5-12-2 Regenerative Braking Function
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When the motor decelerates, moves downward, or is rotated by an external load (that is, when the
output torque direction and the rotation direction are opposite), it serves as a generator and the
regenerated energy is fed back to the inverter.
However, if the motor load inertia is large, the amount of regeneration may become large, which
causes an overvoltage during rapid deceleration or when driving an elevating axis.
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The regenerative braking function uses the built-in or an external regenerative braking circuit to
decrease the internal main circuit DC voltage of the inverter by converting the regenerated energy
from the motor into heat via external braking resistors.
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Connect external braking resistors or external regenerative braking units according to the description
of External Braking Resistor Connection Terminal/Regenerative Braking Unit Connection Terminal in
2-3-4 Wiring for Main Circuit Terminals on page 2-17.
The regenerative braking function is enabled only when the inverter is connected with one or more
external braking resistors/external regenerative braking units.
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The 3G3MX2-EV2 Series has a built-in regenerative braking circuit. Connect external braking
resistors only.
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If a large braking torque is required or if a large regenerative energy must be processed, the built-in
regenerative braking processing circuit may not be sufficient, forcing you to use the Regenerative
Braking Unit.
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To use the built-in regenerative braking function of the inverter, set the Regenerative Braking Selec-
tion (b095) to 01 or 02 (Enabled).
Normally, this parameter is set to 01 (Enabled: Disabled during stop). Set this parameter to 02
(Enabled: Enabled during operation and stop) when regenerative braking is required due to external
force, for example, when using a PM motor.
At this time, set the usage rate (%) of the braking resistor in use in the Usage Rate of Regenerative
Braking (b090).
Note that the regenerative braking function is enabled only when both b090 and b095 are set.
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Be sure to set the resistance of the braking resistor connected to the inverter in the Braking Resistor
Value (b097).
This setting, together with the Usage Rate of Regenerative Braking (b090) data, is used by the
regenerative braking protective function.
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For the Regenerative Braking ON Level (b096), you need not change the default data normally.
This parameter is used for adjusting the level at which the regenerative braking function turns ON
according to the input power supply voltage to the inverter.
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When the external regenerative braking unit is used, regenerative braking is performed in the exter-
nal regenerative braking unit. Therefore, set the inverter parameter, Regenerative Braking Selection
(b095) to 00 (Disabled). In this case, the b090, b096, and b097 settings are ignored.
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To use the regenerative braking function, set the Overvoltage Suppression Function Selection During
Deceleration (b130) to 00 (Disabled).
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