There are three main types of stepper motors in construction: reactive (Variable Reluctance, VR), permanent magnet (Permanent Magnet, PM), and hybrid (Hybrid Stepping, HS).
There is a rotor on the stator and the winding is composed of soft magnetic materials. Low cost, simple structure, small step angle, up to 1.2°, but poor dynamic performance, low efficiency, large heat generation, and difficult to ensure reliability.
Permanent magnet type
The rotor of a permanent magnet stepping motor is made of permanent magnet material, and the number of poles of the rotor is the same as that of the stator. The characteristic is that the output torque is large, the dynamic performance is good, but the step angle is large (generally 7.5° or 15°), and the accuracy of this motor is poor.
A hybrid stepping motor has the advantages of reactive and permanent magnet type. The rotor adopts permanent magnet material, the stator has multi-phase windings, and the stator and rotor have multiple small teeth to improve stepping accuracy. Its characteristics are good dynamic performance, small step angle, and large output torque, but the cost is relatively high and the structure is complex.
According to the winding on the stator, there is two-phase, three-phase, and five-phase series. At present, the most popular is the two-phase hybrid stepper motor, which accounts for more than 96% of the market share. The reason is that it is cost-effective, and the effect is good after subdivided drivers. The basic step angle of this kind of motor is 1.8°/step. With a half-step driver, the step angle is reduced to 0.9°. With a subdivision driver, the step angle can be subdivided up to 256 times (0.007°/step). Microstep). Due to manufacturing accuracy and friction, the actual control accuracy is low. The same stepping motor can be equipped with different subdivision drivers to change the accuracy and effect.
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