MOSFET field effect tube power frequency 100W inverter power supply

The device has a simple circuit, is easy to debug, has reliable performance, can automatically switch between inversion and charging, and has a battery charge indicator. Because it uses a high-power VMOS tube, it has high efficiency and low cost, and is suitable for assembly by electronics enthusiasts.
Working Principle

The working principle of the circuit is shown in Figure 1 (click to download the schematic diagram). VT1 and VT2 form a multivibrator with an oscillation frequency of 5Hz. When the voltage drops, in order to keep the frequency unchanged, the oscillator is powered by the voltage regulator VD1. The square wave voltage output by the multivibrator directly drives the VMOS high-power tube, and the 220V AC power after the transformer boost is drawn from the socket CZ.
Relay J1 is used for automatic conversion between inversion and charging. When the power grid is transmitting power, J1 is energized, then J1-3 connects to the power grid, and J1-2 jumps from the ⑧ pin of the transformer T to the ⑤ pin, so that the transformer ① and ② generate a 15V AC voltage to the 0 pin, and J1-1 disconnects the multivibrator power supply, so the gate voltage of the VMOS tube is zero. At this time, the VMOS tube is equivalent to a diode, and the 15V AC is full-wave rectified by the VMOS tube to charge the battery. LED1 is the charging end indication, and LED2 is the discharge end indication. The neon lamp LD indicates high voltage. When the grid supplies power but the battery is fully charged, or when there is a power outage but the inverter is not needed, turn off the power switch S1.

Component selection and production
component list are shown in the table below.

When all components are welded and checked, connect the 12V power supply. The circuit should be able to oscillate. Use an oscilloscope to observe the voltage waveform of the collectors of VT1 and VT2. Adjust RP1 and RP2 to 50Hz and symmetrical waveforms. Change the power supply voltage and adjust RP3 to make LED1 light up when the power supply voltage is 16.8V and turn off when the power supply voltage is below 16V. Adjust RP4 to make LED2 light up when the power supply voltage is greater than 11V and turn off when it is less than 10.5V. 2CW17 should be able to provide 9V DC voltage to the multivibrator when the power supply voltage is 10.5-17V. The other parts of the circuit do not need to be debugged. The cross-sectional area of ​​the transformer core should not be less than 10cm2. The winding data is shown in Figure 2 (see the table above for winding data). When 220V AC is applied to pins ③ and ⑧, the voltage at terminals 0-1 and 0-2 is 11V; pins ⑦, ⑥, ⑨, and ⑩ are designed to adjust the inverter voltage; when 220V AC is applied to pins ③ and ⑤, the voltage at terminals 0-1 and 0-2 is 15V, which is used to replenish the battery power; when 220V AC is applied to pins ③ and ④, the voltage at terminals 0-1 and 0-2 is 17V, which is used to quickly charge the discharged battery.

When the power grid is out of power, the inverter will automatically start running, and the inverter voltage will be drawn from the socket. Turn on the power switch, the neon light should light up, and LED2 should also light up (green). When the green light goes out, it means that the battery has been discharged and the inverter should be stopped. It should be noted that the battery cannot be depleted for a long time, nor can it be fully charged and not used for a long time. It should be discharged for about 1 hour a week, and fully charged in time after discharge. It should be completely discharged once every one or two months, and fully charged in time for standby after discharge.