International Journal of Circuit Theory and Applications最新文献

DC-DC converters based on partial power processing (PPP) offer the advantage of high power density and high efficiency and are considered an attractive solution in various systems like photovoltaic systems, energy storage systems. It has been demonstrated that PPP topologies can be synthesized starting from buck-boost converter in a limited number of steps. Based on these steps, this paper proposes a new rapid modeling method for PPP topologies. It has been demonstrated that the voltage gains of all synthesized topologies can be obtained from the voltage gain of buck-boost converter and the corresponding voltage gain formulas. Similarly, the models of all synthesized topologies can be obtained from the model of buck-boost converter and the corresponding modeling formulas. This method requires no manual circuit analysis, only a computer to execute the program. It is rapid and significantly simplifies the modeling process. The proposed modeling method is validated through the models of several classic topologies and frequency sweeping in the simulation.

In low-power multiple-voltage applications, single-input, multiple-output nonisolated converters are becoming popular as alternative dc-dc topologies to increase efficiency and reduce the size and cost of the converter. This article presents a novel high-gain fault-tolerant multiport (HGFTM) dc-dc converter for low- and medium-voltage applications. The proposed converter is a combination of conventional boost and buck converter topologies with time multiplexing control. The switched boost action divides power into two ports using time multiplexing control. The noncascading structure of the converter provides high gain with improved efficiency. The proposed converter provides open circuit switch fault (OCSF) tolerant capability without any additional device requirement. This provides controlled output voltages for a wide range of applications. The main objective of this research is to attain robust and fault-tolerant operations in multiport converter systems, ensuring continued power delivery even under component failure. A closed-loop control technique is implemented to control the output voltages and assure the system's stability and accuracy under different load conditions. The physical implementation of the converter is tested in various scenarios to ensure its real-time application. The experimental findings closely match the simulation results, showing the effectiveness of the proposed fault-tolerant multiport dc-dc converter.

Load-independence constant current (CC) and constant voltage (CV) charging are the two stages of charging the Li-ion battery. In this article, a method to design the inductive power transfer (IPT) system is proposed for charging the Li-ion battery based on the equivalent transmission line circuit model with constant outputs. First, the equivalent transmission line circuit model with constant outputs is clarified, and the quarterwave transformer equivalent to the magnetic coupling unit is illuminated as well as other four usually used LC circuits. Second, the progress mapping the model to the IPT system with CV or CC output is explained in detail. By taking parasitic resistances into account, the outputs and efficiency of the system are then investigated with ABCD matrix. The method is simple, intuitive, and easy to comprehend, which can greatly simplify the design. A three-coil IPT system for charging Li-ion batteries is designed for example. Two switches set at the transmitter make the charging switch from CC to CV mode smoothly when the critical condition is met. An experimental platform is established and measured to verify the proposed method. The maximum efficiency is measured as 89.24% in CC stage and 91.81% in CV stage.

In underwater environments, existing capacitive power transfer (CPT) systems only consider the capacitance or conductivity of the coupling plate when analyzing transfer efficiency. This is inconsistent with the characteristics of the underwater coupler. Thus, it would lead to inaccurate efficiency models and difficult efficiency optimization design. To address the above issue, this paper models the underwater CPT system by simultaneously considering the capacitance and conductivity of the coupler in the efficiency model, so a more accurate efficiency model of CPT system in the underwater environment is derived. On this basis, the efficiency optimization design of the underwater CPT system is carried out, and the optimization design process is provided. Finally, the accuracy of the proposed efficiency model and the effectiveness of the design method have been demonstrated through simulation and experimentation. With the proposed optimization method, the underwater CPT system achieves a transfer efficiency of 82% within a load range of 10 Ω to 60 Ω at a plate spacing of 100 mm. The maximum transfer efficiency reaches 90%.

The increasing demand for electric vehicles necessitates advancements in efficient and compact on-board charging systems. This paper presents a bidirectional DC–DC converter with a high voltage conversion ratio based on an inductor current-sharing network for on-board charger applications. The proposed converter features a simple structural, reduced inductor size, and fewer components while achieving significant voltage gain in both step-up and step-down modes. The converter's performance is rigorously evaluated through detailed theoretical analysis and simulation. A comprehensive comparison with recent converter topologies is provided, demonstrating the proposed design's distinct advantages. Additionally, a steady-state analysis is included. To validate the concept, a 500 W prototype is developed, and experimental results at a 50 kHz switching frequency are presented, confirming the effectiveness and potential of the proposed bidirectional converter.

Omnidirectional wireless power transfer (OWPT) systems are widely used in consumer electronic products (CEPs), industrial robots, medical devices, and more. However, the different CEPs usually have different power and frequency requirements to ensure various transmission characteristics. In order to meet the transmission requirements of CEPs with different power and frequency needs, this paper proposes a novel dual-frequency power allocation method for OWPT. This method achieves independent regulation of output power for loads of different frequencies through the designed SS topology dual-frequency resonant compensation structure and establishes corresponding parameter design methods. A dual-frequency OWPT platform operating at 40 kHz/100 kHz was built to verify the correctness and effectiveness of the power allocation method. Experimental results show that when the input voltage corresponding to only one frequency changes, only the output power of the load corresponding to that frequency changes accordingly. Meanwhile, under the condition of dual-load power supply, when the receiving coil is within a 90° offset range, the system's output power ranges from 49.25 to 57.15 W with a fluctuation rate of 14.8%, and the output efficiency ranges from 76.67% to 78.68% with a fluctuation rate of 2.59%.

A set of measurement techniques that can find multiple DC operating points, as well as explore regions of operation that are unobservable with traditional experimental methods, is described. These techniques are particularly useful for transistor circuits that exhibit hysteresis, S- and N-type current-versus-voltage curves and multiple DC operating points (typically with different physical stability properties). These techniques are the experimental version of well-known homotopy techniques used in the simulation of DC operating points and can be applied without access to a numerical simulation model. Such numerical simulation techniques used to identify and describe such behaviors are also surveyed and compared with the measurement techniques described herein.

Compared with medium-voltage AC (MVAC) integration system, input independent output series (IIOS) multiport DC/DC converter is a promising method for distributed photovoltaics (PVs) medium-voltage DC (MVDC) integration, which has one power conversion stage and high efficiency. However, the PV power mismatch will lead to the submodule output voltage unbalance. In order to avoid the shift of converter operating point and device damage caused by the mismatched power, an interleaved current-fed boost (ICFB) converter with output voltage self-balancing for PVs MVDC integration system is proposed in this paper. The ICFB converter consists of an interleaved current-fed boost circuit on PV side, half-bridge circuit on MVDC grid side and a transformer which is used to realize the isolation of PV and MVDC grid. By multiplexing the switches of the half-bridge circuit on grid side, the series LC chain is embedded in the output of the adjacent two submodules (SMs) to form an LC voltage balancer (LCVB), which can achieve output voltage self-balancing by open-loop control. In addition, the proposed topology has small input current ripple, high voltage gain, and all switches can achieve zero-current switching (ZCS) on and off, which is conducive to the improvement of system efficiency. Finally, the feasibility of proposed topology is verified by simulation and experiments.

This paper presents a single-phase switched-capacitor (SC)-based boost inverter topology capable of synthesizing a seven-level (7L) output using only nine power switches, two capacitors, and a single DC input source. The proposed topology (PT) achieves a voltage gain of 1.5 while ensuring inherent capacitor voltage self-balancing without the need for complex auxiliary control circuits. A comprehensive analysis of the topology is provided, covering its structural configuration, operational principles, and the embedded self-balancing mechanism. Furthermore, a comparative evaluation with existing topologies is conducted in terms of voltage stress, component count, and cost function to highlight the advantages and limitations of the PT. The theoretical analysis is validated through simulation using a pulse width modulation (PWM) control scheme. Additionally, power loss calculations and the integration of the proposed inverter into a grid-connected photovoltaic (PV) system are explored. The feasibility and performance of the proposed 7L design are further confirmed through both static and dynamic experimental testing.