212
Special operation and speed control
(3) Regeneration avoidance function adjustment (Pr. 665, Pr. 886)
If the speed becomes instable during regeneration avoidance operation, decrease the setting of Pr. 886 Regeneration
avoidance voltage gain. Reversely, if sudden regeneration causes an overvoltage alarm, increase the setting.
When vibration is not suppressed by decreasing the Pr. 886 setting, set a smaller value in Pr. 665 Regeneration avoidance
speed gain.
REMARKS
The acceleration/deceleration ramp while the regeneration avoidance function is operating changes depending on the
regeneration load.
DC bus voltage of the drive unit is usually about of the normal input voltage. (A little higher or lower depending on the input
power supply waveform.) The bus voltage is about 311VDC when the input voltage is 220VAC.
The Pr. 883 setting should be kept higher than the DC bus voltage level. Otherwise, the regeneration avoidance function is
always ON even in the non-regeneration status and the speed increases.
While overvoltage stall ( ) is activated only during deceleration and stops the rotation speed, the regeneration avoidance
function is always ON (Pr. 882 = “1”) or activated only during a constant speed (Pr. 882 = “2”) and increases the speed according
to the regeneration amount.
(2) Limit regeneration avoidance operation speed (Pr. 885)
You can limit the rotation speed compensated (increased) by the
regeneration avoidance function.
The speed is limited to the rotation speed (speed prior to regeneration
avoidance operation) + Pr. 885 Regeneration avoidance compensation speed
limit value during acceleration or constant speed.
If the regeneration avoidance speed exceeds the limit value during
deceleration, the limit value is held until the rotation speed falls to 1/2 of
Pr. 885.
When the speed increased by regeneration avoidance function has
reached Pr. 1 Maximum setting, it is limited to the maximum speed.
When Pr. 885 is set to "9999", regeneration avoidance function operation
speed setting is invalid.
NOTE
The regeneration avoidance function does not operate in the low-speed range (225r/min or lower).
When regeneration avoidance operation is performed, (overvoltage stall) is displayed and the OL signal is
output. Set the operation pattern at an OL signal output using Pr. 156 Stall prevention operation selection. Set the output
timing of the OL signal using Pr. 157 OL signal output timer.
When regeneration avoidance operation is performed, stall prevention is also activated at the same time.
The regeneration avoidance function cannot shorten the actual deceleration time taken to stop the motor. The actual
deceleration time depends on the regeneration energy consumption capability. To shorten the deceleration time,
consider using the regeneration unit (FR-BU2, FR-CV, FR-HC) and brake resistor (MRS type, MYS type, FR-ABR etc.)
to consume regeneration energy at a constant speed.
When using the regeneration unit (FR-BU2, FR-CV, FR-HC) and brake resistor (MRS type, MYS type, FR-ABR etc.), set
Pr. 882 to "0 (initial value)" (regeneration avoidance function invalid). When using the regeneration unit, etc. to
consume regeneration energy at deceleration, set Pr. 882 to "2" (regeneration avoidance function valid only at a
constant speed).
Parameters referred to
Pr. 1 Maximum setting Refer to page 78
Pr. 8 Deceleration time
Refer to page 87
Pr. 22 Stall prevention operation level Refer to page 74
2
Limit level
Time
Pr. 885
Rotation speed (r/min)
Rotation speed (r/min)
Pr. 885/2
