从上式可知，当转差率变化不大时，异步电动机的转速n基本上与电源频率f成

It can be seen from the above formula that when the slip rate does not change much, the rotation speed n of the asynchronous motor is basically proportional to the power frequency f. The frequency of the power supply can be continuously adjusted through the frequency converter to smoothly change the speed of the motor. <br>Inverter is a type of AC electric drive system. It is based on control technology, electronic power technology, microelectronic technology and computer technology. It converts AC power frequency power into a variable voltage and frequency suitable for AC motor speed regulation. The power electronic conversion device is called VVVF (Variable Voltage Variable Frequency). <br>The AC low-voltage AC/DC traffic frequency converter system is mainly composed of rectifier and inverter (the block diagram is shown in Figure 2). Rectifier: A power electronic device that converts AC power to DC. Its input voltage is sine wave, and the input current is non-sinusoidal, with rich harmonics. Inverter: A power electronic device that converts DC power to AC power. Its output voltage is non-sinusoidal. Sine wave, the output current is approximately sine.

From the upper model, it can be known that when the rate of transition changes little, the speed n of the asynchronous motor is basically directly related to the power frequency f. The power supply frequency can be continuously adjusted by the drive, which smoothly changes the speed of the motor.<br>The inverter is a kind of AC electrical transmission system, which is based on control technology, electronic power technology, microelectronics technology and computer technology, the AC frequency power supply is converted into a voltage, frequency can be variable suitable for AC motor speed conversion device, referred to as VVVF (VVVF Variable Variable Frequency).<br>The AC low-voltage traffic inverter system consists mainly of a rectifier and an inverter (frame figure shown in Figure 2). Rectifier: the AC into a DC power electronic device, the input voltage is sine wave, the input current is not sine, with rich harmonics, inverter: the DC power conversion into AC power electronic device, the output voltage is non-sine wave, the output current is similar to the sine.

It can be seen from the above formula that when the slip rate changes little, the speed n of the asynchronous motor is basically proportional to the power frequency f. The frequency of power supply can be adjusted continuously by frequency converter, and the speed of motor can be changed smoothly.<br>Frequency converter is a kind of AC electric drive system. It is based on control technology, electronic power technology, microelectronics technology and computer technology. It can convert AC power frequency power supply into a power electronic conversion device suitable for AC motor speed regulation with variable voltage and frequency, abbreviated as VVVF (variable voltage variable frequency).<br>AC low voltage AC-DC traffic inverter system is mainly composed of rectifier and inverter (block diagram is shown in Fig. 2). Rectifier: a power electronic device that converts alternating current into direct current, whose input voltage is sine wave, and the input current is non sinusoidal, with rich harmonics; inverter: a power electronic device that converts DC into AC, its output voltage is non sinusoidal, and the output current is nearly sinusoidal.<br>