External Regenerative Resistor; Regenerative Power Calculation Method - Delta Electronics AC Servo Drive ASDA-AB User Manual

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 the users should use the external regenerative resistor that the
resistance value following the above table (Built-in Regenerative Resistor Specifications). We ignore the
dissipative power of IGBT (Insulated Gate Bipolar Transistor) in order to let the users easily calculate
the capacity 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

(1) Without Load
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 dissipate the remained regenerative power.
Use the table and procedure described below to calculate the regenerative power.
Servo Drive
(kW)
0.1
0.2
0.4
0.75
1.0
1.5
2.0
2
Eo = J x wr /182 (joule)
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
Set the capacity of regenerative
1
resistor to the maximum
2 Set the operation cycle T
3 Set motor speed wr
4 Set load/motor inertia ratio N
Calculate the max. regenerative
5
power Eo
Set the regenerative power Ec that
6
can be absorbed
Calculate the required
7
regenerative power capacity
Revision January 2009
Chapter 6 Control Modes of Operation|ASDA-AB Series
Rotor Inertia
Regenerative power from empty load
2
3000r/min to stop Eo (joule)
J (kg. m )
0.03E-4
0.18E-4
0.34E-4
1.08E-4
2.60E-4
3.60E-4
4.70E-4
, Wr : r/min
Procedure
0.15
0.89
1.68
5.34
12.86
17.80
23.24
Equation and Setting Method
Change the value of P1-53 to maximum
Input by the users
Input by the users or read via P0-02 Drive State Display
Input by the users or read via P0-02 Drive State Display
2
Eo = J x wr /182
Refer to the table above
2 x (N+1) x Eo－Ec）/ T
Max. regenerative power
of capacitance Ec(joule)
3
4
8
14
18
18
21
6-37