Showing papers on "Voltage multiplier published in 2016"

A Novel High Step-Up Dual Switches Converter With Coupled Inductor and Voltage Multiplier Cell for a Renewable Energy System

Abstract: A novel high step-up converter, which is suitable for a renewable energy system, is proposed in this paper. The proposed converter is composed of the dual switches structure, three-winding coupled inductor, and two voltage multiplier cells in order to achieve the high step-up voltage gain. The dual switches structure is beneficial to reduce the voltage stress and current stress of the switch. In addition, two multiplier capacitors are, respectively, charged during the switch-on period and switch-off period, which increases the voltage conversion gain. Meanwhile, the energy stored in the leakage inductor is recycled with the use of clamped capacitors. Thus, two main power switches with low on-resistance and low current stress are available. As the leakage inductor, diode reverse-recovery problem is also alleviated. Therefore, the efficiency is improved. This paper illustrates the operation principle of the proposed converter; discusses the effect of the leakage inductor; analyzes the influence of parasitic parameters on the voltage gain and efficiency, the voltage stresses and current stresses of power devices are shown; and a comparison between the performance of the proposed converter and the previous high step-up converters is performed. Finally, the prototype circuit with input voltage 20 V, output voltage 200 V, and rated power 200 W is operated to verify its performance.

A New Hybrid Boosting Converter for Renewable Energy Applications

Abstract: A hybrid boosting converter (HBC) with collective advantages of regulation capability from its boost structure and gain enhancement from its voltage multiplier structure is proposed in this paper. The new converter incorporates a bipolar voltage multiplier, featuring symmetrical configuration, single inductor and single switch, high gain capability with wide regulation range, low component stress, small output ripple and flexible extension, which make it suitable for front-end PV system and some other renewable energy applications. The operation principal, component stress, and voltage ripple are analyzed in this paper. Performance comparison and evaluation with a number of previous single-switch single-inductor converters are provided. A 200-W 35 to 380 V second-order HBC prototype was built with peak efficiency at 95.44%. The experimental results confirms the feasibility of the proposed converter.

A Novel Five-Level Voltage Source Inverter With Sinusoidal Pulse Width Modulator for Medium-Voltage Applications

Abstract: This paper proposes a new five-level voltage source inverter for medium-voltage high-power applications. The proposed inverter is based on the upgrade of a four-level nested neutral-point clamped converter. This inverter can operate over a wide range of voltages without the need for connecting power semiconductor in series, has high-quality output voltage and fewer components compared to other classic five-level topologies. The features and operation of the proposed converter are studied and a simple sinusoidal PWM scheme is developed to control and balance the flying capacitors to their desired values. The performance of the proposed converter is evaluated by simulation and experimental results.

Full-Range Soft-Switching-Isolated Buck-Boost Converters With Integrated Interleaved Boost Converter and Phase-Shifted Control

Abstract: A new method for deriving isolated buck-boost (IBB) converter with single-stage power conversion is proposed in this paper and novel IBB converters based on high-frequency bridgeless-interleaved boost rectifiers are presented. The semiconductors, conduction losses, and switching losses are reduced significantly by integrating the interleaved boost converters into the full-bridge diode-rectifier. Various high-frequency bridgeless boost rectifiers are harvested based on different types of interleaved boost converters, including the conventional boost converter and high step-up boost converters with voltage multiplier and coupled inductor. The full-bridge IBB converter with voltage multiplier is analyzed in detail. The voltage multiplier helps to enhance the voltage gain and reduce the voltage stresses of the semiconductors in the rectification circuit. Hence, a transformer with reduced turns ratio and parasitic parameters, and low-voltage rated MOSFETs and diodes with better switching and conduction performances can be applied to improve the efficiency. Moreover, optimized phase-shift modulation strategy is applied to the full-bridge IBB converter to achieve isolated buck and boost conversion. What's more, soft-switching performance of all of the active switches and diodes within the whole operating range is achieved. A 380-V output prototype is fabricated to verify the effectiveness of the proposed IBB converters and its control strategies.

ZVS–ZCS High Voltage Gain Integrated Boost Converter for DC Microgrid

Abstract: A nonisolated soft-switched-integrated boost converter having high voltage gain is proposed for the module-integrated PV systems, fuel cells, and other low voltage energy sources. Here, a bidirectional boost converter is integrated with a resonant voltage quadrupler cell to obtain higher voltage gain. The auxiliary switch of the converter, which is connected to the output port acts as an active clamp circuit. Hence, zero voltage switching turn-on of the MOSFET switches are achieved. Coupled inductor's leakage energy is recycled to the output port through this auxiliary switch. In the proposed converter, all the diodes of the quadrupler cell are turned off with zero-current switching (ZCS). This considerably reduces the high-frequency turn-off losses and reverse recovery losses of the diodes. ZCS turn-off of the diodes also remove the diode voltage ringing caused due to the interaction of the parasitic capacitance of the diodes and the leakage inductance of the coupled inductor. Hence, to protect the diodes from the voltage spikes, snubbers are not required. The voltage stress on all the MOSFETs and diodes are lower. This helps to choose switches of low voltage rating (low $R_{\text{DS}}(\text{ON})$ ) and, thus improve the efficiency. Design and mathematical analysis of the proposed converter are made. A 250-W prototype of the converter is built to verify the performance.

High Gain DC–DC Converter Based on the Cockcroft–Walton Multiplier

Abstract: Recent advancements in renewable energy have created a need for both high step-up and high-efficiency dc–dc converters. These needs have typically been addressed with converters using high-frequency transformers to achieve the desired gain. The transformer design, however, is challenging. This paper presents a high step-up current fed converter based on the classical Cockcroft–Walton (CW) multiplier. The capacitor ladder allows for high voltage gains without a transformer. The cascaded structure limits the voltage stresses in the converter stages, even for high gains. Being current-fed, the converter (unlike traditional CW multipliers) allows the output voltage to be efficiently controlled. In addition, the converter supports multiple input operation without modifying the topology. This makes the converter especially suitable for photovoltaic applications where high gain, high efficiency, small converter size, and maximum power point tracking are required. Design equations, a dynamic model, and possible control algorithms are presented. The converter operation was verified using digital simulation and a 450-W prototype converter.

A Novel SVPWM Algorithm for Five-Level Active Neutral-Point-Clamped Converter

Abstract: The five-level active neutral-point-clamped (5L-ANPC) converter is becoming an attractive topology of multilevel converter family. A novel SVPWM algorithm based on line voltage coordinate was studied in this paper to overcome shortcomings of the traditional algorithm. Through coordinate transformation, steps of determining the basic vectors and the solution about the basic vector corresponding action time are simplified. Combining with the characteristics of 5L-ANPC converter and the new control algorithm, a method of controlling the voltage balancing of dc-link capacitors and floating-capacitors is proposed. According to the voltage of dc-link capacitors, the suitable switching sequence which can balance the voltage of dc-link capacitors is chosen. The high common-mode voltage will affect the service life of motor and reduce the reliability of the system especially in high-voltage converter. The common-mode voltage is also reduced by choosing the right switching state in this paper. The validity of the proposed method was proved by the experimental results.

An Active Cross-Connected Modular Multilevel Converter (AC-MMC) for a Medium-Voltage Motor Drive

Abstract: This paper presents an active cross-connected modular multilevel converter (AC-MMC) based on series-connected half-bridge modules. It is intended for completely enhancing the performance of a medium-voltage motor drive system in the full speed range from standstill to rated speed under all load conditions. The proposed AC-MMC circuit is characterized by the cross connection of upper and lower arm middle taps through a branch of series-connected half-bridge converters, which have an identical voltage and current rating with the submodules in the upper and lower arms. This cross-connected branch provides a physical power transfer channel for the upper and lower arms. By properly controlling the amount of high-frequency current flowing through the cross-connected branch, the power balance between the upper and lower arms is achieved even at a zero/low motor speed under constant torque condition. Meanwhile, no common-mode voltage is introduced in the whole speed range. A control strategy with focus on submodule capacitor voltage control is also proposed in this paper to guarantee the normal converter operation. Simulation results obtained from a 4160-V, 1-MW model verify the feasibility of the proposal. Experiments on a downscaled prototype also confirm the validity of the novel circuit and the associated control strategy.

An Advanced Current-Autobalance High Step-Up Converter With a Multicoupled Inductor and Voltage Multiplier for a Renewable Power Generation System

Abstract: In this paper, a novel high step-up dc–dc converter with a multicoupled inductor (MCI) and voltage multiplier is proposed for a sustainable energy system. The combinatorial employment of these components significantly extends the voltage boostability and reduces the voltage stress of the main switches. The special structure of branch cross coupling makes the two branches of current autobalance. Meanwhile, the utilization of MCIs makes the most of the magnetic core to further improve the power density. The diode reverse-recovery problem is alleviated because its current falling rate is controlled by the leakage inductance of the MCI. Moreover, the voltage spike of the main switches at their turn-off is clamped by a clamp capacitor. The interleaved operation results in the cancelation of the input current and output voltage. Next, the operating principle and performance of the converter are discussed in detail. Finally, a prototype circuit with 1-kW output power is implemented to verify the performance of the proposed converter.

Voltage Balancing Control of a Four-Level Hybrid-Clamped Converter Based on Zero-Sequence Voltage Injection Using Phase-Shifted PWM

Abstract: Four-level hybrid-clamped (4L-HC) inverter is a newly proposed topology which is suitable for high-performance medium-voltage drives. Each phase of this topology consists of eight switches and a flying capacitor and the dc-link is split into three parts by two neutral points. In order to ensure the topology operating properly, the voltages across the flying capacitors and three dc-link capacitors should be controlled and maintain balanced at their nominal values. This paper presents a decoupled voltage balancing method for this 4L-HC inverter, including the voltage balancing of dc-link capacitors and flying capacitors. A modified phase-shifted pulse-width modulation method is used to regulate the voltages of flying capacitors and the central dc-link capacitor. The relationship between the neutral-point currents and the output voltage is studied and the upper and lower dc-link capacitor voltages are balanced by injecting an optimum zero-sequence voltage. Simulation and experimental results are presented to verify the validity of this method.

A Modular High-Voltage Pulse-Generator With Sequential Charging for Water Treatment Applications

Abstract: High-voltage pulse-generators can be used effectively for bacterial decontamination in water treatment applications. Applying a pulsed electric field to the infected water sample guarantees killing of harmful germs and bacteria. In this paper, a modular high-voltage pulse-generator with sequential charging is proposed for water treatment via underwater pulsed streamer corona discharge. The proposed generator consists of series-connected modules similar to an arm of a modular multilevel converter. The modules’ capacitors are charged sequentially from a relatively low-voltage dc supply, then they are connected in series and discharged into the load. Two configurations are proposed in this paper, one for low repetitive pulse rate applications, and the other for high repetitive pulse rates. In the first topology, the equivalent resistance of the infected water sample is used as a charging resistance for the generator’s capacitors during the charging process. While in the second topology, the water resistance is bypassed during the charging process, and an external charging resistance with proper value is used instead. In this paper, detailed designs for the proposed pulse-generators are presented and validated by simulation results using MATLAB. A scaled down experimental setup has been built to show the viability of the proposed concept.

Modified DC-Bus Voltage Balancing Algorithm for a Three-Level Neutral-Point-Clamped PMSM Inverter Drive With Reduced Common-Mode Voltage

Abstract: This paper presents an improved dc-link voltage balancing algorithm for a three-level neutral-point-clamped inverter by considering phase current direction. Detailed studies on the effects of change in load current direction on the dc-link capacitor voltages are presented. A maximum value of power factor is numerically derived, above which it affects the capacitor voltage balancing capability. Compared with the previously presented research work, the inputs to the space-vector pulsewidth-modulation block are the three phase currents and the difference between the two capacitor voltages. Depending on the states of the two dc-link capacitor voltages and phase current direction, redundant voltage vector sequences are selected. The selected vectors keep the capacitor voltage deviations within 5% of the total dc-link voltage. Two zero switching vectors (i.e., PPP and NNN) are also removed from all subsectors of the earlier proposed strategy, which one used to produce higher common-mode voltages. Detailed simulation and experimental results are presented in this paper for a 6.0-kW surface permanent-magnet synchronous machine. Both the simulation and experimental results show the required performance of the proposed system.

An Improved Capacitor Voltage-Balancing Method for Five-Level Diode-Clamped Converters With High Modulation Index and High Power Factor

Abstract: The capacitor voltage imbalance is a critical issue of five-level diode-clamped converters (5L-DCC). To address this issue, an inner-hexagon-vector-decomposition-based space-vector modulation (VDSVM-H1) approach is provided in the literature, which obtains the capacitor voltage balancing with high modulation index and high power factor, but renders some drawbacks. To overcome these shortcomings, a novel capacitor voltage balancing method is proposed here. First, the previous VDSVM-H1 approach is modified by introducing six new vector sequences to each triangle and applying a new vector selection rule such that the converter will not violate the 5L-DCC switching mechanism in all operating conditions. Second, the variation of the line-to-line voltage output in one sampling period is restricted to one- or two-level in the optimized region, instead of the three-level in the previous VDSVM-H1 approach, which means less harmonics generating in the ac-side outputs. Finally, the simulation and experimental results show that the proposed method can improve the VDSVM-H1 with convincing results.

A Single-Switch Converter With High Step-Up Gain and Low Diode Voltage Stress Suitable for Green Power-Source Conversion

Abstract: This paper proposes a single-switch converter with high step-up gain and low diode voltage stress, suitable for green power source conversion. By employing a coupled inductor and switched capacitor, the proposed converters achieve high step-up conversion ratio without adopting extremely high duty ratio or high turns ratio. The voltage spike that occurs on the power switch is alleviated, which allows a low-voltage-rated power switch with low $R_{\rm DS(\mathrm{\scriptscriptstyle ON})}$ to be adopted, thus reducing the conduction losses. Because the energy of the leakage inductor is recycled, the efficiency is improved. In addition, all diodes’ voltage stresses are lowered and are the same, so the selection of power diodes is convenient. Finally, a 300-W prototype circuit with an input voltage of 24 V and an output voltage of 400 V is implemented to verify the performance and functionality of the presented converter. Moreover, the measured highest efficiency is 95.4%.

A Three-State Switching Boost Converter Mixed With Magnetic Coupling and Voltage Multiplier Techniques for High Gain Conversion

Abstract: An asymmetrical three-state switching boost converter, combining the benefits of magnetic coupling and voltage multiplier techniques, is presented in this paper. The derivation procedure for the proposed topology is depicted. The new converter can achieve a very high-voltage gain and a very low-voltage stress on the power devices without high turn ratio and extreme duty cycles. Thus, the low-voltage-rated MOSFETs with low resistance r DS (ON) can be selected to reduce the switching losses and cost. Moreover, the usage of voltage multiplier technique not only raises the voltage gain but also offers lossless passive clamp performance, so the voltage spikes across the main switches are alleviated and the leakage-inductor energy of the coupled inductors can be recycled. In addition, the interleaved structure is employed in the input side, which not only reduces the current stress through each power switch, but also constrains the input current ripple. In addition, the reverse-recovery problem of the diodes is alleviated, and the efficiency can be further improved. The operating principles and the steady-state analysis of the presented converter are discussed in detail. Finally, a prototype circuit with 400-W nominal rating is implemented in the laboratory to verify the performance of the proposed converter.

A Novel Transformer-less Interleaved Four-Phase Step-Down DC Converter With Low Switch Voltage Stress and Automatic Uniform Current-Sharing Characteristics

Abstract: In this paper, we propose a novel transformer-less direct current (dc) converter that features low switch voltage stress and automatic uniform current sharing. An interleaved four-phase voltage divider operating from a 400 V dc bus is used to achieve a high step-down conversion ratio with a moderate duty ratio. Based on the capacitive voltage division, the proposed converter achieves two major objectives, i.e., increased voltage conversion ratio, due to energy storage in the blocking capacitors, and reduced voltage stress of active switches and diodes. As a result, the proposed converter permits the use of lower voltage rating MOSFETs to reduce both switching and conduction losses, thereby improving the overall efficiency. In addition, due to the charge balance of the capacitors, the proposed converter enables automatic uniform current sharing of the interleaved phases without adding extra circuitry or complex control methods. The operation principles and performance analyses of the proposed converter are presented, and its effectiveness is verified by a 500 W output power prototype circuit that converts 400 V input voltage into 24 V output voltage.

Electronic optimization for an energy harvesting system based on magnetoelectric Metglas/poly(vinylidene fluoride)/Metglas composites

Abstract: Harvesting magnetic energy from the environment is becoming increasingly attractive for being a renewable and inexhaustible power source, ubiquitous and accessible in remote locations. In particular, magnetic harvesting with polymer-based magnetoelectric (ME) materials meet the industry demands of being flexible, showing large area potential, lightweight and biocompatibility. In order to get the best energy harvesting process, the extraction circuit needs to be optimized in order to be useful for powering devices. This paper discusses the design and performance of five interface circuits, a full-wave bridge rectifier, two Cockcroft–Walton voltage multipliers (with 1 and 2 stages) and two Dickson voltage multipliers (with 2 and 3 stages), for the energy harvesting from a Fe61.6Co16.4Si10.8B11.2 (Metglas)/polyvinylidene fluoride/Metglas ME composite. Maximum power and power density values of 12 μW and 0.9 mW cm−3 were obtained, respectively, with the Dickson voltage multiplier with two stages, for a load resistance of 180 kΩ, at 7 Oe DC magnetic field and a 54.5 kHz resonance frequency. Such performance is useful for microdevice applications in hard-to-reach locations and for traditional devices such as electric windows, door locking, and tire pressure monitoring.

Transformerless high-gain DC–DC converter for microgrids

Abstract: This study proposes a novel non-isolated high-gain high-power DC-DC converter. The converter is developed from a basic high-gain high-power converter structure. The proposed converter comprises of a three-phase interleaved boost converter, one coupled inductor and a voltage multiplier cell which act as gain extension stage. The main desirable features like voltage gain, stress on the switches and diodes, turns ratio, component utilisation factor and efficiency are summarised. The power circuit, operational details, simulation and experimental results of the 60 V/1.1 kV, 3 kW, 100 kHz proposed converter are presented.

A Single-Phase Four-Switch Rectifier With Significantly Reduced Capacitance

Abstract: A single-phase four-switch rectifier with considerably reduced capacitance is investigated in this paper The rectifier consists of one conventional rectification leg and one neutral leg linked with two capacitors that split the dc bus The ripple energy in the rectifier is diverted into the lower split capacitor so that the voltage across the upper split capacitor, designed to be the dc output voltage, has very small ripples The voltage across the lower capacitor is designed to have large ripples on purpose so that the total capacitance needed is significantly reduced and highly reliable film capacitors, instead of electrolytic capacitors, can be used At the same time, the rectification leg is controlled independently from the neutral leg to regulate the input current to achieve unity power factor and also to maintain the dc-bus voltage Experimental results are presented to validate the performance of the proposed strategy

Flying-Capacitor-Based Hybrid LLC Converters With Input Voltage Autobalance Ability for High Voltage Applications

Abstract: An advanced hybrid LLC series resonant converter with integrated flying-capacitor cell is proposed in this paper to enable the high step-down conversion in the high input voltage applications. The inherent flying-capacitor branch in the primary side can effectively halve the primary switch voltage stress compared with the half-bridge LLC converters. And the input voltage can be shared equally and automatically between the two series half-bridge modules without additional balance circuit or control strategies due to the built-in flying-capacitor cell. Moreover, the inherent soft switching performance during wide load range that exists in the LLC converters is still kept to reduce the switching losses, which ensures the high efficiency. Besides, the proposed converter can be extended to further decrease the switch voltage stress by employing stacked connection. Finally, a 500 ∼ 640 V-input 48 V-output 1 kW prototype is built and tested to verify the effectiveness of the proposed converter. The results prove that the proposed converter is an excellent candidate for the high input voltage and high step-down dc/dc conversion systems.

A survey on voltage boosting techniques for step-up DC-DC converters

Abstract: Step-up dc-dc converters are used to boost the voltage level of the input to a higher output level. Despite of its features such as simplicity of implementation, the fundamental boost dc-dc converter has shortcomings such as low boost ability and low power density. With these limitations, researches on new voltage boosting techniques are inevitable for various power converter applications. This can be achieved either by additional magnetic or by electric field storage elements with switching elements (switch and/or diode) in different configurations. Such combination of primary voltage boosting techniques and topologies are large, which at times may be confusing and difficult to follow/adapt for different applications. Considering these aspects and in order to make a clear sketch of the general law and framework of various voltage boosting techniques, this paper comprehensively reviews different voltage boosting techniques and categorizes them according to their circuit performance.

A Fully Integrated Reconfigurable Switched-Capacitor DC-DC Converter With Four Stacked Output Channels for Voltage Stacking Applications

Abstract: This work presents a fully integrated 4-to-1 DC-DC symmetric ladder switched-capacitor converter (SLSCC) for voltage stacking applications. The SLSCC absorbs inter-layer load power mismatch to provide minimum voltage guarantees for the internal rails of a multicore system that implements four-way voltage stacking. A new hybrid feedback control scheme reduces the voltage ripple across stacked voltage layers for high levels of current mismatch, a condition that exacerbates voltage noise in conventional SC converters. Furthermore, the proposed SLSCC dynamically allocates valuable flying capacitor resources according to different load conditions, which improves conversion efficiency and supports more power mismatch between the layers. Implemented in TSMC’s 40G process, the SLSCC converts a 3.6 V input voltage down to four stacked output voltage layers, each nominally at 900 mV.

A General Active Capacitor Voltage Regulating Method for L-Level M-Cell N-Phase Flying Capacitor Multilevel Inverter With Arbitrary DC Voltage Distribution

Abstract: The flying capacitor multilevel inverter (FCMLI) is one of the well-known structures of multilevel inverters having attracted considerable attention because of its merits. In spite of its many advantages, it has some limitations such as high volume and complicated control method because of its bulky capacitors and their voltage balancing requirement. Moreover, the high number of power semiconductors required makes this structure susceptible to failure. To increase the ratio of the number of levels to the number of components, an uneven distribution of capacitor voltages has been suggested in previous reports; however, this approach complicates the control method. Up to now, almost all presented methods suffer from high computational load and/or structure-dependent algorithm. In this paper, a simple state-based and structure-independent method is proposed for capacitor voltage regulation. The proposed method is straightforward and can perform online computation of switching sequences in a computationally efficient manner without any need for stored information or look-up tables. The method is conveniently extendible to any number of cells and levels in an FCMLI structure with arbitrary dc link voltage distribution schemes. Simulation and experimental results show the effectiveness and simplicity of this method.

Capacitor Aging Detection in a DC–DC Converter Output Stage

Abstract: One of the most significant reliability issues in switching-mode power supplies is electrolytic capacitor degradation caused by aging. This paper proposes an output voltage transient analysis method to detect capacitor wear-out at the output stage of a step-down dc–dc converter. Changes in the converter output voltage dynamics are evaluated by analyzing the output voltage step response with respect to a decrease in the capacitance. The sensitivity of the method is assessed with respect to parameter variations using an equivalent main circuit model. The feasibility of the presented method is verified by experimental tests using a converter prototype. The results show that the presented method is practical and adequate for detecting capacitor degradation in various operating conditions.

A Three-Phase Multilevel Hybrid Switched-Capacitor PWM PFC Rectifier for High-Voltage-Gain Applications

Abstract: In this paper, a three-phase multilevel power factor correction rectifier using the hybrid switched-capacitor concept is proposed. The converter is suitable for high-voltage-gain applications from conventional three-phase low-voltage sources. The three-level voltage operation reduces the weight and bulk of the magnetic devices. The main advantages of the proposed converter are low number of active switches, high voltage gain, sinusoidal currents, low voltage stress across all components, and simple control. Both steady-state and dynamic analyses are investigated. Experimental results for a 7500-W/220-V-to-1600-V laboratory prototype with maximum efficiency of 97.78% are presented and discussed.

Innovation of Switched-Capacitor Voltage Multiplier: Part 1: A Brief History

Abstract: The switched-capacitor (SC) voltage multiplier is becoming one of the most critical IC blocks for energy harvesting in wireless sensor nodes to generate a voltage high enough for microwatt sensing and computing ICs in a nanometer complementary metal?oxide?semiconductor (CMOS) from environmental energy sources such as mechanical vibration, electromagnetic wave, and temperature gradient. However, its origin was a 10 m-scale particle accelerator generating 1 MV back to 1920s. There have been several innovative design techniques to realize integrated SC voltage multipliers since the original one. This article overviews such innovations for the last century and describes how 10 m-scale SC voltage multipliers have been integrated in microwatt ICs and what technical considerations are critical for area- and power-efficient design. It also summarizes how device parameters determine circuit performance such as output voltage current and power efficiency. There have been also several design innovations in switching circuits to enable to work at extremely low voltages. This article shows state of the art for switching circuits for both dc-dc and ac-dc voltage multipliers and their applications as well.

Analysis and implementation of a novel high step-up DC–DC converter with low switch voltage stress and reduced diode voltage stress

Abstract: A new high step-up dc–dc converter is proposed in this study. This new high step-up converter utilises the input voltage, clamped-capacitor, and the secondary side of the coupled-inductor to charge the switched-capacitor and the secondary side of the coupled inductor also charges two multiplier capacitors in parallel during the turn-on interval of the switch. The input voltage, coupled-inductor, and multiplier capacitors are in series connection to the output to accomplish the purpose of high voltage gain during the turn-off interval of the switch. By adjusting the turns ratio of the coupled inductors, the proposed circuit does not need to be operated at high duty cycle to achieve the high voltage gain. The voltage stress of the switch and diodes can be decreased to cut down the cost. Moreover, the energy of the leakage inductance can be recovered to reduce the voltage spike of the switch. Therefore, the switch with lower conduction resistance can be applied to reduce the conduction loss and increase the efficiency. Finally, simulation and experiments are conducted. A prototype circuit with input voltage of 24 V, output voltage of 400 V, and output power of 200 W is implemented to validate the property of the proposed converter.

A DC Capacitor Voltage Control Method for Active Power Filters Using Modified Reference Including the Theoretically Derived Voltage Ripple

Abstract: This paper proposes a new dc capacitor voltage control method suitable for active power filters equipped with a small dc capacitor. The proposed control method calculates the theoretical dc capacitor voltage ripple and provides it to the dc capacitor voltage feedback controller as the reference. As a result, the proposed method has the capability to regulate the mean value of the dc capacitor voltage under a large voltage ripple condition. The proposed method also allows us to use a high feedback gain for suppressing the capacitor voltage fluctuations without any performance deterioration in the harmonic compensation. Experimental results confirm a good harmonic compensation and an effective voltage regulation performance under a small dc capacitor condition. The results also demonstrate a significant improvement in the capacitor voltage regulation even when a sudden load change occurs.