High-efficiency DC-DC Converter Research Articles

Performance Measures of Positive Output Superlift Luo Converter Using Multitudinous Controller

In order to meet the increase in energy demand globally it is necessary to harness renewable energy at its maximum potential for the purpose of electric power generation. For the achievement of high output voltage and efficiency DC-DC converters plays a vital role in low voltage PV array and fuel cells. LUO converters are gaining importance because of geometric progression output. . LUO converters find its application because of high transient performance of the system, high power transfer gain, efficiency and reduced ripple .Because of load and line disturbances the output voltage of DC-DC converter must be operated in closed loop mode. This paper interpolates multitudinous controller for positive output elementary super lift LUO converter (POESLL). The pursuance of the converter under manifold such as variation in input, load are developed and compared for current mode controller and SMC.

A high-efficient and fast-transient buck-boost converter using adaptive direct path skipping and on-duty modulation

This paper proposes a high-efficient and fast-transient buck-boost DC-DC converter for battery-powered mobile devices. The proposed converter employs an adaptive direct path skipping to minimize the switching losses caused by power transistors, and thus enhances the power efficiency and extends the usage time of the mobile device. It also adopts an on-duty modulation to achieve a fast line transient response, thereby rapidly regulating its output voltage. The proposed buck-boost converter was fabricated using 0.18-μm CMOS process technology with 1.8 V and 6.0 V CMOS devices. The measurement results show that the maximum power efficiency is achieved up to 97.6% at a load current of 100 mA. In addition, the measured line transient response is 155 μs/V.

High Efficiency Dc-Dc Converter for Renewable Energy Applications and High Voltage Gain with Less Losses

High Efficiency Dc-Dc Converter for Renewable Energy Applications and High Voltage Gain with Less Losses

A high-efficiency DC-DC converter with LC resonant in the load-side of HFT and voltage doubler for solar PV systems

This paper presents the implementation of a prototype phase-shift soft-switching full-bridge PWM DC-DC power converter isolated by a high-frequency transformer (HFT). This circuit topology is based on a new concept of series resonant principle in the secondary side. The step-up HFT and the voltage doubler rectifier make this circuit suitable for low-voltage renewable sources such as fuel cell or PV applications. Meanwhile, all semiconductor switches can achieve zero-voltage soft-switching (ZVS) with the assistance of transformer leakage inductances and lossless capacitive snubbers. The new contribution of this work is that the passive semiconductor switches (diodes) on the secondary side can also perform ZVS and zero-current switching (ZCS) transitions with the assistance of voltage doubler capacitance. The theory of operation and the experimental setup of the proposed circuit with a rated output of 5 kW are presented and discussed. A comparison between simulation and experimental results is explored and illustrated.

A high-efficiency DC-DC converter with LC resonant in the load-side of HFT and voltage doubler for solar PV systems

This paper presents the implementation of a prototype phase-shift soft-switching full-bridge PWM DC-DC power converter isolated by a high-frequency transformer (HFT). This circuit topology is based on a new concept of series resonant principle in the secondary side. The step-up HFT and the voltage doubler rectifier make this circuit suitable for low-voltage renewable sources such as fuel cell or PV applications. Meanwhile, all semiconductor switches can achieve zero-voltage soft-switching (ZVS) with the assistance of transformer leakage inductances and lossless capacitive snubbers. The new contribution of this work is that the passive semiconductor switches (diodes) on the secondary side can also perform ZVS and zero-current switching (ZCS) transitions with the assistance of voltage doubler capacitance. The theory of operation and the experimental setup of the proposed circuit with a rated output of 5 kW are presented and discussed. A comparison between simulation and experimental results is explored and illustrated.

Design of a 5-W power receiver for 6.78 MHz resonant wireless power transfer system with power supply switching circuit

A 6.78 MHz resonant wireless power transfer (WPT) system with a 5 W fully integrated power receiver is presented. A conventional low-dropout (LDO) linear regulator supplies power for operating the circuit in the power receiver. However, as the required operating current increases, the power consumption of the LDO regulator increases, which degrades the power efficiency. In order to increase the power efficiency of the receiver, this work proposes a power supply switching circuit (PSSC). When operation starts, the PSSC changes the power source from the low-efficiency LDO regulator to the high-efficiency step-down DC-DC converter. The LDO regulator operates only for initialization. This chip has been fabricated using 0.18 μm high-voltage bipolar- CMOS-DMOS (double-diffused metal-oxide-semiconductor) (BCD) technology with a die area of 2.5 mm x 2.5 mm. A maximum power transfer efficiency of 81% is measured.

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

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.

SHE–PWM Cascaded Multilevel Inverter With Adjustable DC Voltage Levels Control for STATCOM Applications

This paper presents a new multilevel selective harmonic elimination pulse-width modulation (MSHE-PWM) technique for transformerless static synchronous compensator (STATCOM) system employing cascaded H-bridge inverter (CHI) configuration. The proposed MSHE-PWM method optimizes both the dc-voltage levels and the switching angles, enabling more harmonics to be eliminated without affecting the structure of the inverter circuit. The method provides constant switching angles and linear pattern of dc-voltage levels over the modulation index range. This in turns eliminates the tedious steps required for manipulating the offline calculated switching angles and therefore, easing the implementation of the MSHE-PWM for dynamic systems. Although the method relies on the availability of the variable dc-voltage levels which can be obtained by various topologies, however, the rapid growth and development in the field of power semiconductor devices led to produce high-efficiency dc-dc converters with a relatively high-voltage capacity and for simplicity, a buck dc-dc converter is considered in this paper. Current and voltage closed loop controllers are implemented for both the STATCOM and the buck converter to meet the reactive power demand at different loading conditions. The technique is further compared with an equivalent conventional carrier-based pulse-width modulation to illustrate its enhanced characteristics. The effectiveness and the theoretical analysis of the proposed approach are verified through both simulation and experimental studies.

AlGaN/GaN MOSHFET power switching transistor with embedded fast recovery diode

In this study, a novel AlGaN/GaN power-switching device is proposed for use in high-efficiency DC-DC converters. The proposed structure is composed of a normally-off AlGaN/GaN metal-oxide-semiconductor heterojunction field-effect transistor (MOSHFET) and an embedded freewheeling Schottky barrier diode (SBD). The effects of the embedded freewheeling SBD on conversion efficiency were investigated based on circuit simulation of DCDC synchronous buck converters. The SBD embedment not only reduces the chip size and cost, but also improves the power conversion efficiency at high operation frequencies, due to the reduced off-state power loss. Open image in new window

A Novel Single-SiC-Switch-Based ZVZCS Tapped Boost Converter

A new single-active-switch-based zero voltage and zero current switching (ZVZCS) tapped boost converter is proposed. For the ZVZCS operation of the converter, three diodes and two capacitors were added to an ordinary tapped boost converter. When turned ON, the active switch is in zero current switching with the help of leakage inductance of a tapped inductor. When turned OFF, the energy of the leakage inductance is transferred to a snubber capacitor through a diode, which results in zero voltage switching of the active switch. Then the energy of the snubber capacitor is retrieved by a recovery capacitor connected to the tapped inductor. Different from most conventional soft switching converters that need at least two active switches, the proposed converter requires only one active switch such as JFET and MOSFET to guarantee ZVZCS operation for wide operating ranges of duty cycle, load current, and input voltage. The voltage stress of the active switch is always less than the load voltage, and soft switching turn-on and off is achieved without cumbersome current or voltage sensing, which could not be obtained from quasi-resonant converters that also have an active switch. Furthermore, the dc voltage gain of the proposed converter is quite robust against load change and is determined only by duty cycle like a canonical boost converter; hence, it can be even open-loop controlled. All the diodes are in ZVZCS as well, and all the components except an output diode have the voltage stress less than the load voltage. In this paper, the voltage stress of the output diode was selected to have two times the load voltage. A detailed analysis for the continuous conduction mode and the design procedures of the proposed converter is fully established, and experimentally verified for a 450-W prototype over the input voltage of 100-250 V, achieving 98.1% of maximum efficiency at the switching frequency of 100 kHz with a SiC JFET. Due to its versatile soft switching characteristics, the proposed scheme can be generally applied to high-frequency and high-efficiency dc-dc converters as well as power factor correctors.

A Bidirectional-Switch-Based Wide-Input Range High-Efficiency Isolated Resonant Converter for Photovoltaic Applications

Modular photovoltaic (PV) power conditioning systems (PCSs) require a high-efficiency dc-dc converter stage capable of regulation over a wide input voltage range for maximum power point tracking. In order to mitigate ground leakage currents and to be able to use a high-efficiency, nonisolated grid-tied inverter, it is also desirable for this microconverter to provide galvanic isolation between the PV module and the inverter. This paper presents a novel, isolated topology that is able to meet the high efficiency over a wide input voltage range requirement. This topology yields high efficiency through low circulating currents, zero-voltage switching (ZVS) and low-current switching of the primary side devices, ZCS of the output diodes, and direct power transfer to the load for the majority of switching cycle. This topology is also able to provide voltage regulation through basic fixed-frequency pulsewidth modulated (PWM) control. These features are able to be achieved with the simple addition of a secondary-side bidirectional ac switch to the isolated series resonant converter. Detailed analysis of the operation of this converter is discussed along with a detailed design procedure. Experimental results of a 300-W prototype are given. The prototype reached a peak power stage efficiency of 98.3% and a California Energy Commission (CEC) weighted power stage efficiency of 98.0% at the nominal input voltage.

Design of Soft Switching Sepic Converter Fed DC Drive Applications

High efficiency DC-DC converters with high-voltage gain have been researched due to increasing demands. A softswitching single-ended primary inductor converter (SEPIC) is presented in this work. An auxiliary switch and a clamp capacitor are presented in this project. A coupled inductor and an auxiliary inductor are utilized to obtain ripple-free input current and achieve zero voltage-switching (ZVS) operation of the main and auxiliary switches. The voltage multiplier technique and active clamp technique are applied to the conventional SEPIC converter to increase the voltage gain, reduce the voltage stresses of the power switches and diode. Moreover, by utilizing the resonance between the resonant inductor and the capacitor in the voltage multiplier circuit, the zero-current-switching (ZVS) operation of the output diode is achieved and its reverse-recovery loss is significantly reduced. The converter achieves high efficiency due to soft switching commutation of the power semiconductor device. The circuit is simulated using MATLAB Simulink and output result is verified.

High Efficient Induction Motor Drives Using Triple Lift Converter

This paper proposes a high efficient advanced DC-DC converter by name Triple-Lift converter in the front end of Induction motor (IM) drives system. The conventional IM drives use PWM rectifier, boost converter, buck-boost converter, etc., in the front end which holds inadequacy in pump-up voltage and deprived output current. The Triple-Lift converter (TLC) implemented in the system employs voltage lift technique and produces the output voltage in arithmetic progression. The voltage source inverter (VSI) coupling IM derives a wide range of DC input (ripple free) from TLC which can be adopted for high rated motors with good efficiency. Simulation results using MATLAB show the effectiveness of the proposed converter arrangement for IM drives.

A High Voltage-lift Efficient Isolated Full Bridge DC-DC Converter

The aim of this study is to propose a high voltage lift isolated full bridge dc-dc converter. The proposed converter consists of an isolation transformer a low turn ratio to obtain high step up voltage gain. The secondary of the transformer connected with two boosting capacitors which connects parallel when power switches switch on period and discharged in series during the switch off period. In addition full bridge converter on primary side consists of clamping diode and capacitor, leakage energy is recycled there by improving conversion efficiency. The proposed circuits simulated using PSIM software form input voltage of 48V, an output of 410 V obtained. These results and operations experimented and validated by implementing in hardware model at 20/40 Vdc, 20 Watts.

Microfabricated V-Groove Power Inductors Using Multilayer Co–Zr–O Thin Films for Very-High-Frequency DC–DC Converters

V-groove microinductors are designed, fabricated, and tested for operation above 10 MHz. Multilayer nanogranular Co-Zr-O/ZrO2 magnetic thin films are used as the core material of these inductors, to improve the magnetic performance of the films deposited on the sidewalls of V-grooves and to control eddy-current loss in the core. Prototype V-groove inductors are fabricated in a Si substrate based on optimization results for 7 to 3.3-V, 1-A dc-dc buck converters. The inductors exhibit an inductance of 3.4 nH from 10 to 100 MHz, a dc resistance of 3.83 mΩ, and a quality factor of up to at least 50. The prototype inductors are a promising candidate for high-power-density high-efficiency dc-dc converters. The measured inductor performance indicates that they could be used to make a 7 to 3.3-V, 1-A converter exhibiting a power density of 2.5 W/mm2 and an efficiency of 86% at 100 MHz; or a power density of 0.36 W/mm2 and an efficiency of 91% at 11 MHz.

모듈형 태양광 발전을 위한 개선된 동적응답 특성을 지닌 고효율 DC-DC 컨버터

This paper proposes a high-efficiency DC-DC converter with improved dynamic response characteristics for modular photovoltaic power conversion. High power efficiency is achieved by reducing switching power losses of the DC-DC converter. The voltage stress of power switches is reduced at primary side. Zero-current switching of output diodes is achieved at secondary side. A modified proportional and integral controller is suggested to improve the dynamic responses of the DC-DC converter. The performance of the proposed converter is verified based on a 200 [W] modular power conversion system including the grid-tied DC-AC inverter. The proposed DC-DC converter achieves the efficiency of 97.9 % at 60 [V] input voltage for a 200 [W] output power. The overall system including DC-DC converter and DC-AC inverter achieves the efficiency of 93.0 % when 200 [W] power is supplied into the grid.

High-Efficiency DC–DC Converter With Fast Dynamic Response for Low-Voltage Photovoltaic Sources

This paper proposes a high-efficiency dc-dc converter with fast dynamic response for low-voltage photovoltaic (PV) sources. The voltage stress of power switches is reduced at low-voltage side. Zero-current turn-off of output diodes is achieved at high-voltage side. Power efficiency is improved by reducing switching power losses. A modified proportional and integral controller is also suggested to achieve fast output voltage control. The dynamic response of the proposed converter is improved. The performance of the proposed converter is verified based on an experimental prototype for a 200-W PV module.

High Efficiency DC-DC Converter for Low PV Voltage Sources

A high efficiency DC-DC converter for low PV voltage sources has been proposed in this paper. The proposed converter converts the low dc voltage to a high dc voltage with a high-efficiency. The proposed converter uses the active clamping circuit and voltage doubler rectifier in order to achieve a high step-up ratio and soft switching operation. The output diodes are turned off at zero-current, which can significantly reduce the switching power losses at high output voltage applications. A high-efficiency of 97.5 % is achieved to generate 350V high output voltage from 36 V low PV module voltages which can be connected to grid tie for ac application.

High Efficiency DC-DC Converters Including a Performed Recovering Leakage Energy Switch

In this paper we studied the possibility to use high voltage DC bus to facilitate the energy transport in the smart grids, especially oriented to renewable energies. Recent studies [1] show that it is necessary to increase the output voltage in order to minimize transport losses on high distances. That is possible if we use electronic systems able to convert with a high efficiency the low voltage delivered by the local generators constituted by the Pv panels, the wind generators and other ones systems in various power ranges, and providing a high output voltage. In our study we expect to reach a voltage up to 5kV and more. The facilities offered by the DC bus are essentially in a very easy full synchronization and the possibility of communication supported by the power lines as in a PLC mode. So, as a consequence, it is important to improve the DC-DC converters to reach more than 5kV DC at the output. The main difficulty encountered when the goal is to increase the voltage in a smart DC-DC converter, is the small volume usable of those converter, the low cost, and of course the higher efficiency as possible. High voltage elevation implies the use of specific transformers (THT transformers) with a high voltage isolation performance, and a specific coils configuration to avoid spark discharges. The use of high voltage transformers ineluctably implies lower coupling coefficient between the coils, and undesirable superposed oscillations in the primary and secondary currents and voltages. More over the low coupling factor implies an increasing of the internal energy stored in the leakage inductors, that must recycled in order to keep a good efficiency. Previous studies [2] show the interest of using light structure converters based on one driven switch as the basically step-up boost. Some improvements [3] allow an expanding range working, and more specifically in the high value Vout /Vin of the converter ratio. We demonstrate in this paper that it is possible to use low coupled coils transformers to insure a perfect control and management of the energy without worrying about the leakage non-transferable energies stored in the various distributed inductors.

새로운 DCM-ZVS DC-DC 컨버터에 관한 연구

본 논문에서는 영전압 스위칭(ZVS)과 전류불연속 모드(DCM)에 의한 새로운 고효율의 DC-DC 컨버터에 대해 연구된다. 일반적으로 고효율의 컨버터를 만들기 위해서는 전력변환기내에 사용된 반도체 스위칭 소자의 손실을 최소화하여 이루어진다. 제안한 컨버터는 DCM에 의하여 스위치의 턴-온 동작을 영전류 스위칭(ZCS)으로 만들고, 또한 새로운 유사공진 회로를 접목하여 컨버터의 고효율을 실현시킨다. 제안한 컨버터에 사용된 제어용 스위칭 소자들은 유사공진 기법에 의해 소프트 스위칭, 즉 ZVS와 ZCS으로 동작시키고, 이에 따른 제어용 스위칭 소자들은 전압과 전류의 스트레스 없이 동작한다. 그 결과 제안한 컨버터는 스위칭 손실의 저감에 의해 고효율로 구동된다. 제안한 DCM-ZVS 컨버터의 소프트 스위칭 동작과 시스템 효율은 디지털 시뮬레이션과 실험결과를 통해 그 타당성이 입증된다. This paper is study on a new high efficiency DC-DC converter of discontinuous conduction mode (DCM) with zero voltage switching (ZVS). The converters of high efficiency are generally made that the power loss of the used semiconductor switching devices is minimized. The proposed converter is accomplished that the turn-on operation of switches is on zero current switching (ZCS) by DCM. The converter is also applicable to a new quasi-resonant circuit to achieve high efficiency converter. The control switches using in the converter are operated with soft switching, that is, ZVS and ZCS by quasi-resonant method. The control switches are operated without increasing their voltage and current stresses by the soft switching technology. The result is that the switching loss is very low and the efficiency of the converter is high. The soft switching operation and the system efficiency of the proposed DCM-ZVS converter are verified by digital simulation and experimental results.