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Selecting a motor for a NI9503
Alexander314159
Member
11-13-2017 11:01 AM
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Dear experts;
In choosing a motor to run with a NI 9503 powered by +24V; my colleague has purchased a 3.5V stepper motor (datasheet attached). His feeling is that since power is applied for a fraction of a second, that the RMS power is within the limits of the motor.
To me it seems that the motor we choose should be rated for the applied voltage (IE. +24V).
Has anyone heard of this practice?
Here are the characteristics of the NI 9503:
Input/Output Characteristics
Motor DC power supply (Vsup).......+9 to +30 VDC
Minimum phase inductance..............1 mH
Maximum phase inductance .............20 mH
Type ..................................................PWM
PWM frequency................................ 20 kHz
Current per phase..............................3 A RMS
Thanks for your thoughts.
eltico
NI Employee (retired)
11-14-2017 11:05 AM
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Hi Alexander314159,
I think that you won't have problems. The operating voltage of a stepper motor is irrelevant for pretty much all practical purposes. What you need to take into account is the current per phase that is 1 A while the NI-9503 can drive 3 Arms. These motors are usually driven by much higher voltage ranges.
If you were using a DC motor this will important because the current is changed by the voltage but a stepper motor is pretty much always draw full current. This makes them stay still when they are not moving.
If you are still in doubt, I think the best way to make sure they will work is to ask the manufacturer for a drive they recommend. I took a look at their web page and they don't have any stepper drives for that voltage level.
Regards,
PedroR
11-14-2017 03:06 PM - edited 11-14-2017 03:07 PM
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The main effect seems to be the holding current for the motor.
We have seen smoke come out of a couple of these motors already.
It seems to me we should change the motor, rather than adapting the NI demo software to turn off the holding current.
In principle though the voltage rating for the motor should not be one of the main criteria in making a motor choice then?
eltico
NI Employee (retired)
11-14-2017 05:53 PM
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It shouldn't be an important aspect unless the motors are somehow special but I am pretty sure that's something the vendor should point out. Maybe you can use the SoftMotion function described in the link below
If this doesn't work and you want to keep the motors, I'd recommend using a stepper drive special for that motor voltage and use the NI 9512 to control it. This is a drive interface but this solution might be more expensive than just changing the motors. Check this link for motors sold by NI which have been tested with the hardware you have
http://sine.ni.com/nips/cds/view/p/lang/en/nid/211763
Regards,
PedroR
