Identifying PV module mismatch faults by a thermography-based temperature distribution analysis

Photovoltaic solar power generation is proven to be effective and sustainable but is currently hampered by relatively high costs and low conversion efficiency. This paper addresses both issues by presenting a low-cost and efficient temperature distribution analysis for identifying PV module mismatch faults by thermography. Mismatch faults reduce the power output and cause potential damage to PV cells. This paper firstly defines three fault categories in terms of fault levels, which lead to different terminal characteristics of the PV modules. The investigation of three faults is also conducted analytically and experimentally and maintenance suggestions are also provided for different fault types. The proposed methodology is developed to combine the electrical and thermal characteristics of PV cells subjected to different fault mechanisms through simulation and experimental tests. Furthermore, the fault diagnosis method can be incorporated into the maximum power point tracking (MPPT) schemes to shift the operating point of the PV string. The developed technology has improved over the existing ones in locating the faulty cell by a thermal camera, providing a remedial measure and maximizing the power output under faulty conditions

An integrated switched reluctance motor drive topology with voltage-boosting and on-board charging capabilities for plug-in hybrid electric vehicles (PHEVs)

This paper presents a new topology of switched reluctance motor (SRM) drive for plug-in hybrid electric vehicles (PHEVs). Six operating modes can be achieved as a result. Three of those modes are applied for driving and the others for charging. During the driving mode, the topology can be converted to a four-level one. During the charging mode, two battery packs are charged in parallel with the boost circuit by the external AC source or generators. The main contributions of the proposed topology are as follows: 1) A four-level converter is formed by adopting different ways of connection (series or parallel) of the two battery packs (or the two capacitors), which can accelerate the excitation and demagnetization procedures of SRMs. Moreover, the topology contributes to decreasing the switching losses and extending the constant torque region to improve the drive performance as well. 2) The state of charge (SOC) of the two battery packs (or the voltages of two capacitors) can keep balance on their own by parallel operation of the two battery packs. Furthermore, a detailed comparison between two drive modes of the proposed topology and asymmetric half bridge inverters is undertaken with simulation and experimental studies, the results of which demonstrate the validity of the proposed topology

Energy-efficient Integrated Sensing and Communication System and DNLFM Waveform

Integrated sensing and communication (ISAC) is a key enabler of 6G. Unlike communication radio links, the sensing signal requires to experience round trips from many scatters. Therefore, sensing is more power-sensitive and faces a severer multi-target interference. In this paper, the ISAC system employs dedicated sensing signals, which can be reused as the communication reference signal. This paper proposes to add time-frequency matched windows at both the transmitting and receiving sides, which avoids mismatch loss and increases energy efficiency. Discrete non-linear frequency modulation (DNLFM) is further proposed to achieve both time-domain constant modulus and frequency-domain arbitrary windowing weights. DNLFM uses very few Newton iterations and a simple geometrically-equivalent method to generate, which greatly reduces the complex numerical integral in the conventional method. Moreover, the spatial-domain matched window is proposed to achieve low sidelobes. The simulation results show that the proposed methods gain a higher energy efficiency than conventional methods

Networked Collaborative Sensing using Multi-domain Measurements: Architectures, Performance Limits and Algorithms

As a promising 6G technology, integrated sensing and communication (ISAC) gains growing interest. ISAC provides integration gain via sharing spectrum, hardware, and software. However, concerns exist regarding its sensing performance when compared to dedicated radar systems. To address this issue, the advantages of widely deployed networks should be utilized, and this paper proposes networked collaborative sensing (NCS) using multi-domain measurements (MM), including range, Doppler, and two-dimension angle of arrival. In the NCS-MM architecture, this paper proposes a novel multi-domain decoupling model and a novel guard band-based protocol. The proposed model simplifies multi-domain derivations and algorithm designs, and the proposed protocol conserves resources and mitigates NCS interference. To determine the performance limits, this paper derives the Cram\'er-Rao lower bound (CRLB) of three-dimension position and velocity in NCS-MM. An accumulated single-dimension channel model is used to obtain the CRLB of MM, which is proven to be equivalent to that of the multi-dimension model. The algorithms of both MM estimation and fusion are proposed. An arbitrary-dimension Newtonized orthogonal matched pursuit (AD-NOMP) is proposed to accurately estimate grid-less MM. The degree-of-freedom (DoF) of MM is analyzed, and a novel DoF-based two-stage weighted least squares (TSWLS) is proposed to reduce equations without DoF loss. The numerical results show that the performances of the proposed algorithms are close to their performance limits