Hauke van Hoek

Power electronic architectures for electric vehicles

With the aim to asses power electronic architectures for electric vehicles, modeling of power electronics is discussed in this paper. Drive train topologies are introduced, the investigated power electronic components are described, and the modeling process is discussed. On the basis of an example scenario, selected simulation results are presented.

Comparison of a single-phase and a three-phase dual active bridge with low-voltage, high-current output

In this paper, a comparison of a single-phase and a three-phase dual active bridge for electric vehicle application is presented. The converters are used to connect the traction battery stack with the 12V on-board power supply. The characteristic challenges are illustrated on the basis of an application with 2kW rated power. In total, three different design approaches are described and assessed using analytical considerations and simulation results. Finally, the conclusions are verified with measurements of two prototypes.

A systematic comparison of hard- and soft-switching topologies for inductive power transfer systems

This paper provides a comparison of four series-series compensated inductive power transfer systems for contact-less vehicle charging. A systematic comparison between hard-and soft-switching topologies, as well as different operating frequencies, is performed and the impacts on system efficiency and complexity are assessed in detail. In a holistic design process each system is individually optimized for a charging power of 3kW and a variable air gap from 100mm to 170mm at a coil diameter of 500mm. It is shown that the hard-switching topologies are highly attractive in the considered power range even with state of the art semiconductors. By introducing a dual-side controlled topology a superior system efficiency is demonstrated at an operating frequency of 35 kHz.

Enhanced operating strategy for a three-phase dual-active-bridge converter including frequency variation

Recently, it has been shown that the operating modes of a three-phase dual-active-bridge (3ph-DAB) DC-to-DC converter can be altered. This can be used in particular to enhance low load efficiency. The different operating modes show significant differences concerning the utilization of the core material and the required filter effort. In this paper, an enhanced operating strategy including a dynamic variation of the switching frequency is investigated to further optimize the performance of the converter. For a specific electric vehicle application, the efficiency of certain operating points is boosted by up to 1 %. The proposed concept is highly beneficial as it affects the operating points with the highest losses, which potentially reduces the cooling effort.

Advanced Modular Drive Train Concepts for Electric Vehicles

The paper gives a detailed overview on modular drive train concepts and how significant benefits can be obtained with different levels of modularity. The advantages are assessed with respect to the additional effort. Modularity offers an inherent scalability of power and driving range, which enables car concepts to be composed with building blocks. This lifts the boundaries between different car types, as all consist of the same blocks. Obviously, a high level of modularity comes along with standardization of components as well as interfaces and offers a substantially high impact on cost reduction due to the economy of scale. Other important aspects are component integration, increased reliability due to redundancy and impacts of the system voltage levels on the safety effort.

A systematic comparison of various thermal interface materials for applications with surface-mounted (DirectFET TM ) MOSFETs

Increasing power densities of power electronics with reduced volume requires increased efforts in cooling as little surface and material are available for thermal conduction. A systematic comparison of the thermal resistance of a wide selection of thermal interface materials (TIMs) ranging from solid Al2O3 to elastomeric interface materials as well as thermal greases is investigated in this work. In contrast to the ideal testing conditions used by the TIM manufacturers, a practical application setup using a surface-mounted MOSFET (DirectFETTM) pressed on a heatsink is used. Thereby, additional influences on the thermal resistance due to surface finish or non-homogeneous pressure are considered in the results. The effective contacting area as well as different pressure levels are investigated. On the basis of a B6C converter bridge, it will be shown, how the proper choice of TIM affects the mechanical and thermal design of a converter.

Key Components of Modular Propulsion Systems for Next Generation Electric Vehicles

The objective of this paper is to provide an overview of emerging technologies for modular power converter architectures for electric vehicles. Nowadays, the most common electrical drive-train architecture exhibits one single inverter which is directly tied to the battery. As a consequence, only one high-voltage battery module can be applied and the dc-link voltage of the inverter and its apparent power rating is directly dependent on the available battery voltage. To overcome this restriction, modern power converter architectures with a higher degree of freedom have been proposed. These architectures exhibit modular dc-dc converters to allow different battery technologies to be linked to drive inverters operating independently from each other. To make this development feasible, new components and technologies are evolving which enhance the efficiency over mission cycles while ensuring further integration of the power-converter architectures. Wide-bandgap power semiconductors enable high switching frequencies and miniaturization of passive devices. Smart topology enhancements and control methods allow a significant loss reduction, in particular at light loads, resulting in a higher efficiency of the drive train over the entire driving cycle. Highly integrated bidirectional battery charger systems with intelligent charging strategies inhibit battery degradation and provide opportunities for grid stabilization. It is demonstrated how these technologies are realized and implemented to contribute to the development of future electric vehicles.

Performance analysis of an analytical calculation tool for dual-active-bridge converters

The design process of converters usually requires investigations with different abstraction levels. In this paper, an analytical calculation tool for dual-active-bridge DC-to-DC converters is introduced. This tool is used during a pre-simulation design stage. Its calculations are based on idealized current shapes. One of the most important advantages is the high calculation speed: the tool is faster by a factor of 105 to 106 compared to the simulation of an ideal sample-based model. It is capable of including loss descriptions of devices to provide an insight into parameter sensitivity with respect to losses and efficiency. Ultimately, the presented approach can save a significant amount of time within the design process and make subsequent simulations more target-oriented.