Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: drinu on November 30, 2013, 05:03:15 PM
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Hi,
From where in Europe can I buy a 12V Bipolar stepper motor with a 1 to 1.2Nm (approx.) of torque?
I only found steppers with 24V for that torque.
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Any help please?
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Why can't you use 24V?
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Because I have other motors which operate at 12V. So I already have a 12V supply and a 5V supply for the circuit.
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Is the cost of a 24V supply plus 24V motor higher or lower than trying to find a 12V motor that meets your spec?
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The problem is the space limitation rather than the costs.
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Can you upgrade all the motors to 24V instead, if cost isn't a problem?
That being said, I'm not sure such a motor is actually possible to build. The problem is that higer current leads to more heat and thicker windings to compensate, to some point where there are diminishing returns. In general, stepper motors are specified by acceptable current, not voltage, and you are assumed to raise the voltage until you get to the current you need.
Anyway, if you want a strong 12V motor, you can keep looking. I'm in the US, so I can't help you on locations, but I think all of Kollmorgen, Maxxon, and Faulhaber are actually European based, so I'd be surprised if you couldn't find an assortment of motors at some motion control / factory automation distributor. If they don't have it, it probably doesn't exist.
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Thanks for the reply.
If I use a DC/DC convertor, will it work? I found this on E-bay but I'm not sure if it works when used with stepper motors.
http://www.ebay.co.uk/itm/240W-DC-DC-Converter-DC-12V-to-24V-10A-Boost-Step-up-Car-Power-Module-Waterproof-/271132764032?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3f20c5a780 (http://www.ebay.co.uk/itm/240W-DC-DC-Converter-DC-12V-to-24V-10A-Boost-Step-up-Car-Power-Module-Waterproof-/271132764032?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3f20c5a780)
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Yes that will likely work. Worst case, you can put a couple of fat electrolytic capacitors in parallel on the output if it's too unstable, but that's actually pretty unlikely to be needed.
240W is not a ton of power, though (1/3 HP? something like that.) How fast will you spin those motors, and how fast will you change the speed, and how heavy is the load, and how efficient are the motors?
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I noticed that this DC/DC converter has a Soft start time of 500ms. Can that cause any problems?
Another quick question; Are switching power supplies good to power DC brushed motors?
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I noticed that this DC/DC converter has a Soft start time of 500ms. Can that cause any problems?
I presume that you use the 12V-24V converter BEFORE the H-bridge, so as long as there is 12V power to the system, there is 24V power to the H-bridge. In that case, no, the soft start shouldn't cause any problems, unless your H-bridge has some weird kind of non-resettable under-voltage lock-out (this is not common.)
Another quick question; Are switching power supplies good to power DC brushed motors?
Assuming they are correctly designed, then yes, because they are much more efficient than linear power supplies, and the small ripple voltage on the output doesn't matter for motor control in the way it matters for, say, audio amplifiers or lab equipment.
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Could you just get higher torque using gears?