I wanted to reply to this project earlier but forgot to. Oops! Retrofitting a PSU to deliver more current can be done in several ways.
First, you might be able to cool the output transistors more aggressively. Usually, the output MOSFET's are rated in deliverable current based upon a certain heatsink rating, because they start to self-destruct at a certain output level. However, sometimes the FET's have current limiting shutdown protection so that you CAN'T overload them. I think it's more likely, though, it's a overheat thermal protection rather than over-current protection.
Secondly, you can simply replace the output MOSFET's with beefier versions. Will this work? Maybe. Driving a heavier load might work this way at the expense of more noise in the voltage domain. Switching power supplies are designed to supply a max amount of current at a given max ripple. The bulky capacitors you see are used to smooth out the voltage, but they can only smooth out so much in between each cycle of supply current being switched in (see theory of how switched PSU's operate). You'd have to upgrade the output capacitors too.
But, this might fail to work too! What about the inductors? They are designed for a given workload as well, since they can only store so much energy. Increase the inductor size though, and you might have to fiddle with the timing parameters of the switching feedback/control circuit (to avoid tripping the overcurrent protection for the sudden inrush when you turn it on, and to avoid other more subtle design "bugs").
Get the picture? A switched PSU is a designed SYSTEM, not a rack mount architecture. Weakest link breaks the chain.
Now, don't get all pessimistic. I raised a bunch of bugaboos that might or MIGHT NOT happen. The easiest thing to do is to increase the heatsinking capacity on the PSU (or just increase the fan size or speed) and live with more ripple. TEC's don't like ripple, but they can live with it. They just end up not working as efficiently (i.e. reduced heat moving capacity for the given input energy, which means that the target doesn't get as cool as it should).
If you are really excited about doing something hard core, just build a linear power supply. You need a beefy set of components, but it's not complicated.
Here is a good excerpt from
this website:
Quote:
What is a linear power supply?
A basic linear power supply consists of a transformer, rectifier, and smoothing capacitor. The lower voltage output from the transformer is input to the four diodes which make up a rectifier. The rectifier outputs a varying DC signal (between ground and some peak) which is smoothed and filtered by a capacitor.
More complicated supplies might add protection circuitry or regulation. For example, Taito supplies add an SCR-crowbar circuit which immediately shutdown the power supply if a short circuit is present. A Gottlieb power supply uses a zener diode to adjust the current-flow of the circuit to the known voltage from the zener in case of line-voltage variances. All these still build upon the basic transformer, rectifier, capacitor model.
A linear power supply does not require a load to operate. It is fine to operate most or all linear power supplies with no load. Bench top testing is easy since it is a simple analog circuit.
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The simplest design has no regulation because you know what the output load is going to be, and you know that it doesn't change. That is a TEC, for the most part.
AC -> Bridge -> Capacitor(s) -> TEC
More if you're interested.