SCOPE TO THE 'PHILIPS RESEARCH BOOK SERIES'As one of the largest private sector research establishments in the world, Philips Research is shaping the future with technology inventions that meet peoples' needs and desires in the digital age. While the ultimate user benefits of these inventions end up on the high-street shelves, the often pioneering scientific and technological basis usually remains less visible. This 'Philips Research Book Series' has been set up as a way for Philips researchers to contribute to the scientific community by publishing their comprehensive results and theories in book form.Ad Huijser

Li -ion is the most commonly used battery chemistry in portable applications nowadays. Accurate state-of-charge (SOC) and remaining run-time indication for portable devices is important for the user’s convenience and to prolong the lifetime of batteries. A new SOC indication system, combining the electromotive force (EMF) measurement during equilibrium and current measurement and integration during charge and discharge, has been developed and implemented in a laboratory setup. During discharge, apart from simple Coulomb counting, the effect of the overpotential is also considered. Mathematical models describing the EMF and the overpotential functions for a Li -ion battery have been developed. These models include a variety of parameters whose values depend on the determination method and experimental conditions. In this paper the battery measurement and modeling efforts are described. The method of implementing the battery model in an SOC indication system is also described. The aim is an SOC determination within 1% inaccuracy or better under all realistic user conditions, including a wide variety of load currents and a wide temperature range. The achieved results show the effectiveness of our novel approach for improving the accuracy of the SOC indication.

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Abstract-A new impedance-based approach is introduced in which the integral battery temperature is related to other frequencies than the recently developed zero-intercept frequency (ZIF). The advantage of the proposed non-zero-interceptfrequency (NZIF) method is that measurement interferences, resulting from the current flowing through the battery (pack), can be avoided at these frequencies. This gives higher signal-tonoise ratios (SNR) and, consequently, more accurate temperature measurements. A theoretical analysis, using an equivalent circuit model of a Li-ion battery, shows that NZIFs are temperature dependent in a way similar to the ZIF and can therefore also be used as a battery temperature indicator. To validate the proposed method impedance measurements have been performed with individual LiFePO4 batteries and with large LiFePO4 battery packs tested in a full electric vehicle under driving conditions. The measurement results show that the NZIF is clearly dependent on the integral battery temperature and reveals a similar behavior to that of the ZIF method. This makes it possible to optimally adjust the NZIF method to frequencies with the highest SNR.

Abstract-With the increasing number of voltage conversions that have to be efficiently implemented in a mobile device, the PCB space occupied by switched-mode DC-DC converters with external passive components will become unacceptably high. Therefore, a clear need exists for small-form-factor high-efficiency DC-DC converters having the necessary passive components integrated within one package. This will enable the integration of a DC-DC converter with the load and consequently the system integration of power management. This paper describes the measurement results of an integrated inductive down converter, where the active electronics (power stage and driver circuitry) has been implemented in 0.18-μ μ μ μm CMOS technology and the passive components (output LC filter and decoupling capacitor) have been implemented in a stateof-the-art proprietary passive-integration process technology using high-density trench-MOS capacitors (80 nF/mm 2 ) and an 8-μ μ μ μm thick copper top metallization layer. The active die of the converter has been flip-chipped on top of the passive die to reduce parasitic component values. This yields a System-in-Package (SiP) that achieves a step-down DC-DC conversion without any external components. Due to the limited inductance achievable with the used planar air coil in the acceptable area, the switching frequency of the DC-DC converter has been increased. At the same time, Zero-Voltage-Switching (ZVS) measures have been implemented to reduce the switching losses at this increased frequency. A maximum efficiency of 65% at 80 MHz has been achieved for an input voltage of 1.8 V, an output voltage of 1.1 V and an output current of 100 mA. After explaining the motivation behind integrated power management and the choice for an integrated inductive converter, this paper describes the main design aspects of the realized integrated inductive DC-DC down converter. Next, it presents some details of the used passive-integration process, the design of the passive die including the LC filter and the construction of the SiP. Finally, the measurement results of the converter are discussed and conclusions are drawn.

Abstract-The known methods of State-of-Charge (SoC) indication in portable applications are not accurate enough under all practical conditions. The method presented in this paper aims at designing and testing an SoC indication system capable of predicting the remaining capacity of the battery and the remaining run-time with an accuracy of 1 minute or better under all realistic user conditions, including a wide variety of load currents and a wide temperature range. The basis of the proposed algorithm is current measurement and integration during charge and discharge state and voltage measurement during equilibrium state. One of the main problems in designing an accurate SoC indication system is aging of the battery. A simple method of adapting the maximum battery capacity used in the system with the aging effects will be presented in this paper. A first set of experimental results shows the effectiveness of our novel approach for improving the accuracy of the SoC indication.