Views: 0 Author: Site Editor Publish Time: 2025-09-04 Origin: Site
Bipolar stepper motors typically consist of two independent phases (A phase and B phase), each with two lead wires representing two separate windings. There is no electrical connection between the two phases, so the motor has a total of four leads.
Monopolar stepper motors typically have four phases, with two common lines added to the bipolar two-phase structure. If the public line is connected, 5 wires will be led out; If not connected, lead out 6 wires. Therefore, the number of lead wires for a unipolar motor is 5 or 6.
2、 What does maximum operating frequency/maximum pull-out frequency refer to?
The maximum operating frequency, also known as the maximum pull-out frequency, refers to the highest pulse frequency at which a motor can maintain rotation without load under specific driving conditions, voltage, and rated current. Due to the inertia of the rotor, the torque required for the rotating motor is lower than when starting, so the maximum operating frequency is usually higher than the maximum self starting frequency.
Pulling torque refers to the maximum torque that the motor can output without losing steps during operation. The torque reaches its maximum value at low frequencies or low speeds and gradually decreases as the frequency increases. If the load torque exceeds the pulling torque during operation, the motor will lose step and cannot maintain precise positioning.
Introducing torque represents the maximum load torque that the motor can withstand when starting from a stationary state at a given frequency. If the load torque exceeds the introduced torque, the motor will not be able to start. Due to the influence of rotor inertia, the introduced torque is usually smaller than the pulled torque.
4、 What is the Detent Torque of a stepper motor?
Self positioning torque refers to the holding torque generated by the interaction between the permanent magnet and the stator teeth of a motor in an unpowered state. When manually rotating the motor shaft, a noticeable magnetic resistance or jerking sensation can be felt. If the load exceeds the pulling torque due to overload, the motor will lose synchronization. To prevent step loss or stalling, it is usually necessary to ensure that there is no less than 30% design allowance for the pulling torque when selecting.
Single phase drive (also known as single-phase excitation) only excites one phase winding at a time. For example, when phase A is excited, the stator generates a magnetic field that attracts the rotor to rotate; Then switch to phase B, and the rotor continues to rotate 90 °, and so on.
Dual phase drive (full step drive) simultaneously excites two-phase windings, resulting in greater torque than single-phase drive. The step angle remains unchanged but the output is smoother, making it widely used in conventional motion control.
The one two phase drive (half step drive) alternately adopts single-phase and two-phase excitation methods. For example, first motivate phase A, then simultaneously motivate phase A and phase B, and then only motivate phase B, in this cycle. This mode reduces the step angle by half and improves the motion resolution, but it may also cause torque ripple and resonance problems, which can be considered as the most basic resolution subdivision driving method.
6、 How to choose a suitable stepper motor?
To optimize system performance, the following basic principles should be followed:
1. The motor model should be selected based on the maximum torque/speed requirements (worst-case conditions) in the application scenario;
2. Reserve at least 30% of the design margin from the torque speed curve provided in the product manual (pulling out the torque curve);
3. Ensure that the motor does not stop or lose steps during operation due to external disturbances such as impact loads or sudden movements.
