# How to calculation of PMSM Back EMF

**URL:** <https://forum.plexim.com/t/how-to-calculation-of-pmsm-back-emf/1044>\
**Category:** PLECS\
**Tags:** pmsm, emf, bemf, back-emf\
**Created:** [July 16, 2021, 12:30pm UTC](https://forum.plexim.com/t/how-to-calculation-of-pmsm-back-emf/1044 "2021-07-16T12:30:25Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![oming0731](https://avatars.discourse-cdn.com/v4/letter/o/5f9b8f/32.png) [@oming0731](https://forum.plexim.com/u/oming0731)\
**Post date:** [July 16, 2021, 12:30pm UTC](https://forum.plexim.com/t/how-to-calculation-of-pmsm-back-emf/1044/1 "2021-07-16T12:30:25Z")

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Dear All,

I have a question about back EMF of PMSM.

In the Plecs, how to calculate back EMF of PMSM?

I have back emf constant which measure by line to line peak voltage.

Best regards,

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<div class="post-metadata">

**Author:** ![Bryan\_Lieblick](https://dub1.discourse-cdn.com/flex006/user_avatar/forum.plexim.com/bryan_lieblick/32/10_2.png) [@Bryan\_Lieblick](https://forum.plexim.com/u/Bryan_Lieblick)\
**Post date:** [July 19, 2021, 10:38am UTC](https://forum.plexim.com/t/how-to-calculation-of-pmsm-back-emf/1044/2 "2021-07-19T10:38:01Z")

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The conversion approach is noted at the very bottom of the PMSM component documentation, where KE is the peak-phase voltage, φM is the flux induced by the magnet, and p is the number of pole pairs.

KE = φM·p

Note that if your BEMF constant is line-to-line, opposed to the phase voltage, then you will have to add another scaling factor of sqrt(3) for sinusoidal BEMF.