Hitachi X200 Series - Manual (Page 92)

DC Braking (DB) Settings
Normal DC braking performance ⎯ The DC
braking feature can provide additional
stopping torque when compared to a normal
deceleration to a stop. DC braking is
particularly useful at low speeds when
normal deceleration torque is minimal. When
you enable DC braking, the inverter injects a
DC voltage into the motor windings during
deceleration below a frequency you can
specify (A052).
The braking power (A054) and duration (A055) can both be set. You can optionally
specify a wait time before DC braking (A053), during which the motor will free run.
DC Braking – Frequency Detection ⎯ All above operations are done when the RUN
command (FW signal) turns OFF. But you can even set DC braking during Run by
setting frequency detection at A051. In this case the DC brake operates when the output
frequency comes down to the one you specified (A052) even the Run command is active.
External DB and Internal DC are invalid during the frequency detection mode.
Example 1, above to the left shows the performance when giving the pulsing frequency
set point. In this case, when changing set point to 0, inverter immediately starts DB
because the set point becomes lower than the value specified in A052. And the DB
continues until the set point exceeds A052. And there will be no DC braking at next stop
because the FW is being OFF.
Example 2, above to the right shows the gradual change in frequency set point, for
example by analog input. In this case, there will be a DC braking period at start
because the frequency set point is lower than the value specified in A052.
Running DC brake Free run
+
0
-
t
A053 A055
FW
ON
F-SET
A052
DB
Ex.1) Step change in F-SET.
F-OUT
FW
ON
F-SET
A052
Ex.2) Analog change in F-SET.
F-OUT
DB DB DB
3−18
Confi
guri
ng Driv
e
Parameters