Hiwin D1 - Page 34

Operation Principles D1 Servo Drive User Manual
3-10 HIWIN MIKROSYSTEM CORP.
MD20UE01-2109
B. If
)(

jG
intersects with the negative real axis between 0 and -1,
10  )(
p
jG

and
dBGM 0
. When the Nyquist plot intersects with the negative real axis between 0 and -1 at
any frequency, the system is stable as loop gain increases.
C. If
)(

jG
is on (-1, j0),
1=)(
p
jG

and
dBGM 0=
. When
)(

jG
is on (-1, j0). It means
dBGM =
and the system has reached the boundary of instability. Loop gain must not be
increased anymore.
D. If
)(
 jG
passes (-1, j0),
1)(
p
jG

and
dBGM 0
. When
)(
 jG
passes (-1, j0),
dBGM 0
. Loop gain must be decreased to have stable system.
Figure3.6.1.1 Gain margin
)
(
p
j
G

0
p

=
G
Re
G
j
Im
(
)
Plane
j
G
−

Phase crossover

0

