Comparison of 2-phase, 5-phase motor torque microstepped

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om_tech_support_JT
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Comparison of 2-phase, 5-phase motor torque microstepped

Postby om_tech_support_JT » Tue Jan 08, 2013 6:46 pm

Q: I've read on other motor forums that you lose torque when you use a driver to microstep a stepping motor. Is this true? Does it make a difference if I'm using a 2-phase motor or a 5-phase motor?

A: While there is little difference between the output torque of a 2-phase motor and a 5-phase motor, the 5-phase motor does offer more "useable" torque. This is primarily due to the amount of torque ripple both motors produce. 2-phase, 1.8 deg full step motors have about a 29% torque ripple. 5-phase, 0.72 deg full step motors have about 5% torque ripple. The smaller torque ripple contributes to less vibration and noise which is the main benefit of using 5-phase step motors.

Half-stepping or microstepping a 5-phase motor actually increases torque by up to 10% due to more phases being energized. 2-phase motors will lose torque by up to 40% when half-stepping and microstepping, however, many 2-phase drivers compensate by overdriving the opposite torque vector. While this works, it may introduce other issues such as increased operating temperature and drive costs.

When used with the same 2-phase 1.8 deg step motor, our RBK series drivers can actually generate the same exact torque-speed curve regardless of the microstepping resolution. The reason is because our RBK series drivers, as well as any of our 5-phase drivers, can control torque vectors extremely well. This is also a testament to the quality standards you can expect from Oriental Motor.

To Illustrate this point, I have included our RBK series 56.4mm frame size motor and drive torque-speed performance graphs below. You can see that under the Y-axis, we state different resolutions for the pulse speed in kHz (resolution: 200, and resolution 2000). We also generate our speed-torque graphs based on real test data. Please scroll down to see the graphs.

RBK26 speed torque graphs showing different resolution settings, same curve.jpg
RBK26 speed torque graphs showing different resolution settings, same curve.jpg (472.04 KiB) Viewed 2296 times

Here are some examples of our CRK series 60mm frame size motor and drive torque-speed performance graphs:

CRK56 speed torque graphs showing different resolution settings, same curve.jpg
CRK56 speed torque graphs showing different resolution settings, same curve.jpg (428.75 KiB) Viewed 2296 times

Let us know if you have any questions.

User avatar
om_tech_support_JT
Posts: 1058
Joined: Fri Mar 12, 2010 2:59 pm
Location: Torrance, CA
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Re: Comparison of 2-phase, 5-phase motor torque microstepped

Postby om_tech_support_JT » Tue Jan 15, 2013 3:37 pm

For the rest of the speed-torque performance graphs on the other RBK and CRK series models, or our other products, please click the link below:
http://www.orientalmotor.com/products/CatalogPdfs.htm


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