Questions

Do you have a motor related question? I enjoy exploring anything motor related. I do not claim to be “A Motor God”, but with over 20 years of motor driving and controlling experience, I may have a tip or two on your next project. Feel free to send me a message through this page and I’ll try to answer as soon as possible.

NOTE: If the question requires a long enough answer, I may transform it into a post. Thanks for your understanding!

2 comments for “Questions

  1. April 14, 2018 at 8:08 am

    I have a dc motor that is turning backwards, the wires are right. how do I fix it

    • avayan
      April 16, 2018 at 4:17 am

      The simplest answer is to apply a negative voltage. Of course, this is a super loaded question/answer as there are many things to consider. First of, when you say it is going backwards, remember the rotation is defined by the manufacturer with respect to a side of the motor. For example, if the motor is single shafted (as most of them are), the manufacturer may have defined Clockwise direction by looking at the shaft side or the rear side. I don’t think there is a standard. Second, the wire coloring often implies a connection polarity with red as positive and black as negative, but if the motor has no diodes (and most of them do not), then there is no reason to only use this convention. In other words, you can connect either wire to either power supply output, in order to obtain the rotation direction you need. Lastly is your power stage. If you have a single Half H Bridge to drive the motor, then there is no way to apply a negative voltage. But if you have a full H Bridge, then you can easily flip the direction by controlling the Direction Signal (on PHASE/DIR H Bridges), or reverse the logic, if your H Bridge is of the INx topology. Hope this helps to steer you in the right direction!

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