Experimental study on the loop thermosyphon cooling system for IGBT in high-speed trains

To solve the thermal management challenges of IGBT components in high-speed train traction converters, a loop thermosyphon system using SF-33 as the working fluid was designed. The condenser was installed on the train roof and cooled by running airflow, which reduced the power consumption of condensation-section cooling fans and improved energy efficiency. This study investigated the startup and operational characteristics of the system under varying filling ratios, heating powers, and cooling airflow rates. Experimental results indicated that the minimum startup power was 100 W. The system satisfied the cooling requirements for train IGBT modules at filling ratios of 32 %-50 %, with optimal thermal performance achieved at a 50 % filling ratio. Within this range, the maximum temperature fluctuation of IGBT-simulated heating blocks during stable operation was 2.3 degrees C, while the minimum temperature difference between heating blocks reached 8.5 degrees C. The system exhibited a minimum thermal resistance of 0.0099 degrees C/W. Under high heating power conditions (1800 W to 2100 W), prolonged operation maintained the highest average temperature of heating blocks below 75 degrees C, complying with IGBT thermal specifications while effectively dissipating a heat flux density of up to 20.13 kW/m2. Additionally, the system demonstrated minimal sensitivity to cooling airflow rate variations. This experimental system provides a novel approach and theoretical foundation for cooling IGBT components in high-speed train traction converters.