Increased Magnetic Excitation Deceleration - Mitsubishi Electric FR-CS84-012 Instruction Manual

• Make sure that the setting value of Pr.883 is not below the 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) (OLV) is activated only during deceleration to prevent a decrease in output frequency. The
regeneration avoidance function constantly operates (Pr.882 = "1") or operates only at constant speed (Pr.882 = "2"), and raise
the frequency in accordance with the amount of regeneration.
• When the motor becomes unstable due to operation of the stall prevention (overcurrent) (OLC) during the regeneration
avoidance operation, increase the deceleration time or lower the setting of Pr.883.
 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) +
avoidance compensation frequency limit value
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 half the
• When the frequency that have increased by the regeneration avoidance operation exceeds
be limited to the maximum frequency.
• When = "9999", the regeneration avoidance compensation frequency limit is disabled.
Pr.885
• Set the frequency around the motor rated slip frequency. Increase the setting value if the overvoltage protection function
(E.OV[]) is activated at the start of deceleration.
Rated motor slip frequency =
Output
frequency(Hz)
 Adjusting the regeneration avoidance operation (Pr.665, Pr.886)
• If the frequency becomes unstable during regeneration avoidance operation, decrease the setting of
avoidance voltage gain
• If setting a smaller value in
.
frequency gain
NOTE
• During the regeneration avoidance operation, the stall prevention (overvoltage) "OLV" is displayed and the Overload warning
(OL) signal is output. Set the operation pattern at an OL signal output using Pr.156 Stall prevention operation level. Set the
output timing of the OL signal using Pr.157 OL signal output timer.
• The stall prevention is enabled even during regeneration avoidance operation.
• The regeneration avoidance function cannot decrease the actual deceleration time for the motor to stop. Since the actual
deceleration time is determined by the regenerative power consumption performance, consider using a regeneration unit (FR-
BU2, FR-CV, FR-HC2) to decrease the deceleration time.
• When using a regeneration unit (FR-BU2, FR-CV, FR-HC2) to consume the regenerative power, set Pr.882 = "0 (initial value)"
to disable the regeneration avoidance function. When using a regeneration unit to consume the regenerative power at
deceleration, set Pr.882 = "2" to enable regeneration avoidance function only at the constant speed.
Parameters referred to
Pr.1 Maximum frequency
page 93
Pr.8 Deceleration time
Pr.22 Stall prevention operation level

5.12.8 Increased magnetic excitation deceleration

Increase the loss in the motor by increasing the magnetic flux during deceleration. The deceleration time can be reduced by
suppressing the stall prevention (overvoltage) (OLV).
200
5. PARAMETERS
5.12 (G) Control parameters
Synchronized speed at the time of base frequency – rated rotation speed
Synchronized speed at the time of base frequency
Limit level
Output frequency (Hz)
Pr.885
Pr.885/2
Time
. On the other hand, if an overvoltage fault occurs due to a sudden regeneration, increase the setting.
does not suppress the vibration, set a smaller value in
Pr.886
page 117
page 119
for during acceleration and constant speed. During deceleration, when the
setting.
Pr.885
Pr.885 Regeneration
, it will
Pr.1 Maximum frequency
× Rated motor frequency
Pr.886 Regeneration
Pr.665 Regeneration avoidance