My motor is 3 phase , 48 volts and up to 1500 Watts; it has 51 coils inside and 46 permanent magnets that I counted upon taking it apart. The controller is inside the motor. Also the PWM is set at 0 percent. What should it be?

  • \$\begingroup\$ "PWM is set at 0 percent" sounds something wrong. BTW, What does that mean? As long as you identified it as "3 phase", it has to somehow align at 120'(right?)electrical angle. But the 51 and 46 does not sound like so. It may be multi-phase, like synchronous / stepper motor. You can post more information, like pictures. \$\endgroup\$
    – jay
    Nov 19, 2021 at 1:44
  • \$\begingroup\$ PWM stands for pulse width managment percent. Something to do with the on time verses the off time of the electric pulse (one of the conditions that controls motor speed. This is my humble understanding. \$\endgroup\$ Nov 19, 2021 at 4:59
  • \$\begingroup\$ Jay I will post pictures ASAP. I have to take it apart. Thanks 4 ur reply. \$\endgroup\$ Nov 19, 2021 at 5:15
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    \$\begingroup\$ Thanks Paul! Pictures will help. My Google search says PWM = Pulse Width Modulation. Is this different one?, What I am puzzled is How do you know the PWM = 0%? Where is that PWM occuring? \$\endgroup\$
    – jay
    Nov 19, 2021 at 12:59
  • \$\begingroup\$ I am trying to figure out how to post photos. \$\endgroup\$ Nov 20, 2021 at 2:28

1 Answer 1


If you counted 46 permanent magnets then you have 23 pole-pairs

  • \$\begingroup\$ Aha that is right! I would sincerely appreciate if you can explain 51 coil part as well. \$\endgroup\$
    – jay
    Nov 19, 2021 at 13:03
  • \$\begingroup\$ Jay. Last weekend I took the motor apart because I wanted to run good wires to it. I am getting a 10 volt voltage drop when I use full power and I found a tiny 3 mm thick wire that someone had spliced into the system using tape mot even soldiered. That's Chinese quality I guess. I couldn't run better wires because the hole through the motor shaft is too small. I will machine it out when I have time. So while the motor was open I counted the coils and magnets. \$\endgroup\$ Nov 20, 2021 at 2:01
  • \$\begingroup\$ There are 51 slots because the motor is 3 phase. So 51 slots / 3 phases =17, which is an integer. Windings typically can be described as concentric (i.e each phase is wrapped around a tooth). Otherwise windings can be described as full-pitch (where the coil spans the distance of two neighboring magnets. Finally, a short pitch describes where the windings span less than two neighboring magnets (I believe concentric falls into this category). The coil pattern is used to shape the back emf of the motor to either look like a sinusoid or a trapezoid. \$\endgroup\$ Nov 20, 2021 at 15:11
  • \$\begingroup\$ Thank you very much \$\endgroup\$ Nov 21, 2021 at 12:19

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