Siemens 420 manual Closed-loop Vdc control, Vdcmax controller, DC link undervoltage, Cause, Remedy

Issue 07/04 3 Functions

3.17Closed-loop Vdc control

3.17.1Vdc_max controller

Parameter range:	P1240, r0056 bit 14
	r1242, P1243
	P1250 – P1254
Warnings	A0502, A0910
Faults	F0002
Function chart number:	FP4600

DC link undervoltage

Cause:

Line supply voltage failure or dip (blackout or brownout)

Remedy:

A regenerative torque is entered for the operational drive which compensates the existing losses and therefore stabilizes the voltage in the DC link. This technique is carried-out using the Vdc_min controller (refer to Section 3.18) and is known as kinetic buffering.

A brief regenerative load can be handled using this function (enabled using P1240) without the drive inverter being shut down (tripped) with fault message F0002 ("DC link overvoltage"). In this case, the frequency is controlled so that the motor doesn't go too far into regenerative operation.

If the drive inverter regenerates too much when braking the machine due to a fast ramp-down time P1121, then the braking ramp / ramp time are automatically extended and the drive inverter is operated at the DC link voltage limit r1242 (refer to Fig. 3-55). If the DC link threshold r1242 is again fallen below, then the Vdc_max controller withdraws the extension of the braking ramp.

VDC

r1242
VDC_max -controller active	t
	A0911
r0056 Bit 14 1
	t
0
 f
	fact
	fset
	t

Fig. 3-55 Vdc_max controller

MICROMASTER 420	Operating Instructions
6SE6400-5AA00-0BP0	131