A Novel Multiple DBC-staked units Package to Parallel More Chips for SiC Power Module

Silicon carbide(SiC) power modules play an essential role in the electric vehicle drive system. To improve their performance, reduce their size, and increase production efficiency, this paper proposes a multiple staked direct bonded copper(DBC) unit based power module packaging method to parallel more chips. This method utilizes mutual inductance cancellation effect to reduce parasitic inductance. Because the conduction area in the new package is doubled, the overall area of power module can be reduced. Entire power module is divided into smaller units to enhance manufacture yield, and improve design freedom. This paper provides a detailed design, analysis and fabrication procedure for the proposed package structure. Additionally, this paper offers several feasible solutions for the connection between power terminals and DBC untis. With the structure, 18dies were paralleled for each phase-leg in a econodual size power module. Both simulation and double pulse test results demonstrate that, compared to conventional layouts, the proposed package method has 74.8% smaller parasitic inductance and 34.9% lower footprint.

Thermal fatigue behaviors of SiC power module by Ag sinter joining under harsh thermal shock test

The excellent properties of SiC bring new challenges for the device packaging.In this study,the bonding strength,fracture behaviors and microstructural evolution of micron-porous Ag joint were elevated during thermal cycling(–50 ℃–250 ℃) in SiC/DBC(direct bonding copper) die attachment structure for different time.During harsh thermal shock test,the strength of sintered joint deceased gradually with the increase of cycling number,and the value just was half of the value of as-sintered after 1 000 cycles.Coarsening of Ag grains was observed in micron-porous joint with the structure inhomogeneity and defects increasing,which were the reasons of the strength decease.In addition,it was also found that the fracture behavior of sintered joints was changed from ductile deformation of Ag grain to brittle fracture of crack propagation after 1 000 cycles.This study will add the understanding in the mechanical properties of Ag sinter joining and its applications at high temperature.

RECENT DEVELOPMENTS OF DIRECT BONDED COPPER(DBC)SUBSTRATES FOR POWER MODULES

DBC substrates are the standard circuit boardsfor power modules. Using the DBC technologythick copper foils (0.125mm - 0.Tmm) arecladded to Alumina or Aluminum Nitride,The strong adhesion of the copper to ceramicbond reduces the thermal expansion coefficientin horizontal direction only slightly above theTEC of the ceramic itself. This allows directsilicon attach of large dies without using TECcontrolling layers.As DBC technology is using copper foils,integralleads overhanging the ceramic can be realized...

Dynamic Performance of Fuel Cell Power Module for Mobility Applications

Fuel cell powered vehicles have been developed as another alternative to internal combustion engine powered vehicles for some applications including passenger cars, buses, trains, motorcycles, forklifts, electric wheelchairs, electric trolleybuses, medical carts, military engines, personal sports craft, mobility devices and other self propelled equipment. Up to now, many researches have focused on the development of the power module in the Fuel cell vehicles (FCVs) and the components of these systems such as membranes, bipolar plates, and electrodes. However, our work in this study focuses on operating the integrated fuel cell power module system efficiently for various operating conditions such as pressure, relative humidity and operating modes. In our validation we have utilized PEMFC single cell, with active area geometry 16 cm2 and of 120 cm2. Some results obtained in our study shown significant performance indicators for PEMFC stack (composed of 2 cells and 4 cells in a series) at different humidification levels.

Review of Power Module Automatic Layout Optimization Methods in Electric Vehicle Applications

The layout of power modules is a crucial design consideration,especially for silicon carbide devices.For electrical layout,optimizing the parasitic parameters can improving switching loss and dynamic behavior.For thermal layout,reducing the thermal resistance and controlling thermal capacitance can reduce the local hot point.Conventional layout design iterations are based on human knowledge and experience.But the major drawback of manual design methods is a limited choice of candidates,large time consumption and also the lack of consistency.With the introduce of automatic layout design,these challenges can be overcome which in the meanwhile alleviates current and temperature imbalance.By reviewing element representation,placement,routing,fitness evaluation,and the optimization algorithm approaches,a state-of-the-art power module layout design method for electric vehicle applications is introduced.

Trap Characteristics and Their Temperature-dependence of Silicone Gel for Encapsulation in IGBT Power Modules

Silicone gel is a prevailing material for encapsulation in insulated gate bipolar transistor(IGBT)power modules.The space charge transport behavior in silicone gel is significant to evaluate the electrical insulation characteristics.This paper focuses on the trap characteristics and electrical properties of the silicone gel,which were rarely studied before.The experiments are performed on the surface potential decay of silicone gel after the charge injection.Then,the energy distributions of electron or hole traps are determined by a double-trap energy level model,which can be fitted by the Gaussian distribution.In addition,the mobilities of positive and negative charges are determined,which are 1.38×10^(-12) m^(2)·V^(-1)·s^(-1) and 1.74×10^(12) m^(2)·V^(-1)·s^(-1),respectively.Furthermore,considering the heat as a byproduct resulting in thermal issues,the temperature-dependence of surface potential decay characteristics are also studied in this paper.When temperature rises,the decay rate of surface potential increases,especially when the temperature is higher than 80℃.Finally,the contrastive analysis illustrates that the trap characteristics of silicone gel are between the trap characteristics in liquid-state material and solid-state material,which supports the phenomenon that silicone gel is more resistive to the sharp edges in power modules.This work can provide a useful reference for the design of encapsulation in high-voltage IGBT power modules.

Failure Analysis of Ceramic Substrates Used in High Power IGBT Modules

High voltage power modules are used in numerous applications to build high power converters. Technically, these modules are made of different materials and among them, dielectric materials are organic and inorganic. Organic insulators (gels) are used to avoid corona discharges in the vicinity of connecting wires and high voltage dies (diodes and transistors) and to protect them from moisture and contaminants. Inorganic insulators (ceramic substrates) are used to insulate the high voltage which dies from the grounded elements and to transfer heat to the heat sink. Despite being used since the late 90s, there is a lack of fundamental knowledge about the electrical properties of these substrates. Consequently, manufacturers tend to assure the reliability by over sizing them. As there are no clear rules for how to do that, failures occur, leading to the converter shutdown. The aim of this study is to bring new information about the understanding of the dielectric strength of ceramic materials used in these modules. We have focused our work on the correlation between the mechanical and the dielectric properties of ceramics by using relevant experiments. We provide new information about the impact of existing cracks on the ceramic dielectric failure, according to the electromechanical breakdown model. Our conclusions bring crucial information about the precautions to be taken during manufacturing and implementation of these substrates in power modules to reduce the likelihood of the particular causes of failure.

PS-modules over Rings of Generalized Power Series

Let R be a commutative ring and (S, ≤) a strictly totally ordered monoid which satisfies the condition that 0 ≤ s for every s ∈ S. In this paper we show that if RM is a PS-module, then the module [[MS≤]] of generalized power series over M is a PS [[RS,≤]]-module.

A Study of Efficient Power Consumption Wireless Communication Techniques/ Modules for Internet of Things (IoT) Applications

A study of wireless technologies for IoT applications in terms of power consumption has been presented in this paper. The study focuses on the importance of using low power wireless techniques and modules in IoT applications by introducing a comparative between different low power wireless communication techniques such as ZigBee, Low Power Wi-Fi, 6LowPAN, LPWA and their modules to conserve power and longing the life for the IoT network sensors. The approach of the study is in term of protocol used and the particular module that achieve that protocol. The candidate protocols are classified according to the range of connectivity between sensor nodes. For short ranges connectivity the candidate protocols are ZigBee, 6LoWPAN and low power Wi-Fi. For long connectivity the candidate is LoRaWAN protocol. The results of the study demonstrate that the choice of module for each protocol plays a vital role in battery life due to the difference of power consumption for each module/protocol. So, the evaluation of protocols with each other depends on the module used.

Optimization Design for a High Voltage DC Power Supply Module Based on PSM Technology

Pulse step modulator （PSM） topology is applied to the EAST auxiliary heating system, which consists of a neutral beam injection （NBI） and the related microwave heating system. This paper firstly analyzes the merits and demerits of the traditional PSM modules adopted by other international companies, and then optimizes the topology of the module using the analysis results. Finally, a new topology for the PSM module （a three-phase neutral-point diode-clamped rectifier） is proposed. This new module overcomes the problems of traditional modules and has better cost-effective performance. The experimental results verify that the new module is feasible for engineering applications.

Performance and Stability of Supercapacitor Modules based on Porous Carbon Electrodes in Hybrid Powertrain

Hybrid power sources have attracted much attention in the electric vehicle area. Particularly, electric-electric hybrid powertrain system consisting of supercapacitor modules and lithium-ion batteries has been widely applied because of the high power density of supercapacitors. In this study, we design a hybrid powertrain system containing two porous carbon electrode-based supercapacitor modules in parallel and one lithium ion battery pack. With the construction of the testing station, the performance and stability of the used supercapacitor modules are investigated in correlation with the structure of the supercapacitor and the nature of the electrode materials applied. It has been shown that the responding time for voltage vibration from 20 V to 48.5 V during charging or discharging process decreases from about 490 s to 94 s with the increase in applied current from 20 A to 100 A. The capacitance of the capacitor modules is nearly independent on the applied current. With the designed setup, the energy efficiency can reach as high as 0.99. The results described here provide a guidance for material selection of supercapacitors and optimized controlling strategy for hybrid power system applied in electric vehicles.

Development of 8 MW Power Supply Based on Pulse Step Modulation Technique for Auxiliary Heating System on HL-2A

The high voltage power supply （HVPS） based on pulse step modulation （PSM） has already been developed for the auxiliary heating system on HL-2A. This power supply consists of many switch power supplies, and its output voltage can be obtained by modulating their delay time and pulse widths. The PSM topology and control principle are presented in this paper. The simple algorithms for the control system are explained clearly. The switch power supply （SPS） module has been built and the test results show it can meet the requirements of the auxiliary heating system. Now, 112 SPS modules and the whole system have already been developed. Its maximum output is about 72 kV/93 A. The protection time is less than 5 t＊s. The different outputs of this power supply are used for the electron cyclotron resonant heating （ECRH） system with different duty ratios. The experimental results of the entire system are presented. The results indicate that the whole system can meet the requirements of the auxiliary heating system on HL-2A.

Improving thermal efficiency and stability of laser welding process for magnesium alloy by combining power modulation and subatmospheric pressure environment

The laser welding(LW)process of highly reflective materials presents low thermal efficiency and poor stability.To solve the problem,the effects of subatmospheric environment on LW process,technological parameters in subatmospheric environment on weld formation and welding with sinusoidal modulation of laser power on the stability of LW process in subatmospheric environment were explored.The AZ31magnesium(Mg)alloy was used as the test materials.The test result revealed that the weld penetration in subatmospheric environment can increase by more than ten times compared with that under normal pressure.After the keyhole depth greatly rises,significantly periodic local bulge is observed on the backwall surface of the keyhole and the position of the bulge shifts along the direction of the keyhole depth.Eventually,the hump-shaped surface morphology of the welded seam is formed;moreover,the weld width in local zones in the lower part of the welded seam remarkably grows.During LW in subatmospheric environment,the weld penetration can be further greatly increased through power modulation.Besides,power modulation can inhibit the occurrence of bulges in local zones on the backwall of the keyhole during LW in subatmospheric environment,thus further curbing the significant growth of the weld widths of hump-shaped welding beads and local zones in the lower part of welded seams.Finally,the mechanism of synchronously improving the thermal efficiency and stability of LW process of highly reflective materials through power modulation in subatmospheric environment was illustrated.This was conducted according to theoretical analysis of recoil pressure and observation results of dynamic behaviors of laser induced plasma clouds and keyholes in the molten pool through high speed photography.

Experimental Determination of the ICRF Power Depositing on the Electrons in HT-7

This paper reports for the first time an experimental study on the power deposition profile of the ion cyclotron range frequencies （ICRF） power depositing on electrons in HT-7. The fast Fourier transform （FFT） analysis and the break in slope （BIS） method are utilized to obtain the information of the power deposition. The results indicate that the electrons were heated directly, and the electrons absorbed around 20% of the input power of the discharge of interest.

Electric Vehicle IM Controller Based on Voltage-Fed Inverter

A novel electric vehicle (EV) induction motor (IM) controller based on voltage-fed inverter is presented. It is shown that the proposed adaptive control algorithm effectively both simplifies the structure and expands the capacity of controller. The relationship between stator's voltage and that of current under rotor's flux-oriented-coordinates is first introduced, and then the structure of vector control is analyzed, in which voltage compensation is inducted as the core feedback procedure. Experiments prove that, together with a facility for realization, a smooth transition, a prompt torque response and small concussion are gained. Extensive research conducted by varying parameters that result in practical ripple is proposed in conclusion.

Application of nonlinear fatigue damage models in power electronic module wirebond structure under various amplitude loadings

This paper presents mean fatigue lifetime predic- tion of a wire-bond structure model in power electronic module using a failure physics approach that integrates high fidelity modelling and reduced order modelling. Loading current with variable amplitudes is applied to a finite element model of simplified wirebond structures. The resulting accumulated fatigue damage due to random loads is predicted by using reduced order modelling based on failure physics, a cycle counting algorithm, and various nonlinear fatigue damage models widely used in the literature. The reduced order mod- elling approach based on failure physics uses prediction data for the electro-thermo-mechanical behaviour of the wire-bond design of a power module obtained through non-linear transient finite element simulations, in particular for the fatigue life-time of the aluminium wire attached to the silicon chip of the wire in the module. The reduced order models that capture the black box function of the accumulated plastic strain are used in pre- dicting the mean fatigue life time of the wire bond structure under random loads. One of the widely used cycle counting algorithms, rainflow counting algorithm, is used to count cycles of the temperature profile at the specific point of the wire bond structure in a power electronic module. The cycle data from the rainflow algorithm mean life time of the wire bond structure are predicted with various cumulative fatigue models. Non-linear cumulative fatigue models such as damage curve approach （DCA）, double linear damage rule （DLDR）, and double dam- age curve approach （DDCA）, and linear cumulative fatigue damage model such as Palmgren-Miner rule are used to predict the mean fatigue life of the wire bond structure, and the results are compared.

Ceramic-copper substrate technology introduction

Ceramic-copper substrate is used to achieve the combination between copper and ceramic(Al_(2)O_(3) or AlN)under high temperatures by bonding or brazing process,then through dedicate lamination–etching technology to develop the designed layout in copper surface,finally parts go with plating and singulation process for surface treatment before shipping to the end-user.Ceramic-copper substrate has perfect performance in terms of insulation,thermal conductivity,solderability,and adhesion strength.Besides,the copper on surface can afford huge current due to the fact that ceramic has good reliability and thermal-cycling performance.According to technical visit and audit to suppliers’manufacturing process and based on several years’experience of mass production for electric vehicle power module package,this article introduces two mainstream ceramic-copper substrate processing methods currently on the market:direct bond copper(DBC)and active metal brazing(AMB)which can be widely used for the intelligent power module and electric vehicle power module,also introduces the major failure mode during application and analyzes the root cause for each failure mode,clarifies key incoming monitoring method,like crosshatch,silver plating thickness measurement and blister test.This article also clarifies the Incoming Quality Control system,which can provide guidance to process engineer during the application.

Design of BLDCM Driving and Control System for Motorized Treadmill

To satisfy the requirement of developing a new generation of motorized treadmill for a famous domestic manufacturer, a brushless DC motor （BLDCM） driving and control system for motorized treadmill is developed. High integration and reliability of this system are ensured under the condition that intelligent power module （IPM） is used and the protection module is included. Periodic current control method is applied to reduce the average current flowing through the armature winding of the motor when the treadmill is required to start with low speed while large load is added. Piecewise proportion-integration-differentiation （PID） control algorithm is applied to solve the problem of speed fluctuation when impulse load is added. The motorized treadmill of a new generation with the driving and control system has the advantages of high reliability, good speed stability, wide timing scope, low cost, and long life-span. And it is very promising for practical applications.

Researching the 915 nm high-power and high-brightness semiconductor laser single chip coupling module

Based on the high-speed development of the fiber laser in recent years, the development of researching 915 nm semiconductor laser as main pumping sources of the fiber laser is at a high speed. Because the beam quality of the laser diode is very poor, the 915 nm laser diode is generally based on optical fiber coupling module to output the laser. Using the beam-shaping and fiber-coupling technology to improve the quality of output beam light, we present a kind of high-power and high-brightness semiconductor laser module, which can output 13.22 W through the optical fiber. Based on 915 nm GaAs semiconductor laser diode which has output power of 13.91 W, we describe a thoroughly detailed procedure for reshaping the beam output from the semiconductor laser diode and coupling the beam into the optical fiber of which the core diameter is 105 μm and the numerical aperture is 0.18. We get 13.22 W from the output fiber of the module at 14.5 A, the coupling efficiency of the whole module is 95.03% and the brightness is 1.5 MW/cm2-str. The output power of the single chip semiconductor laser module achieves the advanced level in the domestic use.

A Compact Dual-Port Multi-Band Rectifier Circuit for RF Energy Harvesting

This paper presents a compact multi-band rectifier with an improved impedance matching bandwidth.It uses a combination of–matching network(MN)at Port-1,with a parallel connection of three cell branch MN at Port-2.The proposed impedance matching network(IMN)is adopted to reduce circuit complexity,to improve circuit performance,and power conversion efficiency(PCE)of the rectifier at low input power.The fabricated rectifier prototype operates at 0.92,1.82,2.1,2.46 and 2.65 GHz covering GSM/900,GSM/1800,UMTS2100,and Wi-Fi/2.45–LTE2600.The size of the compact rectifier on the PCB board is 0.13λ_(g)×0.1λ_(g).The fabricated rectifier achieved an RF-to DC(radio frequency direct current)PCE of 31.8%,24%,22.7%,and 15%,and 14.1%for−20 dBm at the five respective measured operating frequencies.The circuit attains a peak RF-to-DC PCE of 82.3%for an input power of 3 dBm at 0.92 GHz.The proposed rectifier realizes an ambient output dc voltage of 454 mV for multi-tone input signals from the two ports.The rectifier drives a bq25504-674 power management module(PMM)to achieve 1.21 V from the two-port connection.The rectifier has the ability to exploit both frequency domain through the multi-band operation with good impedance bandwidth and a spatial domain using dual-port configuration.Hence,it is a potential candidate for various applications in radio frequency energy harvesting(RFEH)system.