irf3205 inverter circuit diagram one

IRF is an inverter. The drawings are similar. Put the two IRF pins down, one on the front and one on the back. The two outermost pins are connected to negative electricity. The middle leg of the front is connected to the side leg of the other tube. , The remaining two legs are also connected with a resistance of 330 ohms, and finally the leads are connected from the middle legs of the two transistors to the primary ends of the transformer, and the middle tap is connected to the positive current. It’s about 0.075 volts per turn, so it won’t get hot.

irf3205 inverter circuit diagram two

This inverter is a high frequency inverter, completely abandoning the bulky power frequency transformer, not only reduces the volume, but also improves the efficiency, and there is no buzzing sound from the power frequency transformer. This inverter is a typical high frequency inverter power frequency output structure: DC-AC-DC-AC structure (12VDC-330VAC0 30KHz-330VDC-230VAC 50HZ). The inverter is equipped with voltage stabilization and output overcurrent protection functions.

First look at the DC-AC-DC part:

This part is a closed loop PWN inverter circuit with SG3525 as the core. The first and second pins of U1 form voltage feedback to stabilize the output voltage. Pin 16 is the reference voltage of 5V, which is divided by R1 and R2 and added to the second pin (inverted input of the internal error amplifier). The normal voltage is 2.5V. The output high voltage is sent to the first through the divided voltage of R7 and RP potentiometer Pin (internal error amplifier same direction input terminal). C1 and R4 of the fifth and sixth pins determine the oscillation frequency of U1 to be about 31KHz (the frequency I carefully selected, higher will increase the high-frequency loss of the FET, and the lower the transformer will make noise), the seventh pin is determined by R5 The dead time (in order that the two power tubes cannot be turned on at the same time, there is a period of time between the two pulses, and both power tubes are turned off at this time). The 9th pin is the compensation terminal, grounding with C3 can enhance the working stability of U1. The follow-up circuit of R6 and IFB of the tenth pin constitutes an output over current protection circuit. When the voltage of the tenth pin is greater than 0.7V, U1 stops driving the power FET. The 11th and 14th pins are power tube driving pins. The 12th pin is the GND of the IC, the 13th pin is the common collector of the internal output transistor, and the 15th pin is the chip power supply. Q1, Q2, and T1 form a high-frequency push-pull inverter circuit (working in forward mode), which changes 12VDC to 330VAC. D1 is four fast recovery rectifier diodes, and C5 is a filter capacitor. The function of this part of the circuit is to rectify high frequency alternating current into direct current.

Let's look at the final DC-AC part:

This part is a DC-AC circuit with multivibrator and H-bridge as the core. Q5, Q6, C1, C2, R1-R4 form a transistor base-collector coupled multivibrator. The collectors of Q5 and Q6 output two square wave pulses with opposite phases. The duty cycle is 50% and the frequency is about 50Hz. , It should be a little higher than 50Hz, mine is 54Hz. The functions of Q7, Q8, R5, and R6 are to improve the waveform to make the upper and lower edges of the output square wave steeper; the second is to increase the ability to push the H bridge.

R7-R10, D1, D3, C3, Q9, Q1, Q2 and R11-R14, D2, D4, C4, Q10, Q3, Q4 respectively form two half bridges of the H bridge. This part of the principle is more complicated, and I will write an article in the future (this article will be produced, and the theory is only an auxiliary production). The first half of the circuit of R15 and IFB constitutes output over-voltage protection (the output stops when the output current is greater than 3A). If this part of the circuit works normally, an AC square wave voltage of 230V can be obtained on the RL.

Production instructions:

1. The circuit made is simple and can be made on the hole board. It is recommended to use two small boards to make the two pictures separately and debug separately. That's how I did it.

2. Get the first picture first. Q1, Q2 choose IRF3205, IRF1010, these field effect transistors with current greater than 50A and withstand voltage greater than 30V. C1 and C3 recommend the use of poison stone capacitors, which can work stably, because the capacity of poison stone capacitors is less affected by temperature and the capacity accuracy is high. C2 cannot be saved, otherwise the power will not come out. T1 production method: T1 uses EC42 magnetic core, and the two primary uses 4 strands of 1mm enameled wire to wind 4 turns on the skeleton, and then lead out. The head of one primary and the tail of the other primary are connected as the place for connecting the 12V power supply. , The remaining two pins are respectively connected to the source of two field effects; the secondary uses 0.6mm enameled wire to wind 200 turns. The transformer must be wound carefully, and the secondary must not be wound randomly. D1 should be composed of 4 FR607s. Power frequency rectifier diodes or rectifier bridges cannot be used. Because the switching speed of power frequency devices cannot keep up, they will get heated and burned. This is a mistake that many beginners are likely to make. The withstand voltage of C2 is 16V, and the withstand voltage of C5 is 400V. After the first picture is made, adjust the RP so that the output voltage is 330V. At this time, a 60W bulb should be able to light up.

3. Get the second picture. C1 and C2 use poison stone capacitors to ensure accurate and stable frequency. Q9 and Q10 use NPN transistors with a withstand voltage greater than 300V and a current greater than 0.1A. Here, MSPA42 is used, preferably MSP40, which has a withstand voltage of 400V, and the former has a withstand voltage of only 300V. Q1-Q4 use field effect transistors with withstand voltage greater than 400V and current greater than 4A. IRF830 is used here. C3 and C4 can use poison stone capacitors such as C1 and C2, or electrolytic capacitors or CBB capacitors. If it is an electrolytic capacitor, the withstand voltage is at least 50V and pay attention to the polarity. The red dot on the side of C3 and C4 is the positive electrode. R15 uses 0.22 ohm 5W cement resistor, do not install it close to the board, but leave the board a little bit. After installation, if you have an oscilloscope, do it. If you don’t have it or you’re lazy, you can skip it: don’t connect the 330V high voltage, first connect to the 12V DC, the collector of Q7, Q8 should be able to detect the duty cycle 50 %, a square wave with a frequency of about 50 Hz, and it is complementary. Connect the 330V high voltage, test the gate and drain of the FET on each H-bridge, you should see a square wave drive signal, and the drive pulses of the upper and lower arms of each half-bridge are opposite in phase. The output should be an AC square wave (two segments of RL, RL is the output socket).

4. The Q1 and Q2 in the first picture and the Q1-Q4 in the second picture must be equipped with radiators. Don't forget to add insulating pads when installing the radiator.

5. If you feel that the output over current protection function is not good, you can short-circuit R15.

6. After the final adjustment, add a 400V 100uF electrolysis between 330V and ground to increase the output power. Why did you add this capacitor to the end? To prevent electric shock during debugging. This capacitor must be discharged first when it is repaired and adjusted in the future!