This high voltage power supply was created as a replacement of a high voltage supply for SGTC (Spark Gap Tesla Coil) with MOTs or NST. It is the simplest halfbridge inverter. As a driver I used integrated circuit IR2153 and as a power switching elements i used IGBTs IRG4PC40W. To the IGBTs antiparallel diodes are connected because selected type of IGBTs has none internal diodes. Capacitor 10n 1000V protects transistors against voltage spikes. It must be the type for pulse operation. Operating frequency is 20-25kHz. Auxiliary voltage 15V for IR2153 is obtained via power resistor from the rectified mains voltage. Zener diode is not needed, it is already incorporated in the IC. Supply voltage of the half bridge is not filtered - filtering is not necessary for Tesla coil and in addition, at high power, proper electrolytes are expensive and bulky and bring problems with power on inrush and power factor. At the output there's a switching high voltage transformer with a voltage of 4 - 10kV. Voltage of transformer is increased by a doubler. The capacitor and diodes in doubler must be rated for sufficient voltage - capacitor of at least 1.5 times the voltage of transformer (6 - 15 kV) and a diode for the tripple voltage (12 - 30kV). Diodes must be fast type, you can make a serial combination of multiple fast diodes, eg UF4007, BA159 (1A 1000V). Capacitance of the capacitor is not critical, it should be at least 30nF for the output voltage of 8 kV, at least 5nF for the output voltage 20kV. Transistors and diodes are located on a common heat sink and are insulated from it using silicone pads. Thermal resistance of the heat sink must not be greater than 2K/W. It is advisable to use fan. HV transformer Tr is wound on a core with a cross section of 2.5 - 3 cm2 and the primary has 18 turns wound using 10 wires diameter 0.6 mm. Secondary depends on the required voltage. Eg. the output voltage is 12kV, then secondary voltage is 6kV. Such secondary then has 720 turns if wire diameter 0.3 mm. First, the primary is wound, then secondary. Transformer itself is not current limiter, so in series with the primary there's an inductor. It has 24 turns using ten wires dia. 0.6 mm and is at the core of cross section 1.7 - 2 cm2. Air gap sets the output current. Max. output current at 12kV is 208 mA.
