Search Results (111)

With the increasing penetration of renewable energy systems, multilevel inverters have been widely adopted to meet the growing demand for high-power and high-quality energy conversion. Among various multilevel topologies, cascaded H-bridge multilevel inverters (CHMIs) are particularly attractive due to their modular structure and improved output voltage quality. However, the increased number of power semiconductor devices and switching states significantly complicates fault diagnosis under practical operating conditions. Currently, most existing neural networks for fault diagnosis are manually designed based on domain expertise. This may limit their adaptability to task-specific fault patterns as well as edge-side inference performance. To reduce the dependence on manually designed diagnostic networks, an edge-oriented fault diagnosis framework based on differentiable architecture search (DARTS) is proposed to automatically design task-specific diagnostic networks. A simplified special cell search strategy is adopted to improve search efficiency and facilitate practical deployment. The searched architectures are lightweight and suitable for deployment on edge platforms. The experiments show that the proposed method achieves an average diagnostic accuracy of 99.44% on the test set under the RL load of $(7\mathrm{\Omega },6\mathrm{mH})$. Furthermore, the searched model contains only 0.2417 M trainable parameters, and edge deployment experiments on the Jetson Orin Nano platform show low-latency inference capability. Full article

The increasing penetration of inverter-based renewable energy resources, especially photovoltaic (PV) systems, has decreased the available system inertia and introduced challenges in maintaining stable grid-forming operation. This paper presents a grid-forming photovoltaic multilevel inverter (MLI) with a modified delta-connected cascaded H-bridge (CHB) multilevel configuration. The proposed system decreases the number of semiconductor switches and provides inherent voltage balancing, while also achieving high power quality, rendering it suitable for grid-forming applications. Each H-bridge cell is connected to an isolated Cúk converter to enable maximum power point tracking (MPPT) of distributed PV modules, allowing for flexible and modular DC-side integration. The proposed MLI operates as a virtual synchronous generator. A control scheme is proposed to attain grid-forming capability, hence providing stable voltage and frequency support. Moreover, a DC-link voltage regulation strategy is also developed to maintain the DC-link voltage at the reference voltage. A detailed mathematical model is developed to characterize the associated dynamics of the proposed MLI and the control system with a grid interface. The model is built in the SIMULINK environment, and the simulation results are presented under variations in solar radiation and grid voltage disturbances to exhibit the functionality of the proposed system and the effectiveness of the control scheme in providing a well-damped frequency response and stable generated voltage and currents. The results demonstrate stable frequency regulation with a settling time of approximately 0.3 s, and the output current exhibits low harmonic distortion, with a Total Harmonic Distortion (THD) of about 0.53%. Simulation results show stable operation and confirm that the proposed approach is a competitive solution for PV-based grid-forming applications. Full article

This work describes the fabrication and characterization of a novel lateral 4H-SiC PiN diode featuring inter-device isolation technology for power integrated circuits (ICs). The device’s architecture includes thick SiO₂ blocking layers and inter-device trench isolation structures, enabling effective electrical isolation between power devices and control circuitry on a single chip. The devices demonstrate good isolation performance, with inter-device leakage currents below 5 nA at a reverse bias of 200 V. The diodes keep reverse leakage current low (<1 μA at 20 V), but exhibit non-distinct turn-on behavior. This is mostly due to the too-shallow N+ and P+ ion implantation region and high series resistance. A monolithically integrated bridge circuit operating at 50 Hz and 200 Hz validates the integration approach; however, large forward voltage drops show that the high series resistance at the device level affects overall conversion efficiency. The transfer length method (TLM) characterization reveals high sheet and contact resistances, which are responsible for the conduction limitations in the PiN diode forward performance. This study establishes the foundation for a lateral SiC device technology with promising inter-device isolation capabilities, as well as the bridge circuit built based on the lateral PiN diodes, which shows the potential of this technology for future monolithic power IC applications. Full article

Cascaded H-bridge converters are the prevalent option for classic energy storage converters due to their excellent battery integration and current sharing capabilities. However, this scheme requires numerous IGBT switchings and exhibits high losses in low-voltage, high-power applications due to high current flowing through the batteries. Furthermore, the limited DC voltage regulation capability makes it difficult to obtain sufficient DC voltage for modulation when the battery is continuously discharging, resulting in shortened continuous discharge duration. To address these issues, this paper proposes a novel energy storage converter based on controllable DC buses. The proposed controllable DC bus consists of cascaded half-bridges and a bidirectional DC converter, where the former topology is designed to preserve voltage and current balancing between batteries, as well as boost the DC voltage—thereby reducing the current flowing through the batteries and minimizing losses. The latter topology is implemented to maintain DC bus voltage during battery discharge, thereby increasing the continuous operating time of the proposed energy storage converter. Moreover, the control and modulation of the proposed controllable DC bus have been optimized, and its effectiveness and performance are verified through simulation results. Full article

The cascaded H-bridge static synchronous compensator (STATCOM) has been widely employed in medium- and high-voltage reactive power compensation applications due to its high modularity, fast response speed, and direct grid connection capability. However, the DC-link voltage exhibits an inherent double-frequency ripple, which poses a serious challenge to power quality. Therefore, numerous Active Power Decoupling (APD) techniques have been proposed. However, existing schemes still exhibit certain limitations: independent APD topologies are associated with higher costs, whereas single bridge-arm multiplexed APD topologies are confronted with issues such as elevated DC-side voltage and increased current stress on the multiplexed arm. Consequently, comprehensive optimization is difficult to achieve in terms of the number of power devices, decoupling accuracy, level of capacitor multiplexing, and device stress. To address the above issues, this paper proposes a DC split capacitor (DC-SC)-based dual bridge-arm multiplexed cascaded H-bridge STATCOM with active power decoupling capability, along with its corresponding control method. By constructing a fundamental-frequency common-mode voltage on the decoupling capacitor, this method effectively suppresses the double-frequency ripple in the DC-side voltage and reduces the current stress on the switching devices. The simulation and experimental results have verified the correctness and effectiveness of the proposed topological structure and control method. Full article

This research paper presents Volvo SmartCell, an AC battery technology that integrates modular multilevel converters and battery cells to form a unified system for electric vehicle propulsion and power supply. The research work addresses the broader challenge of reducing driveline cost and complexity by replacing traditional components such as inverters, onboard chargers, centralized DC/DC converters, vehicle control units and many more. SmartCell uses distributed Cluster Boards comprised of H-bridges which are controlled via wireless communication to generate AC voltage, deliver redundant low voltage power, and support cell level protection mechanisms. The prototype testing demonstrates that the system can supply traction power by engaging clusters according to the required voltage depending on motor speed, achieve AC grid charging by synthesizing sinusoidal voltages without a dedicated charger, and provide autonomous DC/DC operation through cluster level voltage regulation. Simulations further indicate that multilevel voltage generation can reduce switching losses and improve electric machine efficiency compared to conventional systems. Additional benefits include active cell balancing, support for mixed cell chemistries, and high redundancy through multiple independent power branches. Challenges remain in wireless bandwidth limitations and cost optimization of Cluster Boards. Ongoing development aims to enhance communication robustness and validate safety for non-isolated grid charging. Full article

Gel polymer electrolytes (GPEs) typically suffer from sluggish kinetics and interfacial instability at elevated temperatures and high voltages. Herein, 3-(trifluoromethyl)-1H-1,2,4-triazole (TTA) is employed to construct an ultrathin (~25 μm), robust, and homogeneous GPE. TTA acts as a molecular bridge, significantly improving compatibility between the PVDF-HFP (Poly(vinylidene fluoride-co-hexafluoropropylene)) matrix and LLZTO (Li_6.4La₃Zr_1.4Ta_0.6O₁₂) fillers to create continuous ion-conducting pathways. Consequently, the TTA-GPEs exhibits high ionic conductivity (0.267 mS cm⁻¹ at room temperature), low activation energy (0.181 eV), and an increased lithium-ion transference number (0.425). Advanced surface analysis reveals that TTA preferentially reacts to form a dense, gradient hierarchical interphase (solid electrolyte interphase/cathode electrolyte interphase, SEI/CEI) enriched with inorganic species (LiF, Li₃N, and Li₂S) on the inner side. This architecture suppresses parasitic reactions and lithium dendrite growth. Accordingly, NCM811(LiNi_0.8Co_0.1Mn_0.1O₂)//Li batteries with TTA-GPEs demonstrate stable cycling at 80 °C and 1C, retaining 57.68% capacity after 125 cycles—significantly outperforming benchmarks. This study offers a molecular engineering strategy to simultaneously optimize bulk transport and interfacial stability for high-energy-density solid-state batteries. Full article

Hybrid supercapacitors possess high power and energy density, while the cascaded H-bridge converter features rapid response capability. Integrating these two components leads to an energy storage system capable of swiftly responding to power demands, effectively mitigating voltage and frequency instability in weak-grid renewable energy stations. Based on this system, in this paper, a novel automatic frequency–voltage regulation strategy is proposed. First, a fast fault severity detection method is proposed. It evaluates the system’s fault condition by monitoring the voltage response and generates auxiliary signals to enable subsequent rapid compensation of voltage and frequency. Subsequently, fast automatic voltage and frequency regulation strategies are developed. These strategies leverage real-time fault assessment to deliver immediate power support to weak-grid renewable stations following a disturbance, thereby effectively stabilizing the terminal voltage magnitude and system frequency. The effectiveness of the proposed method is validated through simulations. A grid-connected model of a weak-grid renewable energy station is established in MATLAB (2023b)/Simulink. Tests under various fault scenarios with different short-circuit ratios and voltage sag depths demonstrate that the proposed strategy can rapidly stabilize both voltage and frequency after large disturbances. Full article

This work presents a highly compact and scalable 1.2-kV SiC MOSFET half-bridge building-block module enabled by a die-integrated 3D PCB packaging technology. Compared with conventional DBC-based or TO-247-based SiC half-bridge modules, the proposed design reduces the physical volume and weight by more than 90% while maintaining full compatibility with standard PCB manufacturing processes. The vertically laminated DC+/DC− conductors and symmetric PCB–die–PCB stack establish a tightly confined commutation loop, resulting in a measured power-loop inductance of 2.2 nH and a 3.8 nH gate-loop inductance—representing up to 94% and 89% reduction relative to discrete device implementations. Because the parasitic parameters are intrinsically well-balanced across replicated units and the mutual inductance between adjacent modules remains extremely small, the structure naturally supports current sharing during parallel operation. Thermal and insulation evaluations further confirm the suitability of copper filling via high-Tg laminated PCB substrates for high-power SiC applications, achieving withstand voltages exceeding twice the rated bus voltage. The proposed module is experimentally validated through finite-element parasitic extraction and 950 V double-pulse testing, demonstrating controlled dv/dt behavior and robust switching performance. This work establishes a manufacturable and parallel-friendly packaging approach for high-density SiC power conversion systems. Full article

Active-control coils on Keda Torus eXperiment (KTX) are used to suppress error fields and mitigate MHD instabilities, thereby extending discharge duration and improving plasma confinement quality. Achieving effective active MHD control imposes stringent requirements on the coil power supplies: wide-bandwidth and high-precision current regulation, deterministic low-latency response, and tightly synchronized operation across 136 independently driven coils. Specifically, the supplies must deliver up to ±200 A with fast slew rates and bandwidths up to several kilohertz, while ensuring sub-100 μs control latency, programmable waveforms, and inter-channel synchronization for real-time feedback. These demands make the power supply architecture a key enabling technology and motivate this work. This paper presents the design and simulation of the KTX active-control coil power supply. The system adopts a modular AC–DC–AC topology with energy storage: grid-fed rectifiers charge DC-link capacitor banks, each H-bridge IGBT converter (20 kHz) independently drives one coil, and an EMC filter shapes the output current. Matlab/Simulink R2025b simulations under DC, sinusoidal, and arbitrary current references demonstrate rapid tracking up to the target bandwidth with ±0.5 A ripple at 200 A and limited DC-link voltage droop (≤10%) from an 800 V, 50 mF storage bank. The results verify the feasibility of the proposed scheme and provide a solid basis for real-time multi-coil active MHD control on KTX while reducing instantaneous grid loading through energy storage. Full article

The large-scale integration of renewable energy grid-connected converters into the grid has given rise to many broadband oscillation accidents, primarily due to impedance mismatching with the grid. Consequently, accurate measurement of both the grid-connected converter and the grid impedance is a prerequisite for system stability assessment. However, conventional impedance measurement methods are constrained by the breakdown voltage of semiconductor switches, thus rendering them unsuitable for high-voltage, high-capacity applications. This paper aims to enable impedance measurement in large-capacity, high-voltage applications by presenting a newly developed method that overcomes the voltage limitations of conventional approaches. First, a cascaded H-bridge (CHB) topology is adopted to fulfill the impedance measurement requirements in large-capacity, high-voltage renewable energy station applications. Subsequently, a quasi-proportional-resonant (PR) controlled perturbation injection strategy is proposed to achieve rapid current injection across the 10–1000 Hz frequency range. Finally, the effectiveness and accuracy of the proposed impedance measurement method in capturing harmonic impedance are demonstrated through a hardware-in-the-loop (HIL) experiment conducted on an RTDS platform. Full article

This paper presents a novel hybrid modulation technique for Asymmetrical Cascaded H-Bridge Multilevel Inverters (ACHBMLIs), specifically designed to enhance both efficiency and harmonic performance. Unlike conventional strategies, the proposed method optimizes the switching scheme by operating the high-voltage H-Bridge at the fundamental frequency, thereby significantly reducing switching losses while maintaining low harmonic distortion levels comparable to traditional Pulse Width Modulation (PWM). To assess the effectiveness of the approach, a comprehensive comparison was conducted against two widely adopted modulation techniques for ACHBMLIs: Multicarrier Pulse Width Modulation (MPWM) and the Staircase Modulation Strategy (SMS). The evaluation involved both simulation and real-time Hardware-in-the-Loop (HIL) testing of a 7-level three-phase ACHBMLI, with a focus on key performance indicators such as voltage and current harmonic distortion, as well as converter efficiency. The results demonstrate that the proposed hybrid modulation achieves higher efficiency than PWM and lower current Total Harmonic Distortion (THD) than SMS. These findings highlight the potential of the hybrid strategy as a compelling solution for applications that demand an optimal balance between energy efficiency and waveform quality. Full article

Low-voltage power converters in the 25–200 V range are increasingly employed in emerging applications such as hybrid electric vehicles (HEVs), photovoltaic systems with battery storage, and electric propulsion systems for recreational boats. In these contexts, 48 V battery systems have become standard, due to safety considerations. Among various converter topologies, H-bridge configurations operating around 100 V DC are widely used in laboratory-scale prototyping. While MOSFETs are the preferred switching devices in this voltage range, due to their high efficiency and fast switching characteristics, they also introduce design challenges related to high current slew rates and associated overvoltage spikes caused by parasitic inductances in the PCB layout. These overvoltages, though modest in absolute terms, can be critical in low-voltage systems, due to the lower device ratings. This paper presents design strategies and layout best practice for a 120 V, 50 A H-bridge converter using 200 V rated MOSFETs. The effectiveness of various mitigation techniques—including the use of ceramic capacitors in parallel with film and electrolytic types, Schottky diodes across MOSFETs, and snubber circuits—is evaluated and experimentally validated on a dedicated prototype. The results highlight the critical role of PCB design in ensuring switching reliability and device protection in low-voltage converter systems. In addition, with the design solutions shown in this study, it was possible to obtain a voltage overshoot during switching of just 165 V with a 120 V DC-link voltage, which guarantees a sufficient safety margin for the MOSFET rated voltage. Full article

In this work, a novel solid polymer electrolyte with a disordered structure has been designed, combining polyethylene glycol (PEG) as the flexible segments and hexamethylene diisocyanate (HDI) as the rigid segments. The synthesis was realized by alternating flexible PEG with rigid HDI through a peptide bond (–CO–NH–), which disrupts the ordered structures of PEG, generating electron-deficient Lewis acid groups. The pathbreaking introduction of HDI blocks not only bridges links between the PEG molecules but also generates electron-deficient Lewis acid groups. Therefore, the original ordered structures of PEG are disrupted by both the alternating chains between PEG and HDI and the Lewis acid groups. As a result, the PEG_H/L4000 electrolytes (PEG molecular weight of 4000) exhibit a strong anion-capture ability that decreases the crystallinity of polymers, which further achieves a high ionic conductivity close to 10⁻³ S·cm⁻¹ with the lithium-ion transference numbers up to 0.88. The symmetric Li|PEG_H/L4000|Li cells maintain a low and stable voltage polarization for more than 800 h at 0.1 mA·cm⁻². Furthermore, the LiFePO₄|PEG_H/L4000|Li all-solid-state cells perform well both in cycling and rate performances. The design of polymer disordered structures for polymer electrolytes provides a new thought for manufacturing all-solid-state lithium-ion batteries with high safety as well as long life. Full article

Soft open point (SOP) offers a viable alternative to traditional tie switches for optimizing power flow distribution between connected feeders, thereby improving power quality and enhancing the reliability of distribution networks (DNs). Among existing medium-voltage (MV) SOP demonstration projects, the modular multilevel converter (MMC) back-to-back voltage source converter (BTB-VSC) is the most commonly adopted configuration. However, MMC BTB-VSC suffers from high cost and significant volume, with device requirements increasing substantially as the number of feeders grows. To address these challenges, this paper proposes a novel star-connected cascaded H-bridge (CHB) STATCOM SOP (SCS-SOP). The SCS-SOP integrates the static synchronous compensator (STATCOM) and low-voltage (LV) BTB-VSC into a single device, enabling reactive power support within feeders and active power exchange between feeders, while achieving reduced component cost and volume, simplified power decoupling control, and increasing power quality management capabilities. The topology derivation, configuration, operational principles, and control strategies of the SCS-SOP are elaborated. Finally, simulation and experimental models of a two-port 3 Mvar/300 kW SCS-SOP are developed, with results validating the theoretical analysis. Full article