| Frequency converter is a power control equipment,playing the role of frequency conversion energy saving,for high-power inverter,the loss of power during work is very large,it is necessary to design a reasonable cooling system to take away the heat generated,prevent internal device damage,ensure the reliability of the inverter work,extend the service life.At present,the volume of inverters tends to be miniaturized,which puts higher requirements on the heat dissipation of high-power inverters.Aiming at the research and development of EM760-280 k W frequency converter of Wuhan Sinusoidal Electric Technology Co.,LTD.,this paper uses Flotherm software simulation test method to study the cooling system of a high-power frequency converter.The main research conclusions are as follows:(1)The main air duct of the inverter is simulated and modeled.The loss formula of IGBT and SCR rectifier bridge is derived.The thermal loss of single IGBT chip is260.69 W,the thermal loss of single continuous diode chip is 99.02 W,and the loss of single SCR rectifier chip is 75.72 W.According to the calculated loss data,the structure of the main air duct of the inverter,the materials and heating conditions of each component,and the internal thermal resistance data of the module provided by the power module manufacturer,the main air duct model is established in Flotherm,which verifies the effectiveness of the model and the rationality of the air duct.(2)The heat sink structure parameters were optimized by simulation orthogonal test.Flotherm software was applied to optimize the structural parameters of the radiator by using the simulation orthogonal test method.Taking the IGBT temperature rise as the index,the F-test method was used to obtain the significant influence of each parameter and the interaction between parameters on the heat dissipation performance of the radiator.The results are as follows: The thickness of the radiator’s teeth,the number of teeth,and the interaction between the thickness of the radiator and the number of teeth all have a very significant impact on the index,and the significance decreases in turn.The thickness of the radiator substrate,the interaction between the thickness of the radiator and the thickness of the substrate,has a significant impact on the index,while the length of the radiator has no significant impact on the index.The optimized structural parameters of the radiator are: The thickness of the teeth is 2.5mm,the thickness of the substrate is 22 mm,the number of teeth is 113,and the length of the radiator is 308 mm.(3)The matching of the cooling system fan is completed.The diffusion thermal resistance of the optimized heat sink is calculated,and the required air volume is 0.306m~3/s for convection heat transfer and heat dissipation.Based on the local resistance of air flow through the radiator,the local resistance of air flow through the radiator,the total resistance of air flow through the radiator,the pressure-flow curve diagram of the radiator,the intersection point of this curve and the fan P-Q curve of the outgoing wind speed,matching the corresponding fan,that is,the use of two technologies 48 V,rated power144 W,is calculated.The rated speed of the fan is 7300 RPM.After the fan matching verification test,the temperature rise of the IGBT chip is reduced by 2.3℃ compared with that of the original fan.(4)The performance of the heat dissipation system is verified.A test platform was built to measure the temperature rise of IGBT chips before and after the optimization of the cooling system.The results show that the temperature rise of the chip before optimization is 61.6℃,and the temperature rise of the chip after optimization is 53.9℃,which is 7.7℃ lower than that before optimization,indicating that the performance of the optimized high-power inverter cooling system has been significantly improved.In summary,the high power inverter cooling system designed in this paper has reasonable structural parameters of the radiator,strong cooling capacity,good match between the fan performance and the main air duct,and good cooling performance of the cooling system,which meets the working requirements of the IGBT module. |
