Stepper motor classification

Changzhou Finer Motor Co.,ltd（常州方能电器有限公司）

  There are three main types of stepper motors in construction: Variable Reluctance (VR), Permanent Magnet (PM), and Hybrid Stepping (HS).

Reaction type: There is a winding on the stator, and the rotor is composed of a soft magnetic material. The utility model has the advantages of simple structure, low cost and small step angle, up to 1.2°, but the dynamic performance is poor, the efficiency is low, the heat is large, and the reliability is difficult to ensure.

Permanent magnet type: The rotor of the permanent magnet stepping motor is made of permanent magnet material, and the number of poles of the rotor is the same as the number of poles of the stator. It is characterized by good dynamic performance and large output torque, but this motor has poor precision and a large step angle (typically 7.5° or 15°).

  Hybrid: Hybrid stepper motor combines the advantages of reactive and permanent magnets. It has multi-phase winding on the stator, permanent magnet materials on the rotor, and multiple small teeth on the rotor and stator to improve step accuracy. The utility model has the advantages of large output torque, good dynamic performance and small step angle, but the structure is complex and the cost is relatively high.

According to the winding on the stator, there are two phases, three phases and five equal series. The most popular is the two-phase hybrid stepping motor, which accounts for more than 97% of the market share. The reason is that it is cost-effective and works well with the subdivision driver. The basic step angle of the motor is 1.8°/step. With the half-step drive, the step angle is reduced to 0.9°. With the subdivision driver, the step angle can be subdivided by 256 times (0.007°/μ step). The actual control accuracy is slightly lower due to friction and manufacturing precision. The same stepper motor can be equipped with different subdivision drivers to change the accuracy and effect.

  advantage

1. The angle of rotation of the motor is proportional to the number of pulses;

2. The motor has the maximum torque when it stops rotating (when the winding is excited);

3. Since the accuracy of each step is between 3% and 5%, and the error of one step is not accumulated to the next step, it has better positional accuracy and repeatability of motion;

4. Excellent start and stop and reverse response;

5, because there is no brush, the reliability is higher, so the life of the motor depends only on the life of the bearing;

6. The response of the motor is determined only by the digital input pulse, so open loop control can be used, which makes the structure of the motor simpler and controls the cost;

7, only the load can be directly connected to the shaft of the motor can also be rotated at a very low speed;

8, because the speed is proportional to the pulse frequency, so there is a relatively wide range of speed.

  defect

1. If the control is improper, it is easy to generate resonance;

2, it is difficult to run to a higher speed;

3. It is difficult to obtain a large torque;

4. There is no advantage in terms of volume and weight, and energy utilization is low;

5. When the load is exceeded, the synchronization will be destroyed, and vibration and noise will be emitted at high speed.