Today we see the protection circuit. Which is divided into three parts are:
1. the overload output current protection circuit,
2. The output overheat temperature protection circuit
3. the Battery checker.
I’m been talking about the the 200 watts home power inverter projects many articles. Include the following article.
1. Simple working principle of the inverters
2. Operation of 200 watt inverter diagram
3. An oscillator of the 200 watts power inverter
4.The output circuit of 200 watts home power inverter.
5. How to build the 200 watts home inverter projects
If there is malfunction occurs. The protection circuits have to stop the operation of IC2-SG3526N. Which is the frequency generator to stop the output transistors. As prevent damage that may have occurred.
In addition, also has check circuit voltage from battery that is the power supply to the circuit. All checks will stop the the circuit. And diplay with the D1-LED.
1. the overload output current protection circuit have a R8-resistor as main in working. Which is a very low resistance to 0.01 ohm. Work with pin 7 of IC2 (pin + CS). Normally, the voltage at this pin 7 has a very less value. (nearly 0 volts.) But voltage at pin 7 has value as positive up. Makes IC2 frequency generator to stop,and to stop the operation of the output circuits.
The current that flowing in the both output transistor, It can be fully integrated through R8 first. Under normal conditions, the voltage across R8 is very little. Millivolts is called Or an empty time. The voltage drop across the R8 is divided into two parts, with R16 and R17. The voltage drop across the R17 will send directly to pin 7 of IC2.
In when the original source voltage (across R8) no voltage at pin 7 of IC2 so not have as well. Makes IC2 can generate the frequency to bias Q1 and Q2 as normal.
But when the current flows in the output circuit excessive. Will make the current flow through the R8, the voltage drop across so increasing. As a result, pin 7 of IC2 have positive voltage is increased by a positive volts, IC2 stops.
2. The output overheat temperature protection circuit, have important functions are check the heat generated in the output transistors that are too high or not? If found to have unusually high heat, will have to stop the operation of the oscillator circuits. To terminate the operation of the output circuit.
Operation in this section. Can be explained by the lower the circuit. The device monitors the temperature is R9. which is a resistor that changes value with temperature. The R9 can be attached to the heat sink of the output transistors. which is resulted in a lot of heat disorders. R9 resistance will increase.
The IC1 B is op-amp that serves comparater circuits, By there is the reference regulator circuits +5 volts at pin 2. Which is the inverting pin by this voltage from pin 18 of IC2. Which if you go back to the internal structure of IC2. Click here will find that the pin 18 has the Reference Regulator circuits. or VREF +5 volts. That it comes from the power supply voltage at pin 17, by this VREF voltage is constant all time.
The R9 is connected in series with R6 to ground into a Voltage divider circuits. Voltage drop across R6 was sent to the non inverting pin of IC1 B(LM393). Which is usually greater than 5 volts. As a result, the voltage at output pin (pin 7) of IC1 B(LM393) is high. The D2-diode does not conduct current. Makes at pin 8 which is shutdown pin and pin 5 which is reset pin have conditions is high by IC2, So can produce output frequency to 50 Hz normally.
In is currently D1-LED will be dim because there is little voltage across.
However if the output transistors is high temperature up. The R9 is the resistor value should increase. Voltage drop across R6 is less. If this voltage have lower than 5V. At output pin of IC1 B will is LOW. The D2 diode does conduct current at pin 8 and pin 5 of IC2 so is LOW. As a result, IC2 stop production frequency. The output circuit stops.
Currently, D1-LED will light fully. Because at output of IC1A and IC1B conditions is low. The voltage drop across the LED and R3, so much more. The current flowing through. LED is more an indication that the circuit is in state protection.
3. The check battery circuit, the feature similar the over temperature protection circuit in all respects. Devices work in this section is R5, R5 are connected to the divider circuit. By has IC1 A is comparater use Reference Regulator circuits +5 V from pin 18 of IC2. Which is the Reference Regulator with the over heat protection circuit.
Normally, if the battery is full power. Will be output voltage greater than 12V nominal. Which causes the voltage across R5 than 5V output of IC1A is high, The IC2 so generate frequency of 50 Hz it is normal.
When battery power is low. Makes a voltage drop. Voltage drop across R5 so less as well. Which if less than 5 Volt, it will cause the output of IC2 IC1 A is low, resulting in downtime, The output stopped working.