Hybrid Vehicle Applications Research Articles

Characterization of Bi–Ag–X Solder for High Temperature SiC Die Attach

Higher operating temperature (200 °C) SiC power devices simplify the thermal management system for power electronics modules in hybrid and electric vehicle applications. However, common lead-free solders have a melting point of only 217 °C-229 °C, limiting their use in this application. In this paper, a Bi-Ag-X solder paste with a solidus point of approximately 265 °C was characterized on direct bond copper (DBC) and CuMo reactively brazed alumina substrates. The Cu and CuMo surfaces were plated with Ni:B and Au. During high-temperature storage (200 °C) of test vehicles on DBC, there was an initial decrease in die shear strength followed by relatively constant die shear strength with further aging (through 5000 h). The initial decrease in shear strength was determined to be the result of NiBi3 intermetallic formation. The formation of the intermetallic layer was limited by the thickness of the initial Ni plated on Cu or CuMo. Similar results were observed for CuMo samples thermal cycled (-55 °C to +195 °C) up to 2000 cycles.

IGBT 전력반도체 모듈 패키지의 방열 기술

SP Semiconductor & Communication Co., Ltd, 96-1, Dodang-Dong, Wonmi-gu, Bucheon-Si, Gyeonggi-dov 20-803, Korea(2014년 9월 4일 접수: 2014년 9월 5일 수정: 2014년 9월 18일 게재확정)Abstract: Power electronics modules are semiconductor components that are widely used in airplanes, trains,automobiles, and energy generation and conversion facilities. In particular, insulated gate bipolar transistors(IGBT) havebeen widely utilized in high power and fast switching applications for power management including power supplies,uninterruptible power systems, and AC/DC converters. In these days, IGBT are the predominant power semiconductorsfor high current applications in electrical and hybrid vehicles application. In these application environments, the physicalconditions are often severe with strong electric currents, high voltage, high temperature, high humidity, and vibrations.Therefore, IGBT module packages involves a number of challenges for the design engineer in terms of reliability. Thermaland thermal-mechanical management are critical for power electronics modules. The failure mechanisms that limit thenumber of power cycles are caused by the coefficient of thermal expansion mismatch between the materials used in theIGBT modules. All interfaces in the module could be locations for potential failures. Therefore, a proper thermal designwhere the temperature does not exceed an allowable limit of the devices has been a key factor in developing IGBTmodules. In this paper, we discussed the effects of various package materials on heat dissipation and thermal management,as well as recent technology of the new package materials. Keywords: Insulated gate bipolar transistor, package module, heat dissipation, thermal management.

Comprehensive Efficiency, Weight, and Volume Comparison of SiC- and Si-Based Bidirectional DC–DC Converters for Hybrid Electric Vehicles

Silicon carbide (SiC)-based switching devices provide significant performance improvements in many aspects, including lower power dissipation, higher operating temperatures, and faster switching, compared with conventional Si devices. However, tradeoffs in efficiency, size, and weight between Si- and SiC-based converters are still unclear in the literature. In this paper, a bidirectional dc-dc converter that is suitable for hybrid or electric vehicle application is studied based on three sets of device combinations, e.g., all-silicon [conventional silicon insulated-gate bipolar transistors (IGBTs) and silicon PN diodes], hybrid (silicon IGBTs with SiC Schottky diodes), and all-SiC (SiC metal-oxide-semiconductor field-effect transistors with SiC Schottky diodes). At the switching frequency of 20 kHz, comparative analyses regarding the power loss reduction of power devices and efficiency improvements are carried out for the converters. Possible size and weight reduction is also investigated by increasing the operating frequencies of hybrid and all-SiC converters while reducing the capacitance and inductance values.

Nonlinear intelligent DC grid stabilization for fuel cell vehicle applications with a supercapacitor storage device

Abstract This paper presents an intelligent DC link control using a fuzzy logic controller based on the differential flatness control theory for hybrid vehicle applications supplied by a fuel cell (FC) (main source) and a supercapacitor (auxiliary source). The energy in the system is balanced by dc bus energy stabilization (or indirect voltage regulation). A supercapacitor module functions by supplying energy to regulate the dc bus energy. The FC, as a slow dynamic source in this system, supplies energy to the supercapacitor module to maintain its charge. The FC converter combines four-phase parallel boost converters with interleaving, and the supercapacitor converter employs four-phase parallel bidirectional converters with interleaving. These two converters are called a multi-segment converter for high power applications. Because the model of the power switching converters is nonlinear, it is preferable to apply model-based nonlinear control strategies that directly compensate for the nonlinearity of the system without requiring a linear approximation. Using the intelligent fuzzy control law based on the flatness property, we propose straightforward solutions to hybrid energy management and to the dynamic and regulation problems. To validate the proposed method, a hardware system is developed with analogue circuits, and a numerical calculation is generated with a dSPACE controller DS1104. Experimental results for a small-scale power plant (a polymer electrolyte membrane FC (PEMFC) of 1200 W and 46 A with a supercapacitor module of 100 F, 500 A, and 32 V) in the laboratory corroborate the excellent performance of this control scheme during vehicle motor drive cycles.

Ionic Liquid Based Electrolyte Systems Enabling Operation of High Voltage Cathode Materials

Lithium batteries are becoming increasingly important in hybrid and electric vehicle applications. The common cathode materials for these batteries, when based on metal oxides, are reaching their limits in terms of gravimetric capacity (mAh/g). In an effort to push the boundaries in energy density (Wh/kg) for these devices, there is an increasing push to higher voltage cathode materials such as LiMn0.33Ni0.33Co0.33O2 and the LiNi0.5Mn1.5O4 type materials, where the highest capacities of the materials are accessed at potentials greater than 4.6 V vs. Li|Li+. With this push for higher energy and higher voltage there is a limit to the types of electrolytes that are compatible with these materials and allow for the higher operating voltages. Standard battery electrolytes such as (1.2 M LiPF6 in EC/DMC) are well known to be unstable at these high voltages as well allowing severe Aluminium current collector corrosion. A key enabler to increasing the energy density of a lithium battery is an improved electrolyte.At CSIRO, we have been at the forefront of developing new ionic liquid based electrolytes to enable the next generation of high voltage electrodes. The key factors to consider besides essential properties such as solution conductivity, Lithium ion diffusivity, viscosity, etc are the electrochemical windows of these solvents (i.e. stability at high cathodic voltages), the stability of the Aluminium current collector (i.e. limited corrosion in the solvent) and the compatibility of the high voltage cathode materials in these electrolytes (i.e. limited solubility of charge/discharge products in the solvent). At this time, there is a significant effort to identify solvents (blends), lithium salts and / or additives that can stabilize the cathode in contact with the electrolyte and preclude Aluminium current collector corrosion. Specifically described in this work is our progress in developing ionic liquids electrolytes as well as blends of these with other solvents and additives for high voltage cathode applications. SECM characterisation to detect cathode dissolution and current collector corrosion has been carried out, as well as long term cycling of lithium cells incorporating the high voltage cathodes.

Power Factor Correction Rectifier with a Variable Frequency Voltage Source in Vehicular Application

This paper presents a PFCVF (Power Factor Correction) rectifier that uses a variable frequency source for alternators for electric and hybrid vehicles application. In such application, the frequency of the signal in the alternator changes according to the vehicle speed, more over the loading effect on the alternator introduces harmonic currents and increases the alternator apparent power requirements. To overcome these problems and aiming more stability and better design of the alternator, a new third harmonic injection technique is proposed. This technique allows to preserve a good THD (Total Harmonic Distortion) of the input source at any frequency and to decrease losses in semiconductors switches, thereby allowing more stability and reducing the apparent power requirements. A comparative study between the standard and the new technique is made and highlights the effectiveness of the new design. A detailed analysis of the proposed topology is presented and simulations as well as experimental results are shown.

Sandwich-like carbon-anchored ultrathin TiO2nanosheets realizing ultrafast lithium storage

Lithium-ion batteries have long been considered as the most promising energy storage technology for hybrid, plug-in hybrid and electric vehicle applications. However, their large-scale applications are still limited by the low electrical conductivity, easy agglomeration and inferior cycling stability of the active materials. Herein, sandwich-like carbon-anchored ultrathin nanosheets are put forward for the first time as an excellent platform to achieve ultrafast lithium storage kinetics and superior cycling stability. Taking the synthetic sandwich-like carbon-anchored ultrathin TiO2 nanosheets as an example, a capacity of 101.9 mA h g−1 is achieved at a current density as high as 40 C (6.8 A g−1), while a capacity of 150.4 mA h g−1 is obtained even after 1200 cycles at a discharge rate of 5 C. This work develops an in situ carbonization of organic octylamine for fabricating sandwich-like carbon-anchored ultrathin nanosheets, holding great promise for the future design and synthesis of high-performance active materials for lithium-ion batteries.

On the Tuning of Predictive Controllers for Hybrid Fuel Cell Vehicle Applications

While the notion of a hybrid fuel cell vehicles is conceptually promising, due to an off-loading of peak power demands from the fuel cell to the storage devices, the questions of device coordination is unsettled. Clearly the prominent role of equipment limitations, with respect to energy storage capacity and maximum power, suggests the use of predictive control for constraint enforcement. In this work an MPC tuning method specifically tailored to the hybrid vehicle application is presented. The approach is based on the notion of backed-off operating point selection and has the objective of minimizing energy losses from the storage devices. In addition, a soft constraint formulation unique to hybrid vehicle application is proposed.

Design of a lithium-ion battery pack for PHEV using a hybrid optimization method

This paper outlines a method for optimizing the design of a lithium-ion battery pack for hybrid vehicle applications using a hybrid numerical optimization method that combines multiple individual optimizers. A gradient-free optimizer (ALPSO) is coupled with a gradient-based optimizer (SNOPT) to solve a mixed-integer nonlinear battery pack design problem. This method enables maximizing the properties of a battery pack subjected to multiple safety and performance constraints. The optimization framework is applied to minimize the mass, volume and material costs. The optimized pack design satisfies the energy and power constraints exactly and shows 13.9–18% improvement in battery pack properties over initial designs. The optimal pack designs also performed better in driving cycle tests, resulting in 23.1–32.8% increase in distance covered per unit of battery performance metric, where the metric is either mass, volume or material cost.

Influence of PCB and Connections on the Electromagnetic Conducted Emissions for Electric or Hybrid Vehicle Application

This paper presents a fine modeling method for power module used in an Electric or Hybrid Vehicle (EHV) application. A time domain model is developed in order to predict conducted emissions. All parasitic elements of the power components constituting the power module are obtained by modeling, measuring or applying analytical formula. The influence of the Printed Circuit Board (PCB) and the connections of components on conducted emissions levels are shown here. The results obtained by the proposed models are compared with measurements results.

Online battery state of health estimation based on Genetic Algorithm for electric and hybrid vehicle applications

State of health (SOH) of batteries in electric and hybrid vehicles can be observed using some battery parameters. Based on a resistance–capacitance circuit model of the battery and data obtained from abundant experiments, it was observed that the diffusion capacitance shows great correlation with SOH of a lithium-ion battery. However, accurate measurement of this diffusion capacitance in real time in an electric or hybrid electric vehicle is not practical. In this paper, Genetic Algorithm (GA) is employed to estimate the battery model parameters including the diffusion capacitance in real time using measurement of current and voltage of the battery. The battery SOH can then be determined using the identified diffusion capacitance. Temperature influence is also considered to improve the robustness and precision of SOH estimation results. Experimental results on various batteries further verified the proposed method.

Investigation of different binding agents for nanocrystalline anatase TiO2 anodes and its application in a novel, green lithium-ion battery

The electrochemical performance of nanocrystalline anatase TiO2 electrodes made using sodium carboxymethyl cellulose (CMC) binder, alone and in combination with styrene butadiene rubber (SBR), has been investigated. The electrochemical behavior of these electrodes, which were made via a water-based process, has been compared with those of electrodes manufactured using traditional polyvinylidene difluoride (PVDF) and its copolymer with hexafluoropropylene (PVDF-HFP) in N-methyl-2-pyrrolidone solution. Without the need of any post coating treatment, such as roll pressing, CMC and CMC/SBR based electrodes possess higher specific capacity, rate capability, and cycling stability than those prepared using PVDF or PVDF-HFP as binding agent. Using the same water based process, CMC based LiNi1/3Mn1/3Co1/3O2 (NMC) electrodes have been prepared.The combination of CMC based TiO2 and NMC electrodes in a lab-scale lithium-ion full cell showed a stable cycling performance with a total energy density of more than 120 Wh kg−1. These results demonstrate that anatase TiO2 is an attractive candidate for the development of safer and greener lithium-ion batteries for future application in hybrid and electric vehicles and stimulate further research on this full lithium-ion cell combination.

Design and Implementation of Anti-windup PI Control on DC-DC Bidirectional Converter for Hybrid Vehicle Applications

Well-regulated DC bus voltage is the important point to guarantee the power demand in hybrid vehicle applications. Voltage regulation can be achieved with control method that build switching signal on DC-DC converter. This paper describes design and small scale experimental results of bus voltage regulation control of the DC-DC bidirectional converter with battery and supercapacitor as energy source. The control system consists of two control loops, the outer loop that get DC bus voltage feedback using PI anti-windup back calculation control method. This outer loop will generate a reference current for the inner loop that implement hysteresis control. The inner control loop will compare that reference curent with the source current obtained from the current sensor. Simulation and experimental results show that bus voltage is well-regulated under the load changes with 1% voltage ripple.

Experimental investigation of a pulsating heat pipe for hybrid vehicle applications

This paper deals with the experimental results of an unlooped pulsating heat pipe (PHP) developed and tested in an electronic thermal management field with hybrid vehicle applications in mind. The 2.5 mm inner tube diameter device was cooled by an air heat exchanger to replicate the environment of a vehicle.In order to characterize this pulsating heat pipe, four working fluids have been tested. They are acetone, methanol, water, and n-pentane, with applied thermal power ranging from 25 W to 550 W, air temperature ranging from 10 °C to 60 °C and air velocity ranging from 0.25 m s−1 to 2 m s−1. Three inclinations have also been tested according to their horizontal positions: +45° (condenser above the evaporator), 0° and −45° (condenser below the evaporator).Among the different results, some of the most revelatory were obtained with regard to unfavourable inclination (−45°), for which the performances were very interesting considering a terrestrial application. On the other hand, one also observed low temperature limitations for water as a working fluid and degradation of performances for n-pentane tested at 60 °C air temperature. On an overall basis, however, it should be noted that the PHP functioned with high reliability and reproducibility and without any failure during the start-up or working stage.

Design Optimization of a Battery Pack for Plug-in Hybrid Vehicle Applications

not Available.

High Power Current Sensorless Bidirectional 16-Phase Interleaved DC-DC Converter for Hybrid Vehicle Application

A new 16-phase interleaved bidirectional dc/dc converter is developed featuring smaller input/output filters, faster dynamic response and lower device stress than conventional designs, for hybrid vehicle applications. The converter is connected between the ultracapacitor (UC) pack and the battery pack in a multisource energy storage system of a hybrid vehicle. Typically, multiphase interleaved converters require a current control loop in each phase to avoid imbalanced current between phases. This increases system cost and control complexity. In this paper, in order to minimize imbalance currents and remove the current control loop in each phase, the converter is designed to operate in discontinuous conduction mode (DCM). The high current ripple associated with DCM operation is then alleviated by interleaving. The design, construction, and testing of an experimental hardware prototype is presented, with the test results included. Finally, a novel soft switch topology for DCM operation is proposed for future research, to achieve zero-voltage switching (ZVS), or zero-current switching (ZCS) in all transitions.

A new approach to optimally tune the control strategy for hybrid vehicles applications

The paper presents an innovative method for the optimal tuning of energy management control strategies for hybrid electrical vehicles. The method is based on the analysis of an existing optimal control law, which can be obtained using Dynamic Programming, by means of the local partial derivatives. This permits to obtain a set of upper and lower bounds for instantaneous value of the time-varying Lagrange multiplier of the constrained optimization problem, which can be represented in so-called Λ-plots. From that plots, it is possible to provide an estimate of the optimal parameters for tuning energy management control strategies as the Equivalent Consumption Minimization Strategy and Pontryagin Minimum Principle. Λ-plots also provide a good framework for analysing the equivalence of different control strategies. The Λ-plot method is demonstrated for both series and parallel configurations of a hybrid electrical vehicle.

Modeling of Lithium Iron Phosphate Batteries by an Equivalent Electrical Circuit: Part II - Model Parameterization as Function of Power and State of Energy (SOE)

The modelling of Li-ion batteries may work as a powerful tool for the introduction and widespread testing of this technology in alternative energy storage, hybrid, and electric vehicle applications. The aim of this paper is to present a new parameterization method for the typical Equivalent Electrical Circuit (EEC) model of these batteries. The model parameters are determined as function of power and State of Energy (SOE) instead of current and State of Charge (SOC) respectively. This new method allows the simulations of Li-ion batteries subjected to power-controlled operation to be faster and more convergent. Here, the parameterization was based on a combination of Electrochemical Impedance Spectroscopy (EIS) method and charge/discharge curves analysis. The simulated and experimental results were compared, and it was demonstrated that the developed parameterization method provides accurate predictions of the dynamic behaviour of Li-ion batteries over wide SOE/SOC and working power range.

Dynamic Modeling of Li-Ion Batteries Using an Equivalent Electrical Circuit

The modeling of Li-ion batteries may work as a powerful tool for the introduction and widespread testing of this technology in alternative energy storage, hybrid, and electric vehicle applications. In this paper, the authors propose a model for Li-ion batteries that is based on a typical equivalent electrical circuit (EEC) representation of these batteries and valid over a wide frequency range . However, a full parameterization of EEC models was not possible only with the electrochemical impedance spectroscopy (EIS) method, particularly at high charge/discharge currents. Therefore, a method combining EIS and charge/discharge curves analysis has been developed. The simulated and experimental results were compared, and it was demonstrated that the developed method provides accurate predictions of the dynamic behavior of Li-ion batteries over wide state of charge and charge/discharge current range.

A Fully Soft Switched Two Quadrant Bidirectional Soft Switching Converter for Ultra Capacitor Interface Circuits

This paper describes a two quadrant bidirectional soft switching converter for ultra capacitor interface circuits. The total efficiency of the energy storage system in terms of size and cost can be increased by a combination of batteries and ultra capacitors. The required system energy is provided by a battery, while an ultra capacitor is used at high load power pulses. The ultra capacitor voltage changes during charge and discharge modes, therefore an interface circuit is required between the ultra capacitor and the battery. This interface circuit must have good efficiency while providing bidirectional power conversion to capture energy from regenerative braking, downhill driving and the protecting ultra capacitor from immediate discharge. In this paper a fully soft switched two quadrant bidirectional soft switching converter for ultra capacitor interface circuits is introduced and the elements of the converter are reduced considerably. In this paper, zero voltage transient (ZVT) and zero current transient (ZCT) techniques are applied to increase efficiency. The proposed converter acts as a ZCT Buck to charge the ultra capacitor. On the other hand, it acts as a ZVT Boost to discharge the ultra capacitor. A laboratory prototype converter is designed and realized for hybrid vehicle applications. The experimental results presented confirm the theoretical and simulation results.