Mitsubishi Electric FR-F820-00046 Instruction Manual page 547

 Regeneration avoidance operation (Pr.882, Pr.883)
• When the regenerative voltage increases, the DC bus voltage will rise, which may cause an overvoltage fault (E.OV[]). The
regenerative status can be avoided by detecting this rise of bus voltage, and raising the frequency when the bus voltage
level exceeds Pr.883 Regeneration avoidance operation level.
• The regeneration avoidance operation can be selected to operate constantly or operate only during constant speed.
• The regeneration avoidance function is enabled by setting "1 or 2" in Pr.882 Regeneration avoidance operation
selection.
Regeneration avoidance operation
example for acceleration
Pr. 883
During regeneration
avoidance function operation
NOTE
• The slope of frequency rising or lowering by the regeneration avoidance operation will change depending on the regenerative
status.
• The DC bus voltage of the inverter will be approximately
The bus voltage is about 311 VDC (622 VDC) when the input voltage is 220 VAC (440 VAC).
However, it may vary depending on the input power supply waveform.
• Make sure that the setting value of Pr.883 will not get under DC bus voltage level. The frequency will rise with operation of the
regeneration avoidance function even during operation other than the regenerative operation.
• The stall prevention (overvoltage) (oL) will only operate during deceleration, stopping the lowering of output frequency, but on
the other hand, the regeneration avoidance function will constantly operate (Pr.882 = "1") or operate only at constant speed
(Pr.882 = "2"), and raise the frequency depending on the amount of regeneration.
• When the motor becomes unstable due to operation of the stall prevention (overcurrent) (OL) during the regeneration
avoidance operation, increase the deceleration time or lower the setting of Pr.883.
 Detecting the regenerative status faster during deceleration (Pr.884)
• Since a rapid change in bus voltage cannot be handled by bus voltage level detection during the regeneration avoidance
operation, deceleration is stopped by detecting the change in bus voltage and if it is equal to or lower than Pr.883
Regeneration avoidance operation level. Set the detectable bus voltage change rate as the detection sensitivity in
Pr.884 Regeneration avoidance at deceleration detection sensitivity. A larger set value increases the detection
sensitivity.
NOTE
• When the setting value is too small (detection sensitivity is not good), detection will not be possible, and regeneration
avoidance will operate even with the bus voltage change caused by a change in the input power.
 Limiting the regeneration avoidance operation frequency (Pr.885)
• It is possible to assign a limit to the output frequency corrected (rise) by the regeneration avoidance operation.
• Limit of the frequency is output frequency (frequency before regeneration avoidance operation) + Pr.885 Regeneration
avoidance compensation frequency limit value for during acceleration and constant speed. During deceleration, when
the frequency increases due to the regeneration avoidance operation and exceeds the limit value, the limit value will be
retained until the output frequency is reduced to be the half the Pr.885 setting.
• When the frequency that have increased by the regeneration avoidance operation exceeds Pr.1 Maximum frequency, it
will be limited to the maximum frequency.
• When Pr.885 = "9999", the regeneration avoidance compensation frequency limit is disabled.
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5. PARAMETERS
5.13 (G) Control parameters
Regeneration avoidance operation
example for constant speed
Pr. 883
Time
During regeneration
avoidance function operation
Time
Regeneration avoidance operation
example for deceleration
Pr. 883
Time
During regeneration
avoidance function operation
Time
times of the normal input voltage.
Time
Time