Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

push pull SMPS with caps

Status
Not open for further replies.
E

eem2am

Banned
Joined
Jun 22, 2008
Messages
1,179
Helped
37
Reputation
74
Reaction score
24
Trophy points
1,318
Activity points
0
push pull smps

hello,

i did a 10W offline push pull smps, it was current mode, using MC34025, but the MOSFETS were getting very hot.

i believe it was "flux walking" saturation causing the primary overcurrent.

do you think this push pull, with caps and diodes added, would work for a push pull and eliminate flux-walking ? ......

2uhv8z8.jpg


I need to use push pull to keep ripple as low as possible on the secondary.
 

push pull

You need to go and study the basics about power conversion from the beginning. At this stage you know just enough to be dangerous. 8O
 

full bridge and push pull smps

As an advantage, the present circuit surely isn't dangerous: Zero input current, zero output voltage.
 

push pull smps wiki

Woops,

I suppose i must have goofed up here, thanks for letting me know FvM and E-design.

Though i have heard that there is somewhere a cap can be put in push pull to stop that flux walking.

I am just thinking that nobody would ever do a half or full bridge without a cap in the bridge......as they fear flux walk.

...so with the push pull, i think also that cap is needed......but where to put it ?

Any ideas gratefully appreciated.
 

smps push pull

Obviously, a capacitor can be placed in an AC current path only, e.g. in a half or full bridge. However, I don't see that it often used or even necessary in full bridge circuits.
 

smps caps

thankyou FvM,

I am reading the book "demystifying switching power supplies" by Ray Mack, and its just that he is strongly recommending bridge cap in full/half bridge circuits.....he even uses a balancing winding with the half bridge.
 

push-pull smps

I'm not talking about books but real world designs.

P.S.: You may take different viewpoints depending on the power level and application field. At currents of several 10 to 100 A, a capacitor isn't a simple and cheap component, that you can buy from a catalog distributor. You may have serious difficuties to find a usable part at all. Thus it won't be used if it's not absolutely necessary or offers superiour performance.

As another aspect, industrial designs are generally cost driven.

A capacitor on the other hand can achieve a simple design with built-in fail safe behaviour. For small inverters, it may be meaningful to use an AC current sensor and a capacitor.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top