suggestions for tb6600 stepper motor driver.

Thread Starter

Moaz Rao

Joined Sep 19, 2019
3
i am working on a project in which i have to control a stepper motor. earlier i was using L298n motor driver. it was working well until the stepper motor goes for holding. as it draws the maximum current which ultimately fry the driver module.
now i'm upgrading my project to new driver i search a lot and find tb6600 stepper motor driver quite good. now i want to know that will this problem come up again using tb6600 or not.
my stepper motor is mineaba motor 17PM-k406-11v which has 2.8 ohms per coil resistance and in data sheet recommended current is 1.4 amps which i have no idea how they are recommending this as 12volt/2.8ohms=4.3 amps approx per phase. please do guide me about tb660.

please do answer me ASAP!
 

MaxHeadRoom

Joined Jul 18, 2013
23,918
Works for me, I just don't know why adds such as this refer to the NEMA rating which is the mounting frame size, it has nothing to indicate what the the potential motor power/torque etc.!
 

LesJones

Joined Jan 8, 2017
3,571
The L298n does not limit the current through the coils in the stepper motor so when the motor is stopped the current is only limited by the winding resistance. So as you have calculated the current will be 4.3 amps. You could add 5.8 ohm resistors in series with the windings to limit the current to 1.4 amps but that would generate heat and wast power. (Note if you reduce the current it will reduce the holding torque.) Stepper motors are normally driven from a higher voltage than that required to produce the rated current through the coils. This it to reduce the effect of the winding inductance in allowing the current to rise quickly to the desired current. (The higher voltage is required for high stepping rates.) Drivers such as the tb6600 limit the current using PWM (Pulse width modulation.) This is a link to the datasheet on the tb66000 which will help you to understand how they work.
This is a link to information on a driver module using the tb66000.


Les.
 

Thread Starter

Moaz Rao

Joined Sep 19, 2019
3
The L298n does not limit the current through the coils in the stepper motor so when the motor is stopped the current is only limited by the winding resistance. So as you have calculated the current will be 4.3 amps. You could add 5.8 ohm resistors in series with the windings to limit the current to 1.4 amps but that would generate heat and wast power. (Note if you reduce the current it will reduce the holding torque.) Stepper motors are normally driven from a higher voltage than that required to produce the rated current through the coils. This it to reduce the effect of the winding inductance in allowing the current to rise quickly to the desired current. (The higher voltage is required for high stepping rates.) Drivers such as the tb6600 limit the current using PWM (Pulse width modulation.) This is a link to the datasheet on the tb66000 which will help you to understand how they work.
This is a link to information on a driver module using the tb66000.


Les.
Thank you so much it helps a lot.
 

jeffl_2

Joined Sep 17, 2013
56
The TB6600 uses a driver concept similar to PWM and it's also a microstepper drive, and there are loads of inexpensive Chinese-made modules using this chip available from sources like aliexpress, they are very popular to use in applications like engravers and 3D printers, obviously you could build the chip into your own application but it's much easier and cheaper to buy this off the shelf. They also have modules available that they've architected using TI Piccolo DSP to replace the TB6600 in order to get the compliance voltage up to 80 volts instead of 40 volts. I spent a fair amount of time experimenting with these drivers and an awful lot of folks misunderstand the concept of "microstepper drive" because they think the primary advantage of using these parts is mostly if you're attempting to get position control down under a thousandth of an inch or a hundredth of a degree, but that would be missing the point (and if you're trying to control EXTREMELY small dimensions accurately you're likely to be disappointed anyway). Actually you can use these parts very effectively at half-step (you would never use full-step because it's slower) and in order for me to explain this you need to get away from the "stepper motor data sheet" rating of resistance-limited current. Using a part like the TB6600 you can safely run the coil compliance (drive) voltage all the way up to 40 volts REGARDLESS OF the data sheet voltage rating of the stepper, and you do that so you can let the chip run the coil current up as quickly as possible using that high compliance voltage, and still safely regulate the coil current to the "data sheet" value (the motor really only cares about the maximum current). Using this technique you can get a high fraction of the holding torque out of the motor WHILE IT'S RUNNING. For example using the smaller driver I was able to use a NEMA 17 motor like yours to drive an Acme leadscrew and get it up to a step rate equivalent to 375 RPM at 400 steps/rev with a compliance of 29 volts. I even had a NEMA 34 up to 218 RPM with the larger driver at 72 volts compliance, I remember the holding torque for that one was rated at about 1800 in-oz. (about 9 ft-lbs.), you might want to consider the ramifications for what you're trying to do, just remember that to get all the torque you don't want to use a motor that exceeds the maximum current available to select on the driver, which for the smaller (TB6600-based) driver is usually about 3.5 amps.
 

MaxHeadRoom

Joined Jul 18, 2013
23,918
A stepper motor should always be ran at exactly the plate rated current for optimum operation throughout the rpm range, this is achieved using the higher end stepper manuf. controllers. Gecko for e.g.
 

swr999

Joined Mar 30, 2011
34
My quick overview: Motor = 2.8 ohms/phase, Imax = 1.4A. This implies a "rated" or "nameplate" voltage of ~4V. A rule of thumb is to use a supply voltage of at least 4X the 'rated' voltage. In this case that would be 16 volts minimum. 24V would be good. The general idea is that if you use too low a supply voltage you lose torque response/performance. Of course, this means you need a controller with a current-limit function. Most modern step-motor controllers have a current-limiting function, which you 'program' for your motor typically using DIP switches or a programming resistor.

geckodrive.com has a good theory section and "how to" section in their Support page. Worth reading!
 

MaxHeadRoom

Joined Jul 18, 2013
23,918
The reason for the typical Stepper drive using a much higher voltage than the motor rated value now is to enable the PWM generated signal to control the exact plate Current of the motor throughout the rpm range.
The important value is the rated current, not the mean voltage value.
The rated torque is a result of the constant current value of the motor.
Before the existence of PWM drives, a simple series resistor was used.

.
 

jeffl_2

Joined Sep 17, 2013
56
Yes but when you use an advanced current control algorithm and a high compliance voltage to counter the coil inductance, the current hits the rated value MUCH earlier in the step, and stays there for a much longer fraction of the step. That makes for a higher average coil current AND a higher average step torque, because torque is proportional to current. And with more torque earlier you can also use faster steps for a given load, which raises the maximum available rotational speed. You don't have to believe me, you can put a current probe for an oscilloscope in series with a coil winding and SEE the torque being generated at different portions of the step for different drive methods.
 
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