Are switching power supplies good for powering motors?

A bit more "Chaff" !
My response was from experience purely from the reliability issue, regarding SMPS. There is no disputing they will not work, just not the best choice IMO..
This was from implementing motors of all stripes and sizes.
Regulation is rarely if ever needed in motor control, even servo's. As the Electronic Design paper shows.
Many of the stepper motor manuf. also do not recommend SMPS for their products.
Max.
.
And I have explained the likely reason for your experience. But as long as you make such sweeping statements like "Regulation is rarely if ever needed in motor control" and "Many of the stepper motor manuf. also do not recommend SMPS for their products" which are seriously flawed as are so many generalisations of that scope but they also are not substitutes for actual technical detail and content. They are anecdotal comments which may or may not be correct but without the detail it is a guessing exercise for the rest of us. Is this a forum for you to express your opinions or for the exchange of accurate technical information? I guess that is my point.
 
All?
That's Odd I have been working in the industrial field using DC and BLDC motion control servo's etc, in the motion control area since the 80's and the majority i have implemented and spec'd in have used a linear supply.
The OP also mentions stepper motors, one of the popular manuf such as Gecko recommend linear supply also.
Max.
I see you take issue with the hyperbole and generalisations of others... ;-)
For AC motors GH is probably not that far from the mark. Every induction motor I've needed to control the speed of I've used, as do others, a VSD which is an SMPS and which also has an internal regulated DC bus to power the output stage that drives the motor. These VSD don't seem to have any reliability problems that I have ever noticed. I've seen more reliability problems with terminals on contactors burning out because of bad cable termination practices than unreliable VSD's.
 
The phase control power supplies with SCRs or TRIACS are not quite the same as the high frequency switch mode supplies that are in question.
They are more like "adjustable analog" rectifiers.
The phase control types are pretty good for motors. Usually, they are quite tolerant of overloads, assuming they are made well.
The switch mode supplies rectify the mains then chop the high voltage DC into a high frequency transformer and rectifier, where as the phase control circuits operate at the mains frequency.
They may be ok for a DC or universal motor. Not so good for any kind of AC motor such as induction, shaded or salient pole etc. Those tend to overheat with phase control unless they are specifically designed to handle the harmonics. Phase control though for a stepper or such others as the OP describes probably not the way to go.
 

shortbus

Joined Sep 30, 2009
7,838
And I have explained the likely reason for your experience. But as long as you make such sweeping statements like "Regulation is rarely if ever needed in motor control" and "Many of the stepper motor manuf. also do not recommend SMPS for their products" which are seriously flawed as are so many generalisations of that scope but they also are not substitutes for actual technical detail and content. They are anecdotal comments which may or may not be correct but without the detail it is a guessing exercise for the rest of us. Is this a forum for you to express your opinions or for the exchange of accurate technical information? I guess that is my point.
And yet all of the manufacturers of steppers are wrong, according to you. That to me is offensive.
 
And yet all of the manufacturers of steppers are wrong, according to you. That to me is offensive.
I regret your offense but your statement simply cannot be correct. It is, in this modern age, not just unnecessary but in fact not compliant with international regulations (= illegal) to sell a linear supply of any power level of note, especially one as you have described, due to the harmonic distortion of the current waveform on the mains (certain niche industries may be exempt but that is changing or changed also). If you can lay your hands on a copy of the relevant part of EN61000 (or any of the multitude of international equivalents) you can read all about it. If you can look past your offense, you may see my point not to mention the vast number of steppers in the world that are powered by an SMPS.
Your misquote of me to say I refer to 'all manufacturers' and not including my original statement from which you 'quote' is to me also highly offensive. The difference here is that you have used misrepresentation to make your point. I think it best if we let this drop or continue via PM as it adds nothing useful to the thread.
 
I regret your offense but your statement simply cannot be correct. It is, in this modern age, not just unnecessary but in fact not compliant with international regulations (= illegal) to sell a linear supply of any power level of note, especially one as you have described, due to the harmonic distortion of the current waveform on the mains (certain niche industries may be exempt but that is changing or changed also). If you can lay your hands on a copy of the relevant part of EN61000 (or any of the multitude of international equivalents) you can read all about it. If you can look past your offense, you may see my point not to mention the vast number of steppers in the world that are powered by an SMPS.
Your misquote of me to say I refer to 'all manufacturers' and not including my original statement from which you 'quote' is to me also highly offensive. The difference here is that you have used misrepresentation to make your point. I think it best if we let this drop or continue via PM as it adds nothing useful to the thread.
My bad, you did quote my original post (that caused you offense, but) which makes it clear that I did not say "all of the manufacturers of steppers are wrong " at any point. You said that and credited the statement to me. Let's also not forget that to back up your claim that many (or all?) stepper manufacturers recommend linear supplies you have produced a single 'how to' guide from 1998, a full 22 years ago, and it is not from a manufacturer but some random company who were at the time claiming expertise in the area of servo amplifiers and associated gear. Probably because that is what they were trading in. Please note that your offense is based on manufacturers and my supposed statements about power supplies for stepper motors which typically are not used as servo motors as such and are not driven by servo amplifiers either so the paper presented does not actually apply here.. I am sorry but at the end of the day I cannot keep up with your arguments when you shift the ground around in this way and base your statements concerning modern technology on documentation from last century. Things have moved on and technology has changed and improved. If you wish to substitute what you say I said in place of what I did actually say and also to redefine the basis of the discussion on the fly then there is no point in further discussion by PM or otherwise. If you feel compelled to respond, then please, this is just noise for others so let's pick it up in a PM thread if you feel that further discussion might be constructive or you do not wish to let it drop for whatever reason. I regret any cause of offense. It is most definitely not my intention and to be frank, I think is an over reaction anyway, and that over reaction is somewhat offensive to me. Just sayin'. That's all.
 
A bit more "Chaff" !
My response was from experience purely from the reliability issue, regarding SMPS. There is no disputing they will not work, just not the best choice IMO..
This was from implementing motors of all stripes and sizes.
Regulation is rarely if ever needed in motor control, even servo's. As the Electronic Design paper shows.
Many of the stepper motor manuf. also do not recommend SMPS for their products.
Max.
.
Reviewing the to and fro in this thread and noticed a question I did not ask you: "all stripes and sizes" is one of those ambiguous statements that ultimately mean nothing without clarification. You see my motor experience ranges from sub 1W DC motors (really just toy motors) to 300kW induction motors with a predominance in the DC motor category of smaller motors up to 20W and usually mechanically commutated and in the AC motor area 500W to 10kW induction motors are easily the most common motors I have experience with. When they get over 50kW they can be a bit scary. Bad stuff can happen when 50kW of mechanical power is not just focused on where you wanted it to go but starts to wonder off into other things that don't much like the attention. Soon after you may come face to face with the full torque capability of that motor and it will stare you down! ;-)
So your stripes and sizes; what were you dealing with? I'm assuming not massive given the power supplies you described? Or were they? Phase control was in common use even for many 10's or even 100's of kW into the 80's and early 90's that I was aware of. Maybe they still are and I just haven't noticed.
 

MaxHeadRoom

Joined Jul 18, 2013
21,172
So your stripes and sizes; what were you dealing with? I'm assuming not massive given the power supplies you described?
I DO NOT intend to get in to a pi****'ing contest, but as you asked, I have been involved in one way or another since the 1950's, with motor and generators of all stripes, and sizes.
One initial part of the practical side of my training included a term in the re-winding shop that pretty much served a large City.
I have had experience with Railway Locomotive power systems from the older DC traction to the later AC 3phase versions, also included applying dynamic braking conversions.
The highest voltage motors I have worked on, apart from the Locomotive side, was with 4Kv AC induction synchronous motors, (ran up in induction, switched over to DC field synchronism) very large (unknown) HP.
I have ran a business that included CNC retrofitting using servo's of different types. Including small PC based, self designed systems.
My present interest is in designing DC and BLDC motor controllers using small Microprocessors.
That is just a very brief summary.

Hoping my curriculum vitae is satisfactory! :rolleyes:
Max.
 
Last edited:
I DO NOT intend to get in to a pi****'ing contest, but as you asked, I have been involved in one way or another since the 1950's, with motor and generators of all stripes, and sizes.
One initial part of the practical side of my training included a term in the re-winding shop that pretty much served a large City.
I have had experience with Railway Locomotive power systems from the older DC traction to the later AC 3phase versions, also included applying dynamic braking conversions.
The highest voltage motors I have worked on, apart from the Locomotive side, was with 4Kv AC induction synchronous motors, (ran up in induction, switched over to DC field synchronism) very large (unknown) HP.
I have ran a business that included CNC retrofitting using servo's of different types. Including small PC based, self designed systems.
My present interest is in designing DC and BLDC motor controllers using small Microprocessors.
That is just a very brief summary.

Hoping my curriculum vitae is satisfactory! :rolleyes:
Max.
We have crossed paths before (in a good way) on these forums and as I knew little about your background and your posts were quite terse (compared to my wordiness) I thought drawing you out would be interesting for me (and it was) and for others it gives your posts more context. Some people, you see, are terse because they don't really know anything. I knew that was not you. I was just curious and it seemed.appropriate to ask as I did.
BTW: that was not my CV previously. Not even the tiniest bit close. Just relevant details. You have a few years on me, but not decades. A long enough time to experience a great many things ;-)
 
Top