When BLDC motor is used as generator, how does the amount of poles effect the frequency of the 3 phase AC that it generates? For example, if I had a motor with 8 poles and I spun it at 50 rpm, what frequency 3 phase AC would it generate?
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1\$\begingroup\$ "the frequency it outputs": a motor doesn't output frequency. What do you refer to? Do you mean a brushless DC motor used as a generator? That generally doesn't work, because a brushless DC motor is typically a three-or-more phase AC motor with current source electronics to convert the DC to AC; and that doesn't work the other way around.- \$\endgroup\$– Marcus MüllerCommented Aug 6, 2018 at 17:56
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\$\begingroup\$ @MarcusMüller electronics.stackexchange.com/questions/322321/… \$\endgroup\$– MapleCommented Aug 16, 2018 at 15:16
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For an 8-pole motor there are 4 complete cycles of each phase per rotation, so rotating it at 50 RPM gives you 200 cycles per minute or 200/60 Hz.
BTW, an "8-pole" 3-phase motor has 24 magnetic poles.
answered Aug 6, 2018 at 18:10
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\$\begingroup\$ I'm not sure what you mean by 24 magnetic poles. Could You explain? \$\endgroup\$ Commented Aug 15, 2018 at 19:51
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\$\begingroup\$ @JohnBirckhead Poles are in pairs, so the stated number is always even. They are per phase so multiply by three. This answer covers it. \$\endgroup\$ Commented Aug 15, 2018 at 20:05
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\$\begingroup\$ The link shows only motors whose number of slots are equal to the number of poles times the number of phases. I am a little concerned that readers might think that this was always true and become confused. \$\endgroup\$ Commented Aug 15, 2018 at 21:40