The 28 Questions about Stepper Servo Motor

1. How to Select Suitable Servo Motor and Stepper Motor?

It mainly depends on the application. In short, you should determine requirements such as the nature of load(horizontal or vertical load), the torque, the inertia, the speed, the precision, the acceleration and deceleration, upper control requirements(port interface and commutation requirements), the control method is the position, torque or speed, the supply voltage is DC, AC, or battery-powered, voltage scope. According to these, the type of motor and controller can be determined.

2. Whether choosing a step motor or servo motor system?

Each has its characteristic, it should be determined by the application.

3. How to select a suitable stepper motor driver?

Based on the current of the motor, the current of the driver should be greater or equal. If low vibration or high precision is required, the subdivision driver can be chosen. For the high torque motor, using high voltage drivers to get high-speed performance.

4. What is the difference between the 2 phase and 5 phase stepper motor? How can I choose?

The cost of the 2 phase stepper motor is relatively low. but in the low speed, the vibration is relatively high, and torque will decrease drastically in high speed. In terms of the 5 phase motor, the vibration is relatively low and has a good performance. Compared with 2 phase stepper motor, the speed is 30%-50% higher than 2 phase motor. It can replace the servo motor with some applications.

5. When using the DC servo system, what is the difference between the AC servo system?

The DC servo motor can be divided into a brushed and brushless motor. The cost of a brush motor is relatively low, simple structure, high starting torque, wide speed regulation, easy control, easy maintenance(replace carbon brushes). it will produce electromagnetic interference, which has the requirement of the environment. So, it can be used in an environment that is sensitive to the cost.

The volume of the brushless motor is small, lightweight, high response, low inertia, smooth operation, stable torque. Its control is complex, easy to realize intelligence, which has a flexible commutation way and uses square wave commutation and sine wave commutation. The motor is free of maintenance, high efficiency, low operating temperature, small electromagnetic radiation, long life, and can be used in various environments.

AC servo motor is also the brushless motor, it can be divided into the synchronous and asynchronous motor. At present, in motion control, the synchronous motor is mainly used. Its power scope is wide, can be designed with large torque. Large inertia, the maximum speed is low. With the increase of power, the speed will decrease drastically. It is suitable for the application that requires a smooth operation.

6. What problem should I pay attention to when using motors?

Checking the following before power on:

1) Whether the power supply voltage is suitable: The +/- polarity of DC input can not wrongly be connected. The motor model or current setting value of the controller is whether suitable(not too large at the beginning)

2) The control signal line should be firmly connected. It is better to consider the shielding problem in the industrial site.

3) Do not connect the wires that you need. Just connect the basic system. When it connects well, the gradually connects all the wire.

4) Be sure to figure out the grounding method, or using floating air not connect.

5) Within the half-hour after the operation, it is necessary to observe closely the state of the motor such as the movement is whether normal, the sound, and temperature rise. When the problem occurs, stops the motor immediately.

7. When the stepper motor starts, it will sometimes lose a step?

1)  Checking the torque of the motor is enough to drive the load. When selecting the stepper motor, the torque of the motor should be 50%-100% greater than the required torque. The stepper motor can not run at the state of overload, even if it is an instant, it will lose a step. In serious conditions, the stepper motor will stop rotating or rotate repeatedly in situ.

2) The input current of the pulse of the upper controller is whether enough(general, >10mA), which makes photocoupler stable conduction. The input frequency is whether too high, which makes it hard to receive. If the output circuit of the upper controller is CMOS, the CMOS driver should be selected.

3) The starting frequency is whether too high. When setting the acceleration process at the starting application, it is better to start the accelerating process to setting frequency from the specified starting frequency. Even if the acceleration time is very short, it will be unstable, or even in an insert state.

4) When the motor is not fixed properly, this condition will occur. Because of the strong resonance of the motor, it will be in the state of out of step. The stepper motor should be fixed properly.

5) For the 5 phase stepper motor, if the phase is wrongly connected, the motor will also not work.

8. Can I directly control the servo motor using communication?

It’s OK and convenient. But it is suitable for the application that does not have high response speed. If the fast response control parameters are required, it is better to use a servo motion control card. Generally, it has the DSP and high-speed logic processing circuit, to achieve high speed and high precision motion control.

9. Can power the stepper and DC motor with a switching power supply?

It is better not, especially in large torque motor. Unless the power of the switching supply is more than twice the required power. Because, when the motor works, it is a large inductive type of load, which will form a transient high voltage to the power end. The performance of the switching power is not good, which will damage the switching supply to the driver. It is better to use a DC power supply with a conventional ring or R type transformer.

10. Can use ±10V or 4-20mA DC voltage to control the stepper motor?

It’s OK. But the additional transformation module is required.

11. Can the servo driver with a speedometer port control the servo motor with encoder feedback?

It’s OK. But encoder to speed measuring machine signal module should be equipped.

12. Can the code plate of the servo motor be disassembled?

Do not open it. The quartz chip in the code plate is easy to break. When the dust enters, life and precision can not be ensured. It needs professional staff to repair.

13. Can the stepper and servo motor be disassembled or refitted?

It is better to let the customer do. After the disassembling, it is very difficult to install without professional equipment. And the gap between the stator and the rotor can not be ensured. The performance of magnetic steel material is destroyed, even causes the loss of magnetism. The torque of the motor will drastically reduce.

14. Can the servo controller perceive the change of external load?

If it meets the set resistance, stop, return, or maintain a certain thrust.

15. Can the stepper motor and driver manufactured by different manufacturers be used together?

In principle, it is OK. But the technical parameter of the motor should be understood, otherwise, it will decrease the effect, and even affects the operation and life. It is better to consult the supplier.

16. It is safe to use a DC power supply which is greater than the rated voltage to drive the motor?

Commonly, it is not a question. As long as the motor operates at the set speed and the scope of the current limit. Because the speed of the motor is proportional to the line voltage, so choosing a certain supply voltage will not cause Overspeed, but many cause the driver failure.

also, it is necessary to ensure that the motor should meet the requirement of minimum inductance and the current limit value is less than or equal to the rated current of the motor.

If the motor operates slowly at your designed equipment(lower than rated voltage), it is very good.

Running with relatively low voltage will make the brush have less bounce. And the wear of the brush/commutator is also less, and the consumption of the current is low, the life of the motor is relatively longer.

On the other hand, the size of the motor, and the requirements of the performance requires additional torque and speed, the overdrive of the motor is also acceptable. but it will sacrifice the life of the product.

17. How to select a suitable power supply?

The preferred choice is the supply voltage is greater than 10%-50% required voltage. The current value of the driver should be enough to transmit the required energy. It is noticed that the output voltage value of the driver is different from the supply voltage. So the input current of the driver is also different from the input current. To determine a suitable supply current, the required power should be increased by 5%.

18. Which mode of operation can be selected for a servo driver?

Not all different modes exist in all the type of driver.

19. How are the driver and systems grounded?

A. If there is no isolation between AC power and DC bus of the driver, do not connect the non-isolating port of the DC bus or the non-isolating signal to the ground, which will damage the equipment and staff. Because the AC voltage is not to the ground. There exists a high voltage between the DC bus ground and the ground.

B. In many servo systems, all the common ground connects with the ground. Many loops connected to the ground will be susceptible to noise and produce flow at different reference points.

C. To keep the command reference voltage constant, the signal of the driver should connect the signal ground of the controller. It will also connect the ground of external supply, which will affect the working of the controller and driver.

D. The shielding layer grounding is relatively difficult, there are several ways. The correct shielding grounding points are located in the reference potential point. The point is dependent on whether the noise source and receive are both grounded or floating. It is necessary to make sure that the grounding current at the same point will not flow the shield layer.

20. Why the reducer can not match the motor at the standard torque point?

If the maximum continuous torque of the motor through the reducer is considered, many gear ratio will exceed the level of torque of the reducer.

If we design each reducer to match full torque, the internal gear of the reducer has many combinations (the volume is relatively large, the material is much). This will make the price of the product very high, and violate the” high performance, low volume” principle.

21. How to select a planetary reducer or planetary reducer?

The planetary reducer is commonly used in the limited space which requires high torque, namely, small volume and high torque. And its reliability and life are better, compared with spur gear reducer. The spur gearbox is used in the application that requires low current consumption, low noise, high efficiency, low cost.

22. What is the duty cycle?

The duty cycle refers to the ratio of the working time of the motor/(working time + non-working time). if the duty cycle is low, the motor is allowed to run at 3 times continuous current for a short time, which can produce larger power.

23. Can the drive circuit of standard rotary motor be used in the linear motor?

Commonly, it is OK. You can see the linear motor as rotary motors, such as a linear stepper motor, brushed, brushless, and AC linear motor. For details, please contact the supplier.

24. Can the linear motor be installed vertically, and move up and down?

It’s OK. According to the requirements of the customer, for vertical installation, we can add an actuator slider balancing device or a guide rail brake.

25. Can multiple rotors be installed on the same platform?

It’s OK. As long as the rotors will not interfere with each other.

26. Can the rotor coil of many brushless motors be used in the same magnetic track?

It’s OK. As long as the rotors will not interfere with each other.

27. What is the advantage of the linear motor?

Because there is no mechanical connection between stator and rotor, the problem such as backlash, scuffing, jam eliminates. The motion is more smooth. The higher precision, higher speed, faster response, the higher control precision, the high reliability, the compact volume, long life, free maintenance are highlighted.

28. How to choose an electric cylinder, sliding table, precision platform products? How is the cost calculated?

The suitable actuator is based on the parameters that you need. This not only meets your basic needs but also has leeway.