Default plz atlist read this one time. L297 And L298 bepolar stepper motor driver.

[sizala]

hi friends , thankx for reading my this post.

my problem is =
**broken link removed**

i am using the driver which is in the datasheet of l298. i am using it with 24v 20amp bettery(bcoz that is a good power supply). and i am applying 2.34V to Vref , and the sense resistors value is 0.4/5W. it means that my motors are running at 0.98 amp. my stepper motor is 20KG/CM 1amp bipolar.

but the problem is = stepper motor is not going more then 150 Rpm. it doesn't matter if i use half or full step, in runs 150rpm in both modes.

so, plz plz plz plz help me to solve this problem. i want to increase the speed of my motor from 150 to at-list 300 rpm. i will be really thankful to you all.

(i think there is some problem with the chopper rate(i read it from some other online forum that chopper rate can effect stepper motors performance).
i am curently using the same resistors and capacitors as the data sheet is showing.= 3.3nf capacitor,22k resistor, the 470uf25V capacitor.)

plz plz plz plz plz plzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz help me ..(i am controlling this driver form Ubuntu EMC2)

 

[ericgibbs]

hi,
Your link is broken.!

 

[SABorn]

I think this is the link to OP was referring to.

L297

http://www.datasheetcatalog.org/datasheet2/c/0g0gh362kxwx30o7xi4x2i4jzffy.pdf

L298

http://www.datasheetcatalog.org/datasheet2/2/052daje928cw7pc0uqs1ipyryppy.pdf


Pete.

 

[sizala]

oh...i am sorry.... here is the new link = https://www.st.com/stonline/books/pdf/docs/1773.pdf

 

[SABorn]

The speed of the motor is normally directly related to the speed of the instructions sent to the driver chip so would expect your problem lies in the driving software.

As i know nothing about the software you are using to control the driver i can offer no further comment on the problem.

Why do you post the same question in both forums? it makes it confusing to where to comment and to know what other comments have been made.

Pete.

 

[sizala]

thankx for the reply SABorn,
but the software is not the problem. i checked the speed of stepper motor from EMC2, Kcam, Mach3, and i found that the software does not make any difference. if i tell the software to run motor at 170 or 1500 rpm, then after reaching at 150 the motor stars only vibrating. It clearly means that (i hope that) the driver is not giving enough time to move the motor from one step to other.

but i dont know how to solve this problem. i tried to increase the power for the motors from 24VDC to 36VDC, but it burned up L298N in 0.5 second. i also tried to run the motor at 0.5,0.9,1.2,2.0 AMP (per phase) but id does not make much difference. so now i think that there is some problem with the chopper rate.

i hope that now you do understand my problem. and you can always tell me abut any other good bipolar stepper motor driver which i can make by my self.

thankx for reading.
and yes i posted the same question in 2 forums bcoz i didn't knew that which one is the correct forum for my question.

 

[blueroomelectronics]

Steppers lose torque at higher RPMs.

 

[SABorn]

Dont know about the others but i run Mach3, have you tuned the motors in mach3, and adjusted the movement profile.

It took me some fiddling with the setup, before i got good speed and torque.

As for drivers when i built my cnc i had intended to build the driver boards to, but after looking around for suitable driver chips i found it was cheaper and less hassles to buy a full 4 axis board out of China off ebay.

Looking back ever so glad i did and done the same for the second cnc i built as well.

Pete.

 

[sizala]

SABorn , the EMC2 has the same function of motor's torque and speed as the MACH3. i did every thing correct in the software but nothing is working out. and i found on google that many guyz are running there stepper motors at 3000 rpm with the use of l297 and l298, i dont want 3000 rpm but the driver is not giving me atlist 500 rpm (*crap*).

 

[SABorn]

As i said earlier i think your problem is with the software, or rather the way the computer talks to the driver.

If you posted a schematic of how you have things connected it would be of far more help than just the data sheet that we know works.

I have used the driver L298 direct with a micro controller (no L297) and have much higher than 150 rpm so i know they will work.

Mach3 puts out a step pulse and a direction command and bugger all else from what i remember and i question how you have used this data to drive your circuit.

Rather than just quoting others can do this and you cant, how about helping us to help you by giving more details of your circuit.

Are you connected direct to the parallel port or are you going via a usb to parallel cable.

Do you have opto coupler protection on the data lines as is recommended.

Pete.

 

[KeepItSimpleStupid]

Look at the currents in the phases. Those values of Rs and Vref are critical to performance. I believe you should see 1/2 or 2x the current when moved 1 pulse in the 1/2 step mode.

 

[SABorn]

I had a message from another member interested in the cnc stepper driver board i used and a quick look on ebay i found what looks to be the same style of board.

This one is 3 axis stepper driver board and the supplier has a range of boards up to 5 axis and also to suit several motor sizes.

If you scroll to the bottom of the page you will find a listing of many products.

As i said previous i was not able to buy the parts to construct my own driver boards for the cost of a complete working board like listed here.

**broken link removed**

Pete.

 

[sizala]

SABorn , thankx for the info on Driver at ebay, but as i think you suppose to help here for solving the electronic faults and dont advertise .

 

[SABorn]

If you bothered to supply the information about your circuit requested we might be able to help.

As for advertising, its not, its giving an alternative to those who are unable to build a effective circuit, or who dont have money to waste on parts that might work or might not.

As it was a moderator that asked about the driver board i used, i see no problem listing a link to the board i quoted.

Pete.

 

[sizala]

the complete info.

oh!dude.... ok ok man....i was out of my mind bcoz the driver wan't working well, And i am not making this driver to save money, i am making this driver bcoz it feels good to me that i made something ad it is working(i dont have much electronic knowledge but still electronics is my hobby so i think you will understand that why i want to make a driver) ...

and i doesn't know that which information to give to in order to solve my problem..but here is the full data of my driver...plz download the zip. file..
the only difference between the driver in the zip file and mine is = i am not using the same power supply as the file is showing . i am using a 24V 20AH/20HR SEALED LEAD ACID BATTERY .

And i am not using any kind of filter or any other type of bored between the parallel port and the driver. driver is directly connected to the parallel port (i connected the GRD of the parallel port to the GRD of the driver).

 

[sizala]

videos

in 1st file(1st 150 then180) the motor is 1st running at 150 rpm then i changed the speed to 180 rpm, you can see that what is happening to the motor.
all other files shows that what happens to what speed.
(by the way the motor is 20KG bipolar 1 amp per phase, i am running it at 24V 1-2Amp.)

 

[SABorn]

I was unable to open the 3gp files and view them (last post)

What i was trying to find out was how is the circuit connected to the computer, with what pins of the parallel port going to what inputs on your circuit.
This is not shown in the schematic you posted above.

One place you might find some information on about this problem is CNCZone forum, as there is heaps of threads there on these driver chips if you search for "L297, L298".
I was once a member there and now forget my username and password, but sure there was othere circuits like yours on the site.

I had a quick look and it would appear that these drivers can only run upto 170-250 rpm in most applications.
It would seem they are not the best choice of design if you want high speed.

CNCzone.com-Machinist Community Forums - Welcome Page

Pete.

 

[SABorn]

Might be a silly question but have you tried adjusting the current limit on RO4 pot, as this controls a 35khz chopper to limit the power to the coils, and at higher speed the torque will be reduced so if the current is set low the motor might just growl and not rotate.

Pete.

 

[sizala]

yes i did tried to adjust the current limit on RO4 pot. my motor is currently running on 24V 1.75 Amp.
And the clk of the driver is connected to pin 2 of the parallel port , and the cw/ccw is connected to pin 3 on parallel port.

now you got me, i think now you understand that what was i saying befor that "othere guyz are able to get 3000 rpm from the l297 and 298, so why is it not working for me?"

 

[sizala]

OK GUYZ, At-last i found the problem (i hope). = i searched on google and i found that i am not only one who is having this problem, and after researching on l298 i found that 170rpm(34000 puls PM) is the limit of the L298 driver, bcoz after 170rpm speed it cant recover it self (the mosfets inside l298). so if me or anyone want to get more speed from l297 and l298 combination then he must use 1 l297 and two or more l298s for one stepper motor .(wowwwwwwwwwww i finally got my problem solved) .. now i am going to use 1 l297 and 4 l298s for 1 stepper motor, it means that i will get 4x speed then a normal driver. the speed will be 150(speed of 1 L298) * 4(4 l298s) = 600rpm at full torque .
(i am gona use only one phase of each l298s so i think it will give me more then 150 rpm each (who knows ...hehe).


anyway guyz thankx for the help.....you all are really helpful for me...


and if anyone else got the same problem as me .. then you can always contact me here by this post or by private message....