STGAP2SMTR using we design phase shift full bridge convertor

[MD008]

Hello,

Please find the below image we design schematic and doing testing of this circuit. 

This design functionality is working but during capturing the waveform of current waveform and Xfmer input voltage waveform we observed high spike as highlighted in below image. 

Switching frequency: 20KHz

I/P HV: 60V

Phase shift: 50%

Dead time: 400ns

Please help me out to resolve this issue.

Let me know if you have any questions.

Thank you.

[AScha.3]

Hi,

You are using MOSFETs to switch, so you see probably the effect of switching off a forward conducting back diode, typically they are relatively slow and produce an high current to switch them off.

[MD008]

Thank you for your quick answer.

Can you please suggest solution for this?

[MD008]

What will be the solution to make low spike?

Highly appreciate if you will be suggest the solution. 

Thank you.

[MD008]

What will be the solution to make low spike?

Highly appreciate if you will be suggest the solution. 

Thank you.

[AScha.3]

There is no simple "solution" for this.

You can:

- change your circuit (resonant load, search for LLC circuits)

- use switches with better/fast back diode  (SiC or GaN , or try adding schottky back diode)

- reduce dead time, adjust for "sweet spot" (dead time so short, the back diode has no time to switch ON - but very critical to adjust....mosfets will blow up with cross-conduction, if dead time to short)