Abstract : By analyzing the characteristics of ground running-in tests of monorail bogies and based on the specific speed requirements of these tests, this paper proposes a design scheme for the frequency converter of the monorail bogie running-in test bench through calculations of the relationship between vehicle speed and motor speed, and between vehicle speed and inverter output frequency. Keywords : monorail; bogie; running-in test bench; frequency converter design 0 Introduction In recent years, with the continuous expansion of urban areas in China, population dispersion has occurred. This has resulted in a continuous increase in passenger flow, while on the other hand, social infrastructure such as transportation roads has lagged behind, causing traffic congestion and a decline in the convenience of public transportation. To solve these problems, various cities have proposed urban public transportation solutions using rail transit such as subways, light rail, and monorails. In recent years, the Chongqing Municipal Government decided to construct a monorail transit project adapted to the mountainous terrain of Chongqing, and Changchun Railway Vehicles Co., Ltd. undertook the manufacturing of 76 cars. As is well known, the performance of the monorail bogie, the most critical component of a monorail vehicle, is a crucial factor affecting its safe operation. To ensure reliable operation of the monorail bogie, a ground running-in test should be conducted before installation on the vehicle. This test primarily focuses on the motor, gearbox, and couplings of the monorail bogie. 1. Solution The traction motor used on the bogie is a squirrel-cage induction motor. During the running-in test, the motor's load is approximately no-load (only the running wheels are spinning freely). Therefore, traditional voltage and resistance speed regulation methods cannot be used (as these methods are not effective under near-no-load conditions). Only frequency conversion speed regulation is possible. Therefore, the key component in the running-in test bench is the design of the frequency converter. Since the motor operates near-no-load, its rotor frequency is approximately equal to its stator frequency. Because the frequency converter's output frequency is equal to the motor's stator frequency, its output frequency is also approximately equal to the motor's rotor frequency, directly determining the motor's speed. [b][align=center]For details, please click: A Brief Discussion on the Inverter Scheme Design of a Single-Rail Bogie Running-In Test Bench[/align][/b]