The pulsed current has been proposed as a promising battery charging technique to improve the charging performance and maximize the lifetime for lithium-ion (Li-ion) batteries. However, the effect of the pulsed current charging is inconclusive due to the changeable current mode and conditions. This article systematically investigates the effect of various pulsed current charging modes, i.e., positive pulsed current mode, pulsed current-constant current mode, negative pulsed current mode, alternating pulsed current mode, sinusoidal-ripple current mode, and alternating sinusoidal-ripple current mode on battery performance. Moreover, a comprehensive analysis of the frequency impact on the quality of the current mode is performed. The current modes in this work are evaluated considering the maximum rising temperature, discharging capacity, and charging speed according to experimental results. Furthermore, this work provides guidance for developing pulsed current charging strategies to satisfy future charging requirements.

Some studies verified that the pulsed current charging technique could extend the battery lifetime and improve the charging performance of lithium-ion batteries. However, some researchers are skeptical of this opinion because their studies have not found any advantages of pulsed current charging over conventional constant current (CC) charging. Positive pulsed current (PPC), the most common pulsed current mode, was selected for the investigation in this work. The effect of the PPC with various parameters, including the duty cycle, amplitude, and frequency, on the performance and lifetime of lithium-ion batteries, are investigated by experiments. According to the experimental results, the charging speed, charging capacity, and maximum rising temperature are mainly determined by the duty cycle and amplitude of the PPC. The battery lifetime with PPC under the frequency range from 0.05 Hz to 2 kHz has been verified to be extendable. Moreover, the battery lifetime extension can even be over 100% under a specific frequency PPC compared with CC charging. This is the first work that summarizes the law of the pulse frequency on battery lifetime extension. In the future, the pulsed current is expected to be used in fast charging technologies without compromising battery lifetime.

The pulsed current has been proposed to achieve fast charging and extend the lifetime of Lithium-ion (Li-ion) batteries. However, the optimal condition of the pulsed current is still inconclusive in previous studies. This paper experimentally investigated the effect of the low-frequency Positive Pulsed Current (PPC) charging on the lifetime and charging performance of Li-ion batteries. A two-stage degradation model of Li-ion batteries is developed to determine the inhibitory effect of the PPC on degradation mechanisms at different aging stages. Moreover, the changes in the Internal Resistance (IR) and the Incremental Capacity (IC) curve are provided to thoroughly explore the effects of the PPC on the degradation of Li-ion batteries. Compared with the traditional Constant Current (CC) charging, the lifetime, maximum rising temperature, and energy efficiency of the Li-ion batteries that were cycled by the PPC charging are improved by 81.6%, 60.5%, and 9.1%, respectively, after 1000 cycles. Therefore, low-frequency PPC charging should be considered as a promising charging strategy for Li-ion batteries.

The efficient operation of power-electronic-based systems heavily relies on the reliability and longevity of battery-powered systems. An accurate prediction of the remaining useful life (RUL) of batteries is essential for their effective maintenance, reliability, and safety. However, traditional RUL prediction methods and deep learning-based approaches face challenges in managing battery degradation processes, such as achieving robust prediction performance, to ensure scalability and computational efficiency. There is a need to develop adaptable models that can generalize across different battery types that operate in diverse operational environments. To solve these issues, this research work proposes a TransRUL model to enhance battery RUL prediction. The proposed model incorporates advanced approaches of a time series transformer using a dual encoder with integration positional encoding and multi-head attention. This research utilized data collected by the Centre for Advanced Life Cycle Engineering (CALCE) on CS_2-type lithium-ion batteries that spanned four groups that used a sliding window technique to generate features and labels. The experimental results demonstrate that TransRUL obtained superior performance as compared with other methods in terms of the following evaluation metrics: mean absolute error (MAE), root-mean-squared error (RMSE), and $R^2$ values. The efficient computational power of the TransRUL model will facilitate the real-time prediction of the RUL, which is vital for power-electronic-based appliances. This research highlights the potential of the TransRUL model, which significantly enhances the accuracy of battery RUL prediction and additionally improves the management and control of battery-based systems.

Photovoltaic (PV) energy has been competitive in power generation as an alternative to fossil energy resources over the past decades. The installation of grid-connected solar energy systems is expected to increase rapidly with the fast development of the power electronics technology. As the key to the interface of the PV energy and the grid, power converters should be reliable, efficient and comply with the grid requirements. Considering the nature of PV energy, the power conversion should be flexible (e.g., high step-up DC-DC conversion and harmonic-free DC-AC conversion). Accordingly, many power electronic converters have been reported in literature. Compared with isolated inverters, transformerless inverters show great advantages. This paper thus presents an overview of the transformerless step-up single-phase inverters for PV applications based on the dc-link configurations. Grid-connected PV inverters are classified as constant dc-link voltage structures, pseudo-dc-link voltage structures, pulsating dc-link voltage structures and integrated dc-link voltage structures. The discussion on the composition of different dc-link structures is presented, which provides guidance to select appropriate transformerless inverter topologies for PV applications.

This paper proposes a generalized space vector modulation (SVM) strategy for the three-phase quasi-Z-source inverter (qZSI), which can reduce the inductor current ripples by limiting the peaks in different sectors of the vector space. In the conventional ZSVM6 strategy, the shoot-through interval is divided into six equal parts, which is easy to implement. However, the inductor current ripples are not optimized. Generally, larger inductance is required to limit the current ripples, resulting in poor power density. By contrast, the proposed SVM strategy can minimize the current ripple, while maintaining the same total shoot-through time. Although the shoot-through intervals in the proposed SVM strategy are not identical, it is still easy to implement. The generalized strategy can ensure that the inductor current ripples are always smaller than the peak of the inductor discharging current ripple in a switching cycle. The proposed SVM strategy is derived in details and compared with the conventional ZSVM6 strategy. Simulation and experimental results are presented to verify the effectiveness of the proposed modulation strategy for inductor ripple current reduction.