Custom Power Supply

[mlambru]

I need a power supply for the load of 10KW, which will feed it with the alternative currency, but by pulses of 2 KHz. The power in the load will be regulated by regulating the duty cycle of pulses. Control pulses can be generated by PC or programmable controller, as the power in the load should vary depending on the time/date. Can you propose a diagram for such a device? What switching power elements to use - say power transistors, MOSFET SSR, whatever? Maybe exist ready blocks, which can be used to assemble such a device?

 

[crutschow]

10kW? What is your power source?

 

[mlambru]

The power source is 240V AC, power sufficient.

 

[bountyhunter]

I need a power supply for the load of 10KW, which will feed it with the alternative currency, but by pulses of 2 KHz. The power in the load will be regulated by regulating the duty cycle of pulses. Control pulses can be generated by PC or programmable controller, as the power in the load should vary depending on the time/date. Can you propose a diagram for such a device? What switching power elements to use - say power transistors, MOSFET SSR, whatever? Maybe exist ready blocks, which can be used to assemble such a device?

I used to be in the business of designing such units.

"Can you propose a diagram for such a device?"

I would have proposed a development schedule of about 12 months and Vince would have probably proposed a contract price of a couple of hundred thousand dollars.

Do you have any idea how complex a 10kW converter is to design from scratch?

 

[mlambru]

I'm not attracted to the idea of designing it from scratch. If you was in this business, may be you can suggest who are producing such units, just to buy a ready made one? Or at least main blocks?

 

[bountyhunter]

Maybe. You need to give a detailed list of specs for your application.

 

[mlambru]

In fact there is no more specs besides already mentioned. Everything according to this will suite.

 

[arunb]

re:

use a generator set

 

[bountyhunter]

In fact there is no more specs besides already mentioned. Everything according to this will suite.

Then you need to go back to whomever is asking for this and get specifications. I probably designed at least 30 power supplies and I have no idea what it is you are trying to build, which means the information does not define the design.

What is the input voltage source and range of voltage?

What is the output voltage voltage and current required? Just saying a "load of 10kW" is basically useless is designing a power supply.

"will feed it with the alternative currency, but by pulses of 2 KHz."

Sine wave? Square wave? What Amplitude?

Size constraints?

No offense, but if neither you or the originator can even define the device, the hopes of designing and building it are basically zero.

 

[bountyhunter]

One of the problems with people not versed in power is they can't do a simple "sanity check" on the size of a project. For example:

Raw power to run any power converter comes from 230VAC (single phase) or 208VAC three phase which can be rectified and used to create an unregulated DC voltage of about 275 to use to convert power from.

How much current will flow from that 275V line assuming 90% converter efficiency?

OVER 40 AMPS.

Do you know how difficult it is to build a converter which can handle that? To begin with, you can't use a standard H bridge because no transistors exist which can do that. It would require multiple converters in parallel synchronized to spread the input current peaks over time. This is generically called multi-phase synchronous conversion.

Designing the magnetics (switching transformer and inductors) alone would be complex.

Here is my serious suggestion: go to power supply companies and see what they make. Some used to mke 5kW power supplies, we never made anything bigger than that. You can find supplies that can be parallel connected. The engineering horsepower to develop this design would cost about 1000X what buying one made would.

Good luck.

 

[Torben]

I think Brownout's right. You need a genset or an industrial power service. If you're just doing this once the genset is probably cheaper. You can rent them, depending on where you are.


Torben

 

[mlambru]

That's exactly what I need - direction to the company who produce such a power supply. Unfortunately I do not know about anything similar.
The waveform in the load should be 2 KHz pulses, may be square, or semi square, exact form not important, but the envelope curve of this pulses should be normal AC sine wave.
Thus I do not think I need a converter at all - just a device to quickly interrupt the current.
Unfortunately normal electromechanical relays can not do it with such a frequency - thus I need some sort of silicon device.
I think that may be MOSFET SSR will suite, but they normally have optical isolation - whon't it be problem to obtain reliable 2KHz switching?