Being stuck on the road I don't have a lab/shop to perform actual experiments, so I spent some time designing a new HV pulse controller for the dual purpose of having a 1-4 phase HV controller onhand for AVEC work as well as the dual-pulse experiment and some related coil tests.
The controller is rated to 1500-1700v, at least 100w per channel, with what should be a decent switching speed and repetition rate. Nowadays I like to use metal oxide varisters across the source-drain to help prevent spikes+surges. It forces some derating but tend to make the FETs last indefinitely. It is designed as a lowside driver but swapping a battery or isolated source for the gate driver will turn it into a highside driver.
Each iteration of these is a bit of a lessons-learned as small variations in trace size/width, filtering, etc all have an impact on systems like this.
This sounds good for the Tetrahedral Spherics device, which is only 3 phases (channels), and a minimum of 300v pulses. If using MOSFETs for the AVEC, you may want to use a higher voltage range. The slower the switching time, the higher the voltage has to be to have a voltage drop of at least 1000v across the coil. At these voltages, a damper (I use RC and a flyback diode) is a must and I had to determine values manually. You will also have to contend with the Miller Effect with the switched HV trashing your gate pulse. This bad effect doesn't happen at the same parameters for each device. I had two of six channels that were perfect, four were trash. I could slow down the MOSFET, but that is opposite of what you want for the pulse effect. I was using around 2500v with the 4.5kv MOSFETs that I tried to get the 1000v drop across the coil. This is well above the 1500v that Spherics used as an example. Note that he used SCR's, and not MOSFETs. Regarding the wattage, you only need the minimum current to make it work. More like 10W or 20W than 100W. I only recommend avalanche switching devices for the AVEC.I hope to have time this weekend to test my avalanche transistor pulser at 2kv... Note for HV o-scope probes: look at the frequency de-rating chart! BK Precision is OK to 2KV, above that look at LeCroy probes for 4kv and 5kv. I use the 1000:1 40kv BK Precision HV DMM probe, but Cal Test probe looks the same. Spherics said HV is cheap, and it is to generate, but the test equipment and components are not cheap at all!
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