Stepper Mootr Driver - Page 1
Forum section: electronics / projects

author: navidrct
author_rank: Regular Contributor
timestamp: October 30, 2017, 11:00:06 am
content: hii want to build a Stepper Motor Driver that can carry at each phase around 5Aso i decide to use mosfeti decide to use atmega8 and pic above is driver parti have 4 diode as protectionmy mosfet has low Rds ON and it capable of 5 Awhat i should consider in choosing mosfet and all the component?what u suggest me on this project?(any pull up resistor or pull down ? what ever come in mind to consider in this project please tell me)

author: Bootalito
author_rank: Unknown
timestamp: October 30, 2017, 01:02:56 pm
content: My thoughts in no particular order:1.use a 100r resistor to gate2. Use a 10k (or lower) pulldown from gate to ground3. Usually a stepper motor is powered by a totem pole arrangement4. It's good to have a dedicated chip for driving steppers as a uC needs to do another things.5. If you search AliExpress for 8a stepper motor driver, you will find one for ~$150. This will allow micro stepping which may be difficult to implement manuallySent from my VS990 using Tapatalk

author: ataradov
author_rank: Super Contributor
timestamp: October 30, 2017, 04:50:27 pm
content: This is a very bad way to drive stepper motors. You will get a lot of buzzing and vibration.You need to get a proper driver with microstepping, or add current sensing to this driver, and implement a better driving routine (this is not trivial, to say the least).

author: H.O
author_rank: Frequent Contributor
timestamp: October 30, 2017, 04:54:15 pm
content: Is that really a motor with coils designed for 12V and 5A?If it is it's got to be a really old and really big one and you're going to get terrible performance by driving it WITH 12V. If it isn't then you're going to burn it out in no time if you don't limit the current.Unipolar drive of anything but the smallest step motors have been "dead" for decades. If you need to get this turning (slowly) at the the lowest possible cost then go ahead but if you want to get any sort of performance out it buy or build a bipolar driver. If you want the highest torque use the full winding, if you want the highest speed (but less torque) use only half of the winding.Stepper motors are "current driven" devices. To get any sort of performance out of them you must drive the coils with a voltage much higher than what IxR dictates and then limit the current so you don't destroy the motor. In old unipolar drives they used to use used big beefy power resitors while modern drives are more like a constant current SMPS.

author: navidrct
author_rank: Regular Contributor
timestamp: October 31, 2017, 05:04:59 am
content: Quote from: Bootalito on October 30, 2017, 01:02:56 pm150$ is to much for this projectthanks allot ill do all that

author: navidrct
author_rank: Regular Contributor
timestamp: October 31, 2017, 05:06:27 am
content: Quote from: ataradov on October 30, 2017, 04:50:27 pmif I use current sense will this circuit work fine?

author: navidrct
author_rank: Regular Contributor
timestamp: October 31, 2017, 05:08:17 am
content: Quote from: H.O on October 30, 2017, 04:54:15 pmshould i use SMPS to limite the current ?can i use another mosfet or npn or pnp circuit to limit the current?

author: ataradov
author_rank: Super Contributor
timestamp: October 31, 2017, 05:08:31 am
content: Quote from: navidrct on October 31, 2017, 05:06:27 amCurrent sense alone is not enough, you also need to implement correct driving algorithm. You will end up designing that $150 driver, only will will cost you a whole lot more in R&D.

author: navidrct
author_rank: Regular Contributor
timestamp: October 31, 2017, 05:10:51 am
content: Quote from: ataradov on October 31, 2017, 05:08:31 amdo u have any refrence design in mind?i need it realy

author: ataradov
author_rank: Super Contributor
timestamp: October 31, 2017, 05:11:21 am
content: Quote from: navidrct on October 31, 2017, 05:08:17 amPeople spend years perfecting motor drivers. You are getting into a very deep subject. And based on the questions, you will have to learn A LOT before you get anything useful.You will spend $150 on a first day in fried power MOSFETs alone

author: ataradov
author_rank: Super Contributor
timestamp: October 31, 2017, 05:13:16 am
content: Quote from: navidrct on October 31, 2017, 05:10:51 amNo, I'm not an expert in this area. I just buy stuff others designed.You need to clarify your actual motor specs. Right now it looks like a really beefy motor, just the price of components alone will probably get close to $150 even if you decide to make a driver yourself.

author: julianhigginson
author_rank: Frequent Contributor
timestamp: October 31, 2017, 05:31:54 am
content: first up - you actually have a unipolar 6 wire stepper? that's kind of unusual. Most you see these days are bipolar 4 wire.If you just want to see a stepper move, and aren't interested in having a proper designed solution - you could look at an integrated controller IC on an eval board.. though your specs are a little in the high power range for most eval boards.ST powerstep01 might be able to help you (if it manages to do unipolar drive mode?? I'm not sure) Assuming it does uniopolar drive, you would buy the eval board for that, plus an appropriate STM32 eval board that will plug into it and control it, then get the eval code compiled/loaded up and see what you can see. (Also you'd need a power supply to handle your current requirements)keep in mind that the powerstep01 is an amazingly complex chip - even though it probably has everything you need if it does unipolar drive, and even if it has an eval board and project to do something almost out of the box, it will take you a long time to understand it and get it configured the way you want!

author: navidrct
author_rank: Regular Contributor
timestamp: October 31, 2017, 06:37:14 am
content: Quote from: julianhigginson on October 31, 2017, 05:31:54 amthat was good thanks allotit use 8 mosfet and buffer to drive them . so i can use 8 mosfet to avoid any miss clockingand i should use buffer something like npn or pnpplease if u have any comment on this pic tell meit can be an open source project that anybody can be involve

author: H.O
author_rank: Frequent Contributor
timestamp: October 31, 2017, 05:27:16 pm
content: I know this is an electronics forum and this is the project section which is supposed to be about designing and building stuff.If you want to LEARN about designing and building step motor drives, by all means go ahead, start with that unipolar wavedrive thing and learn what works and what doesn't, then move on. But if the actual goal is to get the motor running with ANY sort of performance then use your time and monet wisely and just buy a driver.Go to AliExpress and search for DM860, it'll set you back $60 but it'll drive that motor alot better than anything you can possibly build for $60 in parts alone. Isolate the top (or bottom) end of each winding the other end and center tap, set the drives current limit to what the unipolar rating of the motor is. Since you don't post any data on the motor I'm just going to suggest using a 48V supply.