HF Transformer Connection Problem

Thread Starter

kapadokyali5042

Joined Oct 21, 2017
9
Hi friends,

I design buck converter.I want to connect HF transformer by end of buck converter circuit.I applied only HF transformer sinusoidal signal with signal generator.Hf transformer is normally working.When I connected HF transfomer with buck converter circuit, I have a problem.I added images about problem.If you help me,I will happy.

 

bertus

Joined Apr 5, 2008
20,227
Hello,

A transformer will not work with DC, C3 will make the signal DC.
For the transformer you will need AC to work.

Bertus
 

Thread Starter

kapadokyali5042

Joined Oct 21, 2017
9
I want to design micro inverter.Next I will add H Bridge circuit.Generally,HF transformer is used for micro inverter design.Switching frequency is 45kHZ.If I decrease C3 value,does is it work?
 

crutschow

Joined Mar 14, 2008
24,074
I want to design micro inverter.Next I will add H Bridge circuit.Generally,HF transformer is used for micro inverter design.Switching frequency is 45kHZ.If I decrease C3 value,does is it work?
No.
Decreasing C3 won't help. You are still putting DC (with some ripple) on the transformer (which acts as a short to DC).
As has been stated, transformers need AC.

If you want to built a micro inverter, then why not use a standard microinverter design?

And I suggest you study a tutorial about transformers, since you obviously don't know how they work. :rolleyes:
 

Thread Starter

kapadokyali5042

Joined Oct 21, 2017
9
No.
Decreasing C3 won't help. You are still putting DC (with some ripple) on the transformer (which acts as a short to DC).
As has been stated, transformers need AC.

If you want to built a micro inverter, then why not use a standard microinverter design?

And I suggest you study a tutorial about transformers, since you obviously don't know how they work. :rolleyes:
I want to design 250w microinverter.I bought HF transformer for it.I added its image.You can look it.Which converter topology should I use for microinverter with my HF transformer.
 

ian field

Joined Oct 27, 2012
6,539
Hi friends,

I design buck converter.I want to connect HF transformer by end of buck converter circuit.I applied only HF transformer sinusoidal signal with signal generator.Hf transformer is normally working.When I connected HF transfomer with buck converter circuit, I have a problem.I added images about problem.If you help me,I will happy.

Everyone else has covered that you can't feed DC into the transformer. maybe you should look up inverter topologies and transformer coupled flyback types. The transformer *AND* the buck inductor is more components than you need.

The buck topology has the same failing as the linear regulator emitter follower - failing short circuit dumps the lot into the load. Transformer coupled converters get DC when the switching device fails - as everyone has pointed out; that can't pass through to the load.
 

AlbertHall

Joined Jun 4, 2014
9,008
You might be able to use something as simple as the circuit below, though it is probably going to need parallel transistors to handle 250W and the capacitor value would be reduced to get 50kHz.
 

ian field

Joined Oct 27, 2012
6,539
Well, Is this HF transformer suitable for flyback converter topology?
Well I've done it a few times - My transformer came out of an 80s era plastic case computer. The original PSU was a flyback type blocking oscillator style.

Most such PSUs had bipolar transistors because the BO converter is rather more complex if you use a MOSFET.

The self oscillating BO circuit tends to find the transformer's favourite frequency and go there.

The current peaks will be high, so seeking out a low VCEsat power transistor is worth the effort. Budget for flyback pulses at least 5x V+ - it could be as high as 8x. Using a higher voltage transistor than you need can sacrifice gain figure.
 
Top