The Switched Reluctance Motor

  • View

  • Download

Embed Size (px)


special machine

Text of The Switched Reluctance Motor

  • The Switched Reluctance Motor2012 Dr. B. C. PaulNote Concepts presented here in are considered common knowledge in the field and are found in numerous texts no one of which was intentionally copied. Figures are from various sources including computer simulation technology, Texas A+M University, Electric Motorbike Inc, Hearst Electric Products. List may not exhaustively site all locations where similar figures may be found.

  • The Switched Reluctance MotorThe Stator contains 3 electro-magnets powered by DC Current.

  • The Rotor is a Plain Piece of Steel capable of carrying a magnetic fluxThe rotor is connectedTo a shaft that is it hoped will turn to make something happen.

  • The Path of Least ResistanceWater will follow the path of least resistanceElectricity will follow a path of least resistance

  • Magnetic ReluctanceMagnetic flux likes to find an easy flow pathA nice piece of steel is a much better flow path than airThe magnetic flux will try to get the steel path to line up (considered magnetic reluctance)

  • Making the Motor WorkIf I keep turning magnetic fields offAnd on around the stator I canHave the rotor continuous chasingThe magnetic field and thusTurning the shaft

    I now have a DC motor with noRings or brushes. (But one whollyHeck of a lot of switches)

  • ProblemsThe torque the motor produces is proportional to where the rotor is relative to the polesThe effect is highly non-linearAs the rotor chases the poles the poles the torque ripples up and down

  • Try ThisA bunch of extra poles and then let a project logic controller program do the fieldSwitching to smooth out the torque.

  • Of CourseWe have just created a motor that depends on a bunch of solid state switching technology and a computer to be able to operateThat would have been a big deal in 1912, but not 2012.Its still a big deal if Im talking hp motors, but if I need a big torqueing motor a computer controlled motor is another story.