I'm designing another 3-phase PM alternator simulator, and I need a roughly +-60 volt floating power supply. It will feed three PWM half-bridges to make the three output phases. Here's my first pass at the dc/dc thing. https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 Those Coilcraft planar transformers are radical. 300 watts, surface mount, under a cubic inch. They have a 4t tapped primary and the two secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a lot of possibilities. https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1 -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
dc/dc converter ckt
Started by ●May 26, 2022
Reply by ●May 26, 20222022-05-26
On 5/26/2022 8:16 PM, John Larkin wrote:> I'm designing another 3-phase PM alternator simulator, and I need a > roughly +-60 volt floating power supply. It will feed three PWM > half-bridges to make the three output phases. > > Here's my first pass at the dc/dc thing. > > https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 > > Those Coilcraft planar transformers are radical. 300 watts, surface > mount, under a cubic inch. They have a 4t tapped primary and the two > secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a > lot of possibilities. > > https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1 > > >Maybe an appropriately-selected ferrite bead for the gates but perhaps not a gate resistor or anything elaborate for the LT4444, looks like they figure their adaptive shoot-thru protection can prevent any misbehavior & that kind of fancy is what you pay the LTC device price for I suppose. Looks like just a fat trace is what they recommend.
Reply by ●May 26, 20222022-05-26
On 5/26/2022 7:16 PM, John Larkin wrote:> I'm designing another 3-phase PM alternator simulator, and I need a > roughly +-60 volt floating power supply. It will feed three PWM > half-bridges to make the three output phases. > > Here's my first pass at the dc/dc thing. > > https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 > > Those Coilcraft planar transformers are radical. 300 watts, surface > mount, under a cubic inch. They have a 4t tapped primary and the two > secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a > lot of possibilities. > > https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1Oh. So you don't want to buy one or need help. You just feel compelled to tell us about it, right?
Reply by ●May 26, 20222022-05-26
On Thu, 26 May 2022 20:08:25 -0500, John S <Sophi.2@invalid.org> wrote:>On 5/26/2022 7:16 PM, John Larkin wrote: >> I'm designing another 3-phase PM alternator simulator, and I need a >> roughly +-60 volt floating power supply. It will feed three PWM >> half-bridges to make the three output phases. >> >> Here's my first pass at the dc/dc thing. >> >> https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 >> >> Those Coilcraft planar transformers are radical. 300 watts, surface >> mount, under a cubic inch. They have a 4t tapped primary and the two >> secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a >> lot of possibilities. >> >> https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1 > >Oh. So you don't want to buy one or need help. You just feel compelled >to tell us about it, right?It's an electronic design discussion group. Design something. Discuss it. Or whine. Whatever you're best at. -- Anybody can count to one. - Robert Widlar
Reply by ●May 26, 20222022-05-26
On Thu, 26 May 2022 21:07:57 -0400, bitrex <user@example.net> wrote:>On 5/26/2022 8:16 PM, John Larkin wrote: >> I'm designing another 3-phase PM alternator simulator, and I need a >> roughly +-60 volt floating power supply. It will feed three PWM >> half-bridges to make the three output phases. >> >> Here's my first pass at the dc/dc thing. >> >> https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 >> >> Those Coilcraft planar transformers are radical. 300 watts, surface >> mount, under a cubic inch. They have a 4t tapped primary and the two >> secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a >> lot of possibilities. >> >> https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1 >> >> >> > >Maybe an appropriately-selected ferrite bead for the gates but perhaps >not a gate resistor or anything elaborate for the LT4444, looks like >they figure their adaptive shoot-thru protection can prevent any >misbehavior & that kind of fancy is what you pay the LTC device price >for I suppose.The LTC4444 is about $2.80. That's in the noise floor for this board. The three half-bridges are more voltage, so need the UCC27712. It's more like $1 so I may as well use it everywhere.> >Looks like just a fat trace is what they recommend.Gate resistors might be prudent, stuffed as 0 ohms initially. Could be a resistor or bead if needed. I might also put schottky diodes across the fets, in case the substrate diodes get weird. Excess caution in both cases. -- Anybody can count to one. - Robert Widlar
Reply by ●May 27, 20222022-05-27
John S <Sophi.2@invalid.org> wrote in news:t6p8ag$iuu$2@dont-email.me:> On 5/26/2022 7:16 PM, John Larkin wrote: >> I'm designing another 3-phase PM alternator simulator, and I need >> a roughly +-60 volt floating power supply. It will feed three PWM >> half-bridges to make the three output phases. >> >> Here's my first pass at the dc/dc thing. >> >> https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 >> >> Those Coilcraft planar transformers are radical. 300 watts, >> surface mount, under a cubic inch. They have a 4t tapped primary >> and the two secondaries are available with 4, 5, 6, 7, or 8 turns >> each. That has a lot of possibilities. >> >> https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw= >> 1 > > Oh. So you don't want to buy one or need help. You just feel > compelled to tell us about it, right? > >Pre fashioned, vertically mounted POL devices have been massaged out pretty good. No need to try to design your own power source if the pros already did the hard works for you and offer a far less expensive solution than spending your own time trying to fashion your own device. And most folks doing that examine and copy features from the big boys as well. A bit of a cheat.
Reply by ●May 27, 20222022-05-27
jlarkin@highlandsniptechnology.com wrote in news:2la09ht44t87nlhccjm2660suj06t91gp7@4ax.com:> On Thu, 26 May 2022 21:07:57 -0400, bitrex <user@example.net> > wrote: > >>On 5/26/2022 8:16 PM, John Larkin wrote: >>> I'm designing another 3-phase PM alternator simulator, and I >>> need a roughly +-60 volt floating power supply. It will feed >>> three PWM half-bridges to make the three output phases. >>> >>> Here's my first pass at the dc/dc thing. >>> >>> https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 >>> >>> Those Coilcraft planar transformers are radical. 300 watts, >>> surface mount, under a cubic inch. They have a 4t tapped primary >>> and the two secondaries are available with 4, 5, 6, 7, or 8 >>> turns each. That has a lot of possibilities. >>> >>> https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw >>> =1 >>> >>> >>> >> >>Maybe an appropriately-selected ferrite bead for the gates but >>perhaps not a gate resistor or anything elaborate for the LT4444, >>looks like they figure their adaptive shoot-thru protection can >>prevent any misbehavior & that kind of fancy is what you pay the >>LTC device price for I suppose. > > The LTC4444 is about $2.80. That's in the noise floor for this > board. > > The three half-bridges are more voltage, so need the UCC27712. > It's more like $1 so I may as well use it everywhere. > >> >>Looks like just a fat trace is what they recommend. > > Gate resistors might be prudent, stuffed as 0 ohms initially. > Could be a resistor or bead if needed. > > I might also put schottky diodes across the fets, in case the > substrate diodes get weird. Excess caution in both cases. > > >For the primary, build a trough on the PCB where you then add a nice Silver Plated Copper wire, or get a custom wire formed and stamped to lay in the trough. Done. Your primary is of a large capacity wire now, instead of a circuit trace. Then make a nice 0.032 secondary PCB to sit under your core element. The is for the planar transformer. I think we used Transzorbs and beads on the FET leads.
Reply by ●May 27, 20222022-05-27
On a sunny day (Thu, 26 May 2022 17:16:56 -0700) it happened John Larkin <jlarkin@highland_atwork_technology.com> wrote in <uh509h9ki5momgqptatnult0fnkagcf7e8@4ax.com>:>I'm designing another 3-phase PM alternator simulator, and I need a >roughly +-60 volt floating power supply. It will feed three PWM >half-bridges to make the three output phases. > >Here's my first pass at the dc/dc thing. > >https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 > >Those Coilcraft planar transformers are radical. 300 watts, surface >mount, under a cubic inch. They have a 4t tapped primary and the two >secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a >lot of possibilities. > >https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1Interesting circuit. In the long ago past I used zeners between source and gate to protect against drain-gate spike injection. Dunno much about this driver chip.. The zeners however caused oscillations to occur at many MHz, a few nF caps between drain and source killed that. Scope the thing! Maybe some gate resistors too?
Reply by ●May 27, 20222022-05-27
On 27/05/2022 1:16 am, John Larkin wrote:> I'm designing another 3-phase PM alternator simulator, and I need a > roughly +-60 volt floating power supply. It will feed three PWM > half-bridges to make the three output phases. > > Here's my first pass at the dc/dc thing. > > https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 > > Those Coilcraft planar transformers are radical. 300 watts, surface > mount, under a cubic inch. They have a 4t tapped primary and the two > secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a > lot of possibilities. > > https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1 > > >Neat transformer! How much do they weigh? I'd be wary of relying just on surface mount pads on anything over a couple grams in case the unit gets dropped one day. piglet
Reply by ●May 27, 20222022-05-27
On Thu, 26 May 2022 17:16:56 -0700, John Larkin <jlarkin@highland_atwork_technology.com> wrote:>I'm designing another 3-phase PM alternator simulator, and I need a >roughly +-60 volt floating power supply. It will feed three PWM >half-bridges to make the three output phases. > >Here's my first pass at the dc/dc thing. > >https://www.dropbox.com/s/bwt1vgbb2j94p1d/23S942_x1.jpg?raw=1 > >Those Coilcraft planar transformers are radical. 300 watts, surface >mount, under a cubic inch. They have a 4t tapped primary and the two >secondaries are available with 4, 5, 6, 7, or 8 turns each. That has a >lot of possibilities. > >https://www.dropbox.com/s/3d093msdmuinhxs/Coilcraft_PL300.jpg?raw=1Take care. Chances are, core loss estimates are for a regulated system with '48V' input. For straight DC-DC unregulated, your flux swings will be double the typical application for 48V 'primary', and triple for a 60V 'primary' - core losses scale with a positive exponent greater than one. You might make this up due to lower current and crest factor in the copper, but . . . RL
