Hello ,
We are bulding a solar tracker. We have two nema 23 FL57STH76-1006A. The datasheet stablish tathd the voltage rated is 8.6V and the curret per phase is 1 A.
What kind of driver can we use?
Thanks!
If the current per phase is really just 1 amp (seems low for a Nema 23) then you could use a DRV8825 driver.
You should use as high a voltage as you can (subject to the limit for the driver) and adjust the current limit on the driver board to suit your motor. The Pololu DRV8825 web page has a lot of useful info. Just be careful that if you buy a DRV8825 driver from a different source it may have different current sense resistors.
Thais is they datasheet for our step motor. I suposed that is a nema 23 . Is it true ?
FL57STH76-1006A.pdf (59.2 KB)
Nema 23 is the size of the mounting flange. It has nothing to do with electrical specifications, so stop calling a stepper 'nema 23' unless you talk about mounting it.
Max motor current seems to be 1Amp, so use a stepper driver that can handle and can be set to this current.
Minimum voltage to reach this current is 8.6volt (this stepper) plus some losses in the driver.
So minimum power supply would be 9-10volt, but...
You get higher speeds if you use a higher supply voltage (e.g. 12-24volt).
An old laptop supply (19volt) could work.
Leo..
ram_bene:
Thais is they datasheet for our step motor. I suposed that is a nema 23 . Is it true ?
Nema 23 means that it is 2.3 inches across the face. That is 58.42mm and your datasheet say 56.4mm so I guess it is a Nema23,
Plus what is in Reply #3
...R
Thanks you! . Now,I have other question. Is 1A max. current ? Or is ir going to increase with load?
It is the maximum that the motor can take. Unlike a DC motor a stepper motor draws approximately the same current all the time, even when stationary. That is how it holds position, but it also makes a stepper motor very inefficient.
Some stepper drivers will automatically reduce the current (perhaps by 30%) when the motor is stationary as the lower current is usually sufficient to hold it in position.
...R
i do agree with Robin, steppers tend to be on 'all the time', but there is a caveat though. at the lowest most 'raw' level, a pair of h-bridge setups can drive a stepper e.g. the l293, l298 or even the chinese MX1508 or MX1515, but that h bridges are literally 'low level', i.e. there is no controller in there, it is purely just transistors and it is literlly only the mosfet 'driver' stage. if you bother to deal with just the transistors i.e. the H bridge, you could probably turn that stepper off altogether.
this can be really quite a challenge to 'run' that motor unless one is willing to get down to raw basics and tinker with all that transistor switching, signalling sequences and current control and all (let alone microstepping)
so going with something like DRV8825 is much easier. it reduces all that complicated signalling to just step and direction. that really help if one is pressed for time or that one prefers to 'focus' on other parts that could be more profitable to spend time on.
and one could buy modules with them e.g. from Pololu etc
lots of 3d printers use them, especially those based on the RAMPS design
the other thing is voltage, in the link on the chinese h-bridge driver, i got caught in a situation that i got myself a 12v stepper, and that chinese h-bridge can take a max 10v (recommended 9v) on the bridge. according to various specs that 12v stepper has a 200ohm coil resistance, that give me a mere 50 mA if i put 10V into it and it would be even less if i run my stepper on less voltages e.g. like 5v. most likely it runs very slowly.
but i read somewhere those 'high inductance' stepper motors use thin fine wires and lots more coils hence the large resistance. what literally happen here is that the speed will be very poor, as much of that power is lost as heat (power = I^2 R). the untold benefit here is that the motor can hold on to it for much less currents i.e. it has higher torque and needs less current. but it trades off speed significantly.
the accidental solution for the high inductance motors is however to run it at higher voltage, but this would cause even more heat generation (power = V^2/R) for a modest, probably mild increase in speed
(based on this it seem motors that's rated for less voltages would run faster ! (for less holding torque )
ram_bene:
Hello ,
We are bulding a solar tracker. We have two nema 23 FL57STH76-1006A. The datasheet stablish tathd the voltage rated is 8.6V and the curret per phase is 1 A.What kind of driver can we use?
Thanks!
You need to rethink your approach, stepper motors are very inefficient (they pull maximum power all the time), you risk pouring all your solar power away into the motor.
A DC worm-drive gearmotor or linear actuator is the usual approach to steering a solar panel - this can be powered down completely most of the time. If you power a stepper down it won't hold position against the
wind or gravity.
1 Like
Without knowing what it is you're trying to track the sun with, It's a bit difficult to make a recomendation, but the final speed would be pretty slow, and if you already have the motors, then maybe a worm drive would allow it to maintain position. There are plenty of drivers that will supply 1 amp for stepper motors, and use a power supply a few volts below the drivers maximum voltage. If the application is critical, then buy a driver from a reliable source, there are numerous drivers out there with ambitious ratings. You've got all night to drive the tracker back to the sunrise position!