In one of my previous posts we discussed a 555 pure sine wave equivalent inverter circuit, which was collectively designed by Mr.Marcelin and me.
The email from Mr. Marcelin:
The following assembly nearing completion, based on the 555 (SA 555) and CD 4017
On my first try, with mosfets, earlier this year, I used IRL 1404 which Vdss is 40 volts. In my opinion insufficient voltage. It would be better to use mosfets with a Vdss at least equal to or greater than 250 volts.
In this new installation, I foresee two diodes on the transformer windings.
There will also be a fan for cooling.
mounted by 10 in each branch, like
The final circuit design of the 3 kva modified sine wave inverter should look like this:
Note: In order to safeguard the transistors from a thermal runaway, mount the individual channels over common heatsinks, meaning use a long single finned heatsink for the upper transistor array, and another similar single common heatsink for the lower transistor array.
Mica isolation would be fortunately not required since the collectors are joined together, and the body being the collector would get effectively connected through the heatsink itself. This would actually save a lot of hard work.
In order to obtain maximum power efficiency, the following output stage is recommended by me, and must be employed with the above explained PWM and 4017 stages.
Note: Mount all the upper TIP36 over a larger finned common heatsink, DO NOT use mica isolator while implementing this.
The same must be done with the lower TIP36 arrays.
But make sure these two heatsinks never touch each other.
The TIP142 transistors must be mounted on separate individual large finned hearsinks.