Emerson LPS-10x-M Alternatives

The Emerson has OVP, namely a crowbar. Maybe you're glitching that, or it trips from a big downward load step. Maybe it's a suicide load protector.

Got enough air?

I like the MeanWell supplies. Cheap and reliable.

ttdesign.com

Well I like Phihong wallwarts, but they don't seem to do 240 Watts, Have you trolled through Mouser? They have a lot of supplies.

George H.

How about a 130W 24V Astrdyne, PMMK130S-24 We get hose pretty cheap. Also the Volgen line is pretty robust SPN150-24S, it can take a good surge on the output without collapsing.

Cheers

I did have a bug in the software that was allowing the motor to back-feed into the power supply rail without disconnecting as it should. So it could have been that.

I've got more supplies on the way, I may do some testing with resistors and a switch to see if it can stand simply switching a load on and off. One would _hope_ that would be the case.

Don't count on it!

If you are decelerating a motor, where does the energy go? Mechanical systems can store a bunch of joules.

If the system is working right, it all goes straight into a resistor. As soon as the motor goes into regeneration the motor rail gets disconnected from the power supply (via a FET) and is allowed to float up. Then as soon as it gets above a set voltage the resistor gets switched in. There's a healthy amount of capacitance at the motor rail and the whole shebang gets sampled at the motor PWM rate, so it makes a self- oscillating voltage regulator that holds the motor rail close enough to the set point for things to work smoothly.

When the motor starts to draw power the motor rail drops: when it drops down to match the power supply voltage things are switched on again and it draws power from the supply.

That sounds a little tricky. You could just hang an active zener across the power supply output to clamp at, say, 25 volts. That might keep the ps from crowbarring, too.

I'm sure Jim would be delighted to design an accurate, 10 amp active zener circuit for you.

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He'd probably expect to get paid, and application specific integrated circuits used to need potential sales in excess of 100,000 units back when I knew anything about it.

Cambridge Instruments did have a few made on the basis that the the lithographic patterns would be written by a shaped beam electron beam microfabricator, which made 500 per year economically feasible. They used ES2 (European Silicon Structures) at Aix-en-Provence

which survived into the mid-1990's.

A few years back, I was doing software for a device that had some small (50 W or so) motors with integrated controllers; one end of the motor had a shaft and the other end had connections for 24 V DC and a serial port. These motors would try to regenerate into the power supply when slowing.

Version 0 of the assembly, for bench testing only, had a 120 VAC to

Version 1 of the assembly had a 120 VAC to 30-60 VDC adjustable rackmount supply by Sorensen, a long wire, a DC-DC converter brick to make 24 V DC, a foot or two of wire, and the motors. I don't remember the brand of the brick; it was about 0.5" x 2" x 3", and rated about

The short-term fix, so I could keep working on the software, was to put a few 1000 uF or so capacitors on the 24 V DC rail. I know for sure there was one directly on the output pins of the brick and I think there was one at each motor as well. These seemed to soak up enough of the regeneration energy that the DC-DC brick *usually* didn't shut down. I don't know what the final production fix was.

I have no experience with them.

The Emerson data sheet says "minimum load 0 A" but data sheets have been known to lie before. What happens if you just slap a plain old power resistor across the output of the supply, such that it always draws 5 or 10 W or so at 24 V DC? This is more to find out if the supply needs a minimum load than a production fix. On the other hand, maybe you can provide the minimum load with a lamp and sell it as a high-visibility power indicator. :)

The data sheet also says it has a 12 V DC, 0.5 A fan power output. Maybe loading that output helps the regulation or behavior?

This also appears to be a "medical" power supply. I *think* this mostly has to do with isolation voltages (higher), leakage currents (lower), and more numbers and squiggles on the rating plate. These probably don't have a direct effect on your problem, but if there is a non- medical version of the same supply, it might be worth a try.

Matt Roberds

wrote: [snip].

More demented snarkiness.

But rather trivial to design, even with off-the-shelf discrete's... think a TL431 plus a power PNP.

I've provided tons of schematics here, without remuneration (for Larkin and the other low life here, "remuneration" means "paid" ;-)

The admission price has nothing to do with unit count... figure at least $ 1Million annually to the foundry.

agreed, if a small SW error is fatal to the hardware, you are asking for trouble..

you said efficiency is not an issue, why not a big old diode, Shottky if you prefer, in series with the PS output, that is fail safe. and I guess you need the zener also

Mark

Well, yes. Which means that the per-piece price is pretty much (admission price) / (volume) until the volume gets pretty damned big. Unless someone wants to pay you $2e6 for one chip, if you want to make a profit on it you have to sell lots and lots.

I'm sure I could design an accurate, 10 amp active voltage clamp circuit, too -- it just wouldn't all be on one piece of silicon.

And with such a part -- whether it came from me or from Jim -- I'd still have the issue that if it didn't work then the power supply wouldn't be protected. It is, to quote, "tricky". So I may as well fix what I have, and make sure that I'm using a power supply that doesn't have any unexpected gotchas (which is what this thread is trying to find out about

-- whether my power supply is going to cut me off at the knees).

Well, it was only small in physical size, spanning perhaps four or five words of flash. Once I noticed it, it was about as large and as glaring as two diodes in parallel, where the obvious circuit intent was two diodes in anti-parallel.

I may do that. If the power supply is well behaved I don't see the need for the clamp, but I'm going to at least see what the series diode does to me.

The power consumption isn't an issue, true -- but if I introduce a 10W hot-spot into the design it'll stick out of the overall thermal management landscape like a sore thumb.

Show us.

Well, design a circuit that always works!

So I may as well fix what I have,

How are you disconnecting the PS from the h-bridge rail? That needs a bidirectional switch, not just one mosfet, I think.

Of course if you don't have a full bridge and regen circuit I guess you would have to rely on a DBr circuit to switch in a burden R on the DC buss when it over does it.

A basic active clamp with R in series with it works well.

Jamie

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I have seen problems before when a load has a serious content at the switcher frequency, or one of them is a near harmonic of the other. Both tend to misbehave. The available fixes are a different switcher, a different motor controller frequency, or a heavy LC trap.

YMMV

?-)

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Crikey Larkin, even i can see how to do that. Just how dumb are you?

?-)