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Sine wave power inverter ac output fluctuate between 210~230V. Any idea what is going wrong?

Recently build 300w sine wave inverter. First power on without heatsink it fried off push pull mosfet. Replace mosfet and attached heat sink, repower blown fuse and output mosfet shorting. Replace fuse and mosfet, power up again. Resulting with fluctuating output between 210VAC to 230VAC. Check secondary dc voltage also fluctuated. Any idea what was went wrong. Use KA7500 as input driver and egs002 as output driver.

Reference - please refer https://www.instructables.com/id/Ectable-PCB-With-Eagle/

Thanks in advance.

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tplim (author) 3 months ago

@Josehf Murchison, @steveastrouk and @ Downunder35m

The first test was done with 2 fans. One attached to driving stage and the other attached to output stage. Resulting 20VAC fluctuating.

Today, do another test. getting AC output fluctuate around 5VAC once remove either one fan from driving stage or output stage.

With fan on driving stage getting 220VAC to 225VAC the max output. Increased output the inverter shutdown. And fan on output stage getting 230VAC to 235VAC,increased output inverter shutdown too.

Run the inverter on 60W standing fan with either fan attached, getting 214VAC to 217VAC.

Any idea?

IMG_2843.JPGIMG_2844.JPG

Got a schematic?

What are your mosfets?

What is your mosfet driver?

If you are blowing mosfets I am wondering if you are over powering them, or under driving them.

tplim (author)  Josehf Murchison3 months ago

@Josehf Murchison, @steveastrouk and @ Downunder35m

Just to update, before proceeding build 1500w as per below link I build 300w to verify the working condition of this circuit.

Link to schematic

https://www.instructables.com/file/F4Q2P5YISXX7S5X...

irf3205 was use for driving and 47n60 for power.

Thanks

IMG_2837.JPG

Your screen capture circuit simulator circuit is almost impossible to read.

But I can see one of your problems.

Stacked circuits no ballistes.

One set of your stacked circuits is doing one thing at one voltage.

The other stacked circuits is doing another voltage.

Your feed back circuit only influences one of the five stacked circuits.

tplim (author)  Josehf Murchison3 months ago

@Josehf Murchison

This is the only board that I powered up with fluctuated output.

+1 Absolutely.

2+
Mosfets usually blow because they are not driven or not protected properly.
But unless you provide all vital details we can only provide guesswork as anwers.