In Fig. 8 (a), the mean value of ILED is very approximate to the current reference, showing the validity of proposed control.
When the power switch Qb is turned off, lead acid battery is in the empty load state, and its terminal voltage will rise comparing to battery voltage with load according to the properties of
lead acid battery.
In Fig. 8 (b), ILED fluctuates around the setting point of 350 mA. The ripple component of ILED could be further suppressed by fine-tuning control parameters in Fig. 7.