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Totem pole PFC using GaN on LTspice

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Riya

New Member
Hi..
I am trying to simulate a Totem pole Boost PFC circuit using GaN switches on LTspice. I am unable to achieve the DC output and the circuit is also not boosting up the input voltage. Any suggestions to make my circuit work will be a great help. I have attached my circuit here.

Thanks in advance!
 

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simonbramble

Active Member
can you explain how the circuit is meant to work? Few of us understand how GAN fets work. The transformer made up of L4 and L5 seems to be working (I expect a turns ratio of root(5). The cathodes of D2 and D4 should surely have an ac signal between them? You have got them shorted out. Could this be the reason?
 

ci139

Active Member
you seem to have ideal transistors that may cause your simulation to exceed ??? energy conservation laws or simply hang . . .
other than that inside >> GaN_LTspice_GS66516T_L2V2.lib ::
*** - - - - - - - - - - - - ↓ - - such models (where you use node voltage read e.g V(+node,-node)) require extra care to do anything with (not that achieving it would be impossible) ...
bdtemp 0 TJ I = (if(v(drain,source)>0,
+ (cur*(0.8*PWR((v(TJ)-25+273)/300,-2.7))*log(1.0+exp(26*(v(gate,source)-(7.9+0)+6.2-0.000*(-25))/slp))*
+ v(drain,source)/(1 + max(x0_0+x0_1*(v(gate,source)+4.1),0.2)*v(drain,source)))*
+ v(drainin,sourcein),
+ (cur*(0.8*PWR((v(TJ)-25+273)/300,-2.7))*log(1.0+exp(26*(v(gate,drain)-(7.9+0)+6.2-0.000*(-25))/slp))*
+ v(source,drain)/(1 + max(x0_0+x0_1*(v(gate,drain)+6.1),0.2)*1.0*v(source,drain)))*
+ v(sourcein,drainin)))
*
*
*** ... it is mainly coz the integral continuity of the device "physics" as when there's fast parameter polarity change from say +1V to -1V -- the model must cover the events as if this skip "smoothly" went through the ±Zero Volts . . . - - - . . . which might be impossible if such would also significantly alter the external circuit that lays outside the model(-'s scope) . . .


it may be this it's not a problem here . . . (just a potential one) ???

this seems like a complex task (- a lot of work before you can expect) to achieve anything
so it's better for you to start from simulating each component and/or a functional block on it own first
to get acquainted with their specific Spice behavior (or whether they do simulate in a first place .... there're some op-amp models that seem to have a "backup battery" built in :eek: - so you could power an entire grid from them ???)
 
Last edited:

Riya

New Member
can you explain how the circuit is meant to work? Few of us understand how GAN fets work. The transformer made up of L4 and L5 seems to be working (I expect a turns ratio of root(5). The cathodes of D2 and D4 should surely have an ac signal between them? You have got them shorted out. Could this be the reason?
Hi ..
Thank you for looking into my circuit..

The circuit is meant to work like an AC-DC boost converter (like in a bridge less boost PFC) here the 2 GaN FETs switch complimentary at 100 KHz and the two Mosfets M1 and M2 switch complimentary at line frequency (as the rectifying switches). The diodes D2 and D4 (the bridge) are used for bypassing the inrush current and charge the bulk cap in the first cycle. I see the inductor current going very high upto 400A which should be:( even after adding the bypass diodes.

Thank you.
 

ci139

Active Member
D1,D2,D3,D4 -- ????

Why is there 190uH on the gate of U2 & U6?
-- U2,M2 . . . U2 won't close no matter the "point" G_H does +
+ PC817B opto has max transition frequency 80 to 135 kHz and that with 50% (or -50dB 3%) output !!! in addition to this 190µH -- you obviously didn't plot the Nitrofets side ...
 
Last edited:

ronsimpson

Well-Known Member
Most Helpful Member
I changed L6 & L7 from uH to nH and the gate waveform looks much better.
The L3 current looks OK.
upload_2017-6-21_17-33-52.png
 

sneha thakur

New Member
Hi Riya

I am new to Ltspice and I am also trying to simulate GaN based totem pole PFC. Can you please help me in understanding your circuit.
 

sneha thakur

New Member
Hi..
I am trying to simulate a Totem pole Boost PFC circuit using GaN switches on LTspice. I am unable to achieve the DC output and the circuit is also not boosting up the input voltage. Any suggestions to make my circuit work will be a great help. I have attached my circuit here.

Thanks in advance!
Hi Riya
I am new to Ltspice and I am also trying to simulate GaN based totem pole PFC. Can you please help me in understanding your circuit.
 
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