DC-DC converter from low voltage at high current, to high voltage at low current





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I want to build a DC to DC converter with:



25 V input side

400 V output side

4000 watts of continuous rating



That means (obviously) 160 amps on the input side and 10 amps on the output. I can’t find anything remotely close, that has such a high voltage gap with such a high wattage rating.




  1. Is this feasible? I can’t see why not.

  2. What would be the best way to go about this, or a reference design somewhere that I can scale up? I don’t mind spending the money on quality products, but I prefer to DIY it so I can make changes etc.


I have an adequate voltage source for the input side that can handle the current so that’s not the issue, but I’m failing to find more info and even big companies like Vicor, Lambda, etc. all have 400-600 max rated units. Therefore I have to build it.










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  • 4




    $begingroup$
    Be aware that this project is likely going to cost you thousands of dollars. 4kW is not a trivial amount of power.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    The cost is okay.
    $endgroup$
    – jasonthegreat1955gmailcom
    13 hours ago






  • 3




    $begingroup$
    @ChrisFernandez Cockroft-Walton generators are not very efficient, especially ones with this many stages. I wouldn't recommend it for anything that needs substantial power.
    $endgroup$
    – Hearth
    12 hours ago






  • 2




    $begingroup$
    If you have to ask what is "the best way to go about this", the right answer is that you should find a company which can do this for you rather that doing it yourself.
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago






  • 1




    $begingroup$
    @ChrisFernandez "You could try a Cockcroft-Walton chain" - finally, someone with a sense of humor showed up!
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago


















5












$begingroup$


I want to build a DC to DC converter with:



25 V input side

400 V output side

4000 watts of continuous rating



That means (obviously) 160 amps on the input side and 10 amps on the output. I can’t find anything remotely close, that has such a high voltage gap with such a high wattage rating.




  1. Is this feasible? I can’t see why not.

  2. What would be the best way to go about this, or a reference design somewhere that I can scale up? I don’t mind spending the money on quality products, but I prefer to DIY it so I can make changes etc.


I have an adequate voltage source for the input side that can handle the current so that’s not the issue, but I’m failing to find more info and even big companies like Vicor, Lambda, etc. all have 400-600 max rated units. Therefore I have to build it.










share|improve this question









New contributor




jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$








  • 4




    $begingroup$
    Be aware that this project is likely going to cost you thousands of dollars. 4kW is not a trivial amount of power.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    The cost is okay.
    $endgroup$
    – jasonthegreat1955gmailcom
    13 hours ago






  • 3




    $begingroup$
    @ChrisFernandez Cockroft-Walton generators are not very efficient, especially ones with this many stages. I wouldn't recommend it for anything that needs substantial power.
    $endgroup$
    – Hearth
    12 hours ago






  • 2




    $begingroup$
    If you have to ask what is "the best way to go about this", the right answer is that you should find a company which can do this for you rather that doing it yourself.
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago






  • 1




    $begingroup$
    @ChrisFernandez "You could try a Cockcroft-Walton chain" - finally, someone with a sense of humor showed up!
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago














5












5








5


1



$begingroup$


I want to build a DC to DC converter with:



25 V input side

400 V output side

4000 watts of continuous rating



That means (obviously) 160 amps on the input side and 10 amps on the output. I can’t find anything remotely close, that has such a high voltage gap with such a high wattage rating.




  1. Is this feasible? I can’t see why not.

  2. What would be the best way to go about this, or a reference design somewhere that I can scale up? I don’t mind spending the money on quality products, but I prefer to DIY it so I can make changes etc.


I have an adequate voltage source for the input side that can handle the current so that’s not the issue, but I’m failing to find more info and even big companies like Vicor, Lambda, etc. all have 400-600 max rated units. Therefore I have to build it.










share|improve this question









New contributor




jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




I want to build a DC to DC converter with:



25 V input side

400 V output side

4000 watts of continuous rating



That means (obviously) 160 amps on the input side and 10 amps on the output. I can’t find anything remotely close, that has such a high voltage gap with such a high wattage rating.




  1. Is this feasible? I can’t see why not.

  2. What would be the best way to go about this, or a reference design somewhere that I can scale up? I don’t mind spending the money on quality products, but I prefer to DIY it so I can make changes etc.


I have an adequate voltage source for the input side that can handle the current so that’s not the issue, but I’m failing to find more info and even big companies like Vicor, Lambda, etc. all have 400-600 max rated units. Therefore I have to build it.







dc-dc-converter boost






share|improve this question









New contributor




jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|improve this question









New contributor




jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|improve this question




share|improve this question








edited 14 hours ago









SamGibson

11.7k41739




11.7k41739






New contributor




jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









asked 14 hours ago









jasonthegreat1955gmailcomjasonthegreat1955gmailcom

291




291




New contributor




jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






jasonthegreat1955gmailcom is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.








  • 4




    $begingroup$
    Be aware that this project is likely going to cost you thousands of dollars. 4kW is not a trivial amount of power.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    The cost is okay.
    $endgroup$
    – jasonthegreat1955gmailcom
    13 hours ago






  • 3




    $begingroup$
    @ChrisFernandez Cockroft-Walton generators are not very efficient, especially ones with this many stages. I wouldn't recommend it for anything that needs substantial power.
    $endgroup$
    – Hearth
    12 hours ago






  • 2




    $begingroup$
    If you have to ask what is "the best way to go about this", the right answer is that you should find a company which can do this for you rather that doing it yourself.
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago






  • 1




    $begingroup$
    @ChrisFernandez "You could try a Cockcroft-Walton chain" - finally, someone with a sense of humor showed up!
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago














  • 4




    $begingroup$
    Be aware that this project is likely going to cost you thousands of dollars. 4kW is not a trivial amount of power.
    $endgroup$
    – Hearth
    14 hours ago










  • $begingroup$
    The cost is okay.
    $endgroup$
    – jasonthegreat1955gmailcom
    13 hours ago






  • 3




    $begingroup$
    @ChrisFernandez Cockroft-Walton generators are not very efficient, especially ones with this many stages. I wouldn't recommend it for anything that needs substantial power.
    $endgroup$
    – Hearth
    12 hours ago






  • 2




    $begingroup$
    If you have to ask what is "the best way to go about this", the right answer is that you should find a company which can do this for you rather that doing it yourself.
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago






  • 1




    $begingroup$
    @ChrisFernandez "You could try a Cockcroft-Walton chain" - finally, someone with a sense of humor showed up!
    $endgroup$
    – Dmitry Grigoryev
    10 hours ago








4




4




$begingroup$
Be aware that this project is likely going to cost you thousands of dollars. 4kW is not a trivial amount of power.
$endgroup$
– Hearth
14 hours ago




$begingroup$
Be aware that this project is likely going to cost you thousands of dollars. 4kW is not a trivial amount of power.
$endgroup$
– Hearth
14 hours ago












$begingroup$
The cost is okay.
$endgroup$
– jasonthegreat1955gmailcom
13 hours ago




$begingroup$
The cost is okay.
$endgroup$
– jasonthegreat1955gmailcom
13 hours ago




3




3




$begingroup$
@ChrisFernandez Cockroft-Walton generators are not very efficient, especially ones with this many stages. I wouldn't recommend it for anything that needs substantial power.
$endgroup$
– Hearth
12 hours ago




$begingroup$
@ChrisFernandez Cockroft-Walton generators are not very efficient, especially ones with this many stages. I wouldn't recommend it for anything that needs substantial power.
$endgroup$
– Hearth
12 hours ago




2




2




$begingroup$
If you have to ask what is "the best way to go about this", the right answer is that you should find a company which can do this for you rather that doing it yourself.
$endgroup$
– Dmitry Grigoryev
10 hours ago




$begingroup$
If you have to ask what is "the best way to go about this", the right answer is that you should find a company which can do this for you rather that doing it yourself.
$endgroup$
– Dmitry Grigoryev
10 hours ago




1




1




$begingroup$
@ChrisFernandez "You could try a Cockcroft-Walton chain" - finally, someone with a sense of humor showed up!
$endgroup$
– Dmitry Grigoryev
10 hours ago




$begingroup$
@ChrisFernandez "You could try a Cockcroft-Walton chain" - finally, someone with a sense of humor showed up!
$endgroup$
– Dmitry Grigoryev
10 hours ago










3 Answers
3






active

oldest

votes


















11












$begingroup$

160A at 25V will not give you 4kW out. If it is very well designed, you'll get around 3.2kW. The rest is wasted as heat. As you're just setting out to do this, and you're trying to design it yourself, you need to model it well and simulate to work out where your losses are going to be, and how you're going to cool it.



This is a perfectly do-able boost converter project. I have done a 5kW output DC-DC (admittedly that was 48V), and that required a full automotive style liquid cooling system. That was using a standard DC-boost converter, 48V came in, and we got up to 200V out.



First things are cooling and component ratings, those are the hard bit to do. 25V is low for 4kW, so you'll quickly see (once running the numbers) why it is that higher voltages are chosen for these kinds of power.



At 25V in, 4kW out, 80% efficient means around 200 Amps in, plus a 50% overhead safety factor for your FETs, so you need to find FETs rated to 300A, 800V (high voltage due to high output voltage requirement). Don't forget to de-rate for temperature, and check your simulations for junction temperature rise.



You'll also need an inductor, rated at similarly. But these are probably easier to find.



You could split the power down, using multiple channels in parallel, each channel doing a part of the current (I used 3 channels on my 5kW system). But still, cooling will be your biggest challenge.



In summary:




  • It will get hot

  • You need to simulate it

  • Don't underestimate how hot it will get

  • You can just scale up a standard DC boost converter

  • Watch your cooling

  • Simulation is vital






share|improve this answer









$endgroup$













  • $begingroup$
    FETs would be preferred, but IGBTs might be a cheaper option. High-power modules like this tend to be IGBTs and only recently are FETs on this sort of power level starting to show up. A brief search on digikey shows that a FET module that meets these needs can be expected to be on the order of $800, while a similarly rated IGBT module is more like $130.
    $endgroup$
    – Hearth
    12 hours ago






  • 1




    $begingroup$
    IGBTs are rarely a good choice for low voltage converters, due to their finite VCEsat. FETs will save on cooling, and efficiency. Man small FETs is the way to go, there are literally zillions of new FETs optimised for low voltage high power duty for cars, inverters and the like.
    $endgroup$
    – Neil_UK
    12 hours ago










  • $begingroup$
    @Neil_UK Are you sure you mean low voltage and not low current? It'd be at high currents where the saturation voltage shines, with its i*log(i) power dissipation compared to i² for FETs. Either way, this is (in this particular context) both a low-voltage and low-current application, so FETs win either way. I suggested IGBTs because I'm familiar with using a single module for switching, and not familiar at all with the complexities of paralleling FETs that aren't matched and thermally bonded.
    $endgroup$
    – Hearth
    11 hours ago






  • 2




    $begingroup$
    @Hearth No, it's at high line voltage where VCEsat is less of a problem, IGBTs really get into gear at 400v+. FETs, especially in the last few years, especially in the sub-50v realm, have really pushed RDSon and Qgate down. With a suitable FET for the current, you can get VDS very small, <100/200mV, not the 15% efficiency sapping 1.5v of an IGBT VCEsat with only 12v input. FETs are tame to parallel at the device level for switching, and polyphase converters are the way to reduce input current variations so reduce the requirement for humungeous input caps.
    $endgroup$
    – Neil_UK
    11 hours ago










  • $begingroup$
    I think you could improve the answer better by explaining why would standard non-synchronous dc converter would work here. Why not the synchronous one? How about full bridge, Resonant LLC, etc?
    $endgroup$
    – Unknown123
    11 hours ago



















2












$begingroup$

The inductive coupling must be modeled. As well as eddy currents.



200 amps switched in 200 nanoseconds (for high efficiency, fast switching must occur) and wired to be 1cm away from a 1cm-by-4cm servo-regulator loop, will induce this error voltage:



Vinduce = 2e-7 * Area/Distance * dI/dT



Vinduce = 2e-7 * 1cm*4cm / 1cm * 1Billion amps/second



Vinduce = 2e-7 * 0.04 * 1.0e+9



Vinduce = 2e-7 * 4e-2* 1.0e+9 = 8 volts.



To be completely accurate, you need to write the integrals and extract the equation that uses NATURAL_LOG. And you need to model the eddy currents.



At these levels of dI/dT, ground planes will NOT be ground planes. There will be large differences in voltages across the plane, because of eddy currents.



The math suggests shields and planes (VDD or GROUND) will have EIGHT volts of gradients.



I was brought in to diagnose the failures on a 15,000 horsepower speed controller. A loop of wire, to sense the magnetic field , held near the ground-plane, indicated 2 volts per square-inch. Ground Was Not Ground.






share|improve this answer











$endgroup$













  • $begingroup$
    This isn't a question about EMI. Yes, I know you like discussing these issues, but it isn't relevant here; the OP is just asking whether it's possible at all.
    $endgroup$
    – duskwuff
    49 mins ago



















0












$begingroup$

A programmable voltage three phase inverter with a full bridge (or two that are wired with a 30degree phase off-set) (to gain minimum ripple) with some inductance and capacitance to follow that are designed for 24V input might just be able to be found semi custom.



Some crazy variable speed drive system with a 24V supply and programmable voltage might even work out of the box.



Starting to design one from scratch for a once-off will cost much more than you think, hoping to save money this way is futile. I would spend a week making calls to every VFD and inverter manufacturer with your loosest tolerable specifications and see if anyone can configure OTS parts.






share|improve this answer









$endgroup$














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    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    11












    $begingroup$

    160A at 25V will not give you 4kW out. If it is very well designed, you'll get around 3.2kW. The rest is wasted as heat. As you're just setting out to do this, and you're trying to design it yourself, you need to model it well and simulate to work out where your losses are going to be, and how you're going to cool it.



    This is a perfectly do-able boost converter project. I have done a 5kW output DC-DC (admittedly that was 48V), and that required a full automotive style liquid cooling system. That was using a standard DC-boost converter, 48V came in, and we got up to 200V out.



    First things are cooling and component ratings, those are the hard bit to do. 25V is low for 4kW, so you'll quickly see (once running the numbers) why it is that higher voltages are chosen for these kinds of power.



    At 25V in, 4kW out, 80% efficient means around 200 Amps in, plus a 50% overhead safety factor for your FETs, so you need to find FETs rated to 300A, 800V (high voltage due to high output voltage requirement). Don't forget to de-rate for temperature, and check your simulations for junction temperature rise.



    You'll also need an inductor, rated at similarly. But these are probably easier to find.



    You could split the power down, using multiple channels in parallel, each channel doing a part of the current (I used 3 channels on my 5kW system). But still, cooling will be your biggest challenge.



    In summary:




    • It will get hot

    • You need to simulate it

    • Don't underestimate how hot it will get

    • You can just scale up a standard DC boost converter

    • Watch your cooling

    • Simulation is vital






    share|improve this answer









    $endgroup$













    • $begingroup$
      FETs would be preferred, but IGBTs might be a cheaper option. High-power modules like this tend to be IGBTs and only recently are FETs on this sort of power level starting to show up. A brief search on digikey shows that a FET module that meets these needs can be expected to be on the order of $800, while a similarly rated IGBT module is more like $130.
      $endgroup$
      – Hearth
      12 hours ago






    • 1




      $begingroup$
      IGBTs are rarely a good choice for low voltage converters, due to their finite VCEsat. FETs will save on cooling, and efficiency. Man small FETs is the way to go, there are literally zillions of new FETs optimised for low voltage high power duty for cars, inverters and the like.
      $endgroup$
      – Neil_UK
      12 hours ago










    • $begingroup$
      @Neil_UK Are you sure you mean low voltage and not low current? It'd be at high currents where the saturation voltage shines, with its i*log(i) power dissipation compared to i² for FETs. Either way, this is (in this particular context) both a low-voltage and low-current application, so FETs win either way. I suggested IGBTs because I'm familiar with using a single module for switching, and not familiar at all with the complexities of paralleling FETs that aren't matched and thermally bonded.
      $endgroup$
      – Hearth
      11 hours ago






    • 2




      $begingroup$
      @Hearth No, it's at high line voltage where VCEsat is less of a problem, IGBTs really get into gear at 400v+. FETs, especially in the last few years, especially in the sub-50v realm, have really pushed RDSon and Qgate down. With a suitable FET for the current, you can get VDS very small, <100/200mV, not the 15% efficiency sapping 1.5v of an IGBT VCEsat with only 12v input. FETs are tame to parallel at the device level for switching, and polyphase converters are the way to reduce input current variations so reduce the requirement for humungeous input caps.
      $endgroup$
      – Neil_UK
      11 hours ago










    • $begingroup$
      I think you could improve the answer better by explaining why would standard non-synchronous dc converter would work here. Why not the synchronous one? How about full bridge, Resonant LLC, etc?
      $endgroup$
      – Unknown123
      11 hours ago
















    11












    $begingroup$

    160A at 25V will not give you 4kW out. If it is very well designed, you'll get around 3.2kW. The rest is wasted as heat. As you're just setting out to do this, and you're trying to design it yourself, you need to model it well and simulate to work out where your losses are going to be, and how you're going to cool it.



    This is a perfectly do-able boost converter project. I have done a 5kW output DC-DC (admittedly that was 48V), and that required a full automotive style liquid cooling system. That was using a standard DC-boost converter, 48V came in, and we got up to 200V out.



    First things are cooling and component ratings, those are the hard bit to do. 25V is low for 4kW, so you'll quickly see (once running the numbers) why it is that higher voltages are chosen for these kinds of power.



    At 25V in, 4kW out, 80% efficient means around 200 Amps in, plus a 50% overhead safety factor for your FETs, so you need to find FETs rated to 300A, 800V (high voltage due to high output voltage requirement). Don't forget to de-rate for temperature, and check your simulations for junction temperature rise.



    You'll also need an inductor, rated at similarly. But these are probably easier to find.



    You could split the power down, using multiple channels in parallel, each channel doing a part of the current (I used 3 channels on my 5kW system). But still, cooling will be your biggest challenge.



    In summary:




    • It will get hot

    • You need to simulate it

    • Don't underestimate how hot it will get

    • You can just scale up a standard DC boost converter

    • Watch your cooling

    • Simulation is vital






    share|improve this answer









    $endgroup$













    • $begingroup$
      FETs would be preferred, but IGBTs might be a cheaper option. High-power modules like this tend to be IGBTs and only recently are FETs on this sort of power level starting to show up. A brief search on digikey shows that a FET module that meets these needs can be expected to be on the order of $800, while a similarly rated IGBT module is more like $130.
      $endgroup$
      – Hearth
      12 hours ago






    • 1




      $begingroup$
      IGBTs are rarely a good choice for low voltage converters, due to their finite VCEsat. FETs will save on cooling, and efficiency. Man small FETs is the way to go, there are literally zillions of new FETs optimised for low voltage high power duty for cars, inverters and the like.
      $endgroup$
      – Neil_UK
      12 hours ago










    • $begingroup$
      @Neil_UK Are you sure you mean low voltage and not low current? It'd be at high currents where the saturation voltage shines, with its i*log(i) power dissipation compared to i² for FETs. Either way, this is (in this particular context) both a low-voltage and low-current application, so FETs win either way. I suggested IGBTs because I'm familiar with using a single module for switching, and not familiar at all with the complexities of paralleling FETs that aren't matched and thermally bonded.
      $endgroup$
      – Hearth
      11 hours ago






    • 2




      $begingroup$
      @Hearth No, it's at high line voltage where VCEsat is less of a problem, IGBTs really get into gear at 400v+. FETs, especially in the last few years, especially in the sub-50v realm, have really pushed RDSon and Qgate down. With a suitable FET for the current, you can get VDS very small, <100/200mV, not the 15% efficiency sapping 1.5v of an IGBT VCEsat with only 12v input. FETs are tame to parallel at the device level for switching, and polyphase converters are the way to reduce input current variations so reduce the requirement for humungeous input caps.
      $endgroup$
      – Neil_UK
      11 hours ago










    • $begingroup$
      I think you could improve the answer better by explaining why would standard non-synchronous dc converter would work here. Why not the synchronous one? How about full bridge, Resonant LLC, etc?
      $endgroup$
      – Unknown123
      11 hours ago














    11












    11








    11





    $begingroup$

    160A at 25V will not give you 4kW out. If it is very well designed, you'll get around 3.2kW. The rest is wasted as heat. As you're just setting out to do this, and you're trying to design it yourself, you need to model it well and simulate to work out where your losses are going to be, and how you're going to cool it.



    This is a perfectly do-able boost converter project. I have done a 5kW output DC-DC (admittedly that was 48V), and that required a full automotive style liquid cooling system. That was using a standard DC-boost converter, 48V came in, and we got up to 200V out.



    First things are cooling and component ratings, those are the hard bit to do. 25V is low for 4kW, so you'll quickly see (once running the numbers) why it is that higher voltages are chosen for these kinds of power.



    At 25V in, 4kW out, 80% efficient means around 200 Amps in, plus a 50% overhead safety factor for your FETs, so you need to find FETs rated to 300A, 800V (high voltage due to high output voltage requirement). Don't forget to de-rate for temperature, and check your simulations for junction temperature rise.



    You'll also need an inductor, rated at similarly. But these are probably easier to find.



    You could split the power down, using multiple channels in parallel, each channel doing a part of the current (I used 3 channels on my 5kW system). But still, cooling will be your biggest challenge.



    In summary:




    • It will get hot

    • You need to simulate it

    • Don't underestimate how hot it will get

    • You can just scale up a standard DC boost converter

    • Watch your cooling

    • Simulation is vital






    share|improve this answer









    $endgroup$



    160A at 25V will not give you 4kW out. If it is very well designed, you'll get around 3.2kW. The rest is wasted as heat. As you're just setting out to do this, and you're trying to design it yourself, you need to model it well and simulate to work out where your losses are going to be, and how you're going to cool it.



    This is a perfectly do-able boost converter project. I have done a 5kW output DC-DC (admittedly that was 48V), and that required a full automotive style liquid cooling system. That was using a standard DC-boost converter, 48V came in, and we got up to 200V out.



    First things are cooling and component ratings, those are the hard bit to do. 25V is low for 4kW, so you'll quickly see (once running the numbers) why it is that higher voltages are chosen for these kinds of power.



    At 25V in, 4kW out, 80% efficient means around 200 Amps in, plus a 50% overhead safety factor for your FETs, so you need to find FETs rated to 300A, 800V (high voltage due to high output voltage requirement). Don't forget to de-rate for temperature, and check your simulations for junction temperature rise.



    You'll also need an inductor, rated at similarly. But these are probably easier to find.



    You could split the power down, using multiple channels in parallel, each channel doing a part of the current (I used 3 channels on my 5kW system). But still, cooling will be your biggest challenge.



    In summary:




    • It will get hot

    • You need to simulate it

    • Don't underestimate how hot it will get

    • You can just scale up a standard DC boost converter

    • Watch your cooling

    • Simulation is vital







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 13 hours ago









    PuffafishPuffafish

    1,145113




    1,145113












    • $begingroup$
      FETs would be preferred, but IGBTs might be a cheaper option. High-power modules like this tend to be IGBTs and only recently are FETs on this sort of power level starting to show up. A brief search on digikey shows that a FET module that meets these needs can be expected to be on the order of $800, while a similarly rated IGBT module is more like $130.
      $endgroup$
      – Hearth
      12 hours ago






    • 1




      $begingroup$
      IGBTs are rarely a good choice for low voltage converters, due to their finite VCEsat. FETs will save on cooling, and efficiency. Man small FETs is the way to go, there are literally zillions of new FETs optimised for low voltage high power duty for cars, inverters and the like.
      $endgroup$
      – Neil_UK
      12 hours ago










    • $begingroup$
      @Neil_UK Are you sure you mean low voltage and not low current? It'd be at high currents where the saturation voltage shines, with its i*log(i) power dissipation compared to i² for FETs. Either way, this is (in this particular context) both a low-voltage and low-current application, so FETs win either way. I suggested IGBTs because I'm familiar with using a single module for switching, and not familiar at all with the complexities of paralleling FETs that aren't matched and thermally bonded.
      $endgroup$
      – Hearth
      11 hours ago






    • 2




      $begingroup$
      @Hearth No, it's at high line voltage where VCEsat is less of a problem, IGBTs really get into gear at 400v+. FETs, especially in the last few years, especially in the sub-50v realm, have really pushed RDSon and Qgate down. With a suitable FET for the current, you can get VDS very small, <100/200mV, not the 15% efficiency sapping 1.5v of an IGBT VCEsat with only 12v input. FETs are tame to parallel at the device level for switching, and polyphase converters are the way to reduce input current variations so reduce the requirement for humungeous input caps.
      $endgroup$
      – Neil_UK
      11 hours ago










    • $begingroup$
      I think you could improve the answer better by explaining why would standard non-synchronous dc converter would work here. Why not the synchronous one? How about full bridge, Resonant LLC, etc?
      $endgroup$
      – Unknown123
      11 hours ago


















    • $begingroup$
      FETs would be preferred, but IGBTs might be a cheaper option. High-power modules like this tend to be IGBTs and only recently are FETs on this sort of power level starting to show up. A brief search on digikey shows that a FET module that meets these needs can be expected to be on the order of $800, while a similarly rated IGBT module is more like $130.
      $endgroup$
      – Hearth
      12 hours ago






    • 1




      $begingroup$
      IGBTs are rarely a good choice for low voltage converters, due to their finite VCEsat. FETs will save on cooling, and efficiency. Man small FETs is the way to go, there are literally zillions of new FETs optimised for low voltage high power duty for cars, inverters and the like.
      $endgroup$
      – Neil_UK
      12 hours ago










    • $begingroup$
      @Neil_UK Are you sure you mean low voltage and not low current? It'd be at high currents where the saturation voltage shines, with its i*log(i) power dissipation compared to i² for FETs. Either way, this is (in this particular context) both a low-voltage and low-current application, so FETs win either way. I suggested IGBTs because I'm familiar with using a single module for switching, and not familiar at all with the complexities of paralleling FETs that aren't matched and thermally bonded.
      $endgroup$
      – Hearth
      11 hours ago






    • 2




      $begingroup$
      @Hearth No, it's at high line voltage where VCEsat is less of a problem, IGBTs really get into gear at 400v+. FETs, especially in the last few years, especially in the sub-50v realm, have really pushed RDSon and Qgate down. With a suitable FET for the current, you can get VDS very small, <100/200mV, not the 15% efficiency sapping 1.5v of an IGBT VCEsat with only 12v input. FETs are tame to parallel at the device level for switching, and polyphase converters are the way to reduce input current variations so reduce the requirement for humungeous input caps.
      $endgroup$
      – Neil_UK
      11 hours ago










    • $begingroup$
      I think you could improve the answer better by explaining why would standard non-synchronous dc converter would work here. Why not the synchronous one? How about full bridge, Resonant LLC, etc?
      $endgroup$
      – Unknown123
      11 hours ago
















    $begingroup$
    FETs would be preferred, but IGBTs might be a cheaper option. High-power modules like this tend to be IGBTs and only recently are FETs on this sort of power level starting to show up. A brief search on digikey shows that a FET module that meets these needs can be expected to be on the order of $800, while a similarly rated IGBT module is more like $130.
    $endgroup$
    – Hearth
    12 hours ago




    $begingroup$
    FETs would be preferred, but IGBTs might be a cheaper option. High-power modules like this tend to be IGBTs and only recently are FETs on this sort of power level starting to show up. A brief search on digikey shows that a FET module that meets these needs can be expected to be on the order of $800, while a similarly rated IGBT module is more like $130.
    $endgroup$
    – Hearth
    12 hours ago




    1




    1




    $begingroup$
    IGBTs are rarely a good choice for low voltage converters, due to their finite VCEsat. FETs will save on cooling, and efficiency. Man small FETs is the way to go, there are literally zillions of new FETs optimised for low voltage high power duty for cars, inverters and the like.
    $endgroup$
    – Neil_UK
    12 hours ago




    $begingroup$
    IGBTs are rarely a good choice for low voltage converters, due to their finite VCEsat. FETs will save on cooling, and efficiency. Man small FETs is the way to go, there are literally zillions of new FETs optimised for low voltage high power duty for cars, inverters and the like.
    $endgroup$
    – Neil_UK
    12 hours ago












    $begingroup$
    @Neil_UK Are you sure you mean low voltage and not low current? It'd be at high currents where the saturation voltage shines, with its i*log(i) power dissipation compared to i² for FETs. Either way, this is (in this particular context) both a low-voltage and low-current application, so FETs win either way. I suggested IGBTs because I'm familiar with using a single module for switching, and not familiar at all with the complexities of paralleling FETs that aren't matched and thermally bonded.
    $endgroup$
    – Hearth
    11 hours ago




    $begingroup$
    @Neil_UK Are you sure you mean low voltage and not low current? It'd be at high currents where the saturation voltage shines, with its i*log(i) power dissipation compared to i² for FETs. Either way, this is (in this particular context) both a low-voltage and low-current application, so FETs win either way. I suggested IGBTs because I'm familiar with using a single module for switching, and not familiar at all with the complexities of paralleling FETs that aren't matched and thermally bonded.
    $endgroup$
    – Hearth
    11 hours ago




    2




    2




    $begingroup$
    @Hearth No, it's at high line voltage where VCEsat is less of a problem, IGBTs really get into gear at 400v+. FETs, especially in the last few years, especially in the sub-50v realm, have really pushed RDSon and Qgate down. With a suitable FET for the current, you can get VDS very small, <100/200mV, not the 15% efficiency sapping 1.5v of an IGBT VCEsat with only 12v input. FETs are tame to parallel at the device level for switching, and polyphase converters are the way to reduce input current variations so reduce the requirement for humungeous input caps.
    $endgroup$
    – Neil_UK
    11 hours ago




    $begingroup$
    @Hearth No, it's at high line voltage where VCEsat is less of a problem, IGBTs really get into gear at 400v+. FETs, especially in the last few years, especially in the sub-50v realm, have really pushed RDSon and Qgate down. With a suitable FET for the current, you can get VDS very small, <100/200mV, not the 15% efficiency sapping 1.5v of an IGBT VCEsat with only 12v input. FETs are tame to parallel at the device level for switching, and polyphase converters are the way to reduce input current variations so reduce the requirement for humungeous input caps.
    $endgroup$
    – Neil_UK
    11 hours ago












    $begingroup$
    I think you could improve the answer better by explaining why would standard non-synchronous dc converter would work here. Why not the synchronous one? How about full bridge, Resonant LLC, etc?
    $endgroup$
    – Unknown123
    11 hours ago




    $begingroup$
    I think you could improve the answer better by explaining why would standard non-synchronous dc converter would work here. Why not the synchronous one? How about full bridge, Resonant LLC, etc?
    $endgroup$
    – Unknown123
    11 hours ago













    2












    $begingroup$

    The inductive coupling must be modeled. As well as eddy currents.



    200 amps switched in 200 nanoseconds (for high efficiency, fast switching must occur) and wired to be 1cm away from a 1cm-by-4cm servo-regulator loop, will induce this error voltage:



    Vinduce = 2e-7 * Area/Distance * dI/dT



    Vinduce = 2e-7 * 1cm*4cm / 1cm * 1Billion amps/second



    Vinduce = 2e-7 * 0.04 * 1.0e+9



    Vinduce = 2e-7 * 4e-2* 1.0e+9 = 8 volts.



    To be completely accurate, you need to write the integrals and extract the equation that uses NATURAL_LOG. And you need to model the eddy currents.



    At these levels of dI/dT, ground planes will NOT be ground planes. There will be large differences in voltages across the plane, because of eddy currents.



    The math suggests shields and planes (VDD or GROUND) will have EIGHT volts of gradients.



    I was brought in to diagnose the failures on a 15,000 horsepower speed controller. A loop of wire, to sense the magnetic field , held near the ground-plane, indicated 2 volts per square-inch. Ground Was Not Ground.






    share|improve this answer











    $endgroup$













    • $begingroup$
      This isn't a question about EMI. Yes, I know you like discussing these issues, but it isn't relevant here; the OP is just asking whether it's possible at all.
      $endgroup$
      – duskwuff
      49 mins ago
















    2












    $begingroup$

    The inductive coupling must be modeled. As well as eddy currents.



    200 amps switched in 200 nanoseconds (for high efficiency, fast switching must occur) and wired to be 1cm away from a 1cm-by-4cm servo-regulator loop, will induce this error voltage:



    Vinduce = 2e-7 * Area/Distance * dI/dT



    Vinduce = 2e-7 * 1cm*4cm / 1cm * 1Billion amps/second



    Vinduce = 2e-7 * 0.04 * 1.0e+9



    Vinduce = 2e-7 * 4e-2* 1.0e+9 = 8 volts.



    To be completely accurate, you need to write the integrals and extract the equation that uses NATURAL_LOG. And you need to model the eddy currents.



    At these levels of dI/dT, ground planes will NOT be ground planes. There will be large differences in voltages across the plane, because of eddy currents.



    The math suggests shields and planes (VDD or GROUND) will have EIGHT volts of gradients.



    I was brought in to diagnose the failures on a 15,000 horsepower speed controller. A loop of wire, to sense the magnetic field , held near the ground-plane, indicated 2 volts per square-inch. Ground Was Not Ground.






    share|improve this answer











    $endgroup$













    • $begingroup$
      This isn't a question about EMI. Yes, I know you like discussing these issues, but it isn't relevant here; the OP is just asking whether it's possible at all.
      $endgroup$
      – duskwuff
      49 mins ago














    2












    2








    2





    $begingroup$

    The inductive coupling must be modeled. As well as eddy currents.



    200 amps switched in 200 nanoseconds (for high efficiency, fast switching must occur) and wired to be 1cm away from a 1cm-by-4cm servo-regulator loop, will induce this error voltage:



    Vinduce = 2e-7 * Area/Distance * dI/dT



    Vinduce = 2e-7 * 1cm*4cm / 1cm * 1Billion amps/second



    Vinduce = 2e-7 * 0.04 * 1.0e+9



    Vinduce = 2e-7 * 4e-2* 1.0e+9 = 8 volts.



    To be completely accurate, you need to write the integrals and extract the equation that uses NATURAL_LOG. And you need to model the eddy currents.



    At these levels of dI/dT, ground planes will NOT be ground planes. There will be large differences in voltages across the plane, because of eddy currents.



    The math suggests shields and planes (VDD or GROUND) will have EIGHT volts of gradients.



    I was brought in to diagnose the failures on a 15,000 horsepower speed controller. A loop of wire, to sense the magnetic field , held near the ground-plane, indicated 2 volts per square-inch. Ground Was Not Ground.






    share|improve this answer











    $endgroup$



    The inductive coupling must be modeled. As well as eddy currents.



    200 amps switched in 200 nanoseconds (for high efficiency, fast switching must occur) and wired to be 1cm away from a 1cm-by-4cm servo-regulator loop, will induce this error voltage:



    Vinduce = 2e-7 * Area/Distance * dI/dT



    Vinduce = 2e-7 * 1cm*4cm / 1cm * 1Billion amps/second



    Vinduce = 2e-7 * 0.04 * 1.0e+9



    Vinduce = 2e-7 * 4e-2* 1.0e+9 = 8 volts.



    To be completely accurate, you need to write the integrals and extract the equation that uses NATURAL_LOG. And you need to model the eddy currents.



    At these levels of dI/dT, ground planes will NOT be ground planes. There will be large differences in voltages across the plane, because of eddy currents.



    The math suggests shields and planes (VDD or GROUND) will have EIGHT volts of gradients.



    I was brought in to diagnose the failures on a 15,000 horsepower speed controller. A loop of wire, to sense the magnetic field , held near the ground-plane, indicated 2 volts per square-inch. Ground Was Not Ground.







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited 11 hours ago

























    answered 12 hours ago









    analogsystemsrfanalogsystemsrf

    16k2822




    16k2822












    • $begingroup$
      This isn't a question about EMI. Yes, I know you like discussing these issues, but it isn't relevant here; the OP is just asking whether it's possible at all.
      $endgroup$
      – duskwuff
      49 mins ago


















    • $begingroup$
      This isn't a question about EMI. Yes, I know you like discussing these issues, but it isn't relevant here; the OP is just asking whether it's possible at all.
      $endgroup$
      – duskwuff
      49 mins ago
















    $begingroup$
    This isn't a question about EMI. Yes, I know you like discussing these issues, but it isn't relevant here; the OP is just asking whether it's possible at all.
    $endgroup$
    – duskwuff
    49 mins ago




    $begingroup$
    This isn't a question about EMI. Yes, I know you like discussing these issues, but it isn't relevant here; the OP is just asking whether it's possible at all.
    $endgroup$
    – duskwuff
    49 mins ago











    0












    $begingroup$

    A programmable voltage three phase inverter with a full bridge (or two that are wired with a 30degree phase off-set) (to gain minimum ripple) with some inductance and capacitance to follow that are designed for 24V input might just be able to be found semi custom.



    Some crazy variable speed drive system with a 24V supply and programmable voltage might even work out of the box.



    Starting to design one from scratch for a once-off will cost much more than you think, hoping to save money this way is futile. I would spend a week making calls to every VFD and inverter manufacturer with your loosest tolerable specifications and see if anyone can configure OTS parts.






    share|improve this answer









    $endgroup$


















      0












      $begingroup$

      A programmable voltage three phase inverter with a full bridge (or two that are wired with a 30degree phase off-set) (to gain minimum ripple) with some inductance and capacitance to follow that are designed for 24V input might just be able to be found semi custom.



      Some crazy variable speed drive system with a 24V supply and programmable voltage might even work out of the box.



      Starting to design one from scratch for a once-off will cost much more than you think, hoping to save money this way is futile. I would spend a week making calls to every VFD and inverter manufacturer with your loosest tolerable specifications and see if anyone can configure OTS parts.






      share|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        A programmable voltage three phase inverter with a full bridge (or two that are wired with a 30degree phase off-set) (to gain minimum ripple) with some inductance and capacitance to follow that are designed for 24V input might just be able to be found semi custom.



        Some crazy variable speed drive system with a 24V supply and programmable voltage might even work out of the box.



        Starting to design one from scratch for a once-off will cost much more than you think, hoping to save money this way is futile. I would spend a week making calls to every VFD and inverter manufacturer with your loosest tolerable specifications and see if anyone can configure OTS parts.






        share|improve this answer









        $endgroup$



        A programmable voltage three phase inverter with a full bridge (or two that are wired with a 30degree phase off-set) (to gain minimum ripple) with some inductance and capacitance to follow that are designed for 24V input might just be able to be found semi custom.



        Some crazy variable speed drive system with a 24V supply and programmable voltage might even work out of the box.



        Starting to design one from scratch for a once-off will cost much more than you think, hoping to save money this way is futile. I would spend a week making calls to every VFD and inverter manufacturer with your loosest tolerable specifications and see if anyone can configure OTS parts.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 5 hours ago









        KalleMPKalleMP

        3,6801930




        3,6801930






















            jasonthegreat1955gmailcom is a new contributor. Be nice, and check out our Code of Conduct.










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