PIER Letters | PIER Journals

2024-05-31

PIER Letters

Vol. 120, 39-45, 2024

download: 20

A Topology Reconstruction Based WPT System with CC and CV Outputs Function

Xuebin Zhou , Yonghong Tan , Linhui Wang and Lin Yang

Constant current (CC) charging and constant voltage (CV) charging are the two main charging stages of lithium-ion batteries in wireless charging systems. The traditional LCC-LCC topology has a high degree of design freedom. The conversion from CC to CV output is usually achieved through composite topology or frequency switching, which results in high control complexity and increases system cost. This paper proposes a wireless power transfer (WPT) system with CC and CV output characteristics based on topology reconstruction. Based on the LCC-LCC topology, by introducing one MOSFET in the rectifier and one AC switch which consists of two MOSFETs connected in reverse series to reconfigure the topology, the conversion from CC to CV mode can be achieved without complicated control methods and additional components. In addition, the proposed system works at a fixed operating frequency point, which can effectively avoid frequency bifurcation phenomenon. Therefore, the proposed system features a simple structure, easy control, low cost, and high robustness. In addition, ZPA operation can be realized in both CC and CV modes, ensuring high transmission efficiency. An experimental prototype with a rated power of 480W is built, and a maximum efficiency can reach 93.5%, which verifies the feasibility of the system.

A Topology Reconstruction Based WPT System with CC and CV Outputs Function

2024-05-29

PIER Letters

Vol. 120, 31-37, 2024

doi:10.2528/PIERL24011102

download: 24

Analysis of Slot Antenna Performance for on-Body to in-Body Channel Characterization

Suresh Babu Thandullu Naganathan , Packirisamy Thirumaraiselvan , Anumuthu Priya and Pethaperumal Muthukannan

The propagation study of electromagnetic (EM) waves within a human body is becoming essential due to the growing demand for the design and development of implantable sensing nodes in a body area network (BAN). Many researchers are interested in contributing to the development of propagation models in the ultra-wideband (UWB), i.e. 3.1 to 10.6 GHz, for biomedical applications, as well as the license-free Industrial, Scientific, and Medical (ISM) band. This kind of propagation model is essential in order to design and develop UWB transceivers for in-body, on-body, and off-body communications. This paper looks at the possibility of using a stepped slot patch antenna with a copper ground plane as either an off-body or on-body antenna by comparing measurements taken on a liquid human phantom. In addition, we use the empirical data to propose a statistical model.

Analysis of Slot Antenna Performance for On-body to In-body Channel Characterization

2024-05-29

PIER Letters

Vol. 120, 23-29, 2024

doi:10.2528/PIERL24021502

download: 17

Control Signals for NOMA-Vlc Systems

Safwan Hafeedh Younu and Mohamad A. Ahmed

In wireless communication systems, a control signal (CS) plays a vital role in managing the connection between transmitters (Txs) and the user equipment (UEs). This work presents CSs for non-orthogonal multiple access (NOMA)-based on visible light communication (VLC) systems. Moreover, pairing schemes, successive interference cancellation (SIC), and load balancing are considered with the NOMA-VLC technique for enhancing the entire performance. The CSs, which are single tones or can be described as unmodulated signals, are exploited to estimate the channel between Txs and UEs, and to evaluate the amount of interference at each UE. Thus, a controller, which is employed to manage the connections between Txs and UEs, can balance the load between Txs based on the level of interference at each UE. Each Tx is allocated a unique CS, i.e. a single-tone frequency. A power measurement unit (PMU) is utilized at each UE for measuring the power of each CS. Therefore, the controller divides the UEs into small groups based on the feedback signals from the PMU, then each group is connected to one Tx. Besides, CSs are used to find the optimum number of UEs that can be served by each Tx with a particular data rate of 50 Mbps and with an acceptable error probability of 10^-6, by utilizing on-off keying (OOK) modulation scheme.

2024-05-22

PIER Letters

Vol. 120, 15-21, 2024

doi:10.2528/PIERL24041202

download: 88

Optically Transparent Broadband Microwave Absorber with Tunable Absorptivity Based on Graphene-ITO Structure

Shuomin Zhong , Enbang Yu , Yu Zhang , Xianjia Chen , Zi-Wei Zheng , Qiping Lin and Sailing He

In this study, we present a novel broadband microwave absorber that is both optically transparent and capable of dynamically adjusting its absorptivity. The absorber is composed of a graphene sandwich structure (GSS), a polyvinyl chloride (PVC) layer, an indium tin oxide (ITO) layer, another PVC layer, and an ITO ground plane, arranged in a top-to-bottom configuration. This unique design allows for a working bandwidth of 6.8 GHz to 14.0 GHz, with absorption levels ranging from 95% to 60%, achieved by varying the impedance of the GSS from 1000 Ω/sq to 200 Ω/sq through tuning the bias voltage. By utilizing materials with high optical transmittance, this nonpatterned device maintains exceptional optical transparency. Furthermore, by incorporating additional ITO layers with different impedances at equal intervals, this multilayer design can be extended to create an ultra-broadband absorber covering a range of 5.28-39.52 GHz. This is made possible due to the dispersionless resistance of nonpatterned graphene and ITO sheets in the microwave spectrum. This transparent wideband microwave absorber, with tunable absorptivity, holds great potential for a wide range of applications in broadband and intelligent stealth technology.

Optically Transparent Broadband Microwave Absorber with Tunable Absorptivity Based on Graphene-ITO Structure

2024-05-21

PIER Letters

Vol. 120, 7-13, 2024

doi:10.2528/PIERL24030408

download: 50

Importance of Functional Parameters on the Effective Operation of Resonant Multi-Receiver Wireless Power Transfer System

Pragyan P. Mohanty , Suraj Kumar Panigrahi , Sushree Sangita Biswal , Sivnarayan Bhuyan , Durga Prasanna Kar , Renu Sharma and Satyanarayan Bhuyan

The magnetic resonance coupling based wireless power transfer (WPT) technology has been of great interest due to its usefulness and persistent characteristics in powering multiple devices simultaneously. However, it is the foremost challenge to make possible easy access and manage the effective power transmission to the multiple gadgets through the WPT technology. In order for the multi-receiver system to run at its most favourable operational area, a prompt access is necessary at this point to identify the appropriate selection of functional parameters. Thus, a circuit model analysis has been put forward, and the influences of functioning parameters such as electric load at the receivers, mutual coupling between the coils, frequency of operation on the system's performance indicators like input power, power at the receiver's load, power transfer efficiency at individual receiver, and moreover the input impedance of the system have been investigated. The perception has been validated through a bench-top experimental setup. The observed experimental result closely matches the theoretical data derived from the circuit model. The outcomes are crucial which may provide the important selection criteria for the effective operation and creation of successful electromagnetic coupling based multi-receiver WPT system.

Importance of Functional Parameters on the Effective Operation of Resonant Multi-receiver Wireless Power Transfer System

2024-05-21

PIER Letters

Vol. 120, 1-6, 2024

doi:10.2528/PIERL24031107

download: 91

Metamaterial-Based Compact UWB Bandpass Filter Using Substrate Integrated Waveguide

Senathipathi Udhayanan and Krishnan Shambavi

A compact ultra-wideband (UWB) bandpass filter is realized with the combination of dual-split square complementary split ring resonator (DSS-CSRR) and substrate integrated waveguide and is investigated in this paper. Three DSS-CSRRs are carved on the top and bottom layers of SIW to achieve the required passband and enhance the selectivity of the filter. Slots are etched in the ground to improve the return loss characteristics and to lower the insertion loss. The proposed filter offers a fractional bandwidth of 107% (3.1-10.3 GHz) and an insertion loss range of 0.6-1.6 dB in the entire passband. The prototype was fabricated on an FR-4 substrate, with dimensions of 0.3λ_gL × 1.06λ_gW. The group delay variation is almost flat over the entire passband. The prototype was fabricated and validated the measured results.