Necessary to scope bridge output?
nzoomed, Sun Jan 10 2016, 09:47PMI read that some people scope their bridge output when tuning their DRSSTC.
Is this necessary, or is it perfectly OK to just scope the gates on the IGBT's?
I dont have an isolation transformer, and i question whether or not my scope would handle the bus voltage.
TIA
Re: Necessary to scope bridge output?
Mads Barnkob, Mon Jan 11 2016, 12:24PM
You only need to see your primary voltage / current wave forms if you want to adjust a phase lead driver.
Other than that you can basically rely on simple mathematics as calculating the setting of your over current detection limit and tuning point from JavaTC, JavaTC will hit spot on and then just lower primary frequency until you have the longest sparks flying without hitting peak current limit too much.
If you do have a phase lead driver and use larger bricks that switch slowly, you need atleast a isolation transformer and maybe a home made current transformer to adjust it. Just remember that you might introduce some uncompensated phase shift in home made measurement equipment.
Best method is using a differential probe for the inverter output voltage and a industrial current monitor, that way you can more precisely set your phase shift.
Mads Barnkob, Mon Jan 11 2016, 12:24PM
You only need to see your primary voltage / current wave forms if you want to adjust a phase lead driver.
Other than that you can basically rely on simple mathematics as calculating the setting of your over current detection limit and tuning point from JavaTC, JavaTC will hit spot on and then just lower primary frequency until you have the longest sparks flying without hitting peak current limit too much.
If you do have a phase lead driver and use larger bricks that switch slowly, you need atleast a isolation transformer and maybe a home made current transformer to adjust it. Just remember that you might introduce some uncompensated phase shift in home made measurement equipment.
Best method is using a differential probe for the inverter output voltage and a industrial current monitor, that way you can more precisely set your phase shift.
Re: Necessary to scope bridge output?
nzoomed, Tue Jan 12 2016, 03:15AM
Im using loneoceans UD 2.7 on my coil, which obviously includes phase lead adjustment, im still reading up on exactly everything i need to do to tune the coil.
I will worry about it when i get there, but its simple enough to calculate the bus voltage as you say with the current transformer output.
Im still assembling everything. Ive got quite a bit to complete, but i hope everything works smoothly!
This will be my first DRSSTC build.
nzoomed, Tue Jan 12 2016, 03:15AM
Im using loneoceans UD 2.7 on my coil, which obviously includes phase lead adjustment, im still reading up on exactly everything i need to do to tune the coil.
I will worry about it when i get there, but its simple enough to calculate the bus voltage as you say with the current transformer output.
Im still assembling everything. Ive got quite a bit to complete, but i hope everything works smoothly!
This will be my first DRSSTC build.
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