N- speed of motor (rpm); ? 60- every minute (second); ? F—— power frequency (Hz); ? P—— Polar logarithm of rotating magnetic field of motor.
China stipulates that the standard power frequency is f=50 cycles per second, so the speed of rotating magnetic field is only related to the number of magnetic poles. There are many magnetic pole pairs, and the rotating magnetic field speed is low. ? When the logarithm P= 1, the rotation speed of the rotating magnetic field n = 3000? When the logarithm P=2, the rotation speed of the rotating magnetic field n =1500; ? When the logarithm P=3. The rotating speed of the rotating magnetic field is n= 1000.
In fact, due to the existence of slip, the actual speed of the motor is slightly lower than that of the rotating magnetic field. In the variable frequency speed regulation system, according to the formula n=60f/p, we can know that changing the frequency f can change the speed. Lower the frequency ↓f, and the rotational speed will become smaller: that is, 60 f↓/p = n↓? Increase the frequency ↑f, the speed will also increase: that is, 60 f↑/p = n↑.
The main use of extended data
1, servo motor
Servo motor is widely used in various control systems. It can convert the input voltage signal into the mechanical output on the motor shaft and drag the controlled components, so as to achieve the purpose of control.
Servo motors can be divided into DC and AC. The earliest servo motor was a universal DC motor. In the case of low control accuracy, DC motor is generally used as servo motor. Structurally speaking, DC servo motor belongs to low-power DC motor, and its excitation is mostly controlled by armature and magnetic field, but armature control is usually used.
2. Stepping motor
Stepping motors are mainly used in the field of CNC machine tool manufacturing. Because stepping motor does not need A/D conversion, it can directly convert digital pulse signal into angular displacement, so it has always been considered as the most ideal executive component of CNC machine tools.
In addition to the application in CNC machine tools, stepping motors can also be used in other machines, such as motors in automatic feeders, motors in general floppy disk drives, printers and plotters.
3. Torque motor
Torque motor has the characteristics of low speed and large torque. Ac torque motor is usually used in textile industry, and its working principle and structure are the same as that of single-phase asynchronous motor.
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