rated
load) and slip (r/min). Too large setting will result in slow response.
Example: Rated speed of a 4-pole motor is 1740r/min (60Hz)
Slip Nsp = synchronous speed - rated speed
= 1800 - 1740 = 60 (r/min)
Frequency equivalent to slip (fsp)
fsp =
Speed feedback range
Set value
(Set command)
(2) Pr. 368 "feedback gain". (factory setting: 1)
This parameter is valid when encoder feedback control is valid. Set if rotation is instable or response is slow.
When the setting is greater than 1, response is faster but overcurrent or rotational instability is more
liable to occur. When the setting is less than 1, response is slower but rotation is more stable.
Nsp × number of poles
120
Driven load
ENCODER FEEDBACK CONTROL—A500(L)
60 × 4
=
= 2(Hz)
120
Regenerative load
41
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