Abstract : Selecting the capacity of a frequency converter is not a simple matter and cannot be based solely on the capacity of the motor. In particular, the interference from high-order harmonics generated by the frequency converter and its hazards to the field must be taken seriously. While unavoidable circuit interference generated by the frequency converter is difficult to eliminate, it can be suppressed using appropriate devices. Keywords : Frequency converter, motor speed regulation, interference. With the development of modern high-power electronic technology, the performance of frequency converters used for AC motor speed regulation is rapidly improving. They offer a wide speed range, high speed regulation accuracy, fast dynamic response, high power factor, convenient operation, and easy interface with other equipment, making their application increasingly widespread. However, due to the rapid development of frequency conversion technology, its high knowledge content, and technical complexity, simply knowing basic installation and wiring without understanding the principles and application techniques of frequency converters will make it difficult to use them effectively. Currently, many large machines use frequency converters for driving, making their use and maintenance increasingly important. I. Working Principle of Frequency Converters Frequency converters mainly consist of a main circuit and a control circuit. The main circuit consists of two parts: a rectifier circuit (converting AC power from the mains frequency supply to DC power and smoothing and filtering the DC power) and an inverter circuit (converting DC power to AC power of various frequencies). The control circuit controls the main circuit. The working principle of an inverter has the following key points: the inverter converts DC to AC; the inverter circuit is the inverse of the rectifier circuit; the output frequency is changed by altering the conduction time of the transistors; the inverter changes the rotation direction of the motor by changing the conduction sequence of the transistors. The capacity of the inverter is limited by the capacity of the transistors, which is a challenge in frequency conversion technology. 1. Control Methods of Frequency Converters Understanding the control system of a frequency converter is relatively complex because different control methods result in different output performance. V/F control – a conventional frequency converter control method, where the voltage-to-frequency ratio remains constant; Simple flux vector control – divides the inverter's output current into excitation current and torque component current through vector calculation, then adjusts the voltage to match the generated motor current with the load torque, thereby changing the torque characteristics; [b][align=center]For details, please click: Application Analysis of Frequency Converters in Motor Starting and Speed ​​Regulation[/align][/b]