DC-DC converter from low voltage at high current, to high voltage at low currenthigh voltage Buck-Boost converterCheap high-voltage low-current sourceStep-up converter generating too much voltagecurrent density value for inductor used in boost converterHigh voltage boost converter safetyBuck boost converter - High current 15A@12VDC +why Boost converter output voltage decreases at high power?Boost Converter: Low voltage high current VS. High Voltage, low current?Boost converter - high currentIncrease Boost Converter Current
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DC-DC converter from low voltage at high current, to high voltage at low current
high voltage Buck-Boost converterCheap high-voltage low-current sourceStep-up converter generating too much voltagecurrent density value for inductor used in boost converterHigh voltage boost converter safetyBuck boost converter - High current 15A@12VDC +why Boost converter output voltage decreases at high power?Boost Converter: Low voltage high current VS. High Voltage, low current?Boost converter - high currentIncrease Boost Converter Current
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
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.
- Is this feasible? I can’t see why not.
- 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
edited 13 hours ago
SamGibson
11.7k41739
asked 13 hours ago
jasonthegreat1955gmailcomjasonthegreat1955gmailcom
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.
$endgroup$
|
show 2 more comments
$begingroup$
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.
- Is this feasible? I can’t see why not.
- 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
edited 13 hours ago
SamGibson
11.7k41739
asked 13 hours ago
jasonthegreat1955gmailcomjasonthegreat1955gmailcom
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.
$endgroup$
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
13 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
|
show 2 more comments
$begingroup$
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.
- Is this feasible? I can’t see why not.
- 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
edited 13 hours ago
SamGibson
11.7k41739
asked 13 hours ago
jasonthegreat1955gmailcomjasonthegreat1955gmailcom
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.
$endgroup$
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.
- Is this feasible? I can’t see why not.
- 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
dc-dc-converter boost
edited 13 hours ago
SamGibson
11.7k41739
asked 13 hours ago
jasonthegreat1955gmailcomjasonthegreat1955gmailcom
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.
edited 13 hours ago
SamGibson
11.7k41739
asked 13 hours ago
jasonthegreat1955gmailcomjasonthegreat1955gmailcom
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.
edited 13 hours ago
SamGibson
11.7k41739
edited 13 hours ago
SamGibson
11.7k41739
edited 13 hours ago
SamGibson
11.7k41739
11.7k41739
asked 13 hours ago
jasonthegreat1955gmailcomjasonthegreat1955gmailcom
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.
asked 13 hours ago
jasonthegreat1955gmailcomjasonthegreat1955gmailcom
291
asked 13 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
13 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
|
show 2 more comments
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
13 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
13 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
13 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
|
show 2 more comments
3 Answers
3
active
oldest
votes
$begingroup$
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
answered 13 hours ago
PuffafishPuffafish
1,145113
$endgroup$
$begingroup$
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
10 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
10 hours ago
|
show 1 more comment
$begingroup$
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.
answered 11 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
$begingroup$
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
27 mins ago
add a comment |
$begingroup$
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.
answered 5 hours ago
KalleMPKalleMP
3,6801930
$endgroup$
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
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
answered 13 hours ago
PuffafishPuffafish
1,145113
$endgroup$
$begingroup$
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
10 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
10 hours ago
|
show 1 more comment
$begingroup$
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
answered 13 hours ago
PuffafishPuffafish
1,145113
$endgroup$
$begingroup$
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
10 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
10 hours ago
|
show 1 more comment
$begingroup$
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
answered 13 hours ago
PuffafishPuffafish
1,145113
$endgroup$
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
answered 13 hours ago
PuffafishPuffafish
1,145113
answered 13 hours ago
PuffafishPuffafish
1,145113
answered 13 hours ago
PuffafishPuffafish
1,145113
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
10 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
10 hours ago
|
show 1 more comment
$begingroup$
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
10 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
10 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
10 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
10 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
10 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
10 hours ago
|
show 1 more comment
$begingroup$
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.
answered 11 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
$begingroup$
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
27 mins ago
add a comment |
$begingroup$
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.
answered 11 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
$begingroup$
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
27 mins ago
add a comment |
$begingroup$
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.
answered 11 hours ago
analogsystemsrfanalogsystemsrf
16k2822
$endgroup$
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.
answered 11 hours ago
analogsystemsrfanalogsystemsrf
16k2822
edited 11 hours ago
answered 11 hours ago
analogsystemsrfanalogsystemsrf
16k2822
answered 11 hours ago
analogsystemsrfanalogsystemsrf
16k2822
answered 11 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
27 mins ago
add a comment |
$begingroup$
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
27 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
27 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
27 mins ago
add a comment |
$begingroup$
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.
answered 5 hours ago
KalleMPKalleMP
3,6801930
$endgroup$
add a comment |
$begingroup$
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.
answered 5 hours ago
KalleMPKalleMP
3,6801930
$endgroup$
add a comment |
$begingroup$
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.
answered 5 hours ago
KalleMPKalleMP
3,6801930
$endgroup$
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.
answered 5 hours ago
KalleMPKalleMP
3,6801930
answered 5 hours ago
KalleMPKalleMP
3,6801930
answered 5 hours ago
KalleMPKalleMP
3,6801930
answered 5 hours ago
KalleMPKalleMP
3,6801930
3,6801930
add a comment |
add a comment |
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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
13 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