PFC Switched-Mode Power Supply

[davy_shi]

Alme

thanks

you know, with L4981A,the boost circuit output is always 400VDC, but if i want to get some useful voltage, just like 24vsc,36vdc,or 48vdc, what should i do from the circuit?

thanks.

[Ouroboros]

Do you really need power-factor correction for your charger?

If not, then for your 180W supply I suggest you have a look at the two-transistor forward converter design help at the following site.

http://schmidt-walter.fbe.fh-darmsta..._e/smps_e.html

This will help you design the transformer and the output inductor.

If you really do want PFC, then you can use the L4981 to give you a 400V dc supply, and then use this +400V to feed the two-transistor forward converter. The isolation is done in the forward converter transformer. You can use a control chip such as the UCC3801 for the forward converter, and something like a IRF2110 (or a suitable transformer) to drive the gates of the power FETs. You will also need to learn about using a TL431 and an opto-coupler for the output-sensing feedback, as this has to cross the isolation barrier.

If you want to charge lead-acid batteries you may need to add temperature-compensation to the float chage voltage, to ensure long battery life.

[davy_shi]

well ,Ouroboros,
thanks for your explanation. it's very useful for me.

our tutor want to design a robust, and he ask me to design a battery charger for the robust.

what i want to design is a half bridge circuit, with 220vac 50hz input, and 36vdc 5A output for battery storage charger,

and i want to use a IC (such as L4981) to drive the two MOSFETs, i just post the circuit in a word document, 220vac---transformer---half bridge---battery storage , could it be done?

may be SG3525 IS suitable cause it has two output pins, but I havn't made itvery clear.
i want to pose the circuit here , but it's too big.

[davy_shi]

sorry i made a mistake,

not"robust",it's "robot" automatic machine

[DavidF]

I'm jumping in to mention that the ML4826 is available from Fairchild www.fairchildsemi.com N-Channel had been looking for it early in this thread.

Has anyone used this chip? I'd be interested in any comments on it.

David

[Kenshin]

Buy a electric bicycle charger for 36V lead-acid battery.

Originally posted by davy_shi
well ,Ouroboros,
thanks for your explanation. it's very useful for me.

our tutor want to design a robust, and he ask me to design a battery charger for the robust.

what i want to design is a half bridge circuit, with 220vac 50hz input, and 36vdc 5A output for battery storage charger,

and i want to use a IC (such as L4981) to drive the two MOSFETs, i just post the circuit in a word document, 220vac---transformer---half bridge---battery storage , could it be done?

may be SG3525 IS suitable cause it has two output pins, but I havn't made itvery clear.
i want to pose the circuit here , but it's too big.

[N-Channel]

DavidF-

I am so braindead! I just found the datasheet for the Fairchild Semi ML4826 in my stack o' stuff last week. I forgot I had downloaded it a few months back. I am planning on getting a few samples from Fairchild and giving them a test, but with new child and family, it will be a challenge on getting some time to do this.

Steve

[rannagarden]

I´m sorry, but I can not find this info anywhere;

On an IXYS 12A 1000V Ultrafast, Soft Recovery (FRED)
Epitaxial Diode (trr = 50 ns; TO-220AC package)...

... I can´t seem to find out wich is the "anod" and wich is the "cathod"?

Please advise.
Regards,
Mike