High Side Active Load

I guess it's better to say what I'm trying to do. I'm am trying to create an active load that is on the high side of a circuit(has to be for various reasons) used for automating a test procedure. I figured a mosfet would work nicely but since I need AC a SSR configuration should work. I can parallel several of these for power handling and heat disspation reduction. The only issue is driving them. The load is on the order of 10's of ohms at about

110V rms but may be temporarily shorted(there is an additional fixed load). Current and voltage will be monitored and can be used as a feedback to set the desired gate votage.

I was thinking of using floating gate drive and an opto but not sure if I can get the accuracy needed(say about 1% of the load).

I would rather use a monolithic device rather than try and roll my own but I can't find anything that will work for ac and variable drive(all are bi-stable).

It's not necessary that I use mosfets and BJT's may be easier to use but unless there is compelling reason to go with BJT's I'd rather use mosfets(I have plenty on stock and might need to parallel them).

Reply to
Jeff Johnson
Loading thread data ...



I'm not sure what "high side" means, but... if you need this for an AC power circuit (5 to 15A, 120 to 250VAC), you can make a variable load with a variable autotransformer (Variac) and fixed resistor, or you can make a variable AC source with a Variac, or you can spin a generator/alternator and diddle the output with a controlled current source feeding the field coils.

Other approaches (like using a phase control triac and filtering) are possible, as well.

You could even series up a bunch of resistors (1 ohm, 2 ohm, 4,

8,...128 ohm) and shunt 'em with relays to make a DAC whose output is a variable resistance.
Reply to

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.