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Because a transmitter-side controller of an inductive power transfer (IPT) system cannot directly measure its load conditions, i.e., receiver-side output voltages and currents, wireless communications are commonly used in many IPT systems. However, the wireless communication can cause a devastating failure of the IPT system because of its tens of milliseconds delays and frequent data losses. The mismatch between the transmitted and the received power can destroy the receiver-side power converters. In this article, receiver-side load voltage and current observers for a series–series tuned IPT system are proposed using the well-known disturbance observer theories. A load current observer that has a 10 kHz estimation bandwidth and a load voltage observer that has a 200 Hz bandwidth are proposed. The estimated load voltage and current have much faster dynamics than the wireless feedback signals without any data loss. Therefore, the proposed observers can bring significant advances in reliability and performance of the IPT system. Design guidelines for the observers that have low steady-state errors and fast dynamics are suggested. The theoretical performances of the proposed observers are evaluated by simulations and experiments. The simulated frequency- and time-domain responses of the proposed observers are consistent with the theoretical results. An experimental testbed was built to evaluate the proposed observers. The estimated current follows its actual value in 0.1 ms and the estimated voltage follows its measured value in 4 ms as expected from the simulations. [ABSTRACT FROM AUTHOR]

Solid-state transformers (SSTs) utilize multiple isolated dual-active-bridge (DAB) converters to deliver power from a medium-voltage ac or dc grid to low-voltage dc or ac loads. The DAB converter is a key component of SSTs. This study proposes a novel SST with loosely coupled resonant DABs (LCR-DAB) utilizing loosely coupled inductive power transfer (IPT) coils instead of high-frequency (HF) transformers. Unlike HF transformers, the large air gap between the primary and secondary coils enables easier packaging and high-voltage insulation of the proposed LCR-SST system. Series–series compensated symmetric resonant tanks are selected for the proposed IPT system. The impact of the phase-shift angle and the circuit parameters on the input impedance, efficiency, and power transfer direction of the proposed LCR-DAB is investigated. By performing theoretical analyses, a circuit parameter design method for LCR-DAB is proposed. In addition, a new design approach for low-loss coils of the LCR-DAB is investigated using finite-element analysis results. The proposed LCR-DAB and SST topologies are evaluated using the experimental results. The coil-to-coil and dc-to-dc efficiencies of a single LCR-DAB were 97.4% and 96.7%, respectively, over an air gap of 3 cm. The dc-to-dc efficiency of the three-level LCR-SST was 95.2% at 2.4 kW. [ABSTRACT FROM AUTHOR]

We demonstrate a novel method using electric field cycling to induce a phase transition in HfxZr1−xO2 to reach the morphotropic phase boundary of tetragonal and orthorhombic phase. Conventional methods used to induce the phase transition, such as high temperature annealing, cannot be used with the DRAM cell capacitor fabrication process because it associates with grain enlargement, increased leakage current, and a narrow process margin due to the metastability of the morphotropic phase boundary. To achieve an morphotropic phase boundary in HfxZr1−xO2 without high temperature annealing and without increasing leakage current, we propose a two-step process, using low temperature annealing to form the tetragonal phase and electric field cycling to achieve the morphotropic phase boundary of tetragonal and orthorhombic phase in HfxZr1−xO2 film. This approach enabled us to achieve both low voltage with high dielectric k value, and low leakage current, meeting the requirements for the next-generation DRAM cell capacitor dielectric materials. [ABSTRACT FROM AUTHOR]

A control-oriented circuit model of an inductive power transfer system is needed to design a high-performance controller. In this article, a dq synchronous reference frame model of a series–series tuned resonant inductive power transfer system is proposed. A single-phase dq modeling technique for a resonant converter is used to derive the model. The proposed control-oriented model clearly demonstrates the cross- and mutual-coupling between the state variables of the wireless power transfer system. It is interesting to note that the proposed model is similar to a dq synchronous reference frame model of a three-phase induction motor. The well-known controller design methods, such as proportional-integral controller design, manipulated input decoupling, disturbance input decoupling, state observers, and disturbance observers, etc. can be extended to the inductive power systems with the proposed model. The large- and small-signal responses of the transmitter current versus its input voltage are identified. Considering the frequency response, a new transmitter current controller that has a control bandwidth of 500 Hz is designed to show the validity of the proposed model. The proposed model and the controller are evaluated using simulated and experimental results. The simulated open- and closed-loop frequency responses of the model agree well with the theoretical bode plots of them. Also, the experimental results show that the proportional-integral with feedforward input controller regulates the transmitter current within 1 ms for three conditions: a step change of the reference, a step change of the load, and a step change of the mutual-coupling. [ABSTRACT FROM AUTHOR]

Steel-reinforced concrete has been widely used in the construction of railways because of its robustness and low maintenance cost. This paper focuses on the analysis of unwanted losses in a reinforced concrete track when a high-power online wireless power transfer system is installed on it. Induced dielectric loss in the concrete, and eddy current and hysteresis losses in the reinforcing steel bar are calculated using analytic equations and finite-element analysis. Among the three sources of loss, a dominant one is identified in the first three sections of this paper. It is shown that the dielectric loss in the concrete and the hysteresis loss in the reinforcing bar do not have a critical impact on the efficiency. However, it is found that the eddy current loss of the reinforcing bar is dominant over the other two losses. Furthermore, the eddy current loss of the reinforcing bar overwhelmed the ohmic loss of a transmitter coil if the transmitter coil is not located in a proper position on the concrete track. The theoretical results are evaluated experimentally using a 7-m-long test bed. When the transmitter coil is located 0.14 m above the reinforcing bar, the measured eddy current loss of the steel bar is 3 kW while the Ohmic loss of the transmitter coil is 1.5 kW. As the distance between the transmitter coil and the steel bar increases, the eddy current loss of the bar decreases rapidly. From the simulation and the experimental evaluation of the loss, guidelines for installing a transmitter coil on a reinforcing bar for an in-motion wireless power transfer system are suggested in this paper. [ABSTRACT FROM AUTHOR]

An advanced gate stack of Y-doped ZrO2 high-k dielectric is demonstrated for Ge MOSFETs. ZrO2 is implemented due to its high-permittivity (high-k) value, and additional Y is doped into the ZrO2 to enhance interfacial properties. The gate stack of ZrO2 with 2~4% Y doping shows improved electrical properties, achieving an EOT of 0.67 nm, a low interface trap density ($\text{D}_{\textsf {it}}$) of $\textsf {1.2}\,\,\times \,\,\textsf {10}^{\textsf {12}}$ eV−1cm−2, a record-low gate leakage current of $\textsf {1.14}\,\,\times \,\,\textsf {10}^{-\textsf {7}}$ A/cm2 at −1V, and peak mobility of $\textsf {68 cm}^{\textsf {2}}/\textsf {V}\cdot \textsf {s}$. The proposed gate stack would enhance transistor speed and save power consumption of Ge MOSFETs. [ABSTRACT FROM AUTHOR]

This paper proposes a fork-shaped electrode (FSE) pattern that has high linearity and high spatial accuracy of the extracted touch coordinates for large-sized touch screen panels (TSPs). The proposed FSE pattern has a large variation in mutual capacitance ( $\Delta \text{C}_{\mathbf {M}}$ ) and shows similar $\Delta \text{C}_{\mathbf {M}}$ distributions in various touch directions, thus improving the linearity and spatial accuracy of the extracted touch coordinates. The performances of the proposed FSE pattern were verified by carrying out both simulation and measurement using a 32-inch capacitive TSP with a 12 mm electrode pitch, and compared with those of the conventional Manhattan- and diamond-shaped electrode patterns. The measurement results show that the linearity and spatial accuracy of the extracted touch coordinates are improved by more than 14.40% and 9.64%, respectively, when compared with those achieved in the conventional electrode patterns. [ABSTRACT FROM AUTHOR]

This paper proposes an analog front-end (AFE) IC using a multiple-frequency driving method (MFDM). The proposed AFE IC achieves a high signal-to-noise ratio (SNR) by using an external noise spectrum and locating the frequencies of the excitation signals in low-noise regions. In addition, it employs the MFDM to increase the frame rate by simultaneously sending excitation signals having multiple frequencies to the touch screen panel (TSP). The proposed AFE IC extracts the coordinates of the finger as well as the coordinates, pressure, and tilt angle of the active stylus with the force gauge and gyro sensor. The proposed AFE IC and active stylus were fabricated in a 0.13- \mu \textm standard CMOS process. The measurement results show that the proposed AFE IC achieves a frame rate of 3.9 kHz, and SNRs of 61.0 and 50.1 dB when a finger and active stylus are used, respectively. In addition, the pressure and tilt angle of the active stylus are expressed with 6-bit resolution. A capacitive touch system with the proposed AFE IC is demonstrated with a 65-in $104\times 64$ TSP using ten fingers and the active stylus with the pressure and tilt angle. [ABSTRACT FROM AUTHOR]

In this paper, we analyze the vibration and noise characteristics of the basic and skewed models of permanent brushless direct current (BLDC) motor. The electromagnetic characteristics of the basic model are analyzed by the finite-element method. We analyzed the electromagnetic characteristics for skew angles from 15° to 25°. The skew angle was selected based on the analytical results of the electromagnetic characteristics. We analyzed the characteristics of radial force density for the basic model and the skewed model. The vibration and noise characteristics were analyzed through the mechanical harmonic analysis of the radial force and tangential force generated in the motor. We developed the basic and skewed models, and performed vibration and noise tests. The validity of this analysis is verified by comparing the simulation results with the actual test results of the model. Finally, for the optimal design of the BLDC motor considering vibration, the design variables such as teeth shoe length, yoke thickness, and teeth thickness were used. Based on the results of vibration analysis, the final model is derived and its performance is described. [ABSTRACT FROM AUTHOR]

A high-power online wireless power transfer system has been investigated intensively in recent years. However, no literature has focused on the design methodology of the high-power online wireless power transfer system with low flux density, high efficiency, and high control stability. This paper proposed a new design methodology for a 300-kW, over 96 % coil-to-coil efficiency, International Commission on Non-Ionizing Radiation Protection's safety regulation compatible online wireless power transfer system. Using finite-element analysis and experimental results, the proposed design methodology has been evaluated. [ABSTRACT FROM PUBLISHER]

In this paper, we develop a self-organizing mechanism for spectrum breathing and user association in cellular networks employing frequency reuse patterns. Specifically, our focus is on flow-level cell load balancing under spatially inhomogeneous traffic distributions. Our work adaptively changes the spectrum bandwidth of each base station (BS) so that spectrums of BSs breathe in and out in order to balance the loads of BSs. Spectrum breathing is further combined with delay-optimal user association for better load balancing. Our problem is challenging because the problem is not a convex optimization. To tackle the difficulty, we decouple spectrum breathing and user association and propose an iterative algorithm that always converges to a fixed point, which is possibly an optimal solution. We show that spectrum breathing dominates a family of $\alpha$-optimal user association in cell load balancing. Surprisingly, the flow-level delay performance under spectrum breathing gets even better as spatial traffic distribution becomes unbalanced, which is not the case of $\alpha$-optimal user association. Our extensive simulations confirm that spectrum breathing significantly improves the system performances: decreasing the delay more than 10 times or increasing the admittable traffic load by more than 125%. Furthermore, spectrum breathing outperforms full frequency reuse when spatial traffic distribution is inhomogeneous. [ABSTRACT FROM PUBLISHER]

Design and fabrication of a 1-MW inductive power transfer (IPT) system that supplies power to the vehicle in real time without any battery charge is proposed for a high-speed train. The IPT system consists of a 1-MW resonant inverter, a 128-m transmitter, four pickups, including rectifiers, and a wireless feedback network to maintain a constant output voltage of the pickups. The operating frequency of the system is 60 kHz to achieve efficient power transfer with a large air gap. The measured efficiency of the IPT system at the 818-kW output power of the pickups for the 5-cm air gap is 82.7%. The electromagnetic field and the induced voltage at the rail are also measured for safety evaluation. The fabricated IPT system was adapted to the high-speed train, and the train successfully accelerates to a speed of 10 km/h according to startup procedures. [ABSTRACT FROM PUBLISHER]