Delta Electronics none manual „ External Regenerative Resistor

Chapter 6 Control Modes of OperationASDA-AB Series

„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	Rotor Inertia	Regenerative power from empty load	Max. regenerative power
	(kW)	J (kg. m2)	3000r/min to stop Eo (joule)	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
Eo = J x wr2/182 (joule)			, Wr : r/min

If the load inertia is N × motor inertia, the regenerative power will be (N+1) xE0 when servo motor brakes from 3000r/min to 0. Then, the regenerative resistor can dissipate: (N+1) xE0 - Ec (joule). If the time of repeat operation cycle is T sec, then the regenerative power = 2 x((N+1) xE0 - Ec) / T. The calculating procedure is as follows:

Step	Procedure	Equation and Setting Method
1	Set the capacity of regenerative	Change the value of P1-53 to maximum
	resistor to the 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	Eo = J x wr2/182
	power Eo
6	Set the regenerative power Ec that	Refer to the table above
	can be absorbed
7	Calculate the required	2x (N+1) x Eo－Ec）/ T
	regenerative power capacity

Revision March 2008, Doc. Name: 2007PDD23000011 6-37