M. Gerber

Interleaving optimization in synchronous rectified DC/DC converters

Interleaving in synchronous rectifiers can lead to reduced losses in both the active and passive components. However, this depends on selecting the correct number of phases and the correct phase inductance for a particular application and requirements. In this paper optimizing the number of phases and the phase inductance is considered to maximize the interleaved synchronous rectifiers efficiency over the desired operating range. To do this, the RMS currents and losses in the bus capacitors, the phase inductances and the switching devices as a function of the number of phases and duty cycle are considered. Generic equations are presented and used to predict the RMS currents in the passive components with some non-intuitive results especially concerning the bus capacitors. It is shown in the paper, that the optimum number of phases is dependent on the converter parameters such as the phase inductance and operating requirements. Practical results are presented confirming the synchronous rectifier loss model.

A high-density heat-sink-mounted inductor for automotive applications

Passive components, and inductors, in particular, contribute greatly to the overall volume of power electronic converters. These components are normally packaged individually with little concern for the overall system. For high-density switching power supplies it is imperative to minimize the volume to as great an extent as possible which implies that the passive component volume usage needs to be improved. This can be accomplished by applying suitable packaging and cooling techniques to these components. In this paper, two inductor structures finding application in a 2.1-kW synchronous automotive converter are described. The air-gap placement, losses, cooling methods, and thermal profiles are analyzed and verified experimentally with an inductor designed for operation at 85/spl deg/C ambient.

Design and evaluation of an automotive integrated system module

Power electronic systems that are implemented in the automotive environment are expected to operate under harsh electrical and thermal conditions while achieving high power densities. One example of such a power electronic system is the bi-directional 14/42 V DC/DC converter that is utilized in the dual voltage networks of ultra modern vehicles. This paper presents the design and implementation of such an automotive converter as an integrated system module (ISM). The presented prototype achieves a high power density (120 W/in/sup 3/) within the automotive environment while using the engine liquid coolant having a maximum temperature of up to 125 /spl deg/C for cooling. The complete power conversion system is implemented in the ISM requiring dedicated thermal management structures for all the components, both active and passive. An overview of the design and evaluation of the automotive ISM, as well as the implementation of the novel thermal management concept required for the passive components is presented and supported with practical results.

High density packaging of the passive components in an automotive DC/DC converter

In this paper, a very high power density DC/DC converter module for automotive applications is investigated. The 14-V/42-V converter is specified to operate at a power level of 2.1 kW with a water cooled heat sink at 85/spl deg/C. The design and implementation of very high density passive components are discussed. Using the results of the passive component design, a prototype converter is built, achieving a final power density of 170W/in/sup 3/. The thermal performance of the passive components and the converter module under different electrical and thermal excitations is investigated and recorded. Results are presented over the full excitation range.

A very high density, heatsink mounted inductor for automotive applications

Generally, passive components and inductors in particular, contribute greatly to the overall volume of power electronic converters. These components are normally packaged individually with little concern for the overall system. For high density switching power supplies it is imperative to minimise the volume to as great an extent as possible. which implies that the passive component volume usage needs to be improved. This can be accomplished by applying suitable packaging and cooling techniques to these components. In this paper, two inductor structures finding application in a 2.1 kW synchronous automotive converter are described. The airgap placement, losses, cooling methods and thermal profiles are analysed and verified experimentally with an inductor designed for operation at 85/spl deg/C ambient.

Integral 3-D thermal, electrical and mechanical design of an automotive DC/DC converter

Power electronics is finding increasingly more applications in high temperature environments where power density is also a driving factor. The engine compartment of a passenger vehicle is one such example. In this paper, an integral thermal, electrical, and mechanical design of a high power density dc/dc converter operating in the thermally harsh automotive environment is discussed. The interactions and interdependencies between the three design disciplines are considered. It is illustrated how these interactions can be manipulated and used to an advantage in meeting the harsh temperature and high power density requirements of the automotive converter. Packaging and circuit techniques are identified that can be used to this end. Two case studies of a 2-kW 14-V/42-V dc/dc converter for application in the automotive environment are considered. The first prototype achieved a power density of 170 W/in/sup 3/ while the second prototype, operating with a higher environmental temperature achieved a power density of 120 W/in/sup 3/. The experimental structures and practical results are presented. Technology issues concerning the three-dimensional construction of the prototypes that need research attention are also identified.

A System Integration Philosophy for Demanding Requirements in Power Electronics

There is ever increasing interest in system integration in power electronics. However when asked what exactly system integration is, the answers vary greatly. In this paper, system integration in power electronics is considered, both theoretically and practically. This paper shows that system integration is a process that any correctly functioning power electronic system must undergo if it is to operate within its environment. Further, the environment and the boundary conditions that the environment imposes are the reason that a specific power electronic system is implemented as it is. This paper will discuss system integration as well as the factors that influence it and will illustrate that the system integration process is the same irrespective of the boundary conditions with the aid of several examples all of which require a high power density while operating in demanding environments.

System integration in automotive power systems

System integration is becoming ever more important in the design and implementation of power electronics. In this paper, system integration is considered and a definition is presented. Based on the definition, the interdependence of the electrical, the thermal and the spatial design of a system are considered and identified. These interdependencies provide the means to manipulate a system design so that all the specifications (electrical, thermal and spatial) can be satisfied simultaneously by the system. Two case studies, both automotive in nature are presented to illustrate the system integration concept. The first is an integrated system module implementing a high power density 14 V/42 V DC/DC converter and the second is an integrated drive for hybrid vehicles, both implemented with high temperature cooling. Practical results are presented

High temperature, high power density packaging for automotive applications

The automotive industry is pushing power electronic packaging to higher operating and heatsink temperatures while still requiring very high power densities due to limited space. Currently, the power electronics that is implemented within the engine compartment of the vehicle must operate with heatsink temperatures of approximately 85/spl deg/C and this temperature can be expected to increase to 125/spl deg/C in the near future. The high temperature operation of the power electronic structure is fundamentally limited by the employed materials maximum temperatures. A packaging concept is introduced that describes a structure realisation that enables the materials to operate at high ambient temperatures without exceeding their individual maximum temperatures. This in turn allows the complete power electronic structure to operate at a higher system temperature. In this paper, the packaging concept that can be used to meet these difficult requirements of high temperature and high power-density is introduced, discussed and implemented. Two case studies are considered and implemented to illustrate the packaging concept.

A volumetric optimization of a low-pass filter

The low pass filter is a fundamental component of many power electronic systems, for example the output filters of DC to DC converters. The volume of the two components, that constitute the low pass filter, contribute a majority of the final systems volume, thus effecting the overall power density of the system. To be able to reach the high power densities that are required nowadays, the packaging of these components needs to be addressed. A new packaging approach is considered where the main criteria is to increase the packaging density of the low pass filter. The filter is considered volumetrically and the minimum possible volume is derived. The construction and losses of such a filter are also discussed.