Phase-shifted Full-bridge Converter Research Articles

A Pulse-Frequency-Modulated Full-Bridge DC/DC Converter With Series Boost Capacitor

The conventional zero-voltage switching phase-shift full-bridge (ZVS PSFB) converter has a large circulating energy during the freewheeling interval caused by the small duty cycle, which could increase the primary-side conduction losses, the turn-off switching losses of lagging-leg switches, and the current ripple through the output inductor. To overcome these problems, this paper proposes a new pulse-frequency-modulated full-bridge direct-current (dc)/dc converter with a series boost capacitor (SBC). The proposed converter controls the output voltage by varying the voltage across the SBC according to the switching frequency and has no freewheeling interval due to a 50% fixed duty operation. As a result, since its freewheeling current is eliminated, the conduction losses can be considerably reduced, as compared with those of the conventional ZVS PSFB converter. Moreover, the ZVS of all power switches cannot only be ensured along wide load ranges, but the current ripple through the output inductor can be also significantly reduced. Therefore, it has very desirable merits such as high efficiency, small output inductor, and improved heat generation. Operational principles, theoretical analysis, and design considerations are presented. To confirm the operation, the validity, and the features of the proposed converter, experimental results from a prototype that is 400-12 V/100 A are presented.

Phase-Shifted Full-Bridge Series-Resonant DC-DC Converters for Wide Load Variations

This paper presents the design of a phase-shifted full-bridge series resonant converter (PS-FB SRC). The proposed FB SRC features a novel two-mode operation. It is operated in series resonant mode at normal loads. The switching frequency is varied to regulate the output voltage. The fixed-frequency phase-shifted pulse width modulation, on the other hand, is used to adjust the effective duty cycle and regulate the output voltage at light loads. The proposed converter exhibits high conversion efficiency for wide-range load conditions. The relationships among the voltage gain, the switching frequency, and the effective duty cycle are discussed and analyzed. Finally, a 48-V/42-A prototype is implemented. Experiments are conducted to verify the theoretical analysis.

Monitoring and Diagnosis for the DC–DC Converter Using the Magnetic Near Field Waveform

A new diagnostic method for the dc-dc converter, which utilizes the magnetic near field as the diagnostic criterion, is proposed in this paper. The magnetic near field of the converter is captured using a loop magnetic near field probe. The frequency information in the measured waveform is extracted by the fast Fourier transfer; the interested low-order harmonic components are classified by the neural network while the interested high-order harmonic components are evaluated using the simple mathematical method. Finally, by compromising the results of the two parts, the detailed diagnostic conclusions are obtained. In this paper, the methodologies of the measurement and diagnosis are clearly described; then, the proposed method is used to monitor and diagnose the buck and phase shift full bridge converters. The experimental results are presented to show the validity of the analysis. Since the two chosen examples include most of the potential situations, the proposed method can be generalized and applied to many other types of converters.

Li-ion battery charger based on digitally controlled phase-shifted full-bridge converter

This study is aimed to design and implement a battery charger for 40 series-connected Li-ion batteries. The batteries together set up a rated 144 V DC bus for the latter stage. To obtain higher power output capability and achieve higher conversion efficiency, a phase-shift full-bridge converter is adopted as the power stage of the charger. The operation modes and design considerations are carefully studied and depicted. This charger is controlled by a digital signal processor controller which is responsible for steering the circuit to fulfil constant-current constant-voltage charging profile, accompanied by the overcharging protection mechanism of Li-ion batteries.

A single-stage phase-shifted full-bridge AC-DC converter with variable frequency control

This letter presents a single-stage soft-switched full-bridge AC-DC converter for low-voltage-high-current output applications. A phase-shifted method with a variable frequency control is used to r...

Integrated Magnetic Transformer for ZVS Phase Shift Full Bridge Converter

An integrated magnetic (IM) transformer is proposed for a phase shifted full bridge (PSFB) converter with zero voltage switching (ZVS). In a proposed IM transformer, the transformer is located on the center leg of E-core and the output inductor is wound on two outer legs with air gap. The proposed IM transformer is analyzed by using the magnetic capacitor model. For reducing the core size, EE core is redesigned. The proposed IM transformer is experimentally verified on a 1.2 kW prototype converter. The converter efficiency with the proposed IM transformer is about 93 % at full load and its volume size can be reduced. It can be expected that the power density can be largely increased with the proposed IM transformer.

Zero-voltage switching phase shift full-bridge step-up converter with integrated magnetic structure

A zero-voltage switching (ZVS) phase shift full-bridge (PSFB) step-up converter with integrated magnetic structure is proposed. In order to improve ZVS ranges, an external inductor is imposed. Especially, to save the volume of the magnetic core of external inductor, the external inductor and transformer are integrated into one magnetic core and then the coupling is formed. Furthermore, coupling coefficients are analysed and can be adjusted by the gaps in the three legs of magnetic core. Besides, the fluxes and the maximum flux density in the three legs of magnetic core are also analysed. Finally, a 100 W prototype converter is made and the experimental results are given to verify the analysis.

Control Strategy for Input-Series–Output-Parallel Converters

The input-series-output-parallel (ISOP) converter, which consists of multiple dc-dc converter modules connected in series at the input and in parallel at the output, is an attractive solution for high input voltage and high power applications. This paper reveals the relationship between input voltage sharing (IVS) and output current sharing of the constituent modules of the ISOP converter. A novel IVS control strategy, which is decoupled with the output voltage regulation, is proposed. This control allows IVS and output voltage regulation to be designed independently. An ISOP converter, which uses the phase-shifted full-bridge (PS-FB) converter as the basic module, is considered. Based on the proposed control strategy, this ISOP converter together with the control circuit can be decoupled from several independent single-input and single-output systems. An ISOP converter consisting of three PS-FB modules is used to illustrate the design procedure, and a 3-kW experimental prototype is fabricated and tested.

Analysis and Implementation of an Improved Current-Doubler Rectifier With Coupled Inductors

In this paper, an improved current-doubler rectifier with coupled inductors is proposed. The proposed rectifier can extend duty ratio to reduce the peak current through the isolation transformer winding and lower output current ripple as well as voltage stress of the rectifier diodes. In this study, a 500-W prototype with a full-bridge phase-shift converter, the proposed rectifier, with input voltage of 400 V and output voltage of 12 V was built. Theoretical analysis and experimental results have verified that the proposed rectifier is attractive for high step-down voltage and high-power applications.

A New Phase-Shifted Full-Bridge Converter With Voltage-Doubler-Type Rectifier for High-Efficiency PDP Sustaining Power Module

A new phase-shifted full-bridge converter with a voltage-doubler-type rectifier for a high-efficiency power-sustaining module of a plasma display panel is proposed in this paper. The proposed converter employs a voltage-doubler rectifier without an output inductor. Since it does not have an output inductor, the voltage stresses of the rectifier diodes can be clamped at the output voltage level. Thus, since no dissipative resistor-capacitor snubber for rectifier diodes is needed, high-efficiency low-noise output voltage can be realized. Due to the elimination of the large output inductor, it features simpler structure, lower cost, smaller mass, and lighter weight. Furthermore, the proposed converter has wide zero-voltage-switching ranges of lagging leg switches with low current stresses of the primary power switches by using the magnetizing current. In addition, the resonance between the leakage inductor of the transformer and the rectifier capacitors can reduce the current stresses of the rectifier diodes and conduction losses. In this paper, the operational principles, analysis, design considerations, and experimental results are presented.

Low Voltage and Current Stress ZVZCS Full Bridge DC–DC Converter Using Center Tapped Rectifier Reset

An improved zero-voltage and zero-current-switching (ZVZCS) full bridge dc-dc converter is proposed based on phase shift control. With an auxiliary center tapped rectifier at the secondary side, an auxiliary voltage source is applied to reset the primary current of the transformer winding. Therefore, zero-voltage switching for the leading leg switches and zero-current switching for the lagging leg switches can be achieved, respectively, without any increase of current and voltage stresses. Since the primary current in the circulating interval for the phase shift full bridge converter is eliminated, the conduction loss in primary switches is reduced. A 1 kW prototype is made to verify the theoretical analysis.

Voltage Oscillation Reduction Technique for Phase-Shift Full-Bridge Converter

A conventional phase-shift full-bridge (PSFB) converter has a serious voltage oscillation problem across the secondary rectifier diodes. To overcome this problem, a new voltage oscillation reduction technique (VORT), which effectively reduces the rectifier voltage oscillation by a simple nondissipative manner, is proposed. The concept of VORT is to utilize the operation of leading-leg transition, which does not cause severe rectifier voltage oscillation, to the lagging-leg transition. It is simply implemented by employing only a resonant capacitor in series with the transformer secondary and a small magnetizing inductance of the transformer without any lossy components. Moreover, the VORT can realize zero-voltage switching for all switches over a wide load range using the energy that is stored in the transformer magnetizing inductor and output filter inductor. The concept, operational principle, oscillation analysis, and design considerations of VORT are presented and verified experimentally.

A multicarrier modular photovoltaic grid-connected inverter with a new phase-shift rule

Photovoltaic grid-connected inverters are distributed power generation devices that convert the dc power from solar panels to high-quality ac power at the utility grid interface. Adopting modular design in these systems improves expandability, serviceability, reliability and efficiency. In this paper, the phase-shifted carrier technique, which is normally used in high-power multiconverter schemes, is applied to a modular residential photovoltaic grid-connected inverter to improve the output power quality. First, it is shown, through analysis and simulation, that in the commonly-used grid-connected inverter topology based on the phase-shift modulated full-bridge converter, the well-known rule for the phase-shift between the carrier signals of the adjacent modules is not effective for both odd and even number of modules. Then, a new general rule for the phase-shift is systematically derived and its effectiveness in improving the output power quality for odd and even numbers of modules is verified through simulation.

1-MHz Self-Driven ZVS Full-Bridge Converter for 48-V Power Pod and DC/DC Brick

In this paper, a self-driven zero-voltage-switching (ZVS) full-bridge converter is proposed. With the proposed self-driven scheme, the combination of the ZVS technique and Self-driven technique recycles the gate driving energy by making use of the input capacitor of the secondary side synchronous rectifier (SR) as the snubber capacitor of the primary side switches. Compared with the external driver, the proposed converter can save driving loss and synchronous rectifier body diode conduction loss. Additionally, compared with the existed level-shifted self-driven scheme for bridge-type symmetrical topologies, its gate signal is very clean and suitable for high-frequency applications. A 1-MHz, 1.2-V/70-A prototype is built to verify the analysis. Experimental results show that it can achieve 81.7% efficiency. And there is an efficiency improvement of 4.7% over conventional phase-shifted full-bridge converter with an external driver.

New Zero-Voltage-Switching Phase-Shift Full-Bridge Converter With Low Conduction Losses

A new zero-voltage-switching (ZVS) phase-shift full-bridge (PSFB) converter with low conduction losses is proposed. It is based on the PSFB converter with series-connected two transformers, which features wide ZVS ranges. By adding a capacitor, the proposed converter overcomes the disadvantage of the based converter, such as the high circulating energy. Furthermore, the turns ratio of the transformers can be increased as well. Therefore, high efficiency of the proposed converter can be achieved. Operational principles and experimental results for a 100-W (5 V, 20 A) prototype are presented to validate the proposed converter.

Analysis and Design of Phase Shift Full Bridge Converter With Series-Connected Two Transformers

A new phase shift full bridge (PSFB) converter with series-connected two transformers is proposed. The proposed converter shows wide zero voltage switching (ZVS) ranges and no output inductor is needed since each transformer individually acts as an inductor or a transformer during different times of the switching cycle. The operational principle, large signal modeling, and design equations are presented. Experimental results demonstrate that the proposed converter can achieve a significant improvement in the efficiency for a 100W (5 V, 20 A) telecommunication on-board power supply.

Analysis and design for RCD clamped snubber used in output rectifier of phase-shift full-bridge ZVS converters

Detailed analysis and parameter design for a resistor-capacitor-diode (RCD) clamped snubber used in the output rectifier of phase-shift full-bridge zero-voltage-switching (PS-FB-ZVS) power converters are presented. Design equations and some properties of the clamped circuit are also highlighted.