# \[Myxa\] Current limiting behavior

**URL:** <https://forum.zubax.com/t/myxa-current-limiting-behavior/1299>\
**Category:** Electric drives\
**Tags:** myxa\
**Created:** [May 1, 2019, 7:51pm UTC](https://forum.zubax.com/t/myxa-current-limiting-behavior/1299 "2019-05-01T19:51:45Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![Evan1010](https://forum.zubax.com/user_avatar/forum.zubax.com/evan1010/32/159_2.png) [@Evan1010](https://forum.zubax.com/u/Evan1010)\
**Post date:** [May 3, 2019, 4:35pm UTC](https://forum.zubax.com/t/myxa-current-limiting-behavior/1299/3 "2019-05-03T16:35:09Z")

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Thank you for moving this into its own topic - I wasn’t sure it was sufficiently novel, but now I can supply more information without cluttering the old thread.

At this point I can accept the standard Myxa falling short of supplying the necessary current, and I will contact your colleague regarding the OpenMyxa design. I have been reviewing the design these past couple days, as it seems to fit our power requirement perfectly - I mistakenly assumed that it was not yet ready for testing.

That said, in the interest of not sounding crazy (putting 1.5kW through a Myxa level of crazy), here’s some hardware information:

Battery: 6s (25.2V max) Lithium Ion pack  
Motor: [KDE4215XF-465](https://www.kdedirect.com/products/kde4215xf-465)

- 22 Magnetic Poles
- Motor Constant of 465Kv
- Winding Resistance of 0.052 Ohm

Propeller: [Graupner E-Prop 15" x 8"](https://www.graupnerusa.com/Carbon-reinforced-electric-airplane-propeller-1326.15X8.html)  
ESC: Myxa A (3D-Printed Case)

I’ve reviewed the video I recorded, and the peak phase current I witnessed was 47.4A (775W).  
Do you know off hand what shunt current would trip the hardware overload? Perhaps the GUI sampling was missing the peaks.

I have read up on some of your other posts, and wonder if [this excerpt](https://forum.zubax.com/t/max-current-watts-power-data-sheet-discrepancy/1135/4) may have bearing:

> [@Max current/watts power data sheet discrepancy](https://forum.zubax.com/t/max-current-watts-power-data-sheet-discrepancy/1135/4):
>
> One should beware that most sinewave drive controllers have certain limits on the magnitude of the output voltage they can modulate. For Myxa, the maximum attainable phase voltage is Vdc / sqrt(3) \* 0.91. For example, with the DC link voltage of 22 V, the maximum attainable phase voltage would be 22.2 / 1.73 \* 0.91 = 12 V. Which means that the above setup would be dysfunctional – the controller would be unable to reach the maximum power because the voltage modulation range will be exhausted before the desired power is reached. However, if the speed constant of the motor were higher, it would work out nicely:

Considering the reported RPM and known Kv of the motor, that is.

It may be a rather inconvenient medium, but I have attached a screen recording of my testing. I apologize for the periods of inactivity, as the test stand was in a protected enclosure and slowed down the testing. DC Overcurrent is first reported at the 2:45 mark, and gets more interesting from there.

[vokoscreen-2019-05-01\_14-26-39.mkv](https://forum.zubax.com/uploads/default/original/1X/afed9a27ae6202179a950e8da195abf16a99a3bc.mkv) (4.2 MB)

Thank you for addressing my concerns - at this point I mainly wish to know what triggered the behavior in my case.

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