Delta ASD-B2-0121-B, User Manual

Page: 32 / 313

Chapter 2 Installation and Storage
Revision June 2010
2-11
Servo Drive
(kW)
Servo Motor
Rotor Inertia
J (× 10
-4
kg.m
2
)
Regenerative power
from empty load
3000r/min to stop
Eo (joule)
Max. regenerative
power of
capacitance
Ec(joule)
0.4 ECMA-G21303 8.17 40.40 8
0.75 ECMA-G21306 8.41 41.59 14
High
Inertia
1.0 ECMA-G21309 11.18 55.29 18
Eo = J x wr
2
/182 (joule) , Wr : r/min
If the load inertia is N × motor inertia, the regenerative power will be (N+1) x E0 when
servo motor brakes from 3000r/min to 0. Then, the regenerative resistor can dissipate:
(N+1) x E0 - Ec (joule). If the time of repeat operation cycle is T sec, then the regenerative
power = 2 x ((N+1) x E0 - Ec) / T.
The calculating procedure is as follows:
Step Procedure Equation and Setting Method
1
Set the capacity of
regenerative resistor to the
maximum
Change the value of P1-53 to maximum
2 Set the operation cycle T Input by the users
3 Set motor speed wr
Input by the users or read via P0-02 Drive State
Display
4 Set load/motor inertia ratio N
Input by the users or read via P0-02 Drive State
Display
5
Calculate the max.
regenerative power Eo
Eo = J x wr
2
/182
6
Set the regenerative power Ec
that can be absorbed
Refer to the table above
7
Calculate the required
regenerative power capacity
2 x (N+1) x Eo
－
Ec
）
/ T
For example:
If we use 400W servo drive, the time of repeat operation cycle is T = 0.4 sec, max. motor
speed is 3000r/min, the load inertia = 7 × motor inertia, then the necessary the power of
regenerative resistor = 2 x ( (7+1) × 1.68 - 8) / 0.4 = 27.2W. If the calculation result is
smaller than regenerative power, we recommend the users to use the built-in 60W
regenerative resistor. Usually the built-in regenerative resistor provided by ASDA-B2 series
can meet the requirement of general application when the external load inertia is not
excessive.
The users can see when the capacity of regenerative resistor is too small, the accumulated
power will be larger and the temperature will also increase. The fault, ALE05 may occur if
the temperature is over high. The following figure shows the actual operation of
regenerative resistor.