DIYOSI notes

Roswell Bob

Solar Enthusiast
The DIYOSI power board is coming along. I changed gate drivers to a better TI part with good undervoltage protection, and added negative gate drive for the Sic Fets. Looks like Sic is the best player right now. I have not decided how to sense bus current. I am using a HP Isolator and a wide array of smt resistors now, but will also take a look at Hall Effect sensors. It depends on how the layouts looks with both.

The power board is 75mm x 125mm. Like a 3x5 index card. The inverter section will be composed of modules. Each module will be just under 4” wide. Two inverter modules will be connectable in series or parallel. Split phase if you like. 50Hz/220V is doable. The 75mm x 125mm PCB will be resting on the heatsink to keep the PCB tracks cool. Gap pad or Kapton film might work to get the heat out. Board will be 4ayers of 4oz or 6oz copper.

I expect these modules will be rated at 5kW continuous with a very brawny overload capability. I actually think these modules will each do 10kW, but I’m not going to say that out loud.

I would like the dimensions to be 8.5” x 11” so it will fit in a file cabinet. Two modules next to each other will fit on 8” wide extrusion. I did a kilowatt of audio in a cigar box 30 years ago so time for another little challenge I suppose.

Heatsink will have a crossflow blower on top blowing down. That puts input and output terminal blocks at the bottom. Just flip unit upside down if you want it the other way.

I have had a couple of DIYrs mention doing control boards so we see. Many different control options so maybe somebody will want to do their own control. Or GitHub could host project as suggested. I have homebrew design which uses 8pin pic to generate PWM. I am pic noob so I will run my control board and see where it goes. It has hardware trip circuits and hardware current limit. Leds announce trips to user. Somebody may want to do DSPic or other controller with lots of bells and whistles and display and fancy algorithms to start big compressors and pumps and so forth. As I said my work is open source so anybody can have what I do.

I have decided to put hooks in this inverter to run at 1.88mhz. Some of you may know why I have picked this particular frequency. I have run a full bridge Phase shift ZVS here before and got very good reports. This inverter could also be used to make a 10kW audio amplifier if someone needed one.
 
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