DocID026400 Rev 1

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L9915

Electrical specification

20

3.3.7

Load response control function (LRC)

When an electrical load is applied to the system application, a drop in the regulated voltage

(VB) occurs and the alternator reacts by increasing output current. If the LRC function is

active then the alternator output current is controlled by the Field current variation strategy

that is directly linked to the duty cycle on Field signal.

The LRC function can operate when the alternator runs at low speed (the PH signal

frequency has to be lower than fPLRC) and it is activated when a positive variation between

current duty cycle on Field and its previous duty cycle values is higher than DFLRCEnab.

When the LRC function is required, the duty cycle increase slowly with the defined slope

DFLRCUP starting with the previous duty cycle increases by the fixed value DFLRCBZ. The

actual duty cycle management during a LRC insertion is shown in the Figure 12.

Figure 12. Load response control function (LRC) diagram

Table 12. Load response control function characteristics

Symbol

Parameter

Test condition

MIN

TYP

MAX

Unit

Positive duty cycle vs.

time variation

-

%/s

Load response control

Time (100% to 0% DC)

s

Negative duty cycle vs.

time variation

-

%/s

Current vs. previous

duty cycle variation to

enable LRC function

-

4.1

6.7

9.2

%

Blind zone

-

2.6

5.3

7.8

%