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Special operation and frequency control
4
PARAMETERS
(2) To detect the regeneration status during deceleration faster (Pr. 884)
⋅ As the regeneration avoidance function cannot respond to an abrupt voltage change by detection of the bus
voltage level, the ratio of bus voltage change is detected to stop deceleration if the bus voltage is less than Pr. 883
Regeneration avoidance operation level.
Set that detectable bus voltage change ratio to Pr. 884 as detection sensitivity.
Increasing the setting raises the detection sensitivity
(4) Regeneration avoidance function adjustment (Pr. 665, Pr. 886)
⋅ If the frequency becomes unstable during regeneration avoidance operation, decrease the setting of Pr. 886
Regeneration avoidance voltage gain. Reversely, if sudden regeneration causes an overvoltage fault, increase the
setting.
When vibration is not suppressed by decreasing the Pr. 886 setting, set a smaller value in Pr. 665 Regeneration
avoidance frequency gain.
CAUTION
Too small setting (low detection sensitivity) will disable detection, and too large setting will turn ON the regeneration avoidance
function if the bus voltage is varied by an input power change, etc.
(3) Limit regeneration avoidance operation frequency
(Pr. 885)
You can limit the output frequency compensated for (increased) by
the regeneration avoidance function.
⋅ The frequency is limited to the output frequency (frequency prior to
regeneration avoidance operation) + Pr. 885 Regeneration avoidance
compensation frequency limit value during acceleration or constant
speed. If the frequency increased by regeneration avoidance
function exceeds the limit value during deceleration, the limit value
is held until the output frequency falls to 1/2 of Pr. 885.
⋅ When the frequency increased by regeneration avoidance function
has reached Pr. 1 Maximum frequency, it is limited to the maximum
frequency.
⋅ Pr. 885 is set to "9999", regeneration avoidance function operation
frequency setting is invalid.
CAUTION
⋅ When regeneration avoidance operation is performed, (overvoltage stall) is displayed and the OL signal is output. Set
theoperation pattern at an OL signal output using Pr. 156 Stall prevention operation selection. Set the output timing of the OL
signalusing Pr. 157 OL signal output timer.
⋅ When regeneration avoidance operation is performed, stall prevention 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 regenerative energy consumption capability. When shortening the deceleration time,
consider using the regeneration unit (FR-BU2, BU, FR-BU, MT-BU5, FR-CV, FR-HC, MT-HC) to consume regenerative energy
at constant speed.
⋅ When using a regeneration unit (FR-BU2, BU, FR-BU, MT-BU5, FR-CV, FR-HC, MT-HC) to consume regenerative energy at
constant speed, set Pr. 882 = "0 (initial value)" (Regenerative avoidance function invalid). When using the regeneration unit, etc.
to consume regenerative energy at deceleration, set Pr. 882 = "2" (regeneration avoidance function valid only at a constant
speed).
♦ Parameters referred to ♦
Pr. 1 Maximum frequency Refer to page 87
Pr. 8 Deceleration time Refer to page 101
Pr. 22 Stall prevention operation level Refer to page 81
Limit level
Time
Pr.885
Output frequency (Hz)
Pr.885/2
Output
frequency(Hz)