Products > Test Equipment
Power Supply: Build or Buy?
tautech:
--- Quote from: mawyatt on May 11, 2023, 02:50:25 am ---
--- Quote from: tautech on May 10, 2023, 08:46:14 pm ---
What PSU are you using for that development Mike ?
Have you looked at the SPS5000X range ?
I've been using my 40V 60A unit for charging solar array batteries lately....a remote installation so powered with a genset.
--- End quote ---
The Korad KWR102, but it's not enough for the higher current pump motors which may need up to 50 amps! We should have more data on the motors soon to help with the decision, and the SPS5000X might be a candidate.
Best,
--- End quote ---
Mine's a 5042X 40V/60A 780W but they do have a total output rating in W so can't do both those figures at once. :(
They start getting up in cost and even the 40V/90A 1080W 5043X jobby might not quite meet your needs or the coming 200V 25A 1500W SPS6000X either although that's not due for a bit I believe. I did start a thread for both you can hunt out if required.
nctnico:
--- Quote from: james_s on May 10, 2023, 05:30:12 pm ---
--- Quote from: Fungus on May 10, 2023, 12:45:55 pm ---It won't be easy, there's usually a big capacitor across the output that will absorb it.
--- End quote ---
Not in a bench supply, a big capacitor across the output reduces the effectiveness of current limiting in the event of a short circuit.
--- End quote ---
A reasonably sized capacitor is necessary for control loop stability. But in the end there isn't much energy in it.
About connecting inductive loads: the higher end power supplies from (at least) HP/Agilent/Keysight have an active load circuit inside that sinks current called a 'down programmer'. This is there to make the output voltage lower quickly AND dissipate energy coming into the power supply. You can see this in action when connecting a motor to it and turn the output off. You'll see the current go negative while the motor spins down. This active load circuit is typically engaged for a few seconds at most but it does help.
David Hess:
--- Quote from: nctnico on May 11, 2023, 09:42:39 am ---
--- Quote from: james_s on May 10, 2023, 05:30:12 pm ---
--- Quote from: Fungus on May 10, 2023, 12:45:55 pm ---It won't be easy, there's usually a big capacitor across the output that will absorb it.
--- End quote ---
Not in a bench supply, a big capacitor across the output reduces the effectiveness of current limiting in the event of a short circuit.
--- End quote ---
A reasonably sized capacitor is necessary for control loop stability. But in the end there isn't much energy in it.
About connecting inductive loads: the higher end power supplies from (at least) HP/Agilent/Keysight have an active load circuit inside that sinks current called a 'down programmer'. This is there to make the output voltage lower quickly AND dissipate energy coming into the power supply. You can see this in action when connecting a motor to it and turn the output off. You'll see the current go negative while the motor spins down. This active load circuit is typically engaged for a few seconds at most but it does help.
--- End quote ---
25 to 100 microfarads per amp is typical however with careful design, less than 0.1 microfarads per amp is possible. I just noticed that it is the later designs which always seem to include the class-AB output stage or active load.
mawyatt:
--- Quote from: tautech on May 11, 2023, 03:39:13 am ---
Mine's a 5042X 40V/60A 780W but they do have a total output rating in W so can't do both those figures at once. :(
They start getting up in cost and even the 40V/90A 1080W 5043X jobby might not quite meet your needs or the coming 200V 25A 1500W SPS6000X either although that's not due for a bit I believe. I did start a thread for both you can hunt out if required.
--- End quote ---
We did take a look at the 5000 series, and yes they are kind of expensive!!
Once we get the pump motor profiles for the various pump motors, then we'll have a better idea of what we'll need. The KWR102 isn't going to be enough tho.
The system design is leaning towards separate power supplies, rather than one unified supply. This allows a dedicated supply for the pump motor, and another for the other stuff. With this in mind the heavy load motor supply doesn't need to be accurate or low noise, just have enough to hold up the pump motor and one option is to use a Mean Well Open Frame Supply and design a quick acting current limit, as we don't need a variable voltage range, so this may work out.
It's interesting to see discussions of power supply active sinking capability, IMO this should be a prerequisite in any modern quality Bench Level Supply, but few have this built-in capability. Same goes for output capacitance, this should be as low as possible in a quality Bench Supply. It doesn't take much energy to destroy/damage a modern IC, and even with a low current limit set point the output capacitance energy storage is sufficient to quickly dump into a circuit and take out various chips, as as we know Murphy will direct that energy to the most expensive and elusive chips!!
Best,
armandine2:
:clap: a good time to check my kikusui manual re. sinking current
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