AC Magnetic Analysis of a 4-Phase Stepper Motor in SolidWorks 


1.  What is a Stepper Motor?

A stepper motor, also called step motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The main merit of this kind of motors is that their position can then be controlled to move and hold at any of those equal steps. There is no need to have any kind of feedback sensor and the device can be perfectly controlled in an open loop. DC brush motors rotate continuously when voltage is applied to their terminals. Stepper motors, on the other hand, effectively have multiple "toothed" electromagnets arranged around a central gear-shaped piece of iron. 


 

The electromagnets are energized by an external control circuit, such as a Microcontroller. To make the motor shaft turn, first, one electromagnet is given power, which makes the gear's teeth magnetically attracted to the electromagnet's teeth. When the gear's teeth are aligned to the first electromagnet, they are slightly offset from the next electromagnet. So when the next electromagnet is turned on and the first is turned off, the gear rotates slightly to align with the next one, and from there the process is repeated. Each of those slight rotations is called a "step", with an integer number of steps making a full rotation. In that way, the motor can be turned by a precise angle. 

 

                                                 

 

2.  AC Magnetic analysis of a Stepper Motor

A stepper motor is characterized by the decrease in torque resulting from an increase in rotational speed. Such motors are typically used in laser and optical applications, printers, positioning systems, linear actuators, rotational devices, wind turbines, etc. A four-phase stepper motor, with a cogging torque rotor, is analyzed using AC magnetic analysis using EMS.When a coil is excited, an electromagnetic force is induced causing the plunger to translate. This example treats this kind of phenomena. 

 

                                                             

 

1.   Model View

           

          

Magnetic Flux Density Results at 90 Degrees

 

       

 

              

Magnetic Field Intensity Results at 180 Degrees


  1. Applied Current Density Results at 315 Degrees

         

 

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