Page 104 - CITS - Electronic Mechanic - TT - 2024
P. 104
ELECTRONICS MECHANIC - CITS
The good thing about the circuit is that the transformer does not employ separate winding for this rather works
with the same input winding and reverts DC to the battery with the help of a few DPDT relays. The circuit diagram
of battery charging circuit is given below.
Working of Battery Charging Circuits:
The working of battery charging circuits can be discussed in following points
• The inverter section can be easily recognised in the diagram, R, to R., including the transistors T and T₂ form
a general astable multivibrator circuit for producing the required 50 or 60 Hz pulses.
• These pulses drive the MOSFETs alternately which in turn saturate the transformer by switching the battery
voltage in it. The secondary winding of the transformer generates the corresponding magnitude of AC which is
finally used for operating the connected appliances.
• The given configuration suggests the normal or ordinary inverter operation.
• By adding a couple of DPDT relays in the above discussed operation, we can force the circuit to charge the
battery in the presence of an AC mains source.
• The coils of the two relays are powered through a capacitive low current compact power supply, involving Co,
C, D₁-Ds.
• The battery charging circuit is connected to a mains AC source, this source is also connected to RL, poles.
• The second relay RL, is wired up with input winding of the transformer.
• In the absence of mains AC, the position of the relay contacts are in the NC as shown in the figure.
• In this position the MOSFETs get linked with the transformer input winding, and the battery with the circuit so
that the inverter starts oscillating and the output appliances gets the AC power from the battery.
• In the presence of AC mains, the relay coils instantly get the required DC power and activate the contacts.
• RL, activates and connects the mains input to the transformer, the appliances also get connected with the
mains AC in the process.
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CITS : E & H - Electronics Mechanic - Lesson 48 - 55
