Hitachi SJ Series User Manual page 207

Chapter 12
An actual example of setting up the acceleration or
deceleration time
Output
frequency
Maximum
frequency
[Hb105]/
[Hd105]
Actual
acceleration time
[FA-10]
!
• However short the acceleration or deceleration
time is set, the actual acceleration or deceleration
of the motor cannot be shorter than the minimum
acceleration or deceleration time that is determined
by the moment of inertia J of the mechanical
system and the motor torque. An act of
acceleration or deceleration in a shorter time than
the minimum acceleration or deceleration time may
cause an over current or over voltage trip to
happen.
Acceleration time t
t
S
Set frequency
Deceleration time t
t
B
Time
J
Actual
L
deceleration time
the motor shaft.
J
M
N
M
[FA-12]
T
s
the inverter.
T : Maximum deceleration torque (N·m) of the motor driven by the
B
inverter.
T : required operating torque (N·m)
L
12-8-2
Inverter Function
s
＋J
(J )×N
L M M
＝
9.55×(T -T )
S L
B
＋J
(J )×N
L M M
＝
9.55×(T +T )
B L
2
: Moment of inertia J (kg·m ) of the load converted into that of
2
: Moment of inertia J (kg·m ) of the motor.
: Revolution speed of the motor (r/min)
: Maximum acceleration torque (N·m) of the motor driven by