A previous article(An oscillator of the 200 watts power inverter) I say about the frequency generator circuit of the our 200 watts home inverter. The next we see part of output as well.
As show figure below When IC2-SG3526 can generate the square wave frequency of 50Hz output at pin 13 and pin 16. Both signal that has Phase difference is 180 degrees will send to R13 and R15, to bias pin gate of both transistors Q1 and Q2 number IRFP054. Which are mosfet type N channel, that has diode damper Diode is within, makes both of transistors alternately conduct current. If any one has a bias. signal at gate pin as high will can conduct current(ON). But if it get signal as low will stop conduct current(OFF).
The conduct currents of the two transistors. Cause current to flow in primary coil of transformer T1 into drain out to the source pin of Q1 and Q2, and to fully circuit at ground by pass to R8 value 0.01 ohm. Which is resistor monitoring the amount of current in the output circuit, which is discussed next.
The working of Q1 and Q2 are characterized the switches. The spike voltage will cause the occurs at pin drain of both transistors. Which occurs incunabulum It is changing state from ON to OFF. This spike voltage is the voltage is very high. May be higher than the supply voltage, many times. Which is extremely dangerous to the power output transistors. Therefore, it is necessary to eliminate this spike voltage out. The circuit that performs this function is called a snubber circuit.
The snubber of this circuit consists of D4, D5(BY299), D6, R14, C9 and C10. For D5 and D6 are diode works faster or called Fast Revovery Diode number BY299.
Under normal conditions, D5 and D6 will do not conduct current. Which it will conduct current when voltage at pin drain of Q1 or Q2 rise. Until have value greater power supply (+12 volts), The current will flowing through the both diode into charge to C9 and C10, and if voltage at pin drain of Q1(IRFP054) and Q2(IRFP054) have higher 18 volts, will makes the zener diode D4. Which have value 18 volts conduct current through the R14 of 18 ohm.
Which operation of all the equipment as a result to lower the spike voltage.
Likely that both power transistors will be damaged less.
This article is part of 200 watts home power inverter project using SG3526N You can read each section for continuity.