1. Products Overview

Stepper motor is an executive agency that converts electrical pulses into angle displacement. You can control the angle by controlling the number of pulse to achieve the purpose of accurate position control. At the same time, you can control the speed and acceleration of the motor by controlling the input pulse frequency to achieve the purpose of the speed control.

Step motor, also called as pulse motor is normally classified by structural as: reactive step motors (VR), permanent magnet step motor (PM), and hybrid step motor (HB). Step motor can also be divided into rotation and straight lines according to the form of movement. According to whether there is an encoder, can be divided as open-loop and closed-loop step motors.

Reactive step motor: there are windings on the stator and rotor consisting of soft magnetic materials. The structure is simple, the cost is low, the step distance is small, and it can reach 1.2 °, but the dynamic performance is poor, the efficiency is low, the heating is large, and the reliability is difficult to guarantee.

Permanent Magnet step motor: The rotor of the permanent magnet step motor is made of permanent magnet material, and the rotor is the same as that of the stator. It is characterized by good dynamic performance and large output torque, but this motor has poor accuracy and large steps (generally 7.5 ° or 15 °).

Hybrid Step motor: Hybrid steaming motor integrates the advantages of reaction and permanent magnets both. It has a multi-phase windings, permanent magnet material on the rotor, and multiple small teeth on the rotor and stator to improve the step accuracy. It is characterized by large output torque, good dynamic performance, and small steps, which can meet automation applications which have high precision requirement.

According to the quantity of phases, there are two -phase, three, and five -phase step motors. The most popular is the two-phase hybrid step motor, accounting for about 97%of the market share. The reason is that the two-phase step motor is more cost-effective, and also has satisfactory performance due to subdivision or micro stepping function of its drive.

The basic step angle of a two-phase step motor is 1.8 °/step. Matched with a half-step drive, the step angle is reduced to 0.9 °. Matched with a micro stepping driver, the step angle can be subdivided up to 256 times (0.007 ° per micro step), which can meet the requirement of most applications.

Kaifull two-phase, three-phase, and five-phase hybrid step motors are made of high-temperature permanent magnet and high-quality cold-rolled steel sheets. Our stepper motors range is very rich, covering 20mm to 150mm in frame size. At the same time, there are all-in-one step motors that integrated with drivers, closed-loop stepper motor, and with brake stepper motor etc..

Generally speaking, the characteristics of step motor are:

Easy drive.

No matter how the input current changes, as long as the load can be driven, the step motor moves according to the minimum angle.

No feedback signal is required. The step motor moves according to the pulse frequency and quantity given by the drive, and does not need to rely on the motor actual status feedback.

The positioning error does not accumulate. The reason why the stepping motor does not accumulates is because it does not need to know the actual location, but only needs to know the number of rotating steps. Therefore, the step motor only needs to receive the signal of each step, and then move according to the step angle. It is not necessary to know the starting location or target location. This can avoid the problem of accumulating errors. In addition, the working principle of the stepper motor makes the movement discrete and performed from a specific angle without a continuous accumulation error.

Stepper motor driver principle is simple and easy to develop control system.

Step motor has the characteristics of high power density, high output torque, low noise, low vibration and smooth rotation, high energy conversion efficiency, stable and reliable, long life etc. At the same time, our company supports the flexible customization, too.

Although the stepper motor and its control technology are currently very mature, if not used properly, there may still be a situation of step loss, that is, position error etc. Here, we will analyze some problems and solutions.

Losing pulses when changing direction leads to inaccurate positioning

When changing direction, the pulse is lost, which means that it is accurate in any direction, but as soon as the direction is changed, errors accumulate, and the more times it is changed, the more biased it is.

Solution: Generally, stepper drivers have certain requirements for direction and pulse signals. For example, the direction signal is determined a few microseconds before the first rising or falling edge of the pulse (different drivers have different requirements) arrives. Otherwise, there will be a pulse that runs in the opposite direction of the actual required direction. Finally, the problem will appear as it deviates more and more, with smaller subdivisions becoming more prominent. The main solution is to use software to change the logic of the pulse or add a delay.

The initial speed is too high and the acceleration is too large, which sometimes causes stepping loss.

Solution: Due to the characteristics of the stepper motor, the initial speed should not be too high, especially when the load inertia is large. It is recommended to have the initial speed below 1r/s, so that the impact is small. If the same acceleration is too large, it will also have a large impact on the system, which is simple overshoot

Insufficient motor output torque

Solution: Increase the motor current appropriately, increase the voltage of the progressive driver (pay attention to the optional driver), and choose a motor with higher torque.

Environmental electromagnetic interference causes mis-operation of the controller or driver, resulting in inaccurate positioning.

It is necessary to identify the source of disturbance and reduce its electromagnetic interference on the stepper system, such as increasing spatial distance, using shielded wires for signal lines, and ensuring good grounding of the controller or driver to block communication channels and improve its anti-interference ability.

Solutions:

• Replacing ordinary wires with double shielded wires, the signal lines in the system are separated from wires with high current or high voltage to reduce electromagnetic interference ability.
• Filter out disturbance waves from the power grid using power filters, and add power filters to the input terminals of major electrical equipment under permissible conditions to reduce interference between devices within the system.
• It is best to use photoelectric blocking devices for signal transmission between devices. If conditions permit, pulse and directional signals should be transmitted using differential methods with photoelectric blocking. In rational loads (such as electromagnetic relays, solenoid valves), a resistance capacitance absorption or fast discharge circuit is added at both ends. Rational loads can experience a peak voltage of 10-100 times in the initial moment, if the operating frequency is above 20KHZ.

2. Hybrid Stepper Motor General Technical Specifications
 

 
3. Hybrid Stepper motor Integrated with Gearbox Performance Datasheet

4. Mechanical Dimensions (in mm)

 
5. Wiring Diagram

 
6. Torque Speed Curves