power and controller help

[willheg]

Hello everyone

well firstly if your reading this thanks for doing so and i hope you can help me

sorry if i ask in a round about way but i'm not to good and putting questions into words but hope you can help

i have not so long ago purchased 4 stepper motors and a motor to drive the spindel but i have a few questions

1st one is would anyone have any idea on the best power source for these motors, the steppers are rated 18-60vdc and a rated current of 4.2 amps and the spindel motor is rated 36vdc but will handel 48vdc, running at 12 amps and 350 watts, looking at running them all on 36vdc to there rated current but wondering on what to use (i.e. tranformers and everything) and where to get it all from

2 is what board should i use to drive the steppers as i'm tight for cash i was looking at building my own and wondering if anyone had plans or could put me onto somewhere to find something cheap to run these, i have plans and will attch and if these are ok could someone let me know only thing is i need to run current limiting resistors i think. the board would be running 1x 4030, 1x 4027 and 8 Mosfets or transistors to handel the power and 1 board of this per each stepper motor

anyway thanks for reading and hope people can help

Cheers
William

[irving2008]

That stepper driver design is fine for baby steppers up to maybe 1/2A per coil and 20volts supply voltage but wont drive the 4A units you have. You need a much more functional driver with a chopper current control. Current limiting resistors with 4A motors is just not going to be efficient or cost-effective, not to say HOT.

Stepper motors aren't normally rated at those sorts of voltages, typically they would be rated at between 2 and 5v - they are normally overdriven voltage wise (typically 10 - 20 times the coil rated voltage) using a chopper current limiter to control the coil current and prevent overheating. Do you have model # or other info on the stepper motors?

[willheg]

thanks for the reply so quickly, the information i have on these motors is:

Step Angle (deg) 1.8
Motor Length (mm) 112
Rated Current (A) 4.2
Phase Resistance (ohm) 0.9
Phase Inductance (mH) 3.8
Holding Torque (N.cm Min) 280
Detent Torque (N.cm Max) 12
Rotor Inertia (g.cm²) 800
Lead Wire (No.) 4
Motor Weight (g) 1400

i was told by the supplier they can be run from 18-60vdc so i'm taking they have done the figuers allready to get these numbers thats why i'm looking at running 36vdc because of my spindle motor and to try and keep things simple

on another note while i'm here what transformers and other stuff so i use and can anyone recommend anything to use to get the numbers i require

i'm also looking into another controller i have found in a data sheet which i have attached and wonder if this would work ok to drive the steppers i have choosen just wonderin also what resistors and caps to use and stuff

i value other peoples opitions as i'm new to this and usally many heads are better than 1

cheers for any help

[MrWild]

Go to www.Pminmo.com for all sorts of good driver schematics, PCB layouts, and parts lists. Many drivers to choose from. Or you could just buy a Gecko G540 and take the easy way our.

[willheg]

thanks for the reply i've been looking there but didn't know which driver would suite the motor but i'm keen to try and build it myself as money is tight these days and just want the whole thing of, i did it myself, it may not work out cheaper this way but it will be easyer to buy parts one by one and build up slowly

but if anyone could help me on which driver will work i would thank you very much and also i'm after help on the power supply

i have almost everything else worked out it is just these little nigley things that are getting me, as i'm not to flash at electroinics but want to give it a go like i said before to say hay i did it even with the help of others on the way

Cheers
William

[TOTALLYRC]

Not to disuade you from doing it your way, but if the electronics is not your strong point it will be alot easier to save up and buy a driver ready to go. It will also be a false economy. I am so so at electronics and the thought of making a GOOD driver scares me. If you want to learn electronics I would say that the stepper motor driver is not the best place to start, especially if you want the drivers to run a machine tool.
Do some searching of the forums and you will find a lot of data on drivers and power supplies including recomended suppliers.
Mike

[willheg]

cheers for the reply mike

all i really need is the secmatics and i'd go from there, i'v edone some looking around but there is to much information and not enought time to read it all and then i read one thing but look at something else which either confusses me or makes me think in a bad way and yeah that is why i decided to start me own question to see what information i got back but i guess if i need to sift throw the weeds on here then so be it but i'd just like to get on and start building the rest of my project cause currently i'm on hold till i sort out power supply for the motors listed below which again is 4 x 4.2 amp steppers and a 12 amp spindel motor all running at 36vdc and also the driver boards for the steppers

but your help is thanked and if anyone else could help with my search in controller boards and what sort of power supply it would be of great help

Cheers
William

[TOTALLYRC]

Originally Posted by willheg cheers for the reply mike all i really need is the secmatics and i'd go from there, i'v edone some looking around but there is to much information and not enought time to read it all and then i read one thing but look at something else which either confusses me or makes me think in a bad way and yeah that is why i decided to start me own question to see what information i got back but i guess if i need to sift throw the weeds on here then so be it but i'd just like to get on and start building the rest of my project cause currently i'm on hold till i sort out power supply for the motors listed below which again is 4 x 4.2 amp steppers and a 12 amp spindel motor all running at 36vdc and also the driver boards for the steppers but your help is thanked and if anyone else could help with my search in controller boards and what sort of power supply it would be of great help Cheers William

The formula that I found on the forums is amps/stepper x number of steppers x .6 or .65.
Which is about 10 - 11 amps. That is if your drivers a capable of putting out that much. Max motor voltage is the square root of te inductance in mh times 32. About 62 volts for your motors. If you go 36v you will be somewhat above 1/2 max voltage will get somewhat more than half speed form the motors. Depending on the gearing it might be more than enough for you.

I haven't heard of anyone using the DC stepper power supply to drive the spindle also, but I assume it is possible. However you are looking at 22 amps (12 spindle + 10 Steppers) minimum plus startup torque for the spindle. You would end up needing a 30amp? power supply, not cheap unless you find a nice 36v battery charger with a nice big amp rating. All the fall swap meets are coming up and maybee you could find something there.

It might be easier to find a 110v Ac powerd DC motor supply and just turn down the maximum speed setting so as not to overvolt the spindle motor. Ebay is a good source as well as Craigslist and backpage.com..
I have bought several for $30 on ebay.

I can't help on the driver boards for the steppers unless you want opinions on ready to go stuff. Don't forget, whatever boards you go with, you really need a breakout board to protect the computer/pport.

Best bang for the buck is stil the G540. read the manual and see what you get for $299. Hard to get all that for less even if you build it yourself.
I will get of my soap box now.
Mike

[irving2008]

Originally Posted by willheg cheers for the reply mike all i really need is the secmatics and i'd go from there, i'v edone some looking around but there is to much information and not enought time to read it all and then i read one thing but look at something else which either confusses me or makes me think in a bad way and yeah that is why i decided to start me own question to see what information i got back but i guess if i need to sift throw the weeds on here then so be it but i'd just like to get on and start building the rest of my project cause currently i'm on hold till i sort out power supply for the motors listed below which again is 4 x 4.2 amp steppers and a 12 amp spindel motor all running at 36vdc and also the driver boards for the steppers but your help is thanked and if anyone else could help with my search in controller boards and what sort of power supply it would be of great help Cheers William

I don't know of an open-source design that will handle those steppers, you need something capable of controlling 6A at 50v to get the best out of them. The second diagram you found is good for no more than 3A in practice at 30v. You could build it but you'd have to be careful not to overload it and you'd get nowhere near the rated torque from the motors. Also building from a schematic isn't practical at these current levels... you need to pay very careful attention to layout, current routing, etc.. or it simply wont be reliable... unless you have considerable experience laying out high-current 2 or 4 layer PCBs you want to be buying something that is known to work... else it gets very expensive very quickly..... have a look in the open source drivers forum for some info...

[willheg]

thanks for the replys people

this information is starting to make sense

the problem on the boards is i live in new zealand and yeah the cost of buying the boards is really expencesive for me at the moment not to say the freight cost hense mhy i'm looking to build the boards myself but it's looking more like i'll have to spend the dollars and buy a gecko maybe the 201, cause the other thing is i'll need 4 motor drives as i'm running a 4 axis machine and finding help or people in NZ is so hard that is why i'm asking here

the question i also have is wouldn't i just need a board per motor rated at more than 4.2 amps at around 60vdc yet the power supply would need to run 60vdc at the 10-11 amps posted before

and another question i have is how is it worked out that the chips will only run 30v 3a, i read they are rated 52v 5 aamps max but if i used that i would look at maybe 40v at the 4.2 amps max which should be fine i thought on the L6023 or is that 30v 3 amp the limit on the L297?

once again cheers for the help it is all useful and i'm so thankful and hope i can help others someday once i get my machine done and work out all these things

William

[irving2008]

Originally Posted by willheg ....the question i also have is wouldn't i just need a board per motor rated at more than 4.2 amps at around 60vdc yet the power supply would need to run 60vdc at the 10-11 amps posted before the power supply would be need to be rated at typically 67% of 6 x phase current (for 3 axis, 8 x for 4 axis - remember there are 2 phases per motor), so you are looking at 4.2 x 6 x 67% = 17A capability (3 axis) or 22A (4 Axis). Voltage would be around 60v max. to get the best out of the motors, which means you are looking at 80v drivers - obviously you can run a lower voltage but you'd probably not want to go below 40v. For these currents/volts you might be better looking for a pair of supplies or even one per motor. and another question i have is how is it worked out that the chips will only run 30v 3a, i read they are rated 52v 5 aamps max but if i used that i would look at maybe 40v at the 4.2 amps max which should be fine i thought on the L6023 or is that 30v 3 amp the limit on the L297? Sorry, my typo on the 30v... L6203 chips are rated 52v 5A absolute max but you wont be able to run them reliably at that level... 40v and 4A is pushing the limits (see several threads here where others have tried it with varying degrees of success). The 6023 is very finicky about layout and needs big heatsinking and careful thermal management to get anywhere close to those numbers - reality is nearer 3A in practice with any degree of success. You cannot run these chips at max voltage as you have to take the back-emf of the motor into account and the reverse energy dumped into the power supply on deceleration - this raises the supply volts well above the norm unless you have very high stability switched mode power supplies which will be expensive or some other energy-dump circuit. As I said before, if you have a trusted off the shelf PCB layout it might be worth considering building your own but if you are planning to lay it out yourself then expect to go through several chips to get it right...

William, see my comments in-line above

[TOTALLYRC]

Hi William, I skimmed thru this but can't seem to find what type of machine you are controlling.
It will have a big impact on everything else down the line.
A small mill and a small router could both use those motors but you could power them very differently. Those motors look to be nema 23 double stack. If you are putting them on a large mill they probably won't work.

Depending on the machine you are controlling they could be completly useless and I hate to see you by all of the controls and then have the wrong parts for the wrong application.

Michael