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On Sep 7, 10:18*pm, Grumpy The Mule wrote:
It would be interesting to know the phasing of the transformer windings. Since it's voltage fed and there is no output inductor I would have guessed it was a ZVS flyback supply with active recovery of the leakage inductance energy. *A flyback is a constant power output topology by nature, so it's a natural for powering a magnetron. *But the waveform in the pdf concering the oven looks like a forward converter. *Maybe it's the result of the active clamp? I've designed flyback converters with outputs of a couple KW for TWT tubes but they were hard switched with multiple rectified outputs on the transformer stacked series to reduce the voltage stress. *At low output voltages a flyback is unsuitable for much power because of the high peak current developed in the rectifiers and switches. Sorry to babble on about this but I found the oven circuit fascinating. *The white goods guys are very clever. I hope you can get it working as a power supply for your amplifier. I have my doubts about using it as is too, but I think there is a lot to learn here. For example I hae never used IGBTs before and already I hae begun to learn. This may also be a chance for me to learn to design a transformer that will work at 30Khz. I was thinking of using push-pull driver on the primay of the transformer instead of the flyback circuit. Something similar to a PC power supply. The Panasonic power supply is definately designed for constant current. The input current is monitored through a current transformer and this applied to the contol circuit so that a decrease in input current results in a greater output voltage through pulse width modulation. The plan is to take this feedback from a coil on the output transformer instead of the current transformer and apply it to the control circuit. I am hoping this will turn the constant current power supply into a voltage regulated power supply. Also the output rectifiers use a voltage doubler. My plan is to change this to a full wave bridge, I think David mentioned this too. I may not get full legal power out of it but maybe I can power a couple of 4cx250s. That wouldnt be bad for a $50 power supply. Jimmie |
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