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Hi Sven,
The voltage divider is at signal level. I don't think power resistors are necessary for triggering the power thyristor. The break down voltage is still quite high for the alternative small signal thyristor which makes the voltage divider only decrease the voltage a small part.
"While the circuit is not reflective to the source, a lot of extra power is applied to charge and discharge the capacitors"
Charging the capacitor is real power when not given back the charge to the source. Only by giving back the charge makes the power reactive.
"Somewhere the power factor shifts again direction 1 but how do I find out?"
The power factor is given by which way the phase shift is. A power factor of one means no phase shift between the voltage and current. If the voltage increases/decreases before the current does the power is inductive reactive. If the phase shift is opposite the power is capacitive reactive.
"The stray field energy is also a problem I can not get rid of them so easily because this converter works with alternating polarities for the supply."
To keep stray fields low avoid current running through big loops. This can be done by twisting the wires in pairs. E.g. twist the forward current carrying wire with the return path to minimize the current taking a loop. The twisting makes the small loops left alternate in different directions thus canceling the fields from each other. Alternatively use coaxial cables which also cancel the fields.
Regards
Ole
---In [email protected], <s.friedrich@...> wrote :
Hello Ole, you mean a voltage divider that ensures that the auxiliary thyristor is not so high voltage is applied. This resistance creates additional active power and the capacitor discharges. While the circuit is not reflective to the source, a lot of extra power is applied to charge and discharge the capacitors. I do not know how Hector did that without additional active power. The circuit works perfectly as you can see on the scope images. Somewhere the power factor shifts again direction 1 but how do I find out? The stray field energy is also a problem I can not get rid of them so easily because this converter works with alternating polarities for the supply. I have to keep the power reactive. Greetings Sven
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Hi Sven,
Reconsideration
The small thyristor (SCR) can be used as a non-variable triggering device that trig at its breakdown voltage if the cathode is connected to the gate of the main SCR. The anode is then fed through the current limiting resistor to the opposite side of the capacitor for monitoring the voltage across the capacitor. Perhaps it even can be made variable by some resistor voltage dividing network like shown here if the pasting gets through: