Creating a Coil and its Terminals (CupCoil)

When InfoCoil = 0, the created object includes all coils which are united together. To separate them you can use Modeler > Boolean > Separate Bodies menu command. When InfoCoil = 1, the created object includes only one coil, as shown by the coil in green color in the figure. You can use menu command Edit > Duplicate > Around Axis to duplicate it.

When InfoCoil = 2, you can create a terminal for coil assignment. You can create a return terminal for a coil in 2D by setting InfoCoil = 3. The following figure shows both “go” and “return” terminals, and shows the definition of the CoilPitch parameter (90 degrees in this example).

“go” and “return” terminals for a CupCoil with a given CoilPitch

When CoilType = 1 , the created coil is a lap-type. When CoilType = 2, the created coil is a wave-type. For a wave-type coil, the bottom span will be skewed in the same direction as the top span, and therefore, the bottom tip will shift from the top tip by one pole pitch. The pole pitch will be 180°, 90°, 60°, …, for 2, 4, 6, …, poles, respectively. The input value of CoilPitch will be adjusted to the closest value of possible pole pitches. The following figure compares a wave-type coil with a lap-type coil.

Wave-type coil compared with a lap-type coil

You can set LenTotal = 0 to create coils or terminals in 2D, or directly use InfoCoil = 2 and InfoCoil = 3 with LenTotal > 0 to draw 3D terminals for 2D coils. The difference between 2D terminals and 3D terminals is that: there will be a gap between any two adjacent 3D coil terminals, but there will be no gap between 2D terminals to improve mesh quality, as compared in the figure below.

2D terminals compared with 3D terminals

A user needs to input an average CoilPitch to create coil terminals for 2D FEA model. For a wave-type coil, because the bottom span is continuously skewed without changing the skew direction from the top span, the average coil pitch is the same as the real CoilPitch. For a lap-type coil, the average coil pitch can be derived from:

PitchAve = (Length x CoilPitch + (LenCore – Length) x (CoilPitch + PitchMin) / 2) / LenCore

where LenCore is the length of the inner and outer cores which carry magnetic field, and

PitchMin = (LenTotal – 2 x RadTip – LenCore) / (LenTotal – 2 x RadTip – Length) x CoilPitch

which must be limited within (0, CoilPitch). In the equation above, RadTip is the radius of top and bottom coil tips, which is obtained from:

RadTip = (DiaOuter – DiaInner) / 4

The skew angle for multi-slice 2D FEA model can be obtained from:

AngSkew = (PitchAve – PitchMin) x 2

which is applicable for both lap-type and wave-type coils.