Hitachi WJ Series User Manual page 252

Chapter 9
■ Instantaneous power failure non-stop function, mode selection,
"Voltage controlled deceleration-stop " ([b050] = 02, 03)
 When an instantaneous power failure or undervoltage error occurs during operation and the P-N
voltage falls to or below [b051], the inverter automatically decelerates the motor while
maintaining the P-N voltage at the "Instantaneous power failure non-stop function, target
voltage level [b052]".
 When the duration of the instantaneous power failure is short, the operation is able to continue
without shutting off the output. However, when an instantaneous power failure also causes an
undervoltage error, the output is immediately shut off, ending the operation of this function.
After the instantaneous power failure and operation resumption, the "Restart mode selection
after instantaneous power failure/undervoltage error [b001]" determines the subsequent
operation. For details, refer to "9.9.6 Restarting after Instantaneous Power Failure/
Undervoltage".
 When [b050] is set to "Voltage controlled deceleration-stop (with recovery) (03)", if the power is
restored before the output is shut off, normal operation can be resumed. However, depending
on the setting of [b052], the inverter may decelerate the motor to stop. Details are as follows:
[b050]
02
(Voltage controlled deceleration-
stop (without recovery))
03
(Voltage controlled deceleration-
stop (with recovery))
■ (Example 1) [b052] is greater than the P-N
voltage when the power is received/restored
P-N voltage (VDC)
[b052]
Vre
[b051]
Under constant DC
voltage control
Output frequency (Hz)
[b050] = 02, 03
(deceleration stop)
(Note) Depending on the proportional gain ([b133]) or integral gain ([b134]) setting of the constant DC voltage
control, the P-N voltage may be lower than that of [b052].
 the difference between "Instantaneous power failure non-stop function, start voltage level
If
!
[b051]" and "Instantaneous power failure non-stop function, target voltage level [b052]" is great,
when the value specified for "Constant DC voltage control P gain [b133]" is too large, it may
quickly accelerate immediately after this function starts, resulting in an overcurrent error.
 Use "Constant DC bus voltage control P gain [b133]" and "Constant DC bus voltage control I
gain [b134]" to adjust this function. Setting a larger proportional gain ([b133]) or a shorter
integral gain ([b134]) speeds up the response but make it more likely to trip. Setting a smaller
proportional gain ([b133]) on the other hand, an undervoltage error may occur due to a voltage
drop immediately after this function starts.
[b052]
[b052] > Vre (P-N voltage when the power
is received/restored)
[b052] < Vre (P-N voltage when the power
is received/restored)
[b052] > Vre (P-N voltage when the power
is received/restored)
[b052] < Vre (P-N voltage when the power
is received/restored)
Vre (P-N voltage when the
power is received/restored)
Time
Time
Power is received/restored
9-9-19
Deceleration stop (constant DC voltage control)
(Example 1)
Deceleration stop (normal operation)
(Example 2)
Deceleration stop (constant DC voltage control)
(Example 1)
Operation (normal operation)
(Example 2)
■ (Example 2) [b052] is smaller than the P-N
voltage when the power is received/restored
Vre (P-N voltage when the
P-N voltage (Vdc)
power is received/restored)
Vre
[b052]
[b051]
Under constant DC
voltage control
Output frequency (Hz)
Inverter Functions
Operation
Time
[b050] =
"Operation
resumed (03)"
[b050] =
"Operation not
resumed (02)"
Time
Power is received/restored