Three-phase asynchronous motor speed control mode

The speed regulation characteristic of the three-phase asynchronous motor is used in the case of fans, or the three-phase asynchronous motor with high slip rate has various speed regulation modes, mainly adopting variable pole speed regulation, variable slip speed regulation and frequency conversion adjustment. Speed ​​is the main.

The variable pole speed regulation means that the way of winding the wiring is changed, so that the number of poles of the motor is changed to ensure that the rotation speed of the three-phase asynchronous motor can be changed.

Variable pole speed regulation is a kind of step speed regulation. There are three ways to adjust the speed: Y-YY, D-YY, and sequence Y-reverse string Y.

The speed regulation mode of Y-YY is the constant torque mode, while the other two are constant power mode for speed regulation.

When adjusting the pole speed, the two-phase wiring should be set to ensure that the steering of the motor will not be offset after the speed regulation.

The variable slip speed control mode also includes a series speed regulation, a step-down speed regulation, and a winding rotor asynchronous motor series resistance speed regulation mode.

Frequency control is the main adjustment technology advocated by China at present. It can achieve the goal of high speed and high speed, and can coordinate with constant torque and constant power load.

The motor speed regulation method of the three-phase asynchronous winding rotor is simpler than other methods, and can be easily realized, but it is not smooth in the process of speed regulation, and has different levels, and stability at low speed. Very poor, the characteristics are not obvious, and the consumption of copper in the rotor is very large, which makes the motor less efficient in operation.

A frequency converter is one that converts a voltage from a fixed frequency into a variable voltage and frequency.

In order to achieve a mutual conversion of voltage and frequency on the motor, the alternating current of the voltage should first be converted into direct current. This mechanical process is called rectification.

The process of converting direct electricity into alternating current is called inverter, and the machine that converts direct current into alternating current is called an inverter.

The frequency and voltage of the inverter can be readjusted as the inverter.

The shape of the wave output from the inverter is similar to that of a sine wave. The most important purpose is to adjust the speed of the three-phase asynchronous motor, so it can also be called a high speed device.

The three-phase asynchronous motor speed formula is: n = 60f / p (1-s).

It can be seen from the above formula that changing the power supply frequency f, the pole pair number p of the motor and the slip rate s can all achieve the purpose of changing the speed.

----- Editor-in-Chief: Dalan Oil Pump Motor 02-Procurement Consultant

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