LETS DESIGN A MAGAMP SWITCHER

Shown above is a diagram of a square wave driven audio amplifier.. I give credit to the website below.

http://sparkbangbuzz.com/mag-audio-amp/mag-audio-amp.htm

Schematic Robert L Peever Sept 2014

The above is my schematic of an idea that i have been fooling around with. I will add pictures of the magnetic amplifier coils that i put together at a later date if it is desired.May not be new but i have not seen it exactly like that, lets find out.

When i seen this it reminded me of some things that i had played around with when i was working at a place called Fisher Engineering. Clair Fisher graduated from PU in Indiana in 1919. The year I worked there was 1980 more or less. This man did some bizzar things with inductors. Among these was a 480 Hz power supply using three magnetic amplifier doublers off of the 60 Hz. line. The reason for this was that our 400 Hz. generater was off line and ineeded to do some testing on an mill spec instrument. At that stage in my career for what ever reason that made a large impression on me. I had never seen 60 Hz going in and 120 Hz coming out of an inductor. Well he designed these inductors such that power was transmitted through the control winding and a 90 degree shift was produced for the second coil such that double the frequency was produced in the control winding.

I will not do any design discussion about what goes on in a magnetic core but I did decide after thinking about that for a long time there there was something going on in that core that I could not quite understand. Probably i still don't understand entirely but something does go on that seems to defy logic. Oh yes i sat down with him and he pulled out his 12 inch circular slide rule and described how to figure the size of the capacitor and the windings simple enough using ohms law and explaining that two sine waves 90 degrees displaced and added together produces 120 Hz. He would not say anything about magnetic priority or what is truly happening in that core regarding flux he simply said what do you mean. Well you can go to the internet and type in magnetic amblifiers and they will talk endlessly about the math and the way they are wound and endless configurations to do some pretty amazing things with out tubes or transistors.

I mentioned this to my friend who is a physicist and he went and got some 24 volt transformers and hooked it up and he said it worked fine. I asked him where did he get the square wave and he said he did not he simply hooked 60 Hz power to it and it worked fine, with in those limits of course.

So I was working at the time and they had some torroid cores around and there was a torroid winder there so i put 100 turns on both of those cores distributing it evenly arround the core. I wrapped them and put them together and wound a winding around both of them, another 100 turns this time using a bobbin. I put them on the bench and did everything i could think of with them and they worked fine. Couple of things i will mention are that putting various signals into the two series windings were added together perfectly and power was transmitted. I connected the two series windings together aiding and watched the inductance vary as I varied the dc through the control winding. I also modulated a sine wave using the sine wave in the control winding and produced PWM with one lash up and integrated that into a variable dc.

Well because of time and physical and parts and the fact that every time i said the work magnetic amplifiers at work people walked away from me and i was told not to say that word again. Anyway this is where the physical aspect of it stopped but I did draw the circuit that you see above on a napkin and showed it to the physicist that I mentioned above. I was told from Linkedin that first showing is recorded here for legal purposes. I hereby put the name of Robert Peever on that drawing and date is Mid July 2014.

I will go through how i think this thing works with out trying to explain what goes on in the core of the mag amp. I designed the bridge with IGBT's. when the positive leg pair is turned on current flows through the mag amp and is controled by the inductance in that branch. It ramps up as long as the IGBT is on at the rate controlled by the inductance set by the control winding. We can use a switching frequency fairly high here since it is only one frequency and there is no PWM or dead time. When the IGBT turns off the voltage on that end of the inductor falls off to the diode connected to the negative buss and discharge current flows same direction but decays during off time. The amount of current flowing will depend on the control voltage on the control winding. the exact same process occurs in the negative branch 180 degrees out of phase in the control winding.

Now in all of the text that i have read about the operation of a mag amp there is usually dc added to the control winding. It is necessary to control the point on the historesis curve because you don't want to operate into saturation or maybe you don't want to cross zero flux. I am not going to get in to a discussion about what goes on in there with the flux or ampler turns or flux priority. But there are rules that seem lto apply. One is that that control winding does not end up with any voltage output because the series windings are out of phase in the core. The control winding needs to be many turns so that 1 amp is many ampier turns and this is where the gain occurs. Core materials hae new options including square historisis curves.

Now what are the good things about this circuit. well its push pull so second harmonic is suppressed and the ripple frequency is further reduced because they are out of phase. The output is very clean because of this. the output can be hooked in series with others or used at full voltage within bridge design. The input current is constant except for change over and it may be necessary to compensate for over shoot or diode disconnect or what ever happens when you start to increase the dv/dt. This circuit may exhibit some of the properties of a generator regarding power factor correction and so forth.

Well there it is its out there. What do i want with it? Well of course i would love to get the patent and make a fortune from it but to be honest getting financing because its on old idea or its a radical idea has become so complex and expensive and pretty much useless once all of that is done. So i put it here and someone who has the stuff to hook it up and make a lot of measurements on it regarding efficiency and heat in the cores and so forth and see if it has a practical approach. What ever comes my way or anyone elses way in terms of a job or perks or what ever it takes for me to get along for the few years i have left. But most of all its a great feeling to see it working like one of my ideas that you have in your living room like the on screen readout on your TV that was my idea. Well you can believe it or not but that happens to be true. There is a whole story behind it that maybe should be told. But it does give you an idea of my feeling about ideas and who should benefit from ti with a minimum of ego involved. Yes money is a consideration but what has happened is not what i would call equitable and you have to wonder how many ideas fall by the wayside because of the system.

So i have a couple of those magnetic amp inductors setting around, anything any one else has to add. There it is world does it fit you figure it out in your own head, I think it does. I have gone on to a more exciting idea that needs proof of concept I am trying to gather parts. I don't have a shop any more or parts laying around. let the discussion begin.

Anyone wants to finance or put it on line this project or the next one, that is much more exciting I am available. Robram47@msn.com