基于一体化模型的矿用变频器散热性能分析

Analysis of heat dissipation performance of mine inverter based on the integrated model

  • 摘要: 矿用变频器空间密闭,运行过程中内部功率器件自身会产生大量热量,易产生热退化和热失效现象。现有研究主要是针对矿用变频器某类功率器件或散热器进行单独分析,未考虑它们相互之间的热交换作用,且现有研究与矿用变频器运行状态的结合不够紧密,导致生热和传热过程与实际情况偏差较大,降低了散热性能分析的准确度和全面性。针对上述问题,以630 kW/1 140 V四象限矿用变频器为研究对象,基于一体化模型对矿用变频器散热性能进行分析。建立了考虑等效电阻的矿用变频器主电路拓扑模型,分析母排与电缆、充/放电电阻、吸收电阻、IGBT模块、输出电抗器的电气特性并计算功率损耗。采用强制水冷+风冷+自然冷却方式对矿用变频器的散热系统进行优化设计。将IGBT模块、吸收电阻置于水冷散热器的基板上,配置风机加速输出电抗器的热交换效率,其他功率器件则自然散热。基于一体化模型对矿用变频器内部温度场特性、对流换热特性进行数值模拟分析,并搭建矿用变频器加载试验平台验证基于一体化模型的温度场仿真的正确性及散热设计的有效性。结果表明:① 在内部功率器件的传导、对流及辐射换热作用下,隔爆外壳的温度高于环境温度,最低为36 ℃,且后基板的温度高于其他隔爆面,最高可达70 ℃。矿用变频器内部组件均未超过80 ℃,远低于相关标准规定值,具有良好的散热性能。IGBT模块的温度最高,机心母排组件的温度次之,直流滤波电容组件的温度最低。② 充电过程中功率器件产生了较大的损耗,但由于充电时间极短,该损耗不会引起温度的剧烈变化,功率器件的瞬时温度最高不超过59 ℃;放电电阻的瞬时温度最高可达267 ℃,100 ℃以上的作用时间为200 s,梯形铝壳电阻的耐高温冲击能力可满足该应用场景,且未形成热应力循环,不会产生热击穿、热失效现象。③ 各功率器件在2~3 h后温度逐渐趋于稳定,各标定测温点的实验与仿真结果在整体趋势上保持较好的一致性。

     

    Abstract: The space of the mine inverter is closed. The internal power device itself will produce a lot of heat in the operation process, which is easy to produce thermal degradation and thermal failure. In the existing research, a certain power device or a radiator of the mine inverter is analyzed independently. The heat exchange effect among the power device or the radiator is not considered. The combination with the running state of the mine inverter is not close enough. Therefore, the deviation between the heat generation and heat transfer processes and the actual situation is large. This reduces the accuracy and comprehensiveness of the heat dissipation performance analysis. In order to the above problems, taking the 630 kW/1 140 V four-quadrant mine inverter as the research object, the heat dissipation performance of the mine inverter is analyzed based on integrated model . A topological model of the main circuit of the mine inverter considering equivalent resistance is established. The electrical characteristics of the bus bar and the cable, the charge/discharge resistance, the absorption resistance, the IGBT module and the output reactor are analyzed, and the power loss is calculated. The cooling system of the inverter is optimized by forced water cooling + air cooling + natural cooling. The IGBT module and the absorption resistor are arranged on the substrate of the water-cooling radiator. The fan is configured to accelerate the heat exchange efficiency of the output reactor, and other power devices dissipate heat naturally. Based on the integrated model, the temperature field characteristics and heat transfer characteristics of the mine inverter are numerically simulated and analyzed. The correctness of the temperature field simulation based on the integrated model and the effectiveness of the heat dissipation design are verified by building the loading test platform of mineing inverter . The results show the following points. ① Under the heat transfer of conduction, convection and radiation of the internal power devices, the temperature of the flameproof enclosure is higher than the ambient temperature. The lowest temperature is 36 ℃. The temperature of the rear substrate is higher than that of the other flameproof surfaces, and the highest temperature can reach 70 ℃. The temperature of the internal components of the mine inverter is not higher than 80 ℃, which is far lower than the specified value of relevant standards. The mine inverter has good heat dissipation performance. The temperature of IGBT module is the highest, the temperature of the bus bar assembly is the second, and the temperature of the DC filter capacitor assembly is the lowest. ② The power device in the process of charging has a larger loss. But because of the short charging time, the loss will not cause severe changes in temperature. The instantaneous temperature of the power device is not more than 59 ℃. The maximum instantaneous temperature of the discharge resistance can reach 267 ℃, and the action time above 100 ℃ is 200 seconds. The high-temperature impact resistance of the trapezoidal aluminum shell resistor can meet the application scenario. It does not form a thermal stress cycle, and will not produce thermal breakdown and thermal failure. ③ The temperature of each power device tends to be stable gradually after 2-3 h. The experimental and simulation results of each calibration temperature measurement point keep good consistency in the overall trend.

     

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