Appendix 2. Selection
A2 - 5
Appendix 2-2 Selecting the regenerative resistor
Calculate the regenerative energy for stopping (positioning) from each axis' rapid traverse rate, and
select a regenerative resistor having a capacity that satisfies the positioning frequency determined from
the machine specifications.
Appendix 2-2-1 Calculating the regenerative energy
(1) For horizontal axis
For the horizontal axis, the regenerative energy E
R consumed by the regenerative resistor can be
calculated from expression (2-6). If the E
R value is negative, all of the regenerative energy is
absorbed by the capacitor in the drive unit (capacitor regeneration), and the energy consumed by
the regenerative resistor is zero (E
R= 0).
ER = 5.48×10
-7
•
η • (JL+JM) • N
2
–Ec
(J) • • • (2-6
η
: Motor reverse efficiency
J
L : Motor inertia
(kg
•cm
2
)
J
M : Load inertia
(kg
•cm
2
)
N : Motor speed (r/min)
Ec : Unit charging energy (J)
(Example)
When a load with the same inertia as the motor is connected to the HF53, determine the regenerative
energy to stop from the rated rotation speed. Note that the drive unit is MDS-R-V1-20 in this case.
According to expression (2-6), the regenerative energy E
R is:
ER = 5.48×10
-7
×0.85×(6.1+6.1)×3000
2
–13 = 38.1 (J)
Table 2-3 Drive unit charging energy
Drive unit Charging energy Ec (J) Drive unit Charging energy Ec (J)
MDS-R-V1-20 13 MDS-R-V2-2020 26
MDS-R-V1-40 20 MDS-R-V2-4020 30
MDS-R-V1-60 30 MDS-R-V2-4040 30
MDS-R-V1-80 46 MDS-R-V2-6040 46
MDS-R-V2-6060 46
MDS-R-V2-8040 66
MDS-R-V2-8060 66
MDS-R-V2-8080 66
Table 2-4 Servomotor reverse efficiency
Servomotor Motor reverse efficiency η
HF44 0.85
HF74 0.85
HF53 0.85
HF103 0.85
HF153 0.85
HF203 0.85
HF353 0.85
POINT
The charging energy values apply when the unit input power voltage is 220V. If
the input voltage is higher, the charging energy decreases, and the regenerative
energy increases.
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