Switching Power Supply - 3.3v / 5.0v / 6.0v @ 120+ AMPS?

[oeginc]

I posted this question quite some time ago and got some ideas but I fell short on finding a way to implement them, also some of my requirements have changed slightly since then.

I work on many different robotics type projects, and there are many more I'm interested in but would like to create a single PCB that I can add to any project to provide me the power I might need. The idea here is to come up with a good working design, board it, then make like 10-15 so whenever I need power I just grab a power board and drop it in my project.

Exactly what I am looking for is this:

* Input voltage will be a LiPo battery pack (or packs) around 14-24 VDC with 125 AMP continuous discharge capacity (250A burst).

* I need 3 outputs: +3.3 VDC @ 3A and +5.0 VDC @ 3A for Microcontrollers, and a +6.0 VDC @ 120A for motors/servos/etc.

* I would like them to be regulated (+/- 0.5 volts or so).

* Loads will vary significantly over time (driving large servos with high current draw).

* I expect maximum current draw to be on the order of around 120 AMPS max (each servo can draw ~2.0 AMPS while running and ~5.21 AMPS at stall, we typically run around 24 servos, although it's unlikely that they ALL will hit stall simultaneously)

* I need the circuit to be very efficient, drawing these kinds of loads I need the batteries to last as long as possible.

I've been toying with the idea of using LM2576-3.3's and LM2576-5.0's for the 3.3vdc & 5.0vdc power, but I have no idea what's out there for supplying 120A @ 6.0vdc... Also, is there a better/cheaper way to do switching regulated power than the LM2576's? I saw MikeMI (I believe from here) post something at 2-transistor Black Regulator that didn't use the LM2576, but I didn't see any specifications on how many amps it was capable of.

Any help would be greatly appreciated, even if you could just point me in the right direction.

Thanks!

 

[oeginc]

Start of the power supply

Here is a schematic I started on before I really knew what I wanted.

 

[Diver300]

The easiest solution is a few of these:-

Block | Power Supplies | Power Supplies, Inverters, DC/DC Converters & Generators | DC/DC Converters - Non Isolated | Switching Regulators |SDC60/15-20

With that sort of power, it is quite tricky especially if you haven't made a switch mode power supply before.

It would be a good idea to make sure that the switch mode power supplies are phased so that they do not all switch at the same time. Imagine a car engine where all 4 cylinders fired at the same time: there would be a vibration problem. The regulators in computers that supply the CPU are phased like that.

The LM25576 allows a synchronisation connection to control phasing.

The LM2576 that you suggested is available with preset outputs at 3.3 V, 5 V and 12 V. What you want is the adjustable version that lets you use two resistors to set a wide range of output voltages.