Theoretical And Experimental Study On Thermal Dissipation Of High-power Electronic Component At Small Temperature Difference

High-power thyristors are widely used in special high-voltage direct current transmission and other electronic devices. In addition to the device material properties and the semiconductor manufacturing process, the thyristor thermal performance is also affecting their physical properties greatly. Effectively improve the thermal performance of thyristors to ensure its stability, extend its life, and ensure the reliability and stability of the power electronic devices is very important.Thyristor controlled working temperature is 70℃, and the temperature difference between the ambient temperature is very small, belonging to small temperature difference thermal dissipation. With the understanding of the research situation at home and abroad, based on theoretical analysis, this paper determine the small temperature difference cooling system program, creates a small temperature difference cooling system experimental platform for high-power electronic devices, and make experiments. The results show that:hydraulic characteristics, electrical resistivity characteristics, heat exchange performance and control performance of cooling system meet the SVC (Static Var Compensator) valve requirements. The electrical resistivity in the main circuit≥3MΩ·cm, the electrical resistivity in de-ionized loop≥5MΩ·cm; heat pipe radiator is up to the mustard; control system through the parameter setting and on-line test gives alarms and makes interlocking interactions with the main controller, through the electric heater, electric three-way valve and the cooling fans adjusts water temperature to achieve a fully automatic temperature control.This paper through numerical simulation optimizes the design of radiator because radiator is a key component of cooling system. Two-layer coil and cross slot, two new types of channels of thyristor radiator were proposed. The flow fields and heat transfer characteristics in the two radiators and siphon channel radiator were simulated using Fluent software. The velocity field and temperature field of radiator under different cases were obtained. The siphon channel radiator simulation results show that:with the flow rate increases, the maximum temperature and average temperature of thyristor gradually decrease, the fluid pressure difference betweent imports and exports gradually increases, the optimal fluid flow rate range is 1.5 m/s-2 m/s; with the fluid inlet temperature increased, the thyristor maximum temperature and average temperature gradually increase, and almost linear increase; ambient temperature of the radiator effects radiator little. Three kinds of heat sink simulation results show that:the application of the two-layer coil channel radiator make the thyristor has relatively homogeneous temperature field and smaller temperature raise, the heat transfer factor is about 1.5 times of using siphon channel radiator at the same Reynolds member. The radiator has lower flow resistance by using the cross slot channel and the friction factor is only 1/4 of using siphon channel while the Reynolds member gets equal to each other. Taking into account flow and heat transfer characteristics, two-layer coil channel radiator is the best choice, the cross slot channel radiator could used at the condition of little supply power.