Suppressing Overvoltage By Controlling Output Frequency - Hitachi WJ Series User Manual

Chapter 9
9.9.3

Suppressing Overvoltage by Controlling Output Frequency

 How to avoid overvoltage errors that occur when the motor is decelerated?
Q
 How to avoid overvoltage errors caused by regenerative voltage during deceleration by
automatically extending the deceleration time?
 The overvoltage suppression function can prevent the occurrence of overvoltage error during
A
deceleration.
 This function is activated when the DC bus voltage between the [P] and [N] terminals of the
inverter main circuit (P-N voltage) exceeds the overvoltage suppression active level setting.
 This function makes the actual deceleration time longer than the set value.
!
 Depending on the moment of inertia of the load, it may take a long time to stop.
 Overvoltage trips may occur depending on the deceleration rate or load conditions.
 The overvoltage suppression active level should be set to be equal to or greater than the input
voltage × √2 × 1.1. If a value lower than the P-N voltage value during operation is set, the
motor may not be able to stop.
Code
Overvoltage
[b130]
suppression enable
Overvoltage
[b131]
suppression active level
Overvoltage
[b132]
suppression active time
Constant DC bus
[b133]
voltage control P gain
Constant DC bus
[b134]
voltage control I gain
■ For Constant DC bus voltage control ("Overvoltage suppression enable [b130]" = 01)
 Constant DC bus voltage control automatically decelerates the motor while performing PI
control so that the P-N voltage remains constant during deceleration.
 Setting a larger proportional gain ([b133]) and a shorter integral gain ([b134]) will speed up the
response but make it more likely to trip.
Item
Disable
Constant DC bus voltage control
(deceleration stop)
Enable acceleration
(during deceleration only)
Sets the operation level of the
overvoltage suppression function.
Acceleration time when the
overvoltage suppression function is
in operation.
Proportional gain for PI control of
constant DC bus voltage control.
Integral gain for PI control of
constant DC bus voltage control.
P-N voltage (VDC)
Overvoltage
suppression active
level [b131]
Output frequency (Hz)
Deceleration starts
Deceleration time specified
at [F003]/[F203]
Description
Constant DC bus
voltage control
Actual deceleration time
9-9-4
Inverter Functions
Data
00
01
02
200V class: 330 to 400 (VDC)
400V class: 660 to 800 (VDC)
0.10 to 30.00 (s)
0.00 to 5.00
0.0 to 150.0 (s)
Time
Time