Hybrid Stepper Motors

In hybrid stepper motors, the VR rotor is constructed with a permanent magnet:

Front stack is held by “N” poles of the stator. The back stack is held by “S” poles of the stator. Multi-stacks create more force.

Step angle for the case above:

$$\frac{360°}{(\text{rotor teeth})\times \text{stator phases}}=\frac{360°}{50\times 4}=1.8°$$