RB,

It looks like the motors can be from 18-75vdc with a 10 amp max. I have attached the PDF for the driver, and the motors. The motor part number is k42hlln-lnk-ns-01. I should have some pictures of the first steps in building the actual table tomorrow.

 

Thanks for the datasheet. The 5410 driver needs a 18v to 75v "motor PSU", 36v would be pretty optimal.

It also needs a single REGULATED +12v supply. The datasheet says the motor power and 12v power have their grounds connected inside the unit.

It is also current limited at 5A per phase for full stepping and 3.5A per phase for microstepping.

Fortunately there is a 3rd mode where it microsteps at 3.5A, then goes up to 5A per phase once it exceeds speeds of 500 steps/second. I would suggest that mode.

They are nice looking drivers. I hope you haven't blown them up.

 

OK, so if it's 3.5A to 5A per motor, he's going to need a supply that can output at least 15A @ whatever voltage he chooses to use. Those steppers will draw current even if they're not stepping.

That's going to be a pretty hefty supply.

The 150W supply I suggested earlier will shut down the moment it gets a load like that.

 

guys,

I went on the website that Sarge linked to earlier, and found a couple power supplies:

I am thinking this one will work, but will run the motors slow (24v) right?
http://www.mpja.com/prodinfo.asp?number=16753+PS

This one will be a little faster?
http://www.mpja.com/prodinfo.asp?number=16754+PS

The both run about $120. I would like to get something with higher voltage, but wow does the price jump. Like $900. That's absolutely not in my price range. Are there any other options you guys can come up with, or can you give me an idea of what machinery might already have this type of supply on it?

 

Found this auction on Ebay:
http://cgi.ebay.com/NEW-NOVA-UNREGU...aultDomain_0?hash=item53dd0e3d08#ht_500wt_737
You might wire a pair of them in parallel; 42v @ 16A should do it.
They're unregulated supplies, which is what you really want. The drivers do the regulating.

 

Sarge,

You're going to have to tell me what you mean by wiring in parallel. I have heard of wiring in series and parallel I assume they are opposites of each other, but have not idea what each actually means. I noticed by wiring them as you have said, the 42v doesn't change, but the current doubles. Is this true with any electricity wired in "parallel"?

 

I wouldn't wire regulated supplies in parallel; they will "fight" each other.

However, these are not regulated supplies. The output voltage will be the average of the two unregulated supplies. Since each supply is rated for 42v @ 8A, connecting the two 42v outputs in parallel will result in 42V @ 16A.

Just looking for a cheap-but-effective solution for you.

Wiring these in parallel means that the supply output returns get connected together, and the supply output + get connected together.

 

Sarge,

That's what I'm looking for, a low cost alternative. I was confused about what wiring in parallel was, but I think I get it now. I'll keep my eye out for a power supply.

 

You might be able to pick up something surplus, which is what that Ebay auction was.

MPJA does sell a couple of unregulated supplies that are about in your power range, but they're over $200/ea.

In reality, that's pretty inexpensive for the amount of power you need. Just transformers alone cost in the $130-$250+ range; you'd still need a bridge rectifier, large cap, and case to go along with that.

If you wait around for an ideal supply for dirt cheap, you might have a long wait.

 

OK, so if it's 3.5A to 5A per motor, he's going to need a supply that can output at least 15A @ whatever voltage he chooses to use. Those steppers will draw current even if they're not stepping.

Sgt, I may have read the specs on the motor wrong, but I think the amperage rating is per phase. And I think these are two phase motors. At least that is how I understand steppers.

Earlier in this thread I posted some transformers from Ebay that would work. I lurk on the CNC Zone web site and almost all of there power supplies are made with toroidal transformers.

 

Yes, there are two phases - but the controller shouldn't put 5A through both phases simultaneously, unless it was poorly engineered or malfunctioning.

 

OK, so if it's 3.5A to 5A per motor, he's going to need a supply that can output at least 15A @ whatever voltage he chooses to use. Those steppers will draw current even if they're not stepping.

That's going to be a pretty hefty supply.

The 150W supply I suggested earlier will shut down the moment it gets a load like that.

No! The 5A is at the MOTOR, not the supply input. The motor will be well under 20W with 5A per phase.

Since the driver will be about 70% switchmode efficiency that will require 20W /0.70 = 28W or 36v @ 0.8amps (for each motor) which will need a supply of 36v and 3A+ to run all 3 motors at lowish speeds.

Like I said before that 36v 150W supply is PLENTY.

 

(sorry double post)

 

Yes, there are two phases - but the controller shouldn't put 5A through both phases simultaneously, unless it was poorly engineered or malfunctioning.

I hate to disagree, but these motors are bipolar steppers. As part of the drive waveform both phases are on at the same time. Check out this drawing

It comes from this link; http://electojects.com/motors/stepper-motors-2.htm

Most times people think of unipolar motors and drivers when they think of steppers. Simpler to drive. But these are bipolar.

 

No! The 5A is at the MOTOR, not the supply input. The motor will be well under 20W with 5A per phase.

Since the driver will be about 70% switchmode efficiency that will require 20W /0.70 = 28W or 36v @ 0.8amps (for each motor) which will need a supply of 36v and 3A+ to run all 3 motors.

Like I said before that 36v 150W supply is PLENTY.

RB, could you tell me how you are coming up with your numbers? On the cnc zone site they are figuring 500 VA to power three 2Amp motors.

Doesn't the power supply have to be sized to the motor amperage NOT the driver limited amperage? If it was sized to the limit amperage there would be no "head room."

Not trying to disagree with you just trying to learn.

 

OK, go back and look at the original schematic.

The original schematic was using a 5KVA transformer to drive 3 groups of 3 driver/stepper combinations, or roughly 555va per driver/stepper. The actual unregulated voltage supply is unknown, except it must've been less than 65v, but probably greater than 30v. The purpose of having such a large VA rating was to keep the unregulated voltage supply reasonably stable.

Each group of three driver/stepper combinations had a pair of 20A fuses from the rectifier/filter. According to the driver manual, each stepper will be supplied with 3.5A to 5A of current; so for three driver/stepper combinations, that's 10.5A to 15A.

So, if you're going to use a REGULATED supply, the output must support at least 15A of current flow at the supply's rated voltage. If you use a supply that is rated for less than 15A, it will shut down until the load is removed.

This is why I suggested using a pair of those 42v 8A unregulated supplies wired in parallel, as they would be able to supply the necessary current, even with the 500 Ohm bleeder resistor. The pair of supplies would have a rating of 672VA. That's certainly not overkill, but should be sufficient. With no load, the output may reach nearly 60v, which would still be under the drivers' voltage rating.

I don't understand The_RB's reasoning either.

 

Am I the only person here who has used bipolar chopper stepper drivers??

They act like a switchmode supply, so they have high volts low amps going in, and high amps very low volts coming out.

That motor is rated for max 7A per phase, and has around 0.26ohms per phase resistance. So if driven at 5A it consumes 5 * 5 * 0.26 = 6.5W per phase calculated by I squared R.

So worst case with both phases fully energised at 5A it consumes 13W. The stepper motor chopper driver will run at about 70% efficiency (based on the drivers I have worked with) so to supply the motor with 13W it will consume about 20W.

20W at 36v will be 0.56A.

So the driver needs 36v @ 0.56a to supply ONE motor at 5A / phase.

Now stepper motors will consume slightly more power when accelerating loads at high speeds so you can double that figure for safety. So 150W PSU is plenty!

I think what is confusing people is that massive original transformer, that was never meant for these drivers. It must have been used for some really old heavy duty DC servomotors or something.

 

From page #15 of the PDF file of the driver manual:


Power Supply Input Connector - J2

<snip>


J2 - 1 : motor power +18 to +75 volt DC Maximum @ 10 Amps

 

Copied from; http://www.mechmate.com/forums/showthread.php?t=932



There still seems to be a lot of confusion about selecting power supplies to drive stepper motors. Unfortunately, there is no "one best answer" that works for everyone. I use my machine to cut cabinet parts, so I want the highest cutting speed. Others use their machines to cut delicate 3-D parts, so they may never need speed.

Basically, the motor that you use determines the power supply that you're going to need. A motor has two ratings that are important when selecting a power supply. The inductance rating helps you select the proper voltage and the current rating tells you how much current you'll require.

Unfortunately, how you wire the motor also determines the motor's inductance and the current that the motor will draw. Wiring a motor with the coils in Series give the highest torque, but limits the speed. Wiring a motor half-coil, give the best speed, but only about 70% of the torque. Wiring an 8-lead motor with the coils parallel give you the same speed as half-coil and excellent torque, but it requires 2X the current as half-coil.

We'll assume that most people have six-wire motors and that they're going to wire the motors half-coil.

To find the MAXIMUM voltage, use this formula: 32 X SQRT(inductance) = voltage.

Remember, that is the MAXIMUM voltage for most motors. That means that the motor is going to run HOT, too hot to touch. I don't run motors at the maximum voltage. Instead, I multiply the voltage by 75% and get a voltage that still gives good speed, but a lot less heat.

Let's assume that you need a voltage that is about 35VDC. You can either buy a 35VDC power supply or you can build your own.

Selecting the proper transformer to get 35VDC requires that you multiply the DC voltage by 0.7 (which is 1 / SQRT(2.0)). In this case, you'll need a transformer that gives you about 25VAC.

Add together all the current ratings of the stepper motors to find out how much current you're going to need. We'll assume that each motor requires 3A and that you're going to use four motors.

4 X 3A = 12A

To find the VA that the transformer must provide, multiply the AC voltage by the current.

25VAC X 12A = 300VA

Finally, you'll need to compute the size of capacitor that you'll need.

(80,000 X 12A) / 35VDC = 27,428uF

Those are the basic calculations. To get 35VDC at 12A you'll need a 25VAC transformer, a full-wave bridge rectifier, and a capacitor rated at 25,000 to 30,000 uF (connect several small capacitors in parallel to get the desired total capacitance).

It's good practice to over-rate the voltage of the capacitor by about 15 or 20 Volts, so a 50V, 30,000uF cap would be good.

I've used those basic math formulas when building a "bunch" of power supplies for stepper motors. I never worry about trying to get "exactly" the right components because stepper motors are very forgiving. I've used transformers ranging from 18VAC to 30VAC with PK296B2A-SG3.6 motors. All the transformers worked perfectly. The VA rating of the transformers ranged from 250VA to 500VA, again with perfect performance. I've used capacitors ranging from 11,000uF to 30,000uF, and the motors ran just fine.

So, I do the computations to find what the "ideal" power supply would be then I go to my electronics parts bin to see what I have on hand. I build up a power supply with the parts on hand and then modify things as necessary after I've had a chance to test the motors.

Having adequate current available from the power supply assures that the motor will work at maximum possible torque. Having adequate voltage means that the motor will run at the highest practical speed. The motor will only draw as much current as it needs from the power supply, so having a power supply that gives 1.5X to 2X the current that you need will do no damage (but it will cost more and it will take longer to drain when the switch is turned off). Some people use an old recommendation from Mariss (at Gecko) to multiply the current by 0.66. Mariss now recommends that for SQUARE motors that you do not de-rate the current. I've found that it all depends on how hard you drive the motors. Rarely are all four motors running at full current all the time, but I still use 100% of the computed current as the "ideal" when building a power supply.

Feeding the motors too much voltage WILL cause problems. You'll get excessive heat. If the voltage is high enough, you'll fry the motor(s).

 

Did you want me to argue with all that guff or agree with it? Because he's got some bits right and some bits that sound confused.

However nothing you pasted there changes the calcs I posted before. I've seen the specs of your motors, and of your 5410 drivers. Your proposed 36v unreg 150W PSU is plenty and it's a good match for your motors and drivers.