Characterizing and modeling methods for power converters

“Stable power delivery is becoming increasingly important in modern electronic devices, especially in applications with stringent requirements of its form factor. With the evolution of technology, the switching frequency in a power converter is pushed to a higher frequency range, e.g., several MHz or even higher, to decrease its size. However, the loss generated in the converter increases drastically due to the high switching frequency. In addition, a wide-band feedback controller is required to accommodate the high switching frequency in the converter. We focus on the characterization or modeling of the feedback control circuits and critical components in a switching power converter. A transient-simulation-oriented averaged continuous-time model is proposed to evaluate the transient output noise of a buck converter. The proposed modeling method is developed with time-domain waveforms, which enables a generalized modeling framework for current-mode controllers with constant and nonconstant switching frequencies. In this work, we mainly focus on characterization for two types of components: the switching components, including Si MOSFETs and GaN High-electron-mobility transistor (HEMT), and the magnetic core in an inductor. For the characterization of switching components, a set of test fixtures are designed to characterize the equivalent circuit of Si MOSFETs and GaN HEMTs. The frequency-dependent behaviors of Si MOSFETs are observed, which invalidate the conventional modeling methods for MOSFETs, especially for radiated emission (RE) prediction. For the characterization of magnetic cores, two different probe calibration methods are demonstrated. Accurate phase discrepancy characterization is allowed with the proposed method, which overcomes the main limitation in the conventional two-winding method. In addition, the proposed method supports wide-band loss measurement without resonance tuning, which supports core loss measurement for non-sinusoidal excitation”--Abstract, page iv

Green innovation for the ecological footprints of tourism in China. Fresh evidence from ARDL approach

This study’s objective is to analyze ecological footprints that exist among China’s economic growth, energy consumption, carbon dioxide emissions, and the revenue that is generated from tourism in other countries. The years 1995 through 2020 are the focus of this particular research endeavor. The relationship between tourism and carbon emissions has been discovered by a large number of researchers; nevertheless, the findings have been inconsistent and do not give a clear picture of the situation. We can only hope that the results of the study will improve the existing body of knowledge on tourism and the quality of the surrounding environment. Throughout the whole of this investigation, the autoregressive distributed lagged (ARDL) model was used to explore both long-run and short-run estimations. A dynamic ordinary least squares (DOLS) model was used in the study to arrive at long-term estimations that could be relied upon. Even though money from tourism does not have a substantial influence on the quality of the environment in China, growth and increasing energy usage are primary donors to carbon emissions in the nation. ARDL model’s long-term projections were shown to be correct by the DOLS approach, which offered this validation. The results of the research provide fresh insights into the body of knowledge that has been accumulated on the subject of the linkage between tourism and the natural environment. Because the receipts from tourism do not have any significant negative exteriority toward the environment, energy usage is an important element of environmental degradation and policymakers should prioritize the development of the tourism sector over energy-focused manufacturing activities to maintain the growth of the nation in the upper quartiles. This is because tourismdoes not have any significant negative externalities on the environment. Sustainable tourism minimizes environmental and cultural damage while boosting profits. Developing the appropriate technology, physical infrastructure, and human capital requires money, time, and effort

Efficient and Accurate Phase-Measurement Method for Core-Loss Characterization

Accurate core-loss characterization is essential to push the power density of power converters to their limits. However, existing core-loss measurement methods still have some limitations, such as a slow test speed and a complex probe calibration procedure. In particular, accurate phase-difference measurement is time-consuming because a fast Fourier transform analysis with a kHz-range frequency interval is typically applied to reduce the influence of noise. An automated measurement system for magnetic core-loss characterization is described in this paper. An accurate phase-detection block with programmable attenuators is developed to measure the phase difference between voltage and current waveforms. The proposed system considerably improves the test speed while providing comparable accuracy to the existing method

Audio-visual child-adult speaker classification in dyadic interactions

Interactions involving children span a wide range of important domains from learning to clinical diagnostic and therapeutic contexts. Automated analyses of such interactions are motivated by the need to seek accurate insights and offer scale and robustness across diverse and wide-ranging conditions. Identifying the speech segments belonging to the child is a critical step in such modeling. Conventional child-adult speaker classification typically relies on audio modeling approaches, overlooking visual signals that convey speech articulation information, such as lip motion. Building on the foundation of an audio-only child-adult speaker classification pipeline, we propose incorporating visual cues through active speaker detection and visual processing models. Our framework involves video pre-processing, utterance-level child-adult speaker detection, and late fusion of modality-specific predictions. We demonstrate from extensive experiments that a visually aided classification pipeline enhances the accuracy and robustness of the classification. We show relative improvements of 2.38% and 3.97% in F1 macro score when one face and two faces are visible, respectively.Comment: In review for ICASSP 2024, 5 page

Fixture Design for Parasitic Capacitances of Mosfets for Emi Applications

Due to the fast-switching nature of modern power converters, up to hundreds of MHz of common-mode noise can easily be generated. The characterization of switching components, e.g., Si MOSFETs, is essential for noise reduction. However, limited by the bandwidth of instruments, the voltage-dependent capacitances of high voltage MOSFETs are typically characterized at approximately 1 MHz, which is insufficient for EMI applications. In this paper, the measurement method and the test fixtures are presented. The measurement bandwidth is pushed to 30 MHz and higher, and frequency-dependent capacitances of a MOSFET are observed through measurements

An Analysis on the Effectiveness of 2 and 3 Terminal Capacitors in PDN Design

The Parasitic Inductance of a Capacitor Depends on its Physical Structure. Due to the Geometry of 3-Terminal Capacitors, They Boast a Lower Parasitic Inductance Compared to 2-Terminal Capacitors of the Same and Possibly Smaller Package Sizes. While the Parasitic Inductance of a Single 3-Terminal Capacitor May Be Lower, using Multiple 2-Terminal Capacitors May Result in Similar Performance. in This Work, the Inductance of 2-Terminal (0201, Nominal 2.2 UF) and 3-Terminal (0402, Nominal 4.3 UF) Capacitors is Extracted and Compared through Measurements. from Our De-Embedding Method and Characterized Capacitors, the Inductance of 2-Terminal Capacitors is Only About 20 PH Higher Than the Characterized 3terminal Capacitor. on a Power Net of a Real Product, 3-Terminal Capacitors of the Same Type as Characterized Were Replaced with 2-Terminal Capacitors of the Same Type as Characterized. from Measurement Results, the Measured Inductance at 100 MHz is Lower by Only About 3.45 PH, or 2.62%, When using 3-Terminal Capacitors

Analysis and Introduction of Effective Permeability with Additional Air-Gaps on Wireless Power Transfer Coils for Electric Vehicle based on SAE J2954 Recommended Practice

The wireless power transfer (WPT) method for electric vehicles (EVs) is becoming more popular, and to ensure the interoperability of WPT systems, the Society of Automotive Engineers (SAE) established the J2954 recommended practice (RP). It includes powering frequency, electrical parameters, specifications, testing procedures, and other contents for EV WPT. Specifically, it describes the ranges of self-inductances of the transmitting coil, the receiving coil, and coupling coefficient (k), as well as the impedance matching values of the WPT system. Following the electrical parameters listed in SAE J2954 RP is crucial to ensure the EV wireless charging system is interoperable. This paper introduces a method for adjusting the effective permeability of the ferrite blocks in the standard model, to tune the self-inductance of the coils as well as the coupling coefficient. To guarantee the given values of the self-inductance of the coil and coupling coefficient matched those in the standard, we slightly modified the air-gap between the ferrite tiles in a specific region. Based on this method, it was possible to successfully tune the self-inductance of the transmitting coil and receiving coil as well as the coupling coefficient. The proposed method was verified by simulation and experimental measurements