International Journal of Circuit Theory and Applications最新文献

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.

Vienna rectifier is considered the best power quality conditioner in applying renewable energy systems. The application of the Vienna rectifier can be seen in wind energy systems, aircraft, chargers, and so on. This work mainly focuses on the steady-state and transient analysis of the Vienna rectifier and the performance of the proposed adaptive neutral voltage point regulator under variable load and grid disturbance conditions. The SVPWM (space vector pulse width modulation) controls the Vienna rectifier, proven to be more advantageous than any conventional controller. An adaptive neutral point voltage controller is proposed to enhance the capability of voltage balance across the capacitors during transient analysis. The MATLAB/SIMULINK tool is used to program the control algorithm and simulate the Vienna rectifier system. Different test cases that include variable dc load and the sudden disturbances in the grid are analyzed to prove the robustness of the controller. Power management analysis is also provided to better understand the efficiency of the converter. A 5-KVA Vienna rectifier laboratory prototype is designed in the laboratory to investigate the simulation results. A spartan-6 FPGA controller generates the control algorithm using a highly flexible Xilinx platform

Effective control of DC-DC converters is essential in Electric Vehicles (EVs) to enhance battery efficiency and motor performance. Traditional controllers often struggle with the complex dynamics of fourth-order converters. To overcome these challenges, this paper proposes an optimal Linear Quadratic Regulator (LQR) to control a soft-switching synchronous buck converter. By minimising a cost function that balances state variables and control efforts, the LQR enhances both stability and dynamic response. The controller achieves notable improvements, such as, reducing overshoot to less than 2% and achieving a settling time of approximately 70 $�\mu$S. Bode plot and root locus analysis confirm the converter's robust operation, with a phase margin of 66° and a gain margin of 64.2 dB, ensuring adaptability to varying loads. Experimental tests further demonstrate that soft switching is achieved without performance degradation, even under dynamic conditions, proving the controller's practicality for real-time EV applications. Overall, the proposed control method provides a reliable and efficient solution for high-performance EV power converters under changing load and input conditions.

The integration of wireless power transfer (WPT) and intelligent autopilot technology offers a promising and viable solution for seamless en-route charging of unmanned mobile devices. It is critical to ensure efficient and stable output power transfer along a predetermined line path, in conjunction with a lightweight and general receiver. This involves considering the compatibility of the receiver-side coil structure and keeping the circuitry as simple and essential as possible. In this article, we propose a new stacked transmitter coil (STC) design with switched capacitors (SCs) that integrates an in-plane misalignment-tolerant coil array in the first layer with a considerable power transfer capacity of a circular coil in the secondary layer. The mismatch of this new structure is a one-dimensional mismatch that provides enhanced disorder tolerance while maintaining high energy transfer efficiency, which does not require stacking of the receiving-end coil. Consequently, for a conventional circular receiver coil, output power fluctuations are significantly reduced for 1-D linear movements along the transmitter using switching control. Our experimental setup enables constant energy transfer efficiency of around 80%, which is achieved by solely relying on the transmitter's voltage information for switching control.

This article proposes a Series and Parallel synchronized switching harvesting on capacitor (S&P-SSHC) rectifier to efficiently extract energy from piezoelectric transducer (PZT). By combining the Series synchronized switching harvesting mode (S-mode) together with Parallel synchronized switching harvesting mode (P-mode), the S&P-SSHC rectifier can achieve an excellent energy harvesting efficiency over a wide range of vibration excitation under a fixed low output voltage. Moreover, the synchronized switch harvesting on capacitor technology utilized in S-mode with the same flipping caps as using in P-mode maintains a high-voltage flipping efficiency ($�{�\eta �}_{�F�}$), while avoiding the addition of extra components. A switched-capacitor (SC) DC-DC converter composed of the reconfigured flipping caps aims to enhance the input independence ability and its limited voltage-conversion-ratio (VCR) will not affect harvesting efficiency due to the supplementation of S-mode. The proposed rectifier circuit is designed and simulated in a 0.18-$�\mu$m BCD process. The performance measured by simulation demonstrate that the proposed S&P-SSHC rectifier can maintain a maximum output power improving rate over full-bridge rectifier (FOM) of > 6.01$�\times$ with an open-circuit peak-to-peak voltage of PZT ($�{�V�}_{�o�c�p�z�t�}$) range from 0.5 to 10 V and a fixed loading voltage of 1.5 V.

Grid-forming inverters are essential components linking renewable energy sources to the grid, and their stability is crucial for the reliable operation of the system. Grid-forming inverters based on traditional proportional-integral (PI) control demonstrate good small-signal stability in weak grids characterized by low short-circuit ratios (SCR). However, when connected to strong grids, it often leads to sub/super-synchronous oscillations, causing instability in the system. To enhance the grid-forming inverter's stability under strong grid conditions, this paper employing the linear active disturbance rejection control (LADRC) strategy in place of traditional dual PI voltage-current control loops. This study establishes positive and negative sequence impedance models of grid-forming inverters under traditional dual PI voltage-current control and LADRC voltage loop control using harmonic linearization methods. Based on the established sequence impedance models and Nyquist criterion, the paper identifies the reasons behind sub/supersynchronous oscillations induced by dual PI control under strong grid conditions. Stability comparisons are provided between dual PI control and LADRC control of grid-forming inverters under different grid strengths. The comparative results demonstrate that grid-connected inverters with LADRC exhibit superior adaptability to strong grids, demonstrating enhanced capability to suppress sub/super-synchronous oscillations. Simulation and experimental validations confirm the effectiveness of the LADRC control strategy.

The pulsed power supply system is an effective approach for loads that require higher power than the supply power. This article proposes an efficient capacitor charger converter that can deliver high instantaneous power from a low-power battery using an external capacitor. By switching at the boundary of continuous current mode (CCM) and discontinuous current mode (DCM), the charger converter charges the capacitor step by step. The majority of losses are related to conduction and switching losses during the charging process. Conduction loss is due to resistances in the inductor's current path. Switching loss is caused by the switching frequency of the output MOSFETs of the capacitor charger converter. The proposed structure significantly reduces the total conduction and switching losses by controlling the inductor current ripple and the capability of operating at low frequencies. By reducing losses during charging, the charging efficiency has increased, leading to improved efficiency of the entire proposed circuit. By resuming the charging process after delivering a high instantaneous power, the circuit reduces the load's sleep period and prevents the loss of capacitor's residual energy. The proposed structure was evaluated and simulated in a 0.18-μm CMOS technology. The evaluation results indicate that the proposed pulsed power supply circuit performs better in various load consumption energy levels compared to previous structures. The circuit's efficiency for the energy consumed by the load in the 7.1- to 47.7-μJ range reaches more than 94.6%.

Traditional MLIs face several challenges, such as complex configurations, intricate switching control, difficulty in generating gate pulses, a large number of components, and high voltage stress on semiconductors. Additionally, increasing the number of voltage levels tends to raise the device count, which can add to the system's complexity, cost, and, in some cases, reduce reliability. In this paper, a new multilevel inverter (MLI) incorporating switched capacitors for improved performance is proposed. The proposed single source quadruple boost nine-level inverter (SS-QBNLI) topology addresses these issues by generating a nine-level output voltage using only 10 switches, 1 diode, and 2 capacitors. Notably, the inverter achieves a voltage gain of four times the input. The capacitors are self-balanced without requiring any external balancing circuitry. A simple pulse-width modulation (PWM) technique based on logic gates is employed to ensure balanced capacitor operation. This approach also reduces the number of switches and minimizes voltage stress, while providing built-in fault tolerance. The paper presents a detailed comparison with other related topologies. Simulations are conducted in MATLAB/Simulink under various conditions to validate the performance. Finally, the ability of the proposed inverter to achieve voltage boosting is experimentally confirmed from a laboratory prototype.

To improve the voltage quality and efficiency in a renewable power conversion systems, single-input multilevel inverters (MLIs) with single-stage boosting have become the ultimate choice. This work presents a new single input MLI topology employing reduced number of components and with inherent voltage boosting. The generalized structure of the proposed MLI is presented first, and then the analysis is carried out for a 17-level operation. The design and self-regulating ability of each capacitor is analyzed using one basic module in the MLI. Comparative evaluation with recent-art MLIs shows that the proposed topology has the lowest number of switches and capacitors. Simulation result analysis is provided under different test conditions to verify the circuit operation. Furthermore, extensive experimental analysis is carried out under several dynamic test conditions to validate the MLI.