Delta ASDA-A3 Series User Manual page 49

Installation
Example:
For the motor ECM-A3L-CY0604RS1 (400 W), the reciprocating motion cycle is T = 0.4 sec.
Its maximum rotation speed is 3,000 rpm and the load inertia is 15 times of the motor inertia.
2
Servo drive
(kW)
0.4
Find the maximum regenerative energy: Eo = 0.74 joules (from the table above).
Find the regenerative energy that can be absorbed by the capacitor: Ec = 8.42 joules (from the
table above).
The required capacity of the regenerative resistor =
From the calculation above, the required power of the regenerative resistor is 17.1 W, which is
smaller than the specified capacity. In this case, a built-in 40 W regenerative resistor fulfills the
need. In general, the built-in regenerative resistor can meet the requirement when the external
load is not too great.
Calculation of the regenerative power when there is external torque and the motor does the
(b)
negative work.
Usually, the motor does positive work and the motor's torque direction is identical to the rotation
direction. However, in some instances, the motor's torque direction is opposite to the rotation
direction. This means the motor is doing negative work and the external energy is applied to the
servo drive through the motor. For instance, if the external force direction is identical to the
rotation direction (such as downward motion of the vertically-mounted machine), the servo
system outputs more power to counterbalance the excessive external force (the weight of
vertically-mounted machine) in order to keep up with the specified target speed. In this case,
considerable energy returns to the servo drive. When DC Bus is full and cannot store more
energy, this energy is consumed by the regenerative resistor.
2-22
Motor
ECM-A3L-CY0604RS1
(1) Moving direction of the object; (2) Direction of torque; (3) Regenerative energy
Regenerative energy
generated when the motor
Rotor inertia
decelerates from the rated
J (× 10 kg.m 2 )
-4
speed to 0 without load Eo
0.15
2×((N+1)×�� −��
0
T
Maximum
regenerative
energy of the
capacitance
(joule) Ec (joule)
0.74 8.42
) 2×((15+1)×0.74−8.42)
�� = 17.1 W.
=
0.4
ASDA-A3