UCC28950: Full bridge Boost converter

Hello Colin,

Thank you for your help.
I will get more details about the application and get back to you soon.

Best regards,
Tetsuro

Hello Colin,

Sorry, I have accidentally pushed resolved button...

What is the output power rating : max 1kW

What is the input voltage range (min / max) : min 30V, max 42V

What is the output voltage range (min/max) : min 290V, max 310V


Best regards,
Tetsuro

Hello Tetsuro-san

The PSFB offers ZVS but at 36V in this is of little benefit. It is also of little benefit to use SRs at 300V and diodes are a simpler alternative. I'd use a full bridge output rectifier to reduce secondary voltage stressed. Unless the customer has a very tight efficiency specification.
At this power level I'd use either a PSFB or hard switched full bridge.
The SR control outputs of the UCC28950 are not going to be of much benefit so the UCC3895 would be more suitable.
I would probably put the controller on the primary side rather than the secondary side to eliminate the need for a aux flyback to supply bias power.
You could also look at the LM5046 which will run from up to 105V - this will simplify the bias circuit design and the device has on-board MOSFET drivers.

The hard switched full bridge is also worth looking at and the LM5045 would be a good choice. As I said earlier there is little if any benefit from ZVS switching at these low input voltages.

The Push-Pull topology is often used for high current input stages running off 12V batteries and it might be worth looking at this topology at 36V in using a full bridge secondary rectifier circuit.

Regards
Colin

Hello Colin,

Thank you for your help.

One thing I would like to clarify.  For LM5045 or 46, is there any problem if I do not use SR outputs and apply daiode rectification?

Best regards,

Tetsuro

Hello Colin,

I have one more question.

What is minimum Fsw frequency of LM5045/46? 

The customer wants LO1/LO2=65kHz, Fsw=130kHz. Is it possible?

Best regards,

Tetsuro

Hello Tetsuro-san

If the customer does not want to use the SR outputs then the simplest option is to simply leave the pins on the IC open circuit.

The minimum frequency is a bit more tricky. 65kHz is no problem with the UCC28950 / UCC28951 or the UCC3895.

The minimum Oscillator frequency for the LM5045 and LM5046 will be about 200kHz for a switching frequency of 100kHz. - See Fig 6 in the LM5045 datasheet.

The lower switching frequency will require larger magnetics - especially the transformer. Most applications at this power level use 100kHz as the switching frequency (Oscillator at 200kHz) and this is what I would recommend.

Regards
Colin