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Special operation and speed control
4
PARAMETERS
(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.
The DC bus voltage of the drive unit is about times as input voltage.
When the input voltage is 220VAC, bus voltage is approximately 311VDC.
However, it varies with the input power supply waveform.
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 for (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 speed increased by regeneration avoidance function 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
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 Torque limit selection. Set the output timing of the
OL signal using Pr.157 OL signal output timer.
When regeneration avoidance operation is performed, torque limit is also activated.
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. When shortening the deceleration
time, consider using the regeneration unit (FR-BU2, FR-CV, FR-HC2) and brake resistor (MRS type and FRABR etc.,)
to consume regeneration energy at constant speed.
When using the regeneration unit (FR-BU2, FR-CV, FR-HC2) and brake resistor (MRS type and 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).
Under position control, regeneration avoidance function is disabled.
Parameters referred to
Pr.1 Maximum setting Refer to page 115
Pr.8 Deceleration time Refer to page 125
Pr.22 Torque limit level Refer to page 111
2
Limit level
Time
Pr.885
Rotation peed (r/min)
Pr.885/2
Rotation speed (r/min)