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ASDA-A User Manual
Chapter 6 Control Modes of Operation
© DELTA ELECTRONICS, INC. ALL RIGHTS RESERVED
4th Edition 2005/11/30, HE03
6-41
External Regenerative Resistor
When using external regenerative resistor, connect it to P and C, and make sure the circuit between P and D
is open. We recommend user should use the external regenerative resistor that the resistance value
following the above table. We ignore the discharge power of IGBT in order to let user easily calculate the
power of regenerative resistor. In the following sections, we will describe Regenerative Power Calculation
Method and Simple Calculation Method for calculating the regenerative power capacity of external
regenerative resistors.
Regenerative Power Calculation Method
(a) When there is no external load torque, if the servo motor repeats operation, the returned regenerative
power generated when braking will transmitted into the capacitance of DC bus. After the capacitance
voltage exceeds some high value, regenerative resistor can discharge the remained regenerative power.
Use the table and procedure described below to calculate the regenerative power.
Servo Drive
(kW)
Rotor Inertia
J (kg. m
2
)
Regenerative power from empty load
3000rpm to stop Eo (joule)
Max. regenerative power
of capacitance
Ec(joule)
0.1 0.03E-4
0.15 3
0.2 0.18E-4
0.89
4
0.4 0.34E-4
1.68
8
0.75 1.08E-4
5.34
14
1.0 2.60E-4
12.86
18
1.5 3.60E-4
17.80
18
2.0 4.70E-4
23.24
21
3.0 11.6E-4
57.36
28
Eo= J * wr
2
/182 (joule)
, Wr : rpm
If the load inertia is N
ͪ
motor inertia, the regenerative power will be (N+1)
ͪ
E0 when servo motor
brakes from 3000rpm to 0. Then, the regenerative resistor can discharge: (N+1)
ͪ
E0
Ё
Ec (joule). If the
time of repeat operation cycle is T sec, then the regenerative power = ((N+1)
ͪ
E0
Ё
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 user
3
Set rotation speed wr
Input by user or via parameter P0-02 Drive State
Display
4
Set load/motor inertia ratio N
User Input or via P0-02 Drive State Display
5
Calculate the max. regenerative
power Eo
Eo= J * wr2/182
6
Set the regenerative power Ec that
can be absorbed
Refer to the table above
7
Calculate the required regenerative
power capacity
2
ͪ
(N+1)
ͪ
Eo
Ё
Ec
α
/ T