Hello, just want to share my highest power consumption project to date . It is high power dual resonant solid state Tesla coil. It is capable creating high energy bursts at 50kHz 800V and 5000Apeak. For now i was running only from 3 phase, so input was limited to ~500V and over-current protection was set at around 3000Apeak.Theory of operation is very simple. I have full bridge with series LC circuit that is resonating at 50kHz, and secondary coil have slightly higher resonant frequency due to large inductance, capacitance between windings, and huge top load that acts as capacitor. So interrupter at very low duty cycle enable full bridge via optical fiber to generate resonant frequency, and current start to rise exponentially with every single period, and it is disabled via interrupter or current protection, because IGBT can't handle 3000A for long time. Coupled with gate overdrive and low duty cycle, IGBT are quite happy generating small bursts at 1-1000Hz repetition frequency.
Let start with DRSSTC base. The design had changed very little from original Nicola Tesla coil, But many parts is made from Plexiglas or PVC to get better HV resistance , and looks as well. And i used 1cm diameter flexible copper tubing from primary coil. And even from short active period, it gets quite hot
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Second little job is to make interrupter. As name suggest, it create enable pulses to power electronics, so i can regulate average power. Also it is necessary for IGBT silicon to give up heat buildup during off state. Maximum on time is 350us, and maximum repetition rate is 1kHz. And because it is very high voltage system, i used optical fiber to send pulses, because i don't want to be electrocuted while i get strike from top-load to cable that runs to my hand, also it helps with electromagnetic interference, sine it is basically very high power transmitter, only antenna is not that good
It is simple 555 generator, one for on time, one for off time: and goes to IR laser diode that connects to fiber-optic cable
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Now comes a bit more fun part, is driver electronics. Construction is modular to save headaches and mistakes can be fixed easer (but it is none for now). First easy step is peak current indicator, i am using simple audio power level indicator based on LM3914 , and low pas filter to from very short pulses to delayed pulses. and different color led (4 greens, 3 amber, and 3 red ) to show how much i am pushing this bridge , since peak power depends on ON time, and average power depends on on time and repetition rate.
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Now because i am using solid state gate drivers, i need many isolated power supplies, to be correct, one for main electronics, 3x bipolar +18 ,0,-5V for gate drivers, and two for main current and voltage indicator, and one for soft start circuit, that charges 4700uF 800Vdc. Capacitor bank made from best grade Rifa capacitors , since i need very large pulse current . SMPS is made on IR2153, and it is generating 3 galvanicaly isolated power suplies, two for high side drivers, and single for low side igbt drivers. And i use 7818 and 7905 to make it stable, since output is not regulated due to IR2153 controller. And it works very well.
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Main generator is simple ZCS controller with current feedback, over current protection, and that about it.nothing fancy .
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Gate drivers have saturation detection, and is driven by Gate transformer from main controller, and i am using UCC32321 to generate signal , and amplifying with pair of N-P channel mosfets to get very fast rising and falling edges on IGBT.
Since IGBT has 3uC gate charge (while IRFZ44N has only 0,06uC gate charge, so you get the idea)
So now what is left to do is to bolt everything on main heat-sink, make a nice aluminum box, and that it ! . Oh yea, lot of wiring needs to be done...
And aluminum box, designed in CorelDraw, and cut with water-jet CNC machine, assembled by rivets and metal epoxy with L shape profiles to give strength. And it looks very good
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This box still waiting for powder painting, i guess i will make it happen in summer
Now, some nice pictures to show how it works
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More about this project witch schematics and so on could be found here: