Data provided by: Mr. hisham bahaa-aldeen (firstname.lastname@example.org)
the course of MAINs ON Battery charging may be seen initiated. As we may
understand while in battery charging mode the system may be
functioning using the SMPS technique, let us now understand the working principle
To charge the battery the output circuit (MOSFET and
Inverter transformer) becomes effective in the form of a boost
In this case all the low side
MOSFETs of the two the
mosfet arrays work in sync as a switching stage while the
the inverter transformer behave as an inductor.
As soon as all of the
low side MOSFETs are switched-ON the electric power gets accumulated in
the primary section of transformer, and as soon as the MOSFETs are OFF
this accumulated electric
power is rectified by the in-build diode inside the MOSFETs and the DC
is kicked back to battery pack, the measure of this boosted voltage
would depend on the ON-time of the low side MOSFETs or simply mark/space
ratio of the duty cycle used for the charging process.
the equipment may be conducting in the mains-on mode, the charging PWM (from pin13 of
micro) is progressively augmented from 1% to highest specification,
in case the PWM raises the DC voltage to the battery, the battery voltage too
increases which results in a surge in the battery charging current.
battery charging current is monitored across the DC fuse and negative rail of
the PCB and the voltage is additionally intensified by the amplifier U5 (pin8,
ppin9 and pin10 of the comparator) this amplified voltage
or detected current are applied to the pin5 of microcontroller.
This pin voltage
is scheduled in software in the form of 1V, as soon as the voltage in
this pin is rises above 1V the controller may be seen restricting the PWM duty cycle
until finally it's pulled down to below 1V, assuming the voltage on this
pin is decreased to below 1V the controller would instantly begin improving the
full PWM output, and the process may be expected to go on in this manner with the
controller upholding the voltage on this pin at 1V and consequently
the charging current limit.