Daniel H. Jung

Coil Design and Measurements of Automotive Magnetic Resonant Wireless Charging System for High-Efficiency and Low Magnetic Field Leakage

For wireless charging of electric vehicle (EV) batteries, high-frequency magnetic fields are generated from magnetically coupled coils. The large air-gap between two coils may cause high leakage of magnetic fields and it may also lower the power transfer efficiency (PTE). For the first time, in this paper, we propose a new set of coil design formulas for high-efficiency and low harmonic currents and a new design procedure for low leakage of magnetic fields for high-power wireless power transfer (WPT) system. Based on the proposed design procedure, a pair of magnetically coupled coils with magnetic field shielding for a 1-kW-class golf-cart WPT system is optimized via finite-element simulation and the proposed design formulas. We built a 1-kW-class wireless EV charging system for practical measurements of the PTE, the magnetic field strength around the golf cart, and voltage/current spectrums. The fabricated system has achieved a PTE of 96% at the operating frequency of 20.15 kHz with a 156-mm air gap between the coils. At the same time, the highest magnetic field strength measured around the golf cart is 19.8 mG, which is far below the relevant electromagnetic field safety guidelines (ICNIRP 1998/2010). In addition, the third harmonic component of the measured magnetic field is 39 dB lower than the fundamental component. These practical measurement results prove the effectiveness of the proposed coil design formulas and procedure of a WPT system for high-efficiency and low magnetic field leakage.

Electromagnetic radiated emissions from a repeating-coil wireless power transfer system using a resonant magnetic field coupling

Wireless power transfer technologies have been studied steadily and reached the stage of practical use in recent years. As the commercialized research on the wireless power transfer have been performed, the wireless power transfer system utilizing the repeating-coil have been attempted. Then, the electromagnetic radiated emissions have become an important issue. In this paper, we report the measurement and analysis of the electromagnetic radiated emissions from the repeating-coil wireless power transfer system using a resonant magnetic field. A relationship between the resonance and the transferred power are analyzed with respect to the impedance profile obtained from analytical expressions, simulations and measurements. The results show that the electromagnetic radiated emissions are enhanced at the series resonance peaks of the impedance profile in the repeating-coil wireless power transfer system using a resonant magnetic field coupling in the case of a constant-voltage AC source.

Structure of handheld resonant magnetic coupling charger (HH-RMCC) for electric vehicle considering electromagnetic field

Inductive charging is a convenient method to transfer electrical power from a source to the batteries without any electrical contact. The problem is that inductive charging technologies may have electromagnetic compatibility (EMC) issues caused by leakage magnetic field. In this paper, an inductive charger design for electric vehicles (EVs) named as Handheld Resonant Magnetic Coupling Charger (HH-RMCC) is proposed. The air gap and thickness of the ferrite core are determined considering the core saturation and leakage magnetic field. The maximum value of the simulated magnetic flux density at the distance of 200 mm away from the charger is 2.28 mG and the simulation result of the power transfer efficiency is approximately 99.5%. The simulation results using 3D Finite Element Analysis (FEA) tool show that HH-RMCC satisfies EMF regulation published by the International Commission on NonIonizing Radiation and Protection (ICNIRP) at the frequency of 20 kHz with high performance.

Fault isolation of short defect in through silicon via (TSV) based 3D-IC

Development of through silicon via (TSV) based 3 dimensional integrated circuit (3D-IC) has allowed reduction of form factor and power consumption with higher data transmission speed. Despite the great advantages, various types of defects cannot be avoided in continuously reducing scale of the components. The performance degradation caused by defects has to be analyzed to increase the yield of the products. In this paper, the effect of short defect in TSV channel is analyzed in frequency- and time-domain. A GSG-type daisy-chain structure with eight TSVs per channel is designed for 3D EM simulation and the results are obtained in S-parameter curves and TDR waveforms. Using 2-port analysis, the results from two ends of the channel are compared. The location of short defect is varied for case analysis. Under the assumption that the defect is located closer to one port than the other, the asymmetric structure results in distinguishable S11 and S22. Similarly, TDR waveforms from port 1 and port 2 are compared for fault isolation. By taking the difference between the results from port 1 and port 2, the short defect in TSV channel can be accurately detected and isolated.

Frequency and time domain measurement of through-silicon via (TSV) failure

As a solution to limitlessly growing demand on miniaturization of electronic devices, through silicon via (TSV) based 3-dimensional integrated circuits (3D-IC) have brought another era of technology evolution. However, one of the remaining challenges to overcome is to increase the reliability of the products. Due to the instability of TSV fabrication process, different types of failure may be caused, affecting the performance of 3D-IC. TSV test method is essential for TSV based 3D-IC to be integrated in the products. One of the main failure types is disconnection failure in the channel. The point of defect not only has to be detected, but also has to be localized, so that appropriate channel is chosen to go through the recovery process. By measuring the fabricated test vehicles in frequency and time domain, the location of disconnection along the channel can be detected. S11 and S22 magnitudes are measured for frequency domain analysis. The degrees of decrease in two plots are compared to test how far the signals from each port travel before detecting the disconnection. Applying the similar idea, time domain measurement is analyzed with time-domain reflectometry (TDR) waveforms. The TDR waveforms from port 1 and port 2 are compared by their rising times, which depend on parasitic shunt capacitances within the channel. The values may be quantified for more precise TSV testing.

Contactless wafer-level TSV connectivity testing method using magnetic coupling

With the advent of 3D-IC, Through Silicon Via (TSV) has been highlighted as the key technology for compactly integrating dies of various functions. However, due to the instability in the TSV fabrication process, various types of failure can be resulted, resulting in drastic decrease in the final chip yield with the increase in the number of TSVs and stacked dies. In this paper, we propose a novel contactless wafer-level TSV connectivity testing structure that can detect TSV defects on wafer-level, while overcoming the limitations of the conventional direct probing method. TSVs are aligned and connected as to enable the detection of change in the series capacitance between adjacent TSVs for verification of the TSV defects. Through time- and frequency-domain simulation results, we verified that the proposed structure can successfully detect TSV defects.

Disconnection failure model and analysis of TSV-based 3D ICs

The trend in semiconductor industry is rapidly shifting from 2-dimension to 3-dimension to satisfy the ever-growing demand on the miniaturization of electronic devices. The introduction of through silicon via (TSV) based 3-dimensional integrated circuit (3D-IC) has significantly advanced the technology to realize high speed system with increased functionality. However, challenges remain in reliability of fabrication and testing methods. The size of transistors and interconnections has shrunk to few tens of nanometers, requiring highly advanced technique in the fabrication process. The precision in existing fabrication process is insufficient to reach the acceptable level of chip yield. Thus, TSV failure detection and analysis is essential for 3D-IC technology. One of the main failures that degrades the chip performance is disconnection failure. Disconnection failure may form in any point along the channel, especially in between the stacked layers. Stacked dies with TSVs as interconnects can be analysed by equivalent circuit model. Each component is represented as lumped components according to its material and physical dimensions. A disconnection along the channel is a gap between two conducting materials, which is modelled as series capacitance. The gap between a TSV and the corresponding bump is calculated to analyse its effect on the system; the calculated values for 1 μm, 3 μm and 5 μm gap resulted in 14.07 fF, 4.69 fF, and 2.82 fF, respectively. The modelled components were inserted and S-parameter plots were extracted for analysis.

High-Efficiency PCB- and Package-Level Wireless Power Transfer Interconnection Scheme Using Magnetic Field Resonance Coupling

As technology develops, the number of chips increases while the thickness of mobile products continuously decreases, which leads to the need for high-density packaging techniques with high numbers of power and signal lines. By applying wireless power transfer technology at the printed circuit board (PCB) and package levels, the number of power pins can be greatly reduced to produce more space for signal pins and other components in the system. For the first time, in this paper, we propose and demonstrate a high-efficiency PCB- and package-level wireless power transfer interconnection scheme. We enhance the efficiency by applying magnetic field resonance coupling using a matching capacitor. The proposed scheme can replace a high number of power interconnections with rectangular spiral coils to wirelessly transfer power from the source to the receiver at the PCB and package levels. The equivalent circuit model is suggested with analytic equations, which is then analyzed to optimize the test vehicle design. For the experimental verification of the suggested model, the

Design, implementation and measurement of board-to-board wireless power transfer (WPT) for low voltage applications

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Optimized inverter design of ring oscillator based wafer-level TSV connectivity test (RO-TSV-CT)

-parameter results obtained from the model-based equation and measurement of the designed and fabricated test vehicles are compared at up to 1 GHz. The power transfer efficiency from the source coil to the receiver coil in this scheme is able to reach 85.6%. Finally, we designed and fabricated a CMOS full-bridge rectifier and mounted it on the receiver board to convert the transferred voltage from ac voltage to dc voltage. A measured dc voltage of 2.0 V is sufficient to operate the circuit, which generally consists of 1.5 V devices.