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7 Selection
MITSUBISHI CNC
7-3 Selection of the regenerative resistor
7-3-1 Regeneration methods
When the motor decelerates, rotating load inertia or the operation energy of the moving object is returned to
the drive unit through the motor as electrical power. This is called "regeneration". The three general methods
of processing regeneration energy are shown below.
Table 7-5 Drive unit regeneration methods
The resistance regeneration method are used in the MDS-D-SVJ3/SPJ3. For MDS-D-SVJ3 Series (servo),
the regenerative resistor is mounted in the drive unit as a standard. If the regenerative capacity becomes
large, an option regenerative resistor is connected externally to the unit. (Combined use with the built-in
resistor is not possible.)
When the power supply regeneration method is used, consider using the MDS-D-V1/V2, MDS-D-SP/SP2
Series, MDS-DM-SPV Series.
Regeneration method Explanation
1. Condenser regeneration
method
This is a regeneration method for small-capacity drive units. The regeneration energy is
charged to the condenser in the drive unit, and this energy is used during the next accel-
eration.
The regeneration capacity decreases as the power supply voltage becomes higher.
2. Resistance regeneration
method
If the condenser voltage rises too high when regenerating with the condenser only, the re-
generative electrical power is consumed using the resistance. If the regeneration energy
is small, it will only be charged to the condenser. Because regeneration energy becomes
heat due to resistance, heat radiation must be considered.
In large capacity drive units the regenerative resistance becomes large and this is not
practical.
3. Power supply regeneration
method
This is a method to return the regeneration energy to the power supply. The regeneration
energy does not become heat as in regenerative resistance. (Heat is generated due to re-
generation efficiency problems.)
The circuit becomes complicated, but in large capacity drive units having large regenera-
tion capacity this method improves regeneration frequency than regenerative resistor.
Make sure to mount the optional regenerative resistor outside the MDS-D-SPJ3 Series (spindle) unit.
A built-in regenerative resistor is not mounted.
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