transformer spikes

[darla1]

hi all

I am working of H-bridge dc/dc converter as my battey charger here i designed the transformer for a input range of 120V dc to 440Vdc and the output is 15V.

i am facing the problems like high peaks across the transformer. to reduce the peaks i added some airgap for the transformer, here the pulse is not changing across the transformer, but peaks are controlles well.

can anybosy help me...on this. I am using ETD44 and F is 100Khz

thanks
Ramesh

 

[dknguyen]

CHeck out this thread:
https://www.electro-tech-online.com/threads/calculation-for-snubber-value.36753/

 

[darla1]

dear dknguyen

i dont want to use snubber .... is there any alternative

thanks for ur responce

 

[darla1]

please see this

1. I am operating the dc/dc H-bridge converter from 120Vdc to 650Vdc
(nominal is 325Vdc) to get output 15V regulated output.

2. for this I am using ETD 44 transformer with a turns ratio of
0.15(primary inductance is 2.5 mH).
3. When I am operating this I am getting high peaks across the transformer
and controlling is good.

4. I added (2 microns) air gap to eliminate these spikes (10 times of
input), by adding the air gap I am able to reduce the Spikes but the
waveform is like pure Square Wave at all the duty cycle (i.e. when we
decrease the Pulse width of Gate the waveform width of transformer has to
decrease but this not happening here)

This is the problem I am facing....

In my observation when adding the air gap transformer is not able performs
well.....please help me in this regard.

 

[Hero999]

In what way does it not perform well?

Introducing an air gap will reduce the inductance slightly; have you accounted for this?