Fast retrigger path What threshold level we need for the fast trigger path?

Simulations - Old transistor Schematic Simulation Trigger path Current schematic To IGBT Retrigger path Fast retrigger path : MOSFET Reference 2N6782 Continuous drain current 3.5A Pulsed drain current 14A Turn-ON Delay Time 15ns VGS(th) 2.0-4.0 V This pulse has the voltage as variable parameter.

Vgsth for old and new Mosfet Mosfet IRF7452 (New schematic) Mosfet 2N6782 (Old schematic) Voltage at the secondary of the pulse transformer Vds of the Mosfet Input voltage = 4.1V Input voltage = 4.2V Input voltage = 6V Input voltage = 6.1V Complementary information : -> Length of the pulse = 6 us for both

Switching time 100ns between the input pulse and the Mosfet switching Trigger path Retrigger path 100ns between the input pulse and the Mosfet switching Indicator Circuit Propagation delays IC4 HEF4072B 55ns IC3 HEF4528B 70ns IC1 HEF4049 25ns T1 2N6782 15ns   Total 165ns

IPOC waveforms Complementary information : -> The values given below must be multiplied by 10 MKD RTRIG.B1 MKB RTRIG.B2 Input signals to the PTM. Very low voltage (between 3V and 4V)

MKBH – data coming from Viliam MKBH: Ch1,2 = Cts1, Cts2; Ch3,4 = retrig OUT a,b left: normal pulse at 7.1 TeV with late discharge of accumulated charge right: big sparking and its coupling to RB output (> 6V peak)

Improvements Change the MOSFET in order to reduce the switching sensibility(Vgs). Replace by another with higher Vgs. IPOC : Increase the voltage level in order to be superior to the value of sparking(>6V) => It will be more judicious to have an important difference between the voltage sparking (>6V) and the threshold. If we have to chose between 7.5V and 10V, 10V will be more careful.