6-144
Zero-servo Function (SPEC: E or Later Only)
The zero-servo function holds the motor when the motor is stopped in what is call a zero-servo status. This
function can be used to stop the motor even with an external force acts on the motor or the analog reference
input is offset.
The zero-servo function is enabled when one of the multi-function inputs (H1-01 to H1-06) is set to 72 (zero-
servo command). If the zero-servo command is ON when the frequency (speed) reference falls below the zero-
speed level, a zero-servo status is implemented.
Related Constants
Con-
stant
Number
Name Description
Setting
Range
Factory
Setting
Change
during
Opera-
tion
Control Methods
MEMO
BUS
Regis-
ter
V/f
V/f
with
PG
Open
Loop
Vec-
tor
Flux
Vec-
tor
b2-01
Zero-speed
level (DC
injection
braking start-
ing fre-
quency)
Used to set the frequency which
starts DC injection braking in
units of Hz when deceleration to
stop is selected.
When b2-01 is less than E1-09,
E1-09 is used to set the starting
frequency for the DC injection
braking.
In flux vector control, b2-01 is
used to set the starting frequency
for the zero-speed control.
0.0 to
10.0
0.5 Hz No A A A A 189H
b9-01
Zero-servo
gain
Adjust the strength of the zero-
servo lock.
Enabled when the “zero-servo
command” is set for the multi-
function input. When the zero-
servo command has been input
and the frequency reference
drop below excitation level (b2-
01), a position control loop is
created and the motor stops.
Increasing the zero-servo gain in
turn increases the strength of the
lock. Increasing it by too much
will cause oscillation.
0 to 100 5 No No No No A 1DAH
b9-02
Zero-servo
completion
width
Sets the output width of the
zero-servo completion signal.
Enabled when the “zero-servo
completion (end)” is set for a
multi-function input. The zero-
servo completion signal is ON
when the current position is
within the range (the zero-servo
start position± zero-servo com-
pletion width.)
Set the allowable position dis-
placement from the zero-servo
start position to 4 times the pulse
rate of the PG (pulse generator,
encoder) in use.
0 to
16383
10 No No No No A 1DBH
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