Forums

Emerson LPS-10x-M Alternatives

Started by Tim Wescott April 9, 2013
So, I'm working on a motor drive board for a customer.  Due to a desire 
for performance improvements within the existing space, we're going from 
the traditionally-accepted brute-force power supply to a switcher.

I have this nice board and software set that's carefully designed to 
treat the power supply with kid gloves -- and it works very well with the 
power supply that we used for prototyping.

But for space reasons they went out and found what appears to be the 
smallest possible power supply with the apparent specifications needed 
(24V and 10A):

http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf

It's not that this power supply sucks, per se.  It's just that things 
that work just fine with the original supply (A TDK/Lambda SWS300-24) 
make the Emerson supply either exceedingly unhappy or downright dead.  
Worse, I'm not sure what's taking out the power supplies.

So --

Does anyone have any mileage with these Emerson supplies?  After I told 
the customer "why yes, that should do" I began to notice the name 
"Emerson" on this group, and the view of their stuff seems to be pretty 
dim.  I'd like to know if you feel these are OK, or comprehensively bad, 
or what.

Also, I've carefully designed things so that any time the motor is 
generating the power goes into a resistor and not into raising the motor 
supply rail (and thus backfeeding the supply).  But I did notice that 
doing so kills one of these Emerson supplies (the TDK supply mostly takes 
it in stride, or if you're really egregious about things it turns off 
until you cycle power).

Do you know of anything else that would kill one of these supplies?  
While I've eliminated the backfeeding problem, the board still has a 
current draw that can vary from a few tens of milliamps to ten amps over 
the space of less than a second -- if it would make the supply happier I 
can change this so that whenever the motor is turning the board is always 
drawing some minimum power.  Efficiency will suffer -- but we're not 
after efficiency, we're after performance in a small space.

Also, if anyone knows of a supply that's the same size or not much 
bigger, but comes from a manufacturer that's known to make bulletproof 
stuff, I'd appreciate it.

-- 
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
On Tue, 09 Apr 2013 17:37:22 -0500, Tim Wescott <tim@seemywebsite.com>
wrote:

>So, I'm working on a motor drive board for a customer. Due to a desire >for performance improvements within the existing space, we're going from >the traditionally-accepted brute-force power supply to a switcher. > >I have this nice board and software set that's carefully designed to >treat the power supply with kid gloves -- and it works very well with the >power supply that we used for prototyping. > >But for space reasons they went out and found what appears to be the >smallest possible power supply with the apparent specifications needed >(24V and 10A): > >http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf > >It's not that this power supply sucks, per se. It's just that things >that work just fine with the original supply (A TDK/Lambda SWS300-24) >make the Emerson supply either exceedingly unhappy or downright dead. >Worse, I'm not sure what's taking out the power supplies. > >So -- > >Does anyone have any mileage with these Emerson supplies? After I told >the customer "why yes, that should do" I began to notice the name >"Emerson" on this group, and the view of their stuff seems to be pretty >dim. I'd like to know if you feel these are OK, or comprehensively bad, >or what. > >Also, I've carefully designed things so that any time the motor is >generating the power goes into a resistor and not into raising the motor >supply rail (and thus backfeeding the supply). But I did notice that >doing so kills one of these Emerson supplies (the TDK supply mostly takes >it in stride, or if you're really egregious about things it turns off >until you cycle power). > >Do you know of anything else that would kill one of these supplies? >While I've eliminated the backfeeding problem, the board still has a >current draw that can vary from a few tens of milliamps to ten amps over >the space of less than a second -- if it would make the supply happier I >can change this so that whenever the motor is turning the board is always >drawing some minimum power. Efficiency will suffer -- but we're not >after efficiency, we're after performance in a small space. > >Also, if anyone knows of a supply that's the same size or not much >bigger, but comes from a manufacturer that's known to make bulletproof >stuff, I'd appreciate it.
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. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
On Apr 9, 6:37=A0pm, Tim Wescott <t...@seemywebsite.com> wrote:
> So, I'm working on a motor drive board for a customer. =A0Due to a desire > for performance improvements within the existing space, we're going from > the traditionally-accepted brute-force power supply to a switcher. > > I have this nice board and software set that's carefully designed to > treat the power supply with kid gloves -- and it works very well with the > power supply that we used for prototyping. > > But for space reasons they went out and found what appears to be the > smallest possible power supply with the apparent specifications needed > (24V and 10A): > > http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf > > It's not that this power supply sucks, per se. =A0It's just that things > that work just fine with the original supply (A TDK/Lambda SWS300-24) > make the Emerson supply either exceedingly unhappy or downright dead. > Worse, I'm not sure what's taking out the power supplies. > > So -- > > Does anyone have any mileage with these Emerson supplies? =A0After I told > the customer "why yes, that should do" I began to notice the name > "Emerson" on this group, and the view of their stuff seems to be pretty > dim. =A0I'd like to know if you feel these are OK, or comprehensively bad=
,
> or what. > > Also, I've carefully designed things so that any time the motor is > generating the power goes into a resistor and not into raising the motor > supply rail (and thus backfeeding the supply). =A0But I did notice that > doing so kills one of these Emerson supplies (the TDK supply mostly takes > it in stride, or if you're really egregious about things it turns off > until you cycle power). > > Do you know of anything else that would kill one of these supplies? > While I've eliminated the backfeeding problem, the board still has a > current draw that can vary from a few tens of milliamps to ten amps over > the space of less than a second -- if it would make the supply happier I > can change this so that whenever the motor is turning the board is always > drawing some minimum power. =A0Efficiency will suffer -- but we're not > after efficiency, we're after performance in a small space. > > Also, if anyone knows of a supply that's the same size or not much > bigger, but comes from a manufacturer that's known to make bulletproof > stuff, I'd appreciate it. > > -- > My liberal friends think I'm a conservative kook. > My conservative friends think I'm a liberal kook. > Why am I not happy that they have found common ground? > > Tim Wescott, Communications, Control, Circuits & Softwarehttp://www.wesco=
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.
"Tim Wescott" <tim@seemywebsite.com> wrote in message 
news:SuudnYnN_bS_BfnMnZ2dnUVZ_vGdnZ2d@giganews.com...
> So, I'm working on a motor drive board for a customer. Due to a > desire > for performance improvements within the existing space, we're going > from > the traditionally-accepted brute-force power supply to a switcher. > > I have this nice board and software set that's carefully designed to > treat the power supply with kid gloves -- and it works very well with > the > power supply that we used for prototyping. > > But for space reasons they went out and found what appears to be the > smallest possible power supply with the apparent specifications needed > (24V and 10A): > > http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf > > It's not that this power supply sucks, per se. It's just that things > that work just fine with the original supply (A TDK/Lambda SWS300-24) > make the Emerson supply either exceedingly unhappy or downright dead. > Worse, I'm not sure what's taking out the power supplies. > > So -- > > Does anyone have any mileage with these Emerson supplies? After I > told > the customer "why yes, that should do" I began to notice the name > "Emerson" on this group, and the view of their stuff seems to be > pretty > dim. I'd like to know if you feel these are OK, or comprehensively > bad, > or what. > > Also, I've carefully designed things so that any time the motor is > generating the power goes into a resistor and not into raising the > motor > supply rail (and thus backfeeding the supply). But I did notice that > doing so kills one of these Emerson supplies (the TDK supply mostly > takes > it in stride, or if you're really egregious about things it turns off > until you cycle power). > > Do you know of anything else that would kill one of these supplies? > While I've eliminated the backfeeding problem, the board still has a > current draw that can vary from a few tens of milliamps to ten amps > over > the space of less than a second -- if it would make the supply happier > I > can change this so that whenever the motor is turning the board is > always > drawing some minimum power. Efficiency will suffer -- but we're not > after efficiency, we're after performance in a small space. > > Also, if anyone knows of a supply that's the same size or not much > bigger, but comes from a manufacturer that's known to make bulletproof > stuff, I'd appreciate it. > > -- > My liberal friends think I'm a conservative kook. > My conservative friends think I'm a liberal kook. > Why am I not happy that they have found common ground? > > Tim Wescott, Communications, Control, Circuits & Software > http://www.wescottdesign.com
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
On Tue, 09 Apr 2013 15:52:40 -0700, John Larkin wrote:

> On Tue, 09 Apr 2013 17:37:22 -0500, Tim Wescott <tim@seemywebsite.com> > wrote: > >>So, I'm working on a motor drive board for a customer. Due to a desire >>for performance improvements within the existing space, we're going from >>the traditionally-accepted brute-force power supply to a switcher. >> >>I have this nice board and software set that's carefully designed to >>treat the power supply with kid gloves -- and it works very well with >>the power supply that we used for prototyping. >> >>But for space reasons they went out and found what appears to be the >>smallest possible power supply with the apparent specifications needed >>(24V and 10A): >> >>http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf >> >>It's not that this power supply sucks, per se. It's just that things >>that work just fine with the original supply (A TDK/Lambda SWS300-24) >>make the Emerson supply either exceedingly unhappy or downright dead. >>Worse, I'm not sure what's taking out the power supplies. >> >>So -- >> >>Does anyone have any mileage with these Emerson supplies? After I told >>the customer "why yes, that should do" I began to notice the name >>"Emerson" on this group, and the view of their stuff seems to be pretty >>dim. I'd like to know if you feel these are OK, or comprehensively bad, >>or what. >> >>Also, I've carefully designed things so that any time the motor is >>generating the power goes into a resistor and not into raising the motor >>supply rail (and thus backfeeding the supply). But I did notice that >>doing so kills one of these Emerson supplies (the TDK supply mostly >>takes it in stride, or if you're really egregious about things it turns >>off until you cycle power). >> >>Do you know of anything else that would kill one of these supplies? >>While I've eliminated the backfeeding problem, the board still has a >>current draw that can vary from a few tens of milliamps to ten amps over >>the space of less than a second -- if it would make the supply happier I >>can change this so that whenever the motor is turning the board is >>always drawing some minimum power. Efficiency will suffer -- but we're >>not after efficiency, we're after performance in a small space. >> >>Also, if anyone knows of a supply that's the same size or not much >>bigger, but comes from a manufacturer that's known to make bulletproof >>stuff, I'd appreciate it. > > 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.
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. -- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
On Tue, 09 Apr 2013 18:17:07 -0500, Tim Wescott <tim@seemywebsite.com>
wrote:

>On Tue, 09 Apr 2013 15:52:40 -0700, John Larkin wrote: > >> On Tue, 09 Apr 2013 17:37:22 -0500, Tim Wescott <tim@seemywebsite.com> >> wrote: >> >>>So, I'm working on a motor drive board for a customer. Due to a desire >>>for performance improvements within the existing space, we're going from >>>the traditionally-accepted brute-force power supply to a switcher. >>> >>>I have this nice board and software set that's carefully designed to >>>treat the power supply with kid gloves -- and it works very well with >>>the power supply that we used for prototyping. >>> >>>But for space reasons they went out and found what appears to be the >>>smallest possible power supply with the apparent specifications needed >>>(24V and 10A): >>> >>>http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf >>> >>>It's not that this power supply sucks, per se. It's just that things >>>that work just fine with the original supply (A TDK/Lambda SWS300-24) >>>make the Emerson supply either exceedingly unhappy or downright dead. >>>Worse, I'm not sure what's taking out the power supplies. >>> >>>So -- >>> >>>Does anyone have any mileage with these Emerson supplies? After I told >>>the customer "why yes, that should do" I began to notice the name >>>"Emerson" on this group, and the view of their stuff seems to be pretty >>>dim. I'd like to know if you feel these are OK, or comprehensively bad, >>>or what. >>> >>>Also, I've carefully designed things so that any time the motor is >>>generating the power goes into a resistor and not into raising the motor >>>supply rail (and thus backfeeding the supply). But I did notice that >>>doing so kills one of these Emerson supplies (the TDK supply mostly >>>takes it in stride, or if you're really egregious about things it turns >>>off until you cycle power). >>> >>>Do you know of anything else that would kill one of these supplies? >>>While I've eliminated the backfeeding problem, the board still has a >>>current draw that can vary from a few tens of milliamps to ten amps over >>>the space of less than a second -- if it would make the supply happier I >>>can change this so that whenever the motor is turning the board is >>>always drawing some minimum power. Efficiency will suffer -- but we're >>>not after efficiency, we're after performance in a small space. >>> >>>Also, if anyone knows of a supply that's the same size or not much >>>bigger, but comes from a manufacturer that's known to make bulletproof >>>stuff, I'd appreciate it. >> >> 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. > >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. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
On Tue, 09 Apr 2013 16:51:46 -0700, John Larkin wrote:

> On Tue, 09 Apr 2013 18:17:07 -0500, Tim Wescott <tim@seemywebsite.com> > wrote: > >>On Tue, 09 Apr 2013 15:52:40 -0700, John Larkin wrote: >> >>> On Tue, 09 Apr 2013 17:37:22 -0500, Tim Wescott <tim@seemywebsite.com> >>> wrote: >>> >>>>So, I'm working on a motor drive board for a customer. Due to a >>>>desire for performance improvements within the existing space, we're >>>>going from the traditionally-accepted brute-force power supply to a >>>>switcher. >>>> >>>>I have this nice board and software set that's carefully designed to >>>>treat the power supply with kid gloves -- and it works very well with >>>>the power supply that we used for prototyping. >>>> >>>>But for space reasons they went out and found what appears to be the >>>>smallest possible power supply with the apparent specifications needed >>>>(24V and 10A): >>>> >>>>http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf >>>> >>>>It's not that this power supply sucks, per se. It's just that things >>>>that work just fine with the original supply (A TDK/Lambda SWS300-24) >>>>make the Emerson supply either exceedingly unhappy or downright dead. >>>>Worse, I'm not sure what's taking out the power supplies. >>>> >>>>So -- >>>> >>>>Does anyone have any mileage with these Emerson supplies? After I >>>>told the customer "why yes, that should do" I began to notice the name >>>>"Emerson" on this group, and the view of their stuff seems to be >>>>pretty dim. I'd like to know if you feel these are OK, or >>>>comprehensively bad, >>>>or what. >>>> >>>>Also, I've carefully designed things so that any time the motor is >>>>generating the power goes into a resistor and not into raising the >>>>motor supply rail (and thus backfeeding the supply). But I did notice >>>>that doing so kills one of these Emerson supplies (the TDK supply >>>>mostly takes it in stride, or if you're really egregious about things >>>>it turns off until you cycle power). >>>> >>>>Do you know of anything else that would kill one of these supplies? >>>>While I've eliminated the backfeeding problem, the board still has a >>>>current draw that can vary from a few tens of milliamps to ten amps >>>>over the space of less than a second -- if it would make the supply >>>>happier I can change this so that whenever the motor is turning the >>>>board is always drawing some minimum power. Efficiency will suffer -- >>>>but we're not after efficiency, we're after performance in a small >>>>space. >>>> >>>>Also, if anyone knows of a supply that's the same size or not much >>>>bigger, but comes from a manufacturer that's known to make bulletproof >>>>stuff, I'd appreciate it. >>> >>> 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. >> >>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. -- Tim Wescott Control system and signal processing consulting www.wescottdesign.com
On Tue, 09 Apr 2013 21:43:44 -0500, Tim Wescott <tim@seemywebsite.please> wrote:

>On Tue, 09 Apr 2013 16:51:46 -0700, John Larkin wrote: > >> On Tue, 09 Apr 2013 18:17:07 -0500, Tim Wescott <tim@seemywebsite.com> >> wrote: >> >>>On Tue, 09 Apr 2013 15:52:40 -0700, John Larkin wrote: >>> >>>> On Tue, 09 Apr 2013 17:37:22 -0500, Tim Wescott <tim@seemywebsite.com> >>>> wrote: >>>> >>>>>So, I'm working on a motor drive board for a customer. Due to a >>>>>desire for performance improvements within the existing space, we're >>>>>going from the traditionally-accepted brute-force power supply to a >>>>>switcher. >>>>> >>>>>I have this nice board and software set that's carefully designed to >>>>>treat the power supply with kid gloves -- and it works very well with >>>>>the power supply that we used for prototyping. >>>>> >>>>>But for space reasons they went out and found what appears to be the >>>>>smallest possible power supply with the apparent specifications needed >>>>>(24V and 10A): >>>>> >>>>>http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf >>>>> >>>>>It's not that this power supply sucks, per se. It's just that things >>>>>that work just fine with the original supply (A TDK/Lambda SWS300-24) >>>>>make the Emerson supply either exceedingly unhappy or downright dead. >>>>>Worse, I'm not sure what's taking out the power supplies. >>>>> >>>>>So -- >>>>> >>>>>Does anyone have any mileage with these Emerson supplies? After I >>>>>told the customer "why yes, that should do" I began to notice the name >>>>>"Emerson" on this group, and the view of their stuff seems to be >>>>>pretty dim. I'd like to know if you feel these are OK, or >>>>>comprehensively bad, >>>>>or what. >>>>> >>>>>Also, I've carefully designed things so that any time the motor is >>>>>generating the power goes into a resistor and not into raising the >>>>>motor supply rail (and thus backfeeding the supply). But I did notice >>>>>that doing so kills one of these Emerson supplies (the TDK supply >>>>>mostly takes it in stride, or if you're really egregious about things >>>>>it turns off until you cycle power). >>>>> >>>>>Do you know of anything else that would kill one of these supplies? >>>>>While I've eliminated the backfeeding problem, the board still has a >>>>>current draw that can vary from a few tens of milliamps to ten amps >>>>>over the space of less than a second -- if it would make the supply >>>>>happier I can change this so that whenever the motor is turning the >>>>>board is always drawing some minimum power. Efficiency will suffer -- >>>>>but we're not after efficiency, we're after performance in a small >>>>>space. >>>>> >>>>>Also, if anyone knows of a supply that's the same size or not much >>>>>bigger, but comes from a manufacturer that's known to make bulletproof >>>>>stuff, I'd appreciate it. >>>> >>>> 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. >>> >>>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. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
On 10 Apr, 13:08, John Larkin
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Tue, 09 Apr 2013 21:43:44 -0500, Tim Wescott <t...@seemywebsite.please= > wrote: > >On Tue, 09 Apr 2013 16:51:46 -0700, John Larkin wrote: > > >> On Tue, 09 Apr 2013 18:17:07 -0500, Tim Wescott <t...@seemywebsite.com= > > >> wrote: > > >>>On Tue, 09 Apr 2013 15:52:40 -0700, John Larkin wrote: > > >>>> On Tue, 09 Apr 2013 17:37:22 -0500, Tim Wescott <t...@seemywebsite.c=
om>
> >>>> wrote: > > >>>>>So, I'm working on a motor drive board for a customer. =A0Due to a > >>>>>desire for performance improvements within the existing space, we're > >>>>>going from the traditionally-accepted brute-force power supply to a > >>>>>switcher. > > >>>>>I have this nice board and software set that's carefully designed to > >>>>>treat the power supply with kid gloves -- and it works very well wit=
h
> >>>>>the power supply that we used for prototyping. > > >>>>>But for space reasons they went out and found what appears to be the > >>>>>smallest possible power supply with the apparent specifications need=
ed
> >>>>>(24V and 10A): > > >>>>>http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf > > >>>>>It's not that this power supply sucks, per se. =A0It's just that thi=
ngs
> >>>>>that work just fine with the original supply (A TDK/Lambda SWS300-24=
)
> >>>>>make the Emerson supply either exceedingly unhappy or downright dead=
.
> >>>>>Worse, I'm not sure what's taking out the power supplies. > > >>>>>So -- > > >>>>>Does anyone have any mileage with these Emerson supplies? =A0After I > >>>>>told the customer "why yes, that should do" I began to notice the na=
me
> >>>>>"Emerson" on this group, and the view of their stuff seems to be > >>>>>pretty dim. =A0I'd like to know if you feel these are OK, or > >>>>>comprehensively bad, > >>>>>or what. > > >>>>>Also, I've carefully designed things so that any time the motor is > >>>>>generating the power goes into a resistor and not into raising the > >>>>>motor supply rail (and thus backfeeding the supply). =A0But I did no=
tice
> >>>>>that doing so kills one of these Emerson supplies (the TDK supply > >>>>>mostly takes it in stride, or if you're really egregious about thing=
s
> >>>>>it turns off until you cycle power). > > >>>>>Do you know of anything else that would kill one of these supplies? > >>>>>While I've eliminated the backfeeding problem, the board still has a > >>>>>current draw that can vary from a few tens of milliamps to ten amps > >>>>>over the space of less than a second -- if it would make the supply > >>>>>happier I can change this so that whenever the motor is turning the > >>>>>board is always drawing some minimum power. =A0Efficiency will suffe=
r --
> >>>>>but we're not after efficiency, we're after performance in a small > >>>>>space. > > >>>>>Also, if anyone knows of a supply that's the same size or not much > >>>>>bigger, but comes from a manufacturer that's known to make bulletpro=
of
> >>>>>stuff, I'd appreciate it. > > >>>> 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. > > >>>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 shoul=
d.
> >>> So it could have been that. > > >>>I've got more supplies on the way, I may do some testing with resistor=
s
> >>>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. =
=A0As
> >soon as the motor goes into regeneration the motor rail gets disconnecte=
d
> >from the power supply (via a FET) and is allowed to float up. =A0Then 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 t=
he
> power supply output to clamp at, say, 25 volts. That might keep the ps fr=
om
> crowbarring, too. > > I'm sure Jim would be delighted to design an accurate, 10 amp active zene=
r
> circuit for you.
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 http://www.the-scientist.com/?articles.view/articleNo/10009/title/Is-ES2-Le= ading-A-New-Wave-Of-European-Startup-Companies-/ which survived into the mid-1990's. -- Bill Sloman, Sydney
Tim Wescott <tim@seemywebsite.com> wrote:
> Due to a desire for performance improvements within the existing > space, we're going from the traditionally-accepted brute-force power > supply to a switcher.
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 24 VDC switching power supply, which I think was a Triad AWSP series, a foot or two of wire, and the motors. The motors "liked" this power supply; I could command them from 0 to full speed to 0 again as fast as I liked without any trouble. 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 150 W or so. (Because of where the long wire had to live, there were safety concerns with bringing line voltage AC directly to the device.) At first, the motors were just connected directly to the output of the brick, but that didn't work very well; starting the motors worked, but slowing or stopping them would cause the DC-DC converter brick to shut down. Cycling the input power to the DC-DC brick would bring it back. 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.
> http://www.powerconversion.com/assets/lps200-m_ds_1226129797.pdf > [...] > Does anyone have any mileage with these Emerson supplies?
I have no experience with them.
> While I've eliminated the backfeeding problem, the board still has a > current draw that can vary from a few tens of milliamps to ten amps > over the space of less than a second -- if it would make the supply > happier I can change this so that whenever the motor is turning the > board is always drawing some minimum power.
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