In this paper, a novel LLC-asymmetric half-bridge flyback converter (AHB) that can realize a wide range of voltage gains is proposed. This type of topology utilizes the idea of topology morphing to realize the mode transition between LLC mode and AHB mode by adding a switch. The sharing of the same set of resonant tank parameters for both LLC and AHB can be realized by suitable resonant tank parameter design, which allows this topology to use the AHB mode at low voltage gains and the full-bridge LLC mode (FBLLC) and half-bridge LLC (HBLLC) modes at higher voltage gains, and each topology operates in its more suitable operating range. The design considerations, design ideas of this topology are discussed in this paper. Finally, the performance and realizability of the proposed topology are confirmed by simulation results.

This paper proposes a novel single-stage single-phase transformerless topology based on a buck-boost converter for grid-connected photovoltaic (PV) inverters. The proposed inverter has a wide input voltage range, low total harmonic distortion of current, and effective suppression of common-mode leakage current. The single-input structure ensures that it does not suffer from energy imbalance problems. The new inverter utilizes dead beat control and refines the method of controlling the inverter when the input energy is insufficient. The simulation results verify that the proposed grid-connected PV inverter maintains high grid-connected power quality both during normal operation under conventional conditions and when operating under discontinuous conduction mode (DCM) during energy insufficiency. The simulation models the operating mode of the inverter under abnormal environments, such as load changes and grid voltage transients, which proves that the proposed inverter under dead beat control has a better dynamic performance.

This paper presents the design of an output-series active-clamp flyback high-voltage power supply. By utilizing an output-series connection, the voltage stress on rectifying diodes is reduced. Active-clamp technique is adopted to address issues such as reduced efficiency and high voltage stress on the main switch, which are caused by increased leakage inductance in the transformer due to insulation requirements of high-voltage outputs. The operational principles and design considerations of the converter are introduced, with particular attention given to the transformer's electric field distribution. A prototype is built to validate the feasibility of the system design.

As the search for sustainable, environmentally friendly energy sources continues, DC devices such as new energy-electric vehicles and energy-saving LED lights have been actively promoted. Consequently, the necessity for the DC microgrid in grid system development will become increasingly apparent, and the research on three-terminal output converters is increasing. Besides, double-frequency ripple power is an inherent problem in single-phase power electronic systems. This paper proposes a three-terminal output AC/DC converter with automatic power decoupling and common ground for the DC microgrid as a solution to the issues above. The equivalent circuit has been subjected to a detailed analysis to elucidate its underlying operating principles. Due to the structure of the common ground, the common mode leakage current can be eliminated in this converter. In addition, the implementation of automatic power decoupling enables the replacement of electrolytic capacitors with film capacitors, leading to higher power density and longer lifespan. Furthermore, the employed deadbeat control has a fast dynamic response capability. Finally, the simulation results are presented to verify the theoretical analysis and the performance of this converter.

This article presents a novel transformer-less single-stage buck-boost inverter (SSBBI) utilizing coupled inductors and its dual-mode time-sharing control method. The leakage current can be completely suppressed by connecting the neutral of the electrolytic capacitors to the common ground of the power grid. Besides, only one MOSFET operates at high-frequency in Buck and Boost mode. As a result, in theory, high conversion efficiency can be guaranteed for the proposed inverter. Moreover, compared with conventional Aalborg inverters, the number of switches, diodes, and inductors is further reduced to reduce cost and increase power density. In addition, the operating principle based on equivalent circuits and the control strategy of the proposed inverter are given in this article. As a proof of concept, the simulation results based on PSIM of the proposed SSBBI with different input voltages and output powers and a 110 V power grid are provided.

Virtual oscillator control (VOC) is a grid-forming controller designed for microgrids, where inverters are regulated to mimic the dynamics of weakly nonlinear oscillators. VOC operates in the time domain and offers a faster transient response compared to the virtual synchronous generator. However, conventional VOC implementations often result in reduced power system inertia, which poses a risk to frequency stability due to the lack of inertia. The inertial response is introduced into VOC by integrating the swing equation of a synchronous generator to represent virtual inertia and damping. Unlike real synchronous generators, the parameters of the swing equation can be adjusted in real time to support frequency stability. By employing varying levels of virtual inertia and damping during frequency deviation and recovery, improvements of 10.4% in frequency nadir and 4.9% in the rate of change of frequency are achieved compared to fixed inertia setups. Simulation results confirm the effectiveness of the proposed approach.

3D perception of objects is critical for many real-world applications, such as autonomous cars and robots. Among them, most state-of-the-art (SOTA) 3D perception systems are based on deep learning models. Recently, the research community found that 3D object classifiers on point cloud based on deep learning are easily fooled by adversarial point cloud craft by attackers. To overcome this, adversarial defenses are considered the most effective ways to improve the robustness of deep learning models, and most adversarial defenses on point cloud are focused on input transformation. However, all previous defense methods decrease the natural accuracy, and the nature of the point cloud classifiers itself has been overlooked. To this end, in this paper, we propose a novel adversarial defense for 3D point cloud classifiers that makes full use of the nature of the point cloud classifiers. Due to the disorder of point cloud, all point cloud classifiers have the property of permutation invariant to the input point cloud. Based on this nature, we design invariant transformations defense (IT-Defense). We show that, even after accounting for obfuscated gradients, our IT-Defense is a resilient defense against SOTA 3D attacks. Moreover, IT-Defense does not hurt clean accuracy compared to previous SOTA 3D defenses. Our code will be available at: https://github.com/cuge1995/IT-Defense.

In this paper, the single-stage Maximum Power Point Tracking (MPPT) control strategy for the Aalborg photovoltaic inverter is presented. Aalborg inverter has many advantages, such as high efficiency, wide range of input voltage, minimum voltage drop of the filtering inductors, etc. Nevertheless, it is essentially a “half-bridge” inverter with two input sources, where one source works in MPPT mode, the other is out of control. If without the reasonable parameter design and the proper control, the bus-voltage of this inverter may change greatly, resulting in the serious power oscillation around maximum power point and the reduction of the energy utilization of PV array. In this paper, the MPPT algorithm of two independent PV arrays is proposed, and then the relation between ripple ratio and dc-link capacitance is analyzed. An 110V/50Hz prototype has been constructed. Simulations and experiments show that the proposed control strategy has good steady-state and dynamic performances.