Current-fed Half-bridge Converter Research Articles

Reduction in Circulating Current With Improved Secondary Side Modulation in Isolated Current-Fed Half Bridge AC–DC Converter

Current-fed half bridge converter with bidirectional switches on ac side and a full bridge converter on dc side of a high frequency transformer is an optimal topology for single stage galvanically isolated ac-dc converter for onboard vehicle charging application. AC side switches are actively commutated to achieve zero current switching (ZCS) using single phase shift modulation (SPSM) and discontinuous current phase shift modulation (DCPSM). Furthermore, zero voltage turn-on (ZVS) is achieved for dc side switches. Compared to SPSM, DCPSM maintains a constant peak current in the converter throughout the grid cycle of ac mains voltage. However, constant peak current contributes to a high circulating current near the zero crossings of ac mains voltage and also at light load conditions.This paper proposes an improved discontinuous current phase shift modulation (IDCPSM) to increase the efficiency of the converter across different loading conditions. A dual control variable is adopted to actively reduce the circulating current while maintaining soft switching of both ac and dc side switches across the grid cycle of ac mains voltage. A 1.5 kW laboratory prototype has been developed to experimentally validate the analysis, design and improvement in performance for different loading conditions.

Highly Efficient Current-Fed Half-Bridge Resonant Converter for Pulse Power Applications

This article proposes a highly efficient current-fed half-bridge resonant converter over a wide range of the output voltages. By adding a bidirectional switch across center nodes of the voltage doubler and applying corresponding switching modulation, the converter accomplishes almost zero-voltage switching at the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> instant under the wide output voltage variations. Moreover, the circuit experiences very little instantaneous reactive current even when the output voltage varies widely. Primary-side duty cycle fixed at 0.5 balances the voltages across the capacitors at the primary side and at the secondary side each irrespective of the output voltage variation; it also limits the voltage stress at the active power components. Therefore, the proposed converter delivers high efficiency and compact component size. We fabricated a 400-W experimental prototype to validate the superior properties of the proposed converter.

Optimized Design of 1 MHz Intermediate Bus Converter Using GaN HEMT for Aerospace Applications

This paper presents the possibility of using Gallium Nitride (GaN) high-electron-mobility transistors (HEMTs) instead of the conventional silicon metal oxide semiconductor field effect transistor (MOSFET) to implement a high-frequency intermediate bus converter (IBC) as part of a typical distributed power architecture used in a space power application. The results show that processing the power at greater frequencies is possible with a reduction in mass and without impacting the system efficiency. The proposed solution was experimentally validated by the implementation of a 1 MHz zero-voltage and zero-current switching (ZVZCS) current-fed half-bridge converter with synchronous rectification compared with the same converter using silicon as the standard technology on power switches and working at 100 kHz. In conclusion, the replacement of silicon (Si) transistors by GaN HEMTs is feasible, and GaN HEMTs are promising next-generation devices in the power electronics field and can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters. The best physical properties of GaN HEMTs, such as inherent radiation hardness, low on resistance and parasitic capacitances, allow them to switch at higher frequencies with high efficiency achieving higher power density. We present an optimized design procedure to guaranty the zero-voltage switching condition that enables the power density to be increased without a penalization of the efficiency.

Active-Clamped Zero-Current Switching Current-Fed Half-Bridge Converter

This article presents an auxiliary circuit for the current-fed half-bridge (CFHB) converter, aiming to clamp the high voltage spikes across the main switches caused by the energy stored in the leakage inductance of the transformer. This circuit also provides zero-current switching (ZCS) to the main switches at turn-off. Moreover, the rectifier diodes and the auxiliary switch operates under ZCS at turn-on and turn-off. Another feature of the proposed circuit is that it is composed of just one active switch, reducing the number of auxiliary sources and drivers compared to the conventional active-clamped CFHB converter. In addition, the inclusion of the clamping circuit increases the voltage ratio of the converter. A 300-W prototype was built to validate the analysis and design proposed in this article. The converter was tested for various load conditions at 100 kHz, and a peak efficiency of 96.2% was obtained. Also, a comparison of efficiency for the CFHB employing other conventional clamping circuits is presented.

Analysis and Design of Current-Fed Half-Bridge (C)(LC)–( LC) Resonant Topology for Inductive Wireless Power Transfer Application

This paper proposes and analyzes a new power electronics circuit topology for wireless inductive power transfer application using current-fed half-bridge converter with CCL-LC resonant network. The major focus is analysis and implementation of a new current-fed resonant topology with current-sharing and voltage doubling features. Generally, inductive power transfer circuits with current fed converter use parallel CL resonant tank to transfer power effectively through air gap. However, in medium power application, this topology suffers from a major limitation of high voltage stress across the inverter semiconductor devices owing to high reactive power consumed by loosely coupled coil. In proposed topology, this is mitigated by adding a capacitor in series with the coil developing series-parallel CCL tank. The power flow is controlled through variable frequency modulation. Soft-switching of the devices is obtained irrespective of the load current. For grid-to-vehicle or solar-to-vehicle, the converter is analyzed and detailed design procedure is illustrated. Experimental results are presented to verify the analysis and demonstrate the performance.

Efeito da Conexão do Capacitor de Grampeamento sobre a Corrente de Entrada no Conversor Alimentado em Corrente Meia-ponte Zvs com Grampeamento Ativo

A conexão de geração fotovoltaica (PV) à rede através de microinversores ou em topologia CC paralela, em geral, requer que o conversor CC-CC apresente um elevado ganho de tensão. O conversor CC-CC alimentado em corrente meia- ponte com grampeamento ativo (ACCFHB) tem essa característica. O capacitor de grampeamento pode ser conectado tanto ao nó positivo quanto ao nó negativo da fonte de alimentação. O ponto de conexão tem efeito sobre a corrente drenada da fonte. Em sistemas fotovoltaicos, a ondulação da corrente drenada do módulo é um importante parâmetro de projeto e, em geral, implica na adição de filtros para reduzi-la. Esse trabalho analisa os efeitos da forma de conexão do capacitor de grampeamento sobre a corrente de entrada, propõe que a conexão seja feita no nó negativo para reduzir a ondulação ou para reduzir os requisitos de filtro necessários e analisa o funcionamento de um filtro LC na entrada do conversor. O conversor foi simulado e experimentado em laboratório usando ambas as possibilidades de conexão, com e sem o filtro LC de entrada, para confirmar a proposição teórica.

Novel Zero-Current-Switching Current-Fed Half-Bridge Isolated DC/DC Converter for Fuel-Cell-Based Applications

A novel zero-current-switching (ZCS) current-fed half-bridge isolated dc/dc converter has been proposed in this paper. The proposed converter has potential applications such as front-end dc/dc power conversion for fuel cell and photovoltaic inverters, bidirectional converters for fuel cell vehicles, energy storage, etc. This proposed converter provides a simple solution to the switch turn-off voltage spike problem without any additional components or snubber. It leads to reduced size, lower cost, compactness, and higher conversion efficiency. In addition, the proposed converter has reduced peak current through the components (semiconductor devices and transformer) that reduces their volt-ampere rating and size compared to active-clamped zero-voltage-switching (ZVS) current-fed converters. Voltage across the primary switches is naturally clamped without an additional active clamp or snubber circuit. In addition, voltage across the switch is independent of the duty cycle. ZCS of the primary switches, natural commutation of secondary diodes, and zero-current turn-on of secondary switches are achieved. Therefore, switching transition losses are significantly reduced. Steady-state analysis, operation with the proposed novel ZCS concept, and design of the converter are reported. A 200-W laboratory converter prototype has been built. Experimental results as well as simulation results are presented to validate the analysis and design. A comparison with existing active-clamped ZVS current-fed half-bridge converters has been discussed. The effect of device parasitic is investigated and explained by simulation and experimental results.

능동 클램프 전류원 하프 브릿지 기반 태양광 모듈 집적형 전력변환장치에 대한 연구

태양광 발전 시스템이 대용량화됨에 따라 태양전지 어레이 구성 시 부정합(mismatch) 문제가 대두되는 가운데, 태양전지 모듈을 직접 계통에 연계하는 AC 모듈형 태양광 모듈 집적형 전력변환장치(PV-MIC)에 관한 연구가 지속되고 있다. PV-MIC는 수명 및 고효율이 가장 큰 문제이며 이 문제를 해결하기 위해서 본 논문에서는 ZVS 동작을 통하여 스위칭 손실을 저감시키고 입력전류 리플감소를 통하여 입력 커패시턴스를 저감할 수 있는 능동 클램프 전류원 하프 브릿지 컨버터를 적용한 PV-MIC를 제안하고, 이에 관한 제어분담 및 설계에 대하여 고찰한다. In this paper, photovoltaic module integrated converter (MIC) based on active clamp current-fed half-bridge converter is proposed. The converter stage operates in zero-voltage condition using active clamp technique. The theoretical study and circuit design for proposed inverter are confirmed with PSIM simulator and experimental reusult.

A New Soft Switching Current fed DC-DC Converter for Medium Power Applications

In this paper a new zero voltage switching current fed half bridge converter with an auxiliary circuit is proposed. The auxiliary circuit not only absorbs the voltage surge across switches at turn off instance, but also provides zero voltage switching condition for all converter switches. Therefore in this converter the efficiency is higher than hard switching counterpart and also main switches voltage stresses decrease. Since the switches in auxiliary circuit operate under soft switching conditions, these switches don’t apply additional losses to proposed converter. Implementation of control circuit is very simple since the converter is PWM controlled and the auxiliary switches turn on are complementary with respect to main switches. In this paper the proposed converter operating modes are analyzed and simulation results are presented. To verify the converter operation a 100W laboratory prototype operating at 100kHz is implemented and the experimental results are presented.

Fuel Cell Generation System With a New Active Clamping Current-Fed Half-Bridge Converter

In this paper, a new active clamping current-fed half-bridge converter is proposed, which is suitable for fuel cell power generation systems. The proposed converter is superior to conventional dc-dc converters in terms of efficiency and component utilization. The overall efficiency is estimated to be 94% at full load.

A New Active Clamping Zero-Voltage Switching PWM Current-Fed Half-Bridge Converter

A new active clamping zero-voltage switching (ZVS) pulse-width modulation (PWM) current-fed half-bridge converter (CFHB) is proposed in this paper. Its active clamping snubber (ACS) can not only absorb the voltage surge across the turned-off switch, but also achieve the ZVS of all power switches. Moreover, it can be applied to all current-fed power conversion topologies and its operation as well as structure is very simple. Since auxiliary switches in the snubber circuit are switched in a complementary way to main switches, an additional PWM IC is not necessary. In addition, it does not need any clamp winding and auxiliary circuit besides additional two power switches and one capacitor while the conventional current-fed half bridge converter has to be equipped with two clamp windings, two ZVS circuits, and two snubbers. Therefore, it can ensure the higher operating frequency, smaller-sized reactive components, lower cost of production, easier implementation, and higher efficiency. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200-W, 24-200Vdc prototype are presented.