With the continuous development of variable frequency motors and permanent magnet motors, variable frequency technology and frequency converters have reached an unprecedented development momentum. A frequency converter is a static frequency conversion device that can convert a constant voltage power supply with a fixed frequency provided by the power grid into a controllable power supply with adjustable frequency and voltage. Its most widespread use is as a power supply or adapter for variable frequency motors. With the energy-saving effect of variable frequency motors being recognized by a large number of customers, the functions and technologies of variable frequency drives, which are the core components, have been greatly improved, giving rise to various specialized variable frequency drives.

According to the conversion method of power frequency, there are two frequency conversion modes for frequency converters: "AC-DC-AC" frequency conversion and "AC-AC" frequency conversion; According to the output voltage level, frequency converters are divided into two categories: high-voltage frequency converters and low-voltage frequency converters.

In order to meet the high-performance requirements of different types and purposes of motors, adaptive frequency converters are increasingly developing towards specialized frequency converter modes, such as frequency converters for permanent magnet synchronous motors, air conditioning, elevators, subway locomotives, and electric vehicles.

In recent years, there have been more and more cases of fans and water pumps being matched with variable frequency motors. The frequency converters matched with this type of load are still different from those of general motors. The rated frequency is around high frequency, and the output torque and load current will rapidly increase with the increase of frequency, with a fixed and tight correlation. If the power and control characteristics of the frequency converter are set and optimized according to the above load mode, not only will the application characteristics be excellent and the system energy-saving effect be more significant, but it can also reduce the manufacturing cost of the frequency converter and promote the transformation of frequency converters in specialized fields.

Steel rolling mill is a production machinery with large capacity, high overload and high-speed response. The accompanying frequency converter requires sufficient instantaneous overload capacity, and the frequency converter components must be resistant to vibration and high temperature, which is completely different from the loads of fans and water pumps mentioned above.

Public transportation vehicles or logistics vehicles have basically switched to electric drive mode. Adapting to frequency converters is no longer just about power modules, but also integrated into induction monitoring and wireless network connection. High integration and reliability are the characteristics of this type of dedicated frequency converter power supply, and there is always the possibility of disruptive technology and changes.