LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #14   Report Post  
Old September 8th 08, 05:21 AM posted to rec.radio.amateur.homebrew
external usenet poster
 
First recorded activity by RadioBanter: Dec 2007
Posts: 78
Default microwave oven inverter P.S. revisited

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
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Microwave oven transformers. terry Homebrew 6 November 4th 07 07:59 AM
microwave oven power supply Jimmie D Homebrew 28 August 12th 07 01:32 AM
Microwave oven transformers AndyS Homebrew 13 July 29th 06 10:53 PM
Microwave oven magnetron Frank Antenna 5 June 14th 05 12:50 AM
EM field og GSM and microwave oven in V/m ? Thierry Antenna 3 November 9th 04 04:57 PM


All times are GMT +1. The time now is 03:14 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017