Abstract : PWM control technology is widely used in traction locomotive frequency converters. Because it can simultaneously achieve frequency conversion, voltage conversion, and harmonic suppression, it can change the voltage and frequency values ​​of the traction motor according to the actual needs of the locomotive when converting stable DC power into AC power of a certain frequency. By simplifying the hardware through a dual PWM frequency conversion speed control system, speed control of the locomotive is achieved, improving control accuracy and system reliability. The system is simple and has broad application prospects. Keywords : PWM control; traction frequency converter; design [b][align=center]Design of the frequency converter in track driving system based on the PWM control Liu Xin-hui , Cai Wei (Lanzhou Polytechnic College, Lanzhou, Anhui 730050, China)[/align][/b] According to the electric locomotive actual need, to change the driving voltage frequency value of the electrical machinero Y, and the doublePWM frequency conversion velocity modulation system to simplify hardware, in this way will realize the electric locomotive velocity modulation controlI increase the control precision and the system reliability. The system will be simpleI and also has an extremely broad application prospect． Keywords : PWM control; driving frequency converter design 1 Introduction To meet the transportation traction needs of coal, metallurgy, and mining, China has independently designed various types of traction locomotives with capacities of 7T and above. These locomotives can operate safely in narrow-gauge locomotive tunnels, and their length, width, and turning radius meet the requirements of special working conditions in metallurgical mines and coal mines. Their core technology is variable frequency speed control based on PWM control. Compared with DC speed control and other AC speed control methods, the variable frequency speed controller has significant advantages in terms of speed range, overload capacity, speed accuracy, dynamic response, power factor, operating efficiency, and maintenance requirements. Furthermore, this device is contactless, adjustable in frequency and voltage, simplifies maintenance, and can even achieve maintenance-free operation. 2 Analysis and Design of Traction Frequency Converter Using a traction frequency converter to drive a motor results in a small starting current, enabling soft starting and stepless speed regulation, convenient acceleration and deceleration control, high motor performance, and significant energy savings. [b][align=center]For details, please click: Design of Frequency Converter for Rail Traction System Based on PWM Control[/align][/b]