Search Results (116)

This paper introduces a high-conversion ratio multiphase nonisolated converter built from generic LC cells. The unique architecture that hinges on a generic capacitor inductor switching module enables the high modularity of the topology, providing a quick extension of the converter design in an interleaved configuration for lower ripple and higher current output. The generic module comprises the basic power components of a nonisolated DC–DC converter, where the unique interaction between the capacitor and the inductor results in a soft charging operation, which curbs the losses of the converter, and contributes to a higher efficiency. Additional features of the new converter include a significantly extended effective duty ratio, and a lower voltage stress on the switches, a very high output current, and architecture-inherent output current sharing that balances the loading between the phases. In addition, a power extension using a paralleling and interleaving approach is presented to provide higher output current capabilities. Simulation and experimental results of a modular interleaved three-phase prototype demonstrate an excellent proof of concept and agree well with the theoretical analyzes developed in this study. Full article

This paper presents two new non-isolated DC-DC converters with and without a coupled inductor based on quadratic voltage conversion. Firstly, the coupled inductor-less type is explained in detail. It employs a voltage-boosting cell and a modified SEPIC structure to provide a high voltage boost ability with a lower and practical value for the switching duty cycle. This allows for lower power loss compared to conventional DC-DC converters. Having only one switch in the proposed converter simplifies the control and reduces the required number of control signals. Furthermore, the presented transformer-less structure can help avoid producing huge voltage spikes across the power switch. In traditional quadratic SEPIC converters, the voltage-boosting cell’s capacitor experiences relatively high voltage stress due to the voltage multiplication process. In contrast, the proposed converter offers significantly lower voltage stresses. Hence, it becomes possible to utilize a capacitor with a lower voltage rating, leading to cost savings and improved reliability and availability of suitable components. The first topology can be improved for ultrahigh voltage applications by replacing the middle inductor with a coupled transformer. Consequently, a higher voltage range with a lower switching duty cycle can be attained. Theoretical analysis and mathematical derivations are provided, and the comparison section claims the proposed converter’s ability to minimize voltage stress across the switch and output diode. Finally, experimental results are given to verify the effectiveness of the proposed converters at an output power of 260 W. Full article

In this article, a new high step-up interleaved DC–DC converter is presented for renewable energy systems. The converter circuit is based on the interleaved two-phase boost converter and integrates a voltage-lift capacitor and a voltage multiplier cell. A high voltage gain of the converter can be achieved with a reasonable duty ratio and the voltage stresses of semiconductor devices are reduced. Because of low voltage stress, the switches with low on-resistance and the diodes with low forward voltage drops can be adopted to minimize the conduction losses. Additionally, the switching losses are reduced because the switches are turned on under zero-current switching (ZCS) conditions. Due to the existence of leakage inductances of the coupled inductors, the diode reverse-recovery problem is alleviated. Moreover, the leakage energy is recycled and the voltage spikes during switch turn-off are avoided. The parallel input architecture and interleaved operation reduce the input current ripple. The operating principles, steady-state characteristics, and design considerations of the presented converter are proposed in detail. Furthermore, a closed-loop control is designed to maintain a well-regulated output voltage despite variations in input voltage and output load. A prototype converter with a rated 1000 W output power is realized for demonstration. Finally, experimental results show the converter effectiveness and verify the theoretical analysis. Full article

The polar energy router is a key device in the polar clean energy system which converges the output of wind power, photovoltaic units, energy storage units and hydrogen fuel cells through the power electronic power converter to the DC bus, which requires the use of a variety of specifications of DC/DC converters; as a result, the efficiency of the DC/DC converter is directly connected to the efficiency of the polar energy router. This paper presents an enhanced isolated DC/DC converter with a phase-shifted full-bridge topology designed to meet the high-efficiency conversion requirements of polar energy routers. Although soft switching can be realized naturally in phase-shifted full-bridge topology, it also faces challenges, such as the difficulty of realizing soft switching under light load conditions, large circulation losses, a loss of duty cycle and oscillation in the secondary-side voltage. To solve these problems, an improved scheme of the phase-shifted full-bridge converter with an active clamp circuit is proposed in this paper. The scheme realized zero-voltage switch (ZVS) under light load by utilizing clamp capacitor energy. The on-state loss was reduced by zeroing the primary-side current during the circulating phase. This paper provides a detailed description of the topology, working principle and performance characteristics of the improved scheme, and its feasibility has been verified through experiments. Full article

With the continuous improvement of battery energy density and converter power density, as well as the miniaturization and lightweighting of related airborne electrical equipment, all-electric aircraft with hybrid power supply systems provide more trade-off space and possibilities for the design of future aircraft. It is indispensable to search for a more valuable topology and apply it to airborne power supply. This paper proposes an airborne high-gain unidirectional DC-DC converter suitable for between low-voltage unit and high-voltage bus, which consists of interleaved magnetic integrated switched coupled inductor units and improved switch capacitor units. This paper first analyzes the steady-state operating characteristics under different modes; the new topology has higher voltage gain and lower stress. Secondly, in response to the challenges of high efficiency and high power density, we propose a magnetic integration design method and comprehensive experimental scheme based on the EIE-type magnetic core structure. This successfully integrates multiple discrete inductors into a single magnetic core. Furthermore, based on the comprehensive consideration of steady-state, transient performance and power density, the general design criteria for a high-gain switched coupled inductor are summarized through the equivalent mathematical model of reverse flux coupling. Additionally, by adjusting the coupling coefficient, the converter can achieve zero-voltage switching under light load conditions, demonstrating versatility and scalability and better meeting the application requirements of electric aircraft. The proposed prototype can provide voltage gain in the range of 12–22 times the input voltage gain by varying the input voltage from a 12–24 V fuel cell. The comprehensive performance of the converter, including steady-state, transient, and efficiency, was tested under D < 0.5 and D > 0.5. The experimental results show that the proposed converter possesses advantages such as high gain and low stress, a high dynamic response and low ripple, and high efficiency and high power density, which can provide a more advantageous DC-DC converter solution for airborne hybrid power supply systems. Full article

This article presents a power-efficient DC-DC converter based on a switched-capacitor (SC) cell in power management systems supplied for fully integrated photovoltaic (PV) modules. These modules shall provide high-performance point-of-load voltage regulation. The primary objective of this study is to better utilize capacitance and switches by selecting a proper SC topology in order to improve the power efficiency of SC converters. A general steady-state performance model is investigated to optimize and compare a variety of SC DC-DC topologies. The investigation method relies on a charge-multiplier approach and considers the impact of area constraint on capacitors. To identify the most suitable topology for a given conversion ratio, the performance-limit metrics of SC converters are calculated. The analysis provides framework to determine optimum switch size and switching frequency for a two-phase 3:1 series–parallel converter for a target load current of 10 mA implemented on a 22 nm process technology. The results shows that a minimum of 250 MHz switching frequency is desirable for achieving a target efficiency greater than 85% while maintaining the minimum output voltage of 0.34 V. The analysis results are verified through MATLAB and PSpice-based simulations. Full article

This paper presents an integrated approach for a retinal prosthesis that overcomes the scalability challenges and limitations of conventional systems that use external cameras. Silicon nanowires (SiNWs) are utilized as photonic sensors due to their nanoscale dimensions and high surface-to-volume ratio. To enhance these properties and achieve high photoresponsivity, our research team developed a vertically stacked SiNW structure using a fabrication method entirely based on dry etching. The fabricated SiNW photodetector demonstrated excellent electrical and optical characteristics, including linear I–V characteristics that confirmed ohmic contact formation and high photoresponsivity exceeding 10⁵ A/W across the 400–800 nm wavelength range. The SiNW photodetector, following its integration with a switched capacitor stimulator circuit, exhibited a proportional increase in stimulation current in response to higher light intensity and increased SiNW density. In vitro experiments confirmed the efficacy of the integrated system in inducing neural responses from retinal cells, as indicated by an increased number of neural spikes observed at higher light intensities and SiNW densities. This study contributes to sensor technology by demonstrating an approach to integrating nanostructures and electronic components, which enhances control and functionality. Full article

An interleaved high voltage gain DC-DC converter with winding-cross-coupled inductors (WCCIs) and voltage multiplier cells is proposed for photovoltaic systems. The converter configuration is based on the interleaved boost converter integrating the diode-capacitor clamp circuits, the winding-cross-coupled inductors, and voltage multiplier cells to increase the voltage gain and reduce the semiconductor voltage stresses. The equal current sharing of two phases is achieved with the help of the winding-cross-coupled inductors. The converter achieves high voltage gain while operating at a proper duty ratio. The low-voltage-rated MOSFETs with low on-resistance are available to reduce the conduction losses due to the low switch voltage stress. The leakage energy of the coupled inductors is recycled such that the voltage spikes on the power switches are avoided. The input current ripple is decreased due to the interleaved operation. The operating principle and steady-state analysis of the proposed converter are proposed in detail. The design guidelines of the proposed converter are given. In addition, the closed-loop controlled system of the proposed converter is designed to diminish the effect of the variations in input voltage and load on the output voltage. Finally, the experimental results of a 1000 W converter prototype with 36 V input and 400 V output are given to validate the theoretical analysis and the converter performance. Full article

This study introduces an innovative two-range, 12-stage Marx pulse generator employing thyristor switches designed specifically for the electroporation of biological cells. The generator consists of two module capacitors of different capacitances (1 μF and 0.25 μF), which enable the generation of electrical pulses with different durations and amplitudes of up to 25 kV. Safety aspects, including overcurrent and overvoltage protection mechanisms, are implemented in both the software and the hardware. In the experimental section, the tests of the Marx generator with resistive load are described in detail, and the results for the voltage fluctuations, pulse duration, and output characteristics of the generator are presented. The advantages of the design, including the high output voltage, the wide range of repetition rates, and the flexibility of the pulse parameters, are emphasized. Additionally, the research showcases the utilization of the devised generator for industrial purposes. Hence, an investigation into the efficiency of protein extraction from microalgae (Chlorella vulgaris) and the impacts of pulsed electric fields (PEFs) on the structural characteristics of casein micelles (CSMs) was chosen as an illustrative example. The obtained results provide valuable insights into the application of PEF in food processing and biotechnology and underline the potential of the developed generator for sustainable and environmentally friendly practices. Full article

A high conversion ratio DC-DC converter is crucial for fuel cell electric vehicles (FCEV). A fuel cell-based non-isolated high gain integrated DC-DC converter for electric vehicles is proposed in this paper. The system comprises an interleaved boost converter (IBC) at the source end, a switched capacitor cell, coupled inductors, a passive clamp circuit, and a voltage multiplier circuit (VMC). Its significance is to achieve the voltage conversion gain of 12.33 at a conversion ratio of 0.45. The idea is to use a proton exchange membrane fuel cell to power electric vehicles through a high-gain DC-DC converter. The use of an ineffective MPPT can result in lower energy conversion efficiency. Thus, this system incorporates a maximum power point tracking (MPPT) controller based on a neural network, which relies on the radial basis function network (RBFN) algorithm to track the maximum power point of the PEMFC accurately. The comparative study of the fuel cell electric vehicle (FCEV) structure with the RBFN-based MPPT technique was evaluated with that of the fuzzy logic technique using the MATLAB/Simulink platform (R2021b (MATLAB 9.11)). A 1.5 kW experimental prototype is designed with a switching frequency of 10 kHz to validate the design analysis, and its pursuance is compared between RBFN and FLC-based controllers. This manuscript will be a significant contribution towards evidencing a sustainable environment. Full article

Photovoltaic (PV), battery, and fuel cell (FC) technologies are emerging forms of renewable energy gaining popularity. However, one of the key limitations is their production of direct current (DC) voltage, which hinders the connectivity and integration with the electrical grid. To address this issue, various DC/DC boost converters have been introduced. This study presents an innovative Luo converter with a switched-inductor–capacitor (SLC) cell at the input and a switched-capacitor (SC) cell at the output. The SLC cell not only increases the input voltage, but also enhances the source’s lifespan and reliability. The SC cell further amplifies the voltage, especially for high-gain applications. The proposed converter simplifies control processes by using a single power switch, significantly boosting the input voltage by 21 times with a duty ratio of 0.8. This surpasses the gains achieved by conventional boost converters by over fourfold and Luo converters by sevenfold. The second challenge when a converter is connected to these voltage sources is the potential reduction in the lifespan of the sources and the overall system due to large input current ripples. The proposed converter addresses this issue by incorporating a switched-capacitor cell on the input side. This cell charges the inductors in parallel and discharges them in series, reducing the magnitude of the input current. Another advantage of the proposed converter is its simplicity, as it employs only one power switch, minimizing the complexity of the controller system. Additionally, the distribution of the output voltage passing through the diodes between the switch and output capacitor helps mitigate voltage stress for all semiconductor devices and capacitors. The study includes thorough mathematical analyses, simulations, and laboratory tests to validate the research’s theoretical foundations. Full article

In this study, a wind energy conversion system is designed using a three-phase permanent magnet synchronous generator, a six-diode bridge rectifier, a DC–DC boost converter, an inverter, and a load. The proposed inverter is a Packed U-Cell-based multilevel inverter having five or seven voltage levels at the output. It is also a topology that is not widely used in wind energy applications. Furthermore, a dual-mode PI-PI control technique is proposed to regulate the auxiliary capacitor voltage in the PUC MLI. The inverter is designed and simulated for a permanent magnet synchronous generator-based variable speed wind energy conversion system. Additionally, the design and experimental application of the proposed system is carried out in a laboratory environment. In the experimental application, the rated voltage of the Packed U-Cell multilevel inverter is chosen as 45 V. The switching frequency of the multilevel inverter is set to 4 kHz, and a generator with rated power of 700 W is selected. The output voltage of the generator is varied between 25 V and 35 V through an induction motor. This varying voltage is increased to 45 V using a DC–DC boost converter. Finally, it is observed that the power generated by the permanent magnet synchronous generator is successfully transferred to the load and the designed system operates with low harmonic content. Full article

Bridge sensors are widely used in military and civilian fields, and their demand gradually increases each year. Digital sensors are widely used in the military and civilian fields. High-precision and low-power analog-to-digital converters (ADCs) as sensor read-out circuits are a research hotspot. Sigma-delta ADC circuits based on switched-capacitor topology have the advantages of high signal-to-noise ratio (SNR), good linearity, and better compatibility with CMOS processes. In this work, a fourth-order feed-forward sigma-delta modulator and a digital decimation filter are designed and implemented with a correlated double sampling technique (CDS) to suppress pre-integrator low-frequency noise. This work used an active pre-compensator circuit for deep phase compensation to improve the system’s stability in the sigma-delta modulator. The modulator’s local feedback factor is designed to be adjustable off-chip to eliminate the effect of process errors. A three-stage cascade structure was chosen for the post-stage digital filter, significantly reducing the number of operations and the required memory cells in the digital circuit. Finally, the layout design and engineering circuit were fabricated by a standard 0.35 μm CMOS process from Shanghai Hua Hong with a chip area of 9 mm². At a 5 V voltage supply and sampling frequency of 6.144 MHz, the modulator power consumption is 13 mW, the maximum input signal amplitude is −3 dBFs, the 1 Hz dynamic range is about 118 dB, the modulator signal-to-noise ratio can reach 110.5 dB when the signal bandwidth is 24 kHz, the practical bit is about 18.05 bits, and the harmonic distortion is about −113 dB, which meets the design requirements. The output bit stream is 24 bits. Full article

This work proposes, analyzes, designs, and validates superior topologies of UHGH converters that are capable of supporting extremely large conversion ratios up to ∼2000× and output voltage up to ∼4–12 kV for future mobile soft robots from an input voltage as low as the range of a 1-cell battery pack. Thus, the converter makes soft robots standalone systems that can be untethered and mobile. The extremely large voltage gain is enabled by a unique hybrid combination of a high-gain switched magnetic element (HGSME) and a capacitor-based voltage multiplier rectifier (CVMR) that, together, achieve small overall size, efficient operation, and output voltage regulation and shaping with simple duty-cycle modulation. With superior performance, power density, and compact size, the UHGH converters prove to be a promising candidate for future untethered soft robots. Full article

The simplest DC/DC converter for supplying an Internet-of-Things device is definitely a switched-capacitor converter. The voltage from a mere 1.2 V battery may be stepped up to 2 V. A quite large operating frequency is required in order to reach the smallest possible output impedance value of the DC/DC converter. The overall efficiency is then limited even more so if the power area density of the system should be large. The article details how a microbial fuel cell may substitute one capacitor in the switched-capacitor converter, achieving a better efficiency at a much lower operating frequency. In that perspective, the microbial fuel cell acts as a kind of battery range extender. Some limitations exist that are discussed. A simple converter is experimentally evaluated to support the discussion. Substituting a microbial fuel cell inside a 100 $\mathsf{\mu }$W switched-capacitor converter compensates for losses in the order of 5% of efficiency. Moreover, the microbial fuel cell extends the lifespan of the battery, as 1.6 V output voltage is still possible when the battery voltage drops to 0.8 V. More than 94% efficiency is measured for a range of output power between 100 $\mathsf{\mu }$W and 1 mW, which is sufficient to address a lot of frugal IoT applications. Full article