Reliability enhancement by integrated liquid cooling in power IGBT modules for hybrid and electric vehicles

Insulated Gate Bipolar Transistor (IGBT) modules in power train system of Hybrid and Electric Vehicles (HEV/EV) are working in harsh environment and high reliability and long lifetime are required. In this work, reliability enhancement by integrated liquid cooling structure in HEV/EV IGBT module is investigated. The thermal resistance of junction to heat sink can be reduced more than 50% by direct liquid cooling as eliminating thermal grease layer, so both active and passive temperature swings decrease significantly which will enhance module reliability and lifetime. The lifetime of modules with conventional and integrated liquid cooling structures are estimated under mission of standard driving cycles. We found that lifetime is prolonged obviously by direct cooling pin–fin base plate, and the compact module also makes the application power system simple and reliable.     

Lifetime control in silicon power P-i-N diode by ion irradiation: Suppression of undesired leakage

The irradiation with high-energy (7.35 MeV) protons through a set of energy degraders was used to suppress leakage of the silicon power diodes subjected to local lifetime control. The aim was to modify the profile of recombination centers and to reduce production of vacancy complexes. The high-energy proton irradiation was compared with standard local lifetime killing by high-energy alphas. Recombination centers arising from irradiation were characterized after irradiation and subsequent annealing at 220 and 350 °C by deep level transient spectroscopy and I-V profiling. Static and dynamic parameters of irradiated diodes were also measured and compared. Results show that the applied irradiation with protons provides 3-10 times lower leakage compared to standard alphas for equivalent reduction of the reverse recovery current maximum. On the other hand, the excessive formation of hydrogen donors at high proton fluences and their diffusion during annealing at 350° decreases diode blocking capability.     

Design concept for wire-bonding reliability improvement by optimizing position in power devices

The most effective way to increase the reliability of wire bonds in IGBT modules is reduction of temperature difference between the aluminum wires and the device. However, this lowers the power handling capability of the modules. In this paper, we show that the configuration of aluminum wire bonds on power devices has a considerable effect on the temperature distribution of the device, and that the optimization of the layout by thermo-electric simulation can make the temperature distribution of the devices more uniform and consequently reduce the maximum junction temperature difference, ΔT_jmax. Tentative experiments showed that rearranging the bonding position resulted in reduction of ΔT_jmax by five to 8 °C, and that the chip temperature distribution estimated by the thermo-electric simulation was qualitatively similar to the actual measurement results. These results suggest that wire-bonding optimization by thermo-electric simulation can contribute not only to realizing more compact power modules but also to improving the module reliability.     

Design of multiple-input power converter for hybrid vehicles

This paper deals with designing and sizing of a multiple-input power electronic converter (MIPEC) to be used in an electric vehicle propulsion system that includes a fuel cell (FC) generator and a combined storage unit. The combined storage unit is composed by an ultracapacitors tank (UC) and a battery unit (BU). MIPEC is responsible for power-flow management on-board the vehicle for each mode of operation. Specifications for MIPEC designing come out from many considerations concerning traction drive and reference driving cycle, on-board power source and storage unit characteristics. However, to date sizing and configuration of both storage units and on-board generators are directly related to traction drive and driving profile (i.e., vehicle performances and characteristics) and no relation with power electronic interface is considered during preliminary design. Then, power electronic interface is selected in order to fit traction drive requirements with power source and storage unit characteristics; as a consequence converter mode of operation lacks of optimization, as well dynamic behavior and efficiency cannot be maximized. In this paper, MIPEC design and power source and storage unit selection are achieved at the same project stage according to traction drive requirements. Experimental results on 60-kW power electronic interface are presented.     

SHORT COMMUNICATION: Price/efficiency correlations for 2004 photovoltaic modules

The claim is often made that efficiency is a key factor in determining the marketability of photovoltaic products. If this is the case, a strong correlation between the price of modules and their efficiency might be expected. This relationship is investigated using module pricing data that have recently become available. Conclusions are that there is little correlation between module price and efficiency in this data set and that some thin‐film modules currently appear to attract a pricing premium. Copyright © 2004 John Wiley & Sons, Ltd.     

PSIM-based modeling of automotive power systems: conventional, electric, and hybrid electric vehicles

Automotive manufacturers have been taking advantage of simulation tools for modeling and analyzing various types of vehicles, such as conventional, electric, and hybrid electric vehicles. These simulation tools are of great assistance to engineers and researchers to reduce product-development cycle time, improve the quality of the design, and simplify the analysis without costly and time-consuming experiments. In this paper, a modeling tool that has been developed to study automotive systems using the power electronics simulator (PSIM) software is presented. PSIM was originally made for simulating power electronic converters and motor drives. This user-friendly simulation package is able to simulate electric/electronic circuits; however, it has no capability for simulating the entire system of an automobile. This paper discusses the PSIM validity as an automotive simulation tool by creating module boxes for not only the electrical systems, but also the mechanical, energy-storage, and thermal systems of the vehicles. These modules include internal combustion engines, fuel converters, transmissions, torque couplers, and batteries. Once these modules are made and stored in the library, the user can make the car model either a conventional, an electric, or a hybrid vehicle at will, just by dragging and dropping onto a schematic blank page.     

基于OPNET~（TM）的电力系统传感器网络IEEE1588同步协议仿真

随着现代电力系统的发展,对电力系统自动化和安全基础设施提出了更高的要求。在这个背景下,电力系统的监测和控制均向广域测量方向发展。为此,提出了电力系统传感器网络的新方案来为电力系统安全监控提供服务。测量的时间同步精度问题是该广域测量系统的最关键的因素之一。本文对电力系统传感器网络中的IEEE1588高精度时间同步协议在OPNETTM仿真软件中进行建模并仿真,验证了IEEE1588在电力系统广域时间同步测量中的有效性。     

混合动力汽车用电池包结构分析及改进

动力电池是混合动力汽车的主要储能元件,对整车的性能具有重要影响。而电池包作为电池模组的载体,则起着保护电池模组正常、安全工作的关键作用,其结构强度是否可靠直接影响整车的安全性。以某混合动力汽车用电池包为研究对象,建立其三维有限元模型,通过Abaqus软件分析电池包结构在6种典型工况下的应力及位移分布情况。基于强度分析结果对电池包结构进行改进设计。仿真结果表明,改进后的电池包结构强度满足混合动力汽车对电池包的强度要求,为电池包产品结构的定型设计提供理论依据。     

Thermal management of power electronics modules packaged by a stacked-plate technique

The research presented in this paper is part of a multidisciplinary research program of the Center for Power Electronics Systems at Virginia Tech. The program supported by the Office of Naval Research focuses on the development of innovative technologies for packaging power electronics building blocks. The primary objective of this research is to improve package performance and reliability through thermal management, i.e., reducing device temperatures for a given power level. The task of thermal management involves considering trade-offs in the electrical design, package layout and geometry, materials selection and processing, manufacturing feasibility, and production cost. Based on the electrical design of a simple building block, samples of packaged modules, rated at 600 V and 3.3 kW, were fabricated using a stacked-plate technique, termed metal posts interconnected parallel plate structure (MPIPPS). The MPIPPS technique allows the power devices to be interconnected between two direct-bond copper substrates via the use of metal posts. Thermal modeling results on the MPIPPS packaged modules indicate that the new packaging technique offers a superior thermal management means for packaging power electronics modules.     

超小型、高效率S波段星用收发组件

在高可靠星用模块研究中,采用特殊工艺,将频率综合器、混频器、微波放大器、中放等微波单元集成在尺寸为100mm×100mm×45mm模块中,大大减小了体积,降低了重量,从而应用更广泛,使用更灵活.     

A real-time detector for parked vehicles based on hybrid background modeling

In this paper, a real-time detection system based on hybrid background modeling is proposed for detecting parked vehicles along the side of a road. The hybrid background model consists of three components: (1) a scene background model, (2) a computed restricted area map, and (3) a dynamic threshold curve for vehicles. By exploiting the motion information of normal activity in the scene, we propose a hybrid background model that determines the location of the road, estimates the roadside and generates the adaptive threshold of the vehicle size. The system triggers a notification when a large vehicle-like foreground object has been stationary for more than a pre-set number of video frames (or time). The proposed method is tested on the AVSS 2007 PV dataset. The results are satisfactory compared to other state-of-the-art methods.     

Study of thermal cycling and temperature aging on PbSnAg die attach solder joints for high power modules

High power modules are still facing the challenges to increase their power output, increase the junction temperature, and increase their reliability in harsh conditions. Therefore this study is doing a detail analysis of the soldering joint between a direct copper bonded substrate and a high power IGBT made with the high lead solder alloy Pb_92.5Sn_5.0Ag_2.5. The intermetallic phases and the microstructure of standard chip to substrate solder joint will be analysed and compared to deteriorated joints coming from modules which have undergone an active thermal cycling. As expected, the as soldered joint was clearly different than solder joints made for ball grid array or small components on PCBs. The as soldered joint shows no sign of Cu₆Sn₅ intermetallic layer, but instead shows the presence of Ag₃Sn particles at the solder–chip interface. Furthermore, the failure mechanisms under active thermal cycling also seem to be different. There is no growth of intermetallic phases and no strong delamination of the device. Instead a large network of intermetallic particles (Ag₃Sn) is produced during aging and seems to degrade the solder thermal properties.     

动态红外图像的建模与仿真技术

讨论了红外场景的动态图像建模与仿真技术，由于目标、背景、大气状态的复杂性，红外图像建模与仿真的难度很大。首先介绍了在SGI工作站环境下，红外图像序列建模和仿真软件的设计思想、实现方法和软件框架。然后分析各种辐射对成像的影响，给出辐射计算公式，分别就无源和有源场景进行了分析，提出无源场景温度的求解方法，说明了场景模型、大气传输模型和材料的物理特性对红外成像的作用。最后给出了建模与仿真的一些实例和综合评价。     

Failure analysis and improvement of 60 V power UMOSFET

In this paper, the failure modes of a 60 V power UMOSFET firstly have been discussed by analyzing the test data of the die, and our hypothesis is that the merger of the P-base regions under the trench leads to larger on-resistance and threshold voltage of 60 V UMOSFET. To further verify the hypothesis, the formula for the resistance of the drift region has been derived, and the simulating model of UMOSFET has been given with various mergers of the P-base regions. Then the simulation model has been corrected and the parameters of UMOSFET have been optimized. The re-design of 60 V UMOSFET has been taped out successfully, with its electric parameters totally meeting the requirements.     

凝视红外成像制导系统数学建模与仿真技术

基于凝视红外成像制导工作的原理,论述了凝视红外成像末制导系统虚拟样机及其工作环境建模方法,介绍了红外成像制导仿真系统数学软硬件环境和仿真方法,给出了初步的数学仿真结果,对开展凝视红外成像末制导系统技术研究具有指导意义。     

Validation of the DJOSER analytical thermal simulator for electronic power devices and assembling structures

The present communication deals with the tests for the validation of the DJOSER steady-state thermal simulation program, purposely designed for power electronic assembling structures and which is based on the resolution of analytical relationships. The validation experiments were carried out theoretically by comparing the thermal maps with those obtained using standard finite-elements programs and yielding temperature accuracy below 1%. Experimental tests were also performed on purposely built multi-layer structures and industrial circuits with power diodes mounted in naked-chip configuration. The simulated maps were compared with accurate thermo-graphic recordings and showed a good agreement, testifying the validity of the mathematical model.     

Influence of initial power stabilization over crystalline‐Si photovoltaic modules maximum power

Measurements that suppliers offer in specification sheets are not always close to the actual power measured in independent laboratories such as CIEMAT. Independent measurements tend to be lower than those printed on the label sometimes even lower than the allowed tolerance indicated by the manufacturer on the same label. Furthermore, a potentially significant power reduction has been reported when Standard EN50380 (which requires photovoltaic (PV) modules to be exposed to more than 20 kWh/m² of sunlight prior to taking the measurements that appear on the label) is followed. This is the initial power stabilization and this work studies the power stabilization that tends to appear in crystalline PV modules. Crystalline PV modules usually decrease in power around 1%, but decreases >4% have also been reported. These power losses are only detected after the mentioned power stabilization. Copyright © 2010 John Wiley & Sons, Ltd.     

Circuit models for quasi-3D spice simulation of turn-on transients in four-layer power bipolar devices

Improved transport models for quasi-3D circuit-based simulation (Q3DSim) of four-layer devices such as thyristors and transient over-voltage protectors (TOVPs) are presented. Q3DSim is an attractive alternative to full 3D transport equations based simulations (3D-TES), since it is much faster and requires less computer power. In Q3DSim, the thyristor is divided into four-layered square prisms, and a 1D PNP-NPN transistor pair model is associated to each of them in the anode to cathode direction. The PNP-NPN elements are interconnected through two transversal grid planes of circuit elements. The resulting equivalent circuit is simulated with Spice. Plasma-spreading velocity, used here as a benchmark, depends strongly on the current-dependent transport properties in the anode to cathode path given by the transistor gains, and on the transversal transport properties of both transistor bases.The new circuital models reported here, based on the quasi-static approximation, add drift and diffusion current components to Q3DSim transversal base planes. The circuit version of the base model was implemented with finite differences in Spice. The PNP transistor of the PNP-NPN basic model was complemented with a second PNP transistor that simulates the transport enhancement in the N-base due to the ohmic effect. All the required parameters are extracted from static TES. The power of the method was demonstrated by comparing 2D-TES plasma spreading velocity simulations with Q3DSim simulations. Both simulations were very close to each other in the 50-1200 A/cm² anode current density range. Moreover, the Q3DSim current wave front shapes were very close to 2D-TESs in the same current density range, showing the validity of the presented models.     

Roughness of amorphous/crystalline interface in pre-amorphization implantation: Molecular dynamic simulation and modeling

Pre-amorphization implantation has been applied as a shallow junction technology. Roughness at amorphous/crystalline (a/c) interface should be controlled to improve junction characteristics. To understand and model a/c interface roughness, molecular dynamic method is applied in simulating pre-amorphization implantation. A method to reproduce roughness at a/c interface by molecular dynamic simulation is presented. A model of interface roughness is presented. Si and Ge implantation from 2-20 keV at a dose of 1 × 10¹⁵ cm⁻² is simulated. The depth of a/c interface is reproduced. Experimental results of a/c interface roughness are successfully simulated. The interface roughness is well reproduced and interpreted by the model presented.