Sure? A high frequency converted down to a low frequency?I need that high frequency to be converted down to mains frequency.
No. The RATIO will be the same.but as a high frequency transformer its turns ratio would be different than a typical mains transformer,
No. There will only be 50Hz at the secondary if you put in 50Hz at the primary.yet the secondary side of the transformer still has mains 50 Hz across it
the transformer is there just for voltage step up, the main idea is for one way power flow. Normally 50 Hz or any other frequency flow through a transformer both ways but here the power comes from a coil generating as you said SPWM which I understand is just a better way of doing PWM for a fixed frequency sine wave to result in less harmonics right? So essentially due to the high frequency high inductance primary loop, power can only flow from the high frequency side into the low frequency side but whatever power is at the low frequency side cannot flow back into the high frequency generating loop due to it having a high reactance blocking practically all low frequency current down to very low valueHi,
so this is not "general PWM" but "SPWM". (you need to say this)
SPWM is low frequency sine modulated by with high frequency PWM.
If you want a sine, you just need the low pass filter. No extra transformer neded at all.
And exatly this is done billion times already. Nothing new so far.
So what exactly is the question/issue?
Btw: your LPF needs a third leg to the bottom line. Especially because the load impedance of the filter varies in a wide range.
Klaus
so a quite usual low frequency transformer?the transformer is there just for voltage step up,
Same is here.Normally 50 Hz or any other frequency flow through a transformer both ways
I don´t know what "fixed frequency sine wave" means.a better way of doing PWM for a fixed frequency sine wave
Power flow is form source to load.So essentially due to the high frequency high inductance primary loop, power can only flow from the high frequency side into the low frequency side
The only part that really is frequency dependent is the filter, not the transformer. (for it´s operation principle)low frequency side cannot flow back into the high frequency
If there is a "blocking part" then it acts both ways.having a high reactance blocking practically all low frequency current down to very low value
Why purely theoretical? Apart from some possible misconception on my part on where to best put the LPF, otherwise I believe what I showed in my drawings is a high impedance AC current source. The left side coil generates high frequency PWM square wave that then after filtering leaves only the 50 Hz low frequency. The left side coil might be of low impedance itself as it is a high frequency coil with only a few turns, but the series capacitor is also of low capacitance. 50 Hz power through a 1uF capacitor for example would be limited to mA at best. So what did I say wrong when I stated that this has to be a "one way" power flow schematic. The power realistically can only flow from the high frequency side to low frequency side because the low frequency will experience a high impedance load if it tries to pass through the left side coil and capacitor forming a series LC.The "one way power flow" or "low frequency current blocking" concept doesn't work, as already stated by others, except for the purely theoretical idea of making a high impedance AC current source. Practical inverters are either voltage sources or current sources with very limited impedance, e.g. Z-source inverters.
One way power flow of a converter has to be achieved by controller design, generally speaking by setting the converter AC voltage so that the output current has intended phase and magnitude.
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A simple time-continuous equivalent circuit is comprised of converter output voltage, grid e.m.f. and a connection impedance, the sum of grid impedance and converter output impedance. The connection impedance is mostly inductive, current is set by controlling the voltage drop along the connection impedance.
You are analyzing a fictive circuit not a real converter. I conclude that you didn't understand the explanations given in the above discussion. Specifically there's no way to block low frequency reverse power flow by a filter or blocking capacitor, it would also block forward power flow.The power realistically can only flow from the high frequency side to low frequency side because the low frequency will experience a high impedance load if it tries to pass through the left side coil and capacitor forming a series LC.
Also @KlausST Ok. I get it, the 50Hz would be present on the primary loop on the left side , although not much would get through the series capacitor due to it's high reactance.You are analyzing a fictive circuit not a real converter. I conclude that you didn't understand the explanations given in the above discussion. Specifically there's no way to block low frequency reverse power flow by a filter or blocking capacitor, it would also block forward power flow.
Your posts don't yet show a way to implement a high impedance AC source.
The switches are not within this diagram. The coil on the left side loop is a generating coil, current is induced in the coil. You can disregard the LPF block for reasons already discussed here.Can you show principle diagram of the intended circuit, showing at least pwm switches up to output terminals?
Load = R (usable power)the whole primary loop is when the transformer load is highest
Well at resonance the reactance of the series LC becomes zero and only the ohmic passive resistance of the wires/coils are left.Hi,
Load = R (usable power)
Resonance = LC.
Do you notice there is no "R" involved in resonance.
Indeed R is somehow the opposite of resonance.
It rather kills a resonance. In the meaning of: on a resosnce case you usually get high voltage .. if you add an R usually the voltage becomes lower. Independent whether the R is in series or in parallel.
For sure one can use resonance to (optimize) transfer power from A to B. But from your description I can´t see how.
Klaus
Well if the generating coil on the left side generates 50 Hz current in the primary left side loop, then if I want maximum power transfer at maximum achievable efficiency then I need to factor the inductances of the 3 coils such that in total they resonate with the capacitor at 50Hz. Two of the 3 coils have fixed inductance but the transformer primary inductance changes with load, therefore I factor the other two coils such that resonance is achieved when the transformer primary inductance is at it's lowest.But from your description I can´t see how.
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