A different idea from A More Efficient Bridge Rectifier?
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From: MooseFET on 14 Feb 2010 10:43 Joe G: You don't have your settings right. When you quote someone's text, you should see ">" inserted in front of each line. It is the standard way to mark the quoted text. [.... My SEPIC idea ....] On Feb 13, 8:13 pm, "Joe G \(Home\)" <jo...(a)optusnet.com.au> wrote: > Why not model it in a spice program (eg like the free LTSpice) to prove your > theory. Then build it. There is a very good reason why I don't spice it up to prove it and then make it. I am very lazy. Although there are very few people in the world smarter than me there are also very few who can match me for being lazy. Others have already proven the no input ripple SEPIC circuit. The rest of it, D from BC can be trusted to see how to do. There is good evidence that D from BC isn't nearly as lazy as me so I can let him to all the work. Being as lazy as I am, if he wants to take credit for the design I don't see myself bothering to do anything about it. I hope this helps
From: Fred Bartoli on 14 Feb 2010 11:00 MooseFET a �crit : > Joe G: You don't have your settings right. When you quote someone's > text, you should see ">" inserted in front of each line. It is the > standard way to mark the quoted text. > > [.... My SEPIC idea ....] > On Feb 13, 8:13 pm, "Joe G \(Home\)" <jo...(a)optusnet.com.au> wrote: >> Why not model it in a spice program (eg like the free LTSpice) to prove your >> theory. Then build it. > > There is a very good reason why I don't spice it up to prove it and > then > make it. I am very lazy. Although there are very few people in the > world > smarter than me there are also very few who can match me for being > lazy. > Yes but, compared to me you're way substandard... (I mean regarding laziness :-))) > Others have already proven the no input ripple SEPIC circuit. The > rest > of it, D from BC can be trusted to see how to do. There is good > evidence > that D from BC isn't nearly as lazy as me so I can let him to all the > work. Being as lazy as I am, if he wants to take credit for the > design > I don't see myself bothering to do anything about it. > > I hope this helps > > > -- Thanks, Fred.
From: Paul E. Schoen on 14 Feb 2010 13:02 "MooseFET" <kensmith(a)rahul.net> wrote in message news:50cfb635-5888-428a-be43-efdc1cd3318d(a)x10g2000prk.googlegroups.com... On Feb 13, 3:51 pm, Joerg <inva...(a)invalid.invalid> wrote: > D from BC wrote: > > In article <aabc57bc-4faf-4067-8ed2-df32f921f214 > > @b9g2000pri.googlegroups.com>, kensm...(a)rahul.net says... > >> On Feb 9, 5:06 pm, D from BC <myrealaddr...(a)comic.com> wrote: > >>> My offline smps design has 3 parts making the most heat. > >>> A power diode, a mosfet and a bridge rectifier. > > >>> I'm interested in any cookbook designs that replaces a bridge > >>> rectifier. > >>> Any pointers? > > >> Imagine the no input ripple version of the transformer coupled SEPIC > >> circuit. > >> ie: there are 3 windings the third being the isolated output. > >> Now take the power MOSFET and replace it with a pair in series source > >> to source. > > >> This circuit can be connected directly to the unrectified maines. It > >> makes > >> an isolated squarewavish wave form. This can then be run into a > >> sychronous > >> rectifier to make a DC output. > > >> All this involves no diode drops from the mains to the DC output. > > > Neato :) > > Except then you still have to replace the Schottky diode in the SEPIC > with a synchronously controlled FET circuit ;-) Yes, it requires some good timing control on the fets and a pair of perhaps 600V MOSFETs. This is two less of the costly parts than the MOSFET bridge idea. It can be a PFC replacement for the transformer, bridge and capacitor style power supply. The SEPIC doesn't put all that high of demands on the core. It only has to hold the energy of one cycle plus a little to make the current continuous to keep the ripple at zero. ------------------------------------------------------------------------- I still say that the bridge rectifier, or perhaps a doubler circuit, will be the most efficient solution if one takes into account cost, complexity, and reliability. One or two volts drop on 120 or 240 VAC mains is at most 2% loss. Even better overall efficiency may be obtained by converting our electrical distribution system to DC. There will be less losses due to EMF effects. Most appliances can be made to use DC directly. Anything with a switching power supply can bypass the input rectifiers, and induction motors can be driven by PWM bridge controllers. And of course lighting and heating work as well on DC as AC. Paul
From: MooseFET on 14 Feb 2010 14:03 On Feb 14, 10:02 am, "Paul E. Schoen" <p...(a)peschoen.com> wrote: > "MooseFET" <kensm...(a)rahul.net> wrote in message > > news:50cfb635-5888-428a-be43-efdc1cd3318d(a)x10g2000prk.googlegroups.com... > On Feb 13, 3:51 pm, Joerg <inva...(a)invalid.invalid> wrote: > > > > > D from BC wrote: > > > In article <aabc57bc-4faf-4067-8ed2-df32f921f214 > > > @b9g2000pri.googlegroups.com>, kensm...(a)rahul.net says... > > >> On Feb 9, 5:06 pm, D from BC <myrealaddr...(a)comic.com> wrote: > > >>> My offline smps design has 3 parts making the most heat. > > >>> A power diode, a mosfet and a bridge rectifier. > > > >>> I'm interested in any cookbook designs that replaces a bridge > > >>> rectifier. > > >>> Any pointers? > > > >> Imagine the no input ripple version of the transformer coupled SEPIC > > >> circuit. > > >> ie: there are 3 windings the third being the isolated output. > > >> Now take the power MOSFET and replace it with a pair in series source > > >> to source. > > > >> This circuit can be connected directly to the unrectified maines. It > > >> makes > > >> an isolated squarewavish wave form. This can then be run into a > > >> sychronous > > >> rectifier to make a DC output. > > > >> All this involves no diode drops from the mains to the DC output. > > > > Neato :) > > > Except then you still have to replace the Schottky diode in the SEPIC > > with a synchronously controlled FET circuit ;-) > > Yes, it requires some good timing control on the fets and a pair of > perhaps 600V MOSFETs. This is two less of the costly parts than the > MOSFET bridge idea. > > It can be a PFC replacement for the transformer, bridge and capacitor > style power supply. The SEPIC doesn't put all that high of demands on > the core. It only has to hold the energy of one cycle plus a little > to make the current continuous to keep the ripple at zero. > > ------------------------------------------------------------------------- > > I still say that the bridge rectifier, or perhaps a doubler circuit, will > be the most efficient solution if one takes into account cost, complexity, > and reliability. One or two volts drop on 120 or 240 VAC mains is at most > 2% loss. Remember that my idea is a PFC circuit not just a bridge feeding a capacitor. > Even better overall efficiency may be obtained by converting our electrical > distribution system to DC. Large mains transformers are a great way to efficiently change from one voltage to another. There is no reason to go to DC. > There will be less losses due to EMF effects. > Most appliances can be made to use DC directly. Anything with a switching > power supply can bypass the input rectifiers, and induction motors can be > driven by PWM bridge controllers. And of course lighting and heating work > as well on DC as AC. The low cost induction motor that is used in many home appliances is hard to match for cost of production or even efficiency. Brushless DC motors may now be able to replace them but at those power levels, the semiconductors won't be cheap. > > Paul
From: Hammy on 14 Feb 2010 14:14
On Sun, 14 Feb 2010 13:02:20 -0500, "Paul E. Schoen" <paul(a)peschoen.com> wrote: > SNIP >Even better overall efficiency may be obtained by converting our electrical >distribution system to DC. There will be less losses due to EMF effects. >Most appliances can be made to use DC directly. Anything with a switching >power supply can bypass the input rectifiers, and induction motors can be >driven by PWM bridge controllers. And of course lighting and heating work >as well on DC as AC. > >Paul > Electrical 101. Distrubution of DC is will generatae higher losses. I SQUARED * R. |