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In this article, fundamental harmonic analysis (FHA) model is widely used for wireless power transfer due to its physical insight and compact form (for example, 8RL/π2) of diode rectifier equivalent resistance. Because this compact form is valid for continuous conduction mode (CCM), and resonant tank parameters, such as inductance and capacitance, are independent of equivalent resistance, when designing these parameters based on double side LCC FHA model, the selected optimal parameters may not satisfy the CCM prerequisite. This will make actual system characteristics deviate from the FHA model predictions, especially the output voltage and power. Therefore, the original optimal design is invalid, and designer needs to execute a circular design, namely designing resonant tank parameters based on the FHA model, then judging or simulating whether satisfy CCM operation, redesigning parameters if not satisfy CCM. In order to validate the original optimal design even if CCM is not established and make design process straightforward, an effective remedy, which is adding a series LC filter in secondary side, is proposed, and a computational method about the required minimum filter parameter is provided. The effectiveness of the proposed remedy is verified by simulation and experiment. Besides, the computational method is packaged as a program to help researchers design rapidly. [ABSTRACT FROM AUTHOR]

In the application of wireless power transfer system, parameter drift of resonant tank is a general situation which induces natural frequency of primary side or secondary side deviates from switching frequency. This frequency deviation phenomenon will deteriorate load-independent constant current characteristics and decrease output power capacity for an S/S compensation system. This article illustrates the problems caused by frequency deviation through output characteristic analysis and addresses them by a self-tuning method based on switched capacitors (SCs). The proposed self-tuning method requires no resonant parameters such as compensation capacitance and coil self-inductance in advance. Primary and secondary natural frequencies can be both tuned to switching frequency continuously by SCs. The proposed method is verified by a simulation and a 500 W S/S compensation experimental prototype. After completion of self-tuning process, load-independent constant current characteristic is recovered and the output power capacity is boosted, which are in consistent with the theoretical analysis of system output characteristics. The proposed method is also applicable to LCC/S and LCC/LCC topologies. [ABSTRACT FROM AUTHOR]

Zero voltage switching (ZVS) techniques are widely utilized to increase efficiency and reduce electromagnetic interference of wireless power transfer (WPT) systems. Hybrid frequency pacing (HFP) is an excellent modulation method for WPT systems because it can achieve full-load range ZVS without changing the current frequency or adding auxiliary components. Another advantage of HFP is the average switching frequency reduction as decreasing output voltage so that it further reduces switching losses. This article provides an insight into the characteristics of HFP and points out that a large output ripple occurs under some reference conditions. To improve HFP, this article proposes an improved HFP (iHFP) method to minimize output ripple by optimally arranging the hybrid frequencies pulse sequence, but the implementation process of iHFP becomes more complicated. The reason for the unavoidable complicated calculation of HFP is the quantization error. In this viewpoint, this article proposes a modified sigma-delta modulation method with the quantization noise-shaping property for iHFP. As a consequence, the same pulse sequence can be generated by this simple modulator without complex calculations. Experimental results show that iHFP and Σ-Δ  iHFP can reduce more than 60% voltage fluctuations compared with HFP. Under 0.2% input reference resolution, 66%–93% computational time reduction is achieved in going from HFP to Σ-Δ iHFP. [ABSTRACT FROM AUTHOR]

In the wireless power transfer (WPT) control system, estimating the coupling coefficient (k) is an essential step to achieving optimal control over a wide charging range. The estimate required signal of the traditional WPT system is mainly the currentand voltage generated by fundamental. It requires many parameters and complex calculations to estimate k by analyzing these electrical signals, which makes the traditional method of estimating k difficult to achieve good robustness and application in practice. To reduce the process of estimation, a method of estimating k only by the harmonic current is proposed in this article. According to this method, a wide charging range WPT control system is designed. The main feature of the control system is that it is very easy to estimate k because the high frequency harmonic can simplify the circuit. By analyzing the system characteristics under different harmonic currents, the system can achieve optimal control over a wider charging range. In addition, a WPT system that meets the Qi standard is designed and tested. The experimental results show that the original 10 mm Qi standard charging distance can reach 20 mm. [ABSTRACT FROM AUTHOR]

This article presents an $8\times 8$ lattice-reduction-aided (LRA) soft-output multiple-input multiple-output (MIMO) detector for Chinese enhanced ultrahigh throughput (EUHT) wireless local area network (LAN) standard. The preprocessing algorithm combining simplified-sorting Cholesky decomposition and low-complexity decoupled lattice reduction (LDLR) is proposed to reduce computational complexity and latency with parallelism improvement. In addition, K-best detection adopts a sorting-reduced strategy utilizing approximate ordered sequence. Compared with other published LRA K-best detection algorithms, simulation results show that our proposed algorithm has performance improvement. In addition, in order to save hardware resources, a folded K-best architecture and an optimized intermediate storage strategy are introduced. Furthermore, a fully pipelined VLSI architecture is designed in Semiconductor Manufacturing International Corporation (SMIC) 40-nm 1P9M technology to support the $8\times 8.64$ -QAM MIMO-OFDM system. The detector can achieve 3.85-Gb/s data throughput at 641-MHz clock frequency with 0.71- $\mu \text{s}$ latency. The proposed detector is competitive in terms of latency, throughput, and area efficiency to state-of-the-art works and can meet the data-rate requirement of the EUHT standard. [ABSTRACT FROM AUTHOR]

An efficient hybrid method for multiobjective optimization (MO) of time-modulated array (TMA) is proposed. First, by making best use of the convexity in the TMA optimization problem, a set of reference points for Pareto front (PF) are generated by convex programming. Then, with the obtained reference points function as the prior knowledge for the initial strategy of multiobjective particle swarm optimization (MOPSO), the search of the MOPSO is located around the most interested region while the diversity of the population is also guaranteed to achieve a wide spread of PF. With the proposed hybrid method, the multiobjective optimization (MO) of relative large-scale TMA (comparing with other existing TMA MO method) can be achieved in a limited computational budget while the quality of the obtained PF is much better than the traditional nonhybrid method, thanks to the appropriate use of the problem prior knowledge. Examples with 50- and 100-elements linear TMA are presented to demonstrate the robustness of the proposed method to deal with the relative large scale multiobjective TMA optimization problems. [ABSTRACT FROM AUTHOR]

In this paper, a dynamic model based on the sampled-data method is presented for a wireless power transfer (WPT) system. The orders of the derived model are equal to the orders of a system. The modeling is different from the existing dynamic modeling for WPT systems, which almost double the model's order. Furthermore, the systematic analysis process is suitable for any WPT topologies and without the higher harmonics neglected and low-frequency approximation. Meanwhile, the state variables are allowed to vary up to twice the switching frequency, since the half-period symmetry property is exploited. In this paper, the series–series (SS) compensated WPT system is chosen as an example and the large-signal model and the steady-state operation point are determined. The small-signal responses perturbed by the phase-shift angle, switching frequency, and input voltage are obtained. The derived model is more adequate with simulation and experimental validation. [ABSTRACT FROM AUTHOR]

A novel circularly polarized (CP) dielectric resonator antenna (DRA) array is introduced. The DRA element operating at the desired frequency is determined by the dielectric waveguide model (DWM), and two orthogonal modes are generated to excite CP waves. A 4 × 4-element DRA array is then developed. The array is fed by the cavity-backed slotted substrate integrated waveguide, without using extra feeding network. Experimental results show that the array obtains a bandwidth of 240 MHz (9.88–10.12 GHz) for reflection coefficients and axial ratios (ARs) less than −10 dB and 1 dB, respectively. Moreover, the array obtains a 16 dBic peak gain, a −33.6 dB cross-polarization level at the boresight, namely 0.5 dB AR at the center frequency, which demonstrate the desirable array performance. In addition, above 62.5% aperture efficiency and above 90% radiation efficiency are realized over the operating bands, with about 76% peak aperture efficiency and about 94% peak radiation efficiency. The proposed array can be regarded as an element to form large planar arrays, which will be useful in beamforming systems. Our design idea may open a new way for developing high-efficiency large millimeter-wave arrays. [ABSTRACT FROM AUTHOR]

Subarrayed monopulse linear and conformal circular arc arrays with low-sidelobe sum and difference patterns are synthesized. For the monopulse array with a subarray partition consisting of contiguous elements to reduce the cross points, the synthesis problem is first formulated as a constrained optimization problem. Then, by defining an appropriate fitness function to convert the problem into an unconstrained one, the problem is efficiently solved by the differential evolution algorithm under successful-parent-selecting framework. The numerical results of small and large monopulse linear arrays are reported by comparisons with the state-of-the-art techniques. At last, synthesis of a monopulse conformal circular arc array is also investigated based on the same technique. [ABSTRACT FROM AUTHOR]