Delta ASD-A2 Series User Manual page 43

ASDA-A2
Take 400W as the example, the cycle of back and forth operation is T = 0.4sec, the maximum
speed is 3000r/min and the load inertia is 7 times to the motor inertia. Then, the needful power of
regenerative resistor is 2 × ((7+1) × 1.68 – 8) / 0.4 = 27.2 W. If it is smaller than the built-in capacity
of regenerative resistor, the built-in 60W regenerative resistor will do. Generally speaking, when
the need of the external load inertia is not much, the built-in regenerative is enough. The diagram
below describes the actual operation. The smaller power of the regenerative resistor it is, the more
energy it accumulates and the higher temperature it will be. When the temperature is higher than a
specific value, ALE05 occurs.
(b) If the external load torque exists, the motor is in reverse rotation.
Usually, the motor is in forward rotation, which means the torque output direction of the motor
is the same as the rotation direction. However, in some applications, the direction of torque
output is different from the rotation. In this situation, the motor is in reverse rotation. The
external energy goes into the servo drive through the motor. The diagram below is one
example. When the external force direction is the same as the moving direction, the servo
system has to use the force of the opposite direction to keep the speed and stability. Huge
amount of energy will return to the servo drive at the moment. When DC-BUS is full and
unable to store the regenerative energy, the energy will be leaded to regenerative resistor
and consumed.
馬達輸出負功
Negative Torque
Negative torque: TL × Wr
For safety reasons, please calculate it by considering the safest situation.
For example, when the external load torque is the +70% rated torque and the rotation
reaches 3000 r/min, then take 400 W (the rated torque is 1.27 Nt-m) as the example, the
user has to connect the regenerative resistor of 40, which is 2 × (0.7× 1.27) × (3000 × 2 × π／
60) = 560W.
2-14
馬達轉速
Motor Speed
External Load Torque
外部負載扭矩
馬達輸出扭矩
Motor Output Torque
正功
Positive Negative Torque
Torque
TL: external load torque
正功
負功
Positive
Torque
Chapter 2 Installation
Revision February, 2017