Abstract : The heat dissipation system of a 6kV, 2.5kW high-voltage frequency converter was studied and designed. Forced air cooling was proposed to solve the overheating problem of the frequency converter. Based on the calculation of the heat generation of each power device in the system, and according to the relationship between heat generation and temperature rise, the thermal resistance of the heat sink required for each power switching device was calculated, and a suitable heat sink was selected. Based on the overall system heat generation and the airflow requirements of the heat sink, the selection of the fan and the design of the air duct were discussed. A front-in, rear-out airflow scheme was designed, with each heat sink independently and sealed to the air cavity. Experimental results show that the heat dissipation system can meet the operational requirements. Keywords : Frequency converter; Power semiconductor device; Heat sink 1 Introduction In recent years, with the development of high-power power electronic devices, high-voltage frequency converters have become a research hotspot. From the literature, current research focuses mainly on the design and implementation of the main circuit of high-voltage frequency converters, with less research on their heat dissipation systems. However, practical experience shows that the quality of the heat dissipation system design for high-power high-voltage frequency converters directly affects whether the frequency converter can operate safely and stably. The heat dissipation system of a high-voltage frequency converter is mainly designed for the power switching devices. This is because the majority of the heat generated by a high-voltage frequency converter comes from the power losses of these switching devices. Furthermore, these devices are highly sensitive to temperature; temperature changes affect their turn-on and turn-off processes, impacting the performance of the high-voltage frequency converter. Excessive temperature increases can even lead to permanent damage to the power switching devices, rendering the frequency converter inoperable. This paper designs a heat dissipation system for a high-voltage frequency converter with a specific structure. 2. Design Ideas for the Heat Dissipation System of a High-Voltage Frequency Converter Figure 1 shows the main circuit structure of the high-voltage frequency converter under study. It uses a 24-pulse uncontrolled rectifier bridge and a neutral-point clamped three-level SPWM inverter bridge. High-power, high-voltage electrical equipment of this structure generally uses forced air cooling or water cooling. Water cooling has extremely high heat dissipation efficiency, but the system structure is complex and expensive. Therefore, forced air cooling is used here. [b][align=center]For more details, please click: Design of Heat Dissipation System for High-Voltage Frequency Converter[/align][/b]