DRSSTC 2


Topload 13"x4" spun aluminum toroid from John Freau
Secondary coil 4.5"x12" 1140 turns 28AWG
Primary coil 5.5 turns 1/4" copper tubing
Tank capacitor 0.1uF 6kV, 3 series 2 parallel strings of 942C20P615K-F
Resonant frequency 150kHz
Peak primary current 500A
Bus capacitor 2x 2800uF 250VDC
Bus voltage 370-400VDC
Bridge IXGN60N60C2D1 half-bridge
Controller EVR driver
Maximum spark length 36"

 

DRSSTC 2 started its life as an EVR MiniBrute, but it quickly came to an end after <10 minutes of total run time. The IGBT gates failed, dumping the energy from the bus caps into the GDT. The ferrite core exploded and the copper wire used to wind the GDT melted. The failure also took out a couple clamping diodes on the output of the driver.

   

The SOT-227 half bridge design was then discarded due to the high cost of each module ($25 each at the time) and the general poor bus layout. A new full bridge was built using parts from two oneTesla boards. The bridge was cut out from the rest of the PCB and thrown on a heatsink. The bridge had 4 FGA60N65SMD TO-247 IGBTs. The original EVR driver was repaired and used again.

 

This bridge proved to be severely underpowered and produced no sparks before hitting the 300A current limit. Because of the low impedance primary, the current in the primary rings up very quickly, and a lot of current is required to get a spark formed.

The coil was then left untouched for a few years and revisited in 2017. A new half bridge was constructed using a CM200 brick. The EVR driver was replaced with a UD2.5 which has phase lead.