Fuji Electric ALPHA5 Smart - Page 615

CHAPTER 15 APPENDIXES
Capacity Selection Calculation 15-23
15
(9) Calculating the regenerative power
Regenerative operation is caused while the torque value is negative, in general as indicated below.
Horizontal feed: During deceleration
Vertical feed: During constant speed feed in the lowering cycle and during deceleration
Regenerative energy during deceleration (E
1
)
E
1
[J] = (2π/60) × T
DC
[Nm] × N[r/min] × t
DC
× (1/2)
Regenerative power during constant speed feed (E
2
) ←Mainly in lowering cycle
E
2
[J] = (2π/60) × T
L
[Nm] × N[r/min] × t
L
Accumulated energy on main circuit capacitor (E
3
)
E
3
[J] = (1/2) × C[F] × V
2
= (1/2) × C[F] × {390
2
- (200√2)
2
}
Regenerative power (P)
P[W] = { | (E
1
+ E
2
) | - E
3
} / (t
cyc
)
P≤0: No external regenerative resistor is necessary.
P>0: The external (internal) regenerative resistor is
necessary.
Calculate the average regenerative power (P) of each cycle of the operation pattern1 to check if P
is within the regenerative resistor capacity. If it is not, an external regenerative resistor is
necessary.
(10) Reviewing the operation pattern and mechanical configuration
If T
rms exceeds TR, review the following items.
 Increase the acceleration/deceleration time a little in the allowable range.
 Reduce the operation frequency (increase the cycle time).
 If the rotation speed allows, increase the reduction ratio.
 Increase the motor capacity.
 If the stopping time of a hoisting machine is too long, adopt a mechanical brake.
 In case of operation at a high frequency, increase the reduction ratio and reduce the inertia.
T
DC
: Deceleration torque [Nm]
T
L
: Load torque [Nm]
t
DC
: Deceleration time [s]
t
L
: Constant speed time [s]
t
cyc
: Cycle time [s]
C : Servo amplifier capacitor capacity [F]
→See page 15-29.
V
2
: Regenerative transistor ON level
2
- (200√2)
2
= 3902 - (200√2)
2