Preview
Pas -by -step engines are mainly classified according to the number of phases, and steps in step in phase and five phases are currently widely used on the market. The best step -by -step engine in two phases can be divided into 400 equal parts per revolution, and the engine step by step in five phases can be divided into 1000 equal parts. Dynamic inertia is low.
With the emergence of all digital AC Servomotes systems, AC servomotors are increasingly used in digital control systems. In order to adapt to the development trend of digital control, most of the movement control systems use step -by -step engines or fully digital AC servocations as execution engines. Although both are similar in control mode (pulse train and directional signal), there are large differences in use performance and application situations.
Let us compare the performance of the two.
1. Different control precision
The angle of steps of the motor step by pace in two phases is generally 3.6 degrees and 1.8 degrees, and the angle of step of the engine with a hybrid step at five phases is generally 0.72 degrees and 0.36 degrees. There are also steps in step high performance with angles of not smaller. For example, a step -confined engine used for slow wire mobilization machines produced by Sitong has an angle of step of 0.09 degrees; is settled on 1.8, 0.9, 0.72, 0.36, 0.18, 0.09, 0.072 and 0.036, which is compatible with the angle of step by step by step hybrid with two phases and five phases.
The control accuracy of the AC servomotor is guaranteed by the rotary encoder at the back of the engine shaft. Taking the example of Panasonic’s entirely digital AC Servomotor, for engines with a 2500 standard wire coder, since the driver uses quadruple frequency technology, its pulse equivalent is 360 degrees / 10000 = 0.036 degrees. For engines with 17-bit coder, the engine runs once every 217 = 131072 pulses received by the driver, that is to say that its impulse equivalent is 360 degrees / 131072 = 9.89 seconds . This is 1/655 of the steady engine impulse equivalent with an angle of step of 1.8 degrees.
Two: Different low frequency characteristics
Step -by -step engines are subject to low -speed low -speed vibrations. The frequency of vibrations is linked to the driver’s load and performance condition. This low -frequency vibration phenomenon determined by the Principle of Pas D engine work is very unfavorable for the normal operation of the machine. When step -by -step engines work at low speed, amortization technology must generally be used to overcome low -frequency vibration phenomena, such as adding engine shock absorbers or the use of subdivided technology on the driver .
The AC Servomotor works very well and does not even vibrate at low speed. The Servo AC system has a resonance deletion function, which can cover the lack of rigidity of the machine.
Three: different torque frequency characteristics
The exit torque of the steam engine decreases with the increase in the rotation speed and will drop sharply at higher speeds, so its maximum working speed is generally between 300 and 600 rpm.
The acted servomotor has a constant torque output, that is to say that it can produce the nominal torque in its nominal speed (generally 2000 rpm or 3000 rpm), and above the nominal speed is a constant output output.
Four: different overload capacities
Pas -by -step engines generally do not have an overload capacity. The AC Servomotor has a strong overload capacity. Take the example of the Panasonic AC system, it has overload and overload capacity of speed torque. Its maximum torque is three times the nominal torque and can be used to overcome the moment of inertia at the start of the moment. Because step -by -step engines have this overload capacity, in order to overcome this moment of inertia, a engine with a larger torque is often required during the selection, and the machine does not need A couple as important during normal operation, so the torque appears. waste phenomenon.
Five: Different operational performance
Control of the step -by -step engine is controlling the open loop. In order to ensure its control precision, it must be well managed. The AC driving system is a closed loop control. And the control performance is more reliable.
Six: speed affects performance differently
It takes 200 to 400 milliseconds so that the engines step by step accelerate from the stationary at work speed (usually several hundred revolutions per minute). The acceleration performance of the AC Servomotor system is good. A judgment is required.
How to choose a model?
1. How to properly choose the servomotor and the steps step by step
It mainly depends on the specific application situation. Control requirements (such as port interface and communication () The main control method is the position, torque or speed method. Is the CC or AC food voltage range, or battery, with battery.
2. How to use the driver of the step by step?
Depending on the engine current, a driver greater than or equal to this current is provided. If low vibration or high precision is required, a subdivided driver can be used. For high torque engines, use high -voltage drivers as much as possible to obtain good high -speed performance.
3. What is the difference between the steps step by step in 2 phases and in 5 phases, and how to choose?
The 2 -phase engine has a low cost, but it has a large low -speed vibration and quick torque at high speed. The 5 -phase engine has fewer vibrations and good high -speed performance, which is 30 to 50% higher than the 2 -phase engine, and can replace the servomotor on certain occasions.
4. When to choose a DC Servo system, what is the difference between computer science and the AC servo?
DC Servo Motors is divided into brushed and brushed engines.
The brushed engine has a low cost, a simple structure, a large starting torque, a high -speed regulation range, easy control and requires maintenance, but it is easy to maintain (modify carbon brushes), which generates electromagnetic interference and has environmental requirements. Therefore, it can be used in general industrial and civil situations which are sensitive to costs.
The brushless engine has a small size, a light weight, a large outlet, a quick response, high speed, small inertia, smooth rotation and stable torque. Control is complex and easy to carry out information. The engine is maintenance -free, has a high efficiency operating temperature, with very small electromagnetic radiation and has a long lifespan.
AC servocators are also broom free engines, divided into synchronous and asynchronous engines. Large moment of inertia, the maximum speed of rotation is low and decreases quickly as the power increases. Therefore, it is suitable for low -speed and stable operating applications.
5. Problems to know when using the engine
Before lighting, check as follows:
1) if the power voltage is appropriate (overvoltage can damage the drive module); (Do not start too much);
2) The control signal wire is firmly connected and it is preferable to consider shielding problems (such as the twisted pair wire);
3) Do not connect all the wires that must be connected at the start and connect them to the most basic system.
4) You must determine the grounding method or use the floating non-connections.
5) Within half an hour of starting operating, you must close the engine condition closely, for example if the movement is normal, the sound and the temperature increase and stop the machine immediately and adjust it if you find problems.
Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.
