Abstract : Based on the stator field-oriented control model of an asynchronous motor, a sensorless speed control traction variable frequency speed controller for mining electric locomotives was developed. The high-performance M16C series MCU was selected as the main control unit, employing PWM dead-time compensation and closed-loop control of speed and excitation current. This resulted in low output current harmonics and high starting torque. It was successfully applied to the traction control of a 10-ton overhead wire mining locomotive in a coal mine. The use of variable frequency speed control traction replaced the previously commonly used resistance-regulating locomotives and DC chopper locomotives, improving production efficiency, significantly reducing energy consumption, and lowering locomotive maintenance and consumable material costs. Keywords : Variable frequency drive; Electric drive; Traction/Sensorless speed control 1 Introduction Compared with DC traction drive systems, AC traction drive systems for rail vehicles have significant advantages in terms of electric traction and braking characteristics, as well as energy consumption and maintenance. Narrow-gauge mining locomotives share common characteristics with railway mainline electric locomotives and urban rail transit vehicles. Mining locomotives are primarily used in the mining industry and tunnel engineering. The key technology for AC traction in mining locomotives is the development of high-performance, high-reliability AC variable frequency speed control technology. Currently, my country produces only a very small number of AC traction mining locomotives, and most are assembled using imported AC frequency converters. The AC traction variable frequency speed control of mining locomotives requires a large starting torque, especially when starting on steep slopes with high resistance; the maximum torque should be greater than the adhesion force obtained from the axle load of the locomotive. Since the traction load is directly connected to the motor, load changes and external disturbances directly affect the system control performance; therefore, closed-loop speed control is generally adopted. Speed ​​sensors operate in high-temperature, vibration, and electromagnetic noise environments, requiring high reliability. Therefore, a sensorless control-based scheme is adopted. This paper develops, studies, and implements a sensorless control traction variable frequency speed controller for mining electric locomotives based on the stator field-oriented control model of an asynchronous motor. It is used for the control of a 10-ton overhead wire mining locomotive in a coal mine. By replacing the previously commonly used resistance-regulating and DC chopper locomotives with asynchronous AC variable frequency speed control traction, production efficiency has been improved, energy consumption has been greatly reduced, and the costs of locomotive maintenance and consumable materials have been lowered. The frequency converter uses an M16 series single-chip microcomputer for control, including a closed-loop flux current regulator (AFR), a speed estimator, and a closed-loop speed regulator (ASR). The rated output power is 90kW, with strong overload capacity; it can operate continuously at 130kW for 60 seconds. Read the full article : Sensorless Controlled Traction Variable Frequency Speed ​​Controller for Mining Electric Locomotives