# Design a 100 watt inverter, but why when the circuit is connected to the power supply sparks out?

I'm making an inverter with 100 Watt power, 220 volt output voltage. The input voltage source of the inverter is from solar panels with a maximum voltage of 18 volts and a maximum current of 5.56 Amperes.

• This inverter circuit consists of a 150 Watt boost converter to increase the DC voltage of the solar panel to 24 Volts.
• Then the inverter circuit uses the P-channel IRF9540 and N-channel IRF540 mosfets, 4N35 mosfet drivers and BD139 transistors to amplify the frequency.
• To generate signals I use the Arduino SPWM program.
• The 24 VAC voltage will be raised to 220 volts with a 5A transformer and a 12-12 Volt voltage tap. The load for this inverter is the lamp and charger.

Before I connect directly to the solar panel. I first tested my circuit with a 16 Volt battery source, when I connected my circuit to the battery, sparks came out so that the input voltage decreased. Then I test by removing the Arduino pin from the circuit and still sparks come out. Is there something wrong with my circuit and what are the suggestions for this series? Is my circuit experiencing a short circuit? Thank you

• sparks come out on the input section of the inverter when connected to the source @jsotola Jun 16, 2020 at 7:27
• sparks usually happen when there is a bad connection or when you connect or disconnect a wire while a circuit is drawing a fairly large current .... were you manipulating wires when the sparks flew? Jun 16, 2020 at 7:41
• Welcome to EE.SE! Please define "the power supply sparks out". Where exactly? Did anything break? Is it inrush current due to large electrolytic capacitors on your boost converter? Jun 16, 2020 at 7:48
• sparks come out on the input of the inverter when connected to the source. I don't know about boost converter because I already bought boost converter module on the internet @winny Jun 16, 2020 at 9:26
• $18V \times 5A = 90W$ You'll never get 100 watts out of your inverter.
– JRE
Jun 16, 2020 at 10:01

This inverter circuit consists of a 150 Watt boost converter to increase the DC voltage of the solar panel to 24 Volts.

From what I can see, with a 24 volts DC supply, Q3 and Q4 will see about 24 volts on their gates with respect to ground. This is significantly beyond the stated absolute maximum rating in the data sheet extract above.

I'm not ruling out other things (should those MOSFETs survive the first few seconds) such as: -

• MOSFET Shoot-through due to both MOSFETs on one side of the bridge simultaneously conducting as the (slow) gate drive switches.
• 1N4004 reverse recovery shoot-through (circa 30 us potentially)
• What does it mean that the 24 volt input voltage is greater than the Vgs MOSFET IRF540 rating in the datasheet? Jun 16, 2020 at 9:39
• It means that the N channel IRF540 transistors will likely be damaged and go short circuit (normally). Jun 16, 2020 at 9:40
• Not really because you have reached the limit for most MOSFETs at 20 volts. Your basic circuit is weak in that as the MOSFETs switch (change over) you will have a high conductance path where both MOSFETs are on for a short period in each half of the H bridge. If you were trying to power a device of a few watts then this can be remedied or lived with but not when the load is 150 watts. You need proper MOSFET driver chips for 150 watts that have anti-shoot-through features and also protect the gate from receiving excessive voltage. Jun 16, 2020 at 9:49
• @NurAqmarina That's not at all what Andy said. I'm staring to beleve this project is above your head. Can you try to reduce the complexity and design and test just one thing at the time? Jun 16, 2020 at 10:04
• @NurAqmarina you need a proper MOSFET driver with anti-shoot-through protection and not an opto. Jun 16, 2020 at 10:09