Abstract : This paper introduces the application of variable frequency speed control technology in hot blast stoves. The results show that the variable frequency speed control system of the combustion blower can effectively achieve constant pressure cold air supply, stabilize cold air flow, save energy, and well meet the requirements of hot blast stove firing, with significant benefits. Keywords : hot blast stove; frequency converter [b]1 Introduction[/b] Hot blast stoves have an important impact on the operation and output of blast furnaces. The existing electrical system of our plant's hot blast stove, especially the electrical system of the combustion blower, has been in operation for a long time, with outdated control methods, many defects, and inability to stabilize cold air pressure, resulting in poor air supply capacity. This causes the hot blast stove to fail to fire and supply air normally, affecting the normal production of the blast furnace. Therefore, the transformation of the electrical system is imperative. In August 1999, the variable frequency speed control system was officially applied to the combustion blower of the No. 6 hot blast stove. [b]2 Composition and Principle of Variable Frequency Speed ​​Control System 2.1 Overview of the Working Principle of Frequency Converter[/b] The speed of an induction AC motor depends approximately on the number of poles and frequency of the motor. The number of poles in a motor is fixed due to its operating principle. Since this number of poles is not continuous (it's a multiple of 2, e.g., 2, 4, 6 poles), it's generally not suitable to adjust the motor speed by changing this value. The frequency can be externally adjusted and supplied to the motor, allowing for free control of the motor speed. Therefore, frequency converters, designed for frequency control, are the preferred choice for motor speed regulation. If only the frequency is changed without changing the voltage, a decrease in frequency can cause overvoltage (overexcitation) in the motor, potentially burning it out. Therefore, frequency converters must change the voltage simultaneously with the frequency. [b][align=center]For more details, please click: Application of Variable Frequency Speed ​​Control Technology for Combustion Fans in Hot Blast Furnaces[/align][/b]