Hi All
I am currently trying to simualte/design a power converter that takes in 12V and outputs +175V and -175V AC sinusoidal output (delivering a maximum power to the load of ~40W a little less than this) Can anyone suggest a good topology that I should use for this any recommendations are warmly welcome I just need a starting point to work from. The output AC waveform will also need the ability to change frequency.

Kind Regards

Art

 

You should consider a flyback converter. I think you will have a hard time with this project because you will need inductors that can work at high power levels without saturating.
Back of the envelope:
40 W of output power at 80% efficiency requires 50 watts of input power
50 watts at 12V is just over 4 Amperes. Your inductors will need to handle twice that or 8+ amperes.
This is a reasonably tall order. Good luck finding components.

 

You should consider a flyback converter. I think you will have a hard time with this project because you will need inductors that can work at high power levels without saturating.
Back of the envelope:
40 W of output power at 80% efficiency requires 50 watts of input power
50 watts at 12V is just over 4 Amperes. Your inductors will need to handle twice that or 8+ amperes.
This is a reasonably tall order. Good luck finding components.

ok I will look into this is it possible to change the frequency of the AC output with this topology?

 

ok I will look into this is it possible to change the frequency of the AC output with this topology?

Yes, it is. Most flyback converters work at a significantly higher frequency so the magnetics can be smaller.

 

I assume what you want is an AC sinusoid that is 350 volts peak-to-peak centred on zero.
You need to be more specific about the range of frequencies you want and you have to know what you want in terms of regulation - if the AC waveform must be precisely regulated in amplitude it is considerably more complex that simple compensation for DC bus voltage which is more complex that assuming the 12 volt supply is regulated and that the AC amplitude will be acceptable if it is in proportion and loading effects are ignored.

If I were doing this as a one-off I would look at using two class-D amps with the primary of a transformer as a bridge-tied load - either an iron core transformer operating at low frequency, if it would handle the freq range required, or a ferrite core transformer operating at high frequency with the filtering on the secondary side which would allow a wide frequency range (there are some hooks here, so it would need be evaluated carefully).
[Edit - I didn't put that very well] When I said "low frequency" I meant at the actual frequency of the sine wave - filtering the PWM waveform of the class-D amp output before applying it to primary side of the step-up iron core transformer. The transformer primary winding would be connected just as if it were a loudspeaker. When I said "high frequency" I meant actually coupling the PWM signal through the ferrite core step-up transformer and then filtering it to recover the sine wave on the secondary side. This would require removing the usual small filter inductors and capacitors at the outputs of the class-D amplifier.

Producing ±175 VDC with a flyback converter is straight forward. Producing an actual AC waveform with flyback is far from straight forward.

 

you can try the PI (power integrations) forum it is mainly dealing with the topic, as well they make ICs for all kinds of switching supplies