【作者】 张健；

【导师】 张东来；

【作者基本信息】 哈尔滨工业大学 ， 电力电子与电力传动， 2015， 博士

【摘要】 随着对航天科技水平要求的不断提高,高可靠性、高功率密度的航天电源技术成为了备受瞩目的关键技术。作为电源系统的核心器件—电力电子器件及装置,必须向小型化和轻量化发展。而电源系统的特殊工作环境和对体积、重量及寿命的更高要求使得散热问题更加严峻,这都使得电力电子器件的热结构设计问题俞显突出。因此,电子设备散热结构的优化研究成为关键技术中的核心技术。本文主要深入研究了多芯片模块(MCM,Multi-Chip Module)散热影响因素的热优化方法、强迫风冷散热器的热阻计算方法、散热器瞬态温度的计算方法和高功率密度电力电子器件强迫风冷散热的热结构优化方法。首先采用有限元方法分析MCM散热的主要影响因素,基于响应面方法提出了MCM结构参数、材料属性与芯片最高结温间关系的回归方程,重点定量计算了导热硅脂导热系数、基板导热系数、基板厚度和对流传热系数对MCM最高结温的影响,应用响应面回归方程对MCM进行热优化研究,并仿真分析了热优化后MCM的热应力分布。该回归方程为MCM初期热设计提供了一种更简单快速的方法。通过研究电子设备强迫风冷散热系统设计中风扇与散热器的设计方法和选取依据,总结了强迫风冷散热系统的一般设计方法。散热器热阻是表征散热器散热能力的最关键参数,提出了强迫风冷散热器的热阻等效电路计算方法,为后文以散热器热阻最小化为目标函数的散热器热结构优化设计奠定了基础。针对电力电子器件实际工作可能处于周期开关或各工况切换等非稳态的问题,本文基于能量守恒原理建立了强迫风冷散热系统的瞬态热分析模型,得出了散热器温升及冷却过程动态温度的计算方法。基于此提出了散热器表面器件总功耗保持不变,布局改变后散热器表面温度的瞬态计算方法,并提出了对应的等效散热器设计方法。瞬态热分析使得散热系统的设计更合理全面。本文通过分析散热器结构参数对其散热能力的影响,以散热器的热阻、压降和重量为目标函数研究了散热器的热优化程序。基于熵产最小化原理采用遗传算法同时研究了热传导和压降引起的散热系统热力学损失,并对散热器的肋片参数进行优化设计。该优化方法便于强迫风冷散热系统的热机械设计。在热优化设计基础上提出了合理设计散热开孔形状和采用风罩的热结构优化方法,该方法可使散热系统中散热器的温升进一步降低,散热效果进一步提高。电力电子器件内部以MCM为例的响应面散热结构优化,在器件实际封装过程中可指导最优设计参数和工艺的选择,以降低其最高结温,为系统级的散热设计奠定基础。电力电子器件外部基于总熵产最小化原理的散热系统优化研究,一方面降低器件结温,提高器件性能和可靠性。另一方面可减小散热系统的体积或重量,为电子设备小型化和轻量化提供思路和方法。更多还原

【Abstract】 With the continuous improvement of the level in aerospace science technology, space power technology with high reliability and high power density has become the key technology anticipated highly. Power electronic device and equipment must be developed to miniaturization and light weight as the core of the power supply system. The special working environment and the higher requirements for the volume, weight and life of the power supply makes the cooling problem more serious. It makes the thermal structure design of the power electronic device more prominent.The thermal optimization method of effecting factor of MCM is deeply studed in this paper. The calculation method of thermal resistance for forced air cooling heat sink, the calculation method of transient temperature of heat sink and the thermal structure and optimization method of high power density power electronic devices in forced air cooling are also analysised in this thesis.Main factors effecting thermal performance of MCM is analysised using finite element method. A regression equation describing the relationship of structure parameters and material properties with the maximum chip junction temperature of MCM is made based on the response surface methodology. Quantitative analysis of the effect of four design parameters on the maximum chip junction temperature of MCM is studied. The four design parameters are the thickness of the substrate, thermal conductivity of the substrate, thermal conductivity of the thermal grease, and convection heat transfer coefficient, respectively. The thermal stress distribution of MCM after optimization is simulated with ANSYS. The regression equation provides a simple and fast method for initial thermal design of MCM.The design method and selection basis of fans and heat sink in forced air cooling system are studied, the general design method of forced air cooling heat dissipation system is summarized. Based on that the thermal resistance is the most key parameter characterizing the cooling capacity of heat sink, the thermal resistant equicalent circuit method of thermal resistance for forced air cooling heat sink is proposed in this paper. The validity and accuracy of the method is verified with simulation and related experimental results. It lays a foundation for the thermal structure of heat sink and the objective function is minimizing thermal resistance of heat sink.Aiming at the sitution that power electronics device is may in cycle switch state or switching of different working condition. The transient thermal model of forced air cooling system is established based on the principle of conservation of energy. A method calculating surface temperature of heat sink is derived. The transient calculation method of surface temperature of heat sink is proposed in this paper when the total loss of power devices remains the same and the power layout is changed. And the equivalent design method of heat sink after changing the power layout is proposed. The method is verified by simulation and experiment results to be accurate. The transient thermal analysis makes the cooling system more reasonable and comprehensive.The influence of structure parameters on the cooling capacity is analysised, thermal resistance, pressure drop and weight are object function, and the thermal optimization procedure of the heat sink is studied in this paper. The entropy generation minimization based on the second law of thermodynamics is used to study the thermodynamic losses caused by heat transfer and pressure drop. The fin parameters are optimized by genetic algorithm.The performance metrics before and after optimization is verified with simulation. The method is is convenient for thermal-mechanical design of forced air cooling system. Base on the optimization of structure the thermal structure optimization methods includes reasonable shape of cooling hole and using wind cover are proposed. The simulation results show that the temperature rise of heat sink is lower and the cooling effect is better after optimizing the air duct.The response surface thermal structure optimization taking MCM as an example in power electronics device can guide the optimal choose of design parameters and the package process. The purpose is to reduce the maximum junction temperature and lay the foundation for the system level thermal design. The optimization of the cooling system based on the entropy generation minimization has two functions. On the one hand, the junction temperature is reduced, the performance and reliability of the device is improved. On the other hand, the volume and weight of the cooling system is reduced. It provides ideas and methods for the miniaturization and lightweight of the electronic equipment.更多还原