This will be my next move:
Replace the 1n4007 diodes in the gate network with HER105.
This beacase the HER105 is a super fast diode compared to the slow 1n4007, trr of 50nS compared to 2000nSReplace the IRFP260 transistors with IRF640.
The gate capacitance of the 260 is 5200pF while that of the 640 is1300pF. The original UHU was designed for IRF540 which has a capacitance of 1700pF
Create a RLC snubber network on the output with these values:
R 25 Ohm
Since it seems to be nearly impossible to obtain this inductor at the time beeing this will be omitted and there will only be a RC snubber there for preliminary tests.
I dont think this should be any problem since the C is so small, of cause this will yeld higher dv/dt rates at the motor.
(frantically searching the web for diy inductor design formulas . . . )
Just to be clear, my goal is not a HP UHU controller just a high voltage version without the snubber heating problem and cross-conduction.
Ultimate goal: 150V 3 A