Improved version of the classic Tesla coil which, thanks to the use of actual technologies in power electronics such as isolated gate bipolar transistors (IGBTs) and the digital circuits such as microcontrollers, allows a degree of control until now unimaginable in this always fascinating device and can, for example, play pieces of polyphonic music in MIDI format.
Below I will explain some of my Dual Resonant Solid State Tesla Coil or DRSSTC.
The DRSSTC consists of a clasic Tesla coil, with its primary LC circuit and the secondary LC circuit (both tuned, being this the first resonance). However to control the current flow through them bridges of MOSFETs are used or, better still, of IGBTs that are controlled by electronic drivers designed to achieve a soft switching, right in the zero crossing of the primary current (English "Zero Current Switching" ZCS). Depending on the semiconductor used and the success of the driver in getting soft switching can work with several hundred amps peak currents. These drivers include a feedback loop of primary current (which could be considered as second resonance) as well as optical input to control the status (ON or OFF) of the device and is usually advisable a simple circuit overcurrent protection if we are to make the machine last us enough to be able to continue learning with it.
The following images illustrate the process of design and construction of what we call Coil 1, a modest system that has more than fulfilled its initial purpose which was not to serve as making contact with this technology and training in the understanding and debugging of circuit.
Based on a full bridge of 4 IXGH60N60C2 TO-247 Package IGBTs with nominal values of 75A, 600V, quite modest for these purposes even though they support 300A at 25°C in 1ms pulses. The truth is that they can work safely handling 400A pulsed with a low duty cycle and always looking for a soft switching. The use of heat sinks and, if possible forced ventilation, is imperative.