Author Topic: Switch mode programable electronic load?  (Read 15456 times)

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Offline zaptaTopic starter

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Re: Switch mode programable electronic load?
« Reply #25 on: July 26, 2015, 07:20:18 pm »
How could you mesure this if you electronic dc load has a responsive time of 1.5 ms ?

Can't you absorb the fast load increase into a capacitor?  This is what switch mode supplies do in the other direction.

Switch mode power supply and load seems to me to be dual problems with similar challenges but in the opposite directions, so a solution in one can hint for a solution in the other.
« Last Edit: July 26, 2015, 07:21:59 pm by zapta »
 

Offline oldway

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Re: Switch mode programable electronic load?
« Reply #26 on: July 26, 2015, 07:56:58 pm »
No, the challenges are not similar...To explain this, let us give an example: you can't measure a 10 ns rise time with a 20Mhz oscilloscope...electronic load must be 10x or more faster than the power supply you want to test. (dynamic test)
 

Offline electr_peter

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Re: Switch mode programable electronic load?
« Reply #27 on: July 26, 2015, 09:37:32 pm »
Besides very complicated design, it is simply not cost effective to recover energy to mains from electronic DC load. The only real advantage is reduced need for cooling (some of electronic loads with energy recovery linked above have ~10 kW rating, so heat is significant issue).

Similar problem occurs during testing of jet engines (or gas generators) of various kinds. When put into test cell, jet engine converts massive quantities of fuel to massive quantity of noise, heat and gas flow - wasted energy, that is. To recover this energy huge investment in infrastructure is needed which is completely uneconomical and very complicated. Also, remember that testing phase consumes many orders less fuel than engine in operation. So nothing to save here.
 

Offline oldway

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Re: Switch mode programable electronic load?
« Reply #28 on: July 27, 2015, 06:02:22 am »
I continue with the idea that the principle of dissipating all the power in semiconductor is not the best.

I choose rather the principle of variable rheostat combining power resistors with semiconductors.

Much of the power should be dissipated in power resistors.

The radiators are then reduced and problems of semi-cnducteurs operating in linear region with high dissipation would be reduced.
 


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