Conventional Phase-shift Full-bridge Converter Research Articles

A Novel Hybrid Mode Control for a Phase-Shift Full-Bridge Converter Featuring High Efficiency Over a Full-Load Range

A novel hybrid mode control technique for a phase-shift full-bridge (PSFB) converter is proposed in this paper. The proposed method can improve power efficiency under both the light-load and heavy-load conditions. The basic concept of the proposed control technique is to decrease the turns ratio to reduce the circulating current, hence resulting in lower circulating losses. However, the output voltage under heavy load may not be stabilized using phase-shift control if smaller turns ratio is utilized. Therefore, the proposed technique employs asymmetrical pulsewidth modulation to achieve higher output voltage. To further improve the efficiency, an adaptive dead-time control method, which determines the dead-time value according to the load level, is also proposed. To validate the correctness and effectiveness of the proposed method, a 480-W PSFB converter is constructed and experiments are carried out accordingly. Comparing with a conventional PSFB converter, the efficiency of the proposed method can be improved up to 3.2%, 1.3%, and 0.6% under light-load, 30% load, and full-load conditions, respectively.

Analysis and Design of a Hybrid-Type Converter for Optimal Conversion Efficiency in Electric Vehicle Chargers

In this paper, a hybrid-type converter, which can overcome the drawbacks of the conventional phase-shifted full-bridge (PSFB) converter, such as narrow zero-voltage-switching range, conduction loss by circulating current, and large output filter inductor, is analyzed and evaluated. The hybrid-type converter discussed in this paper consists of the conventional PSFB converter with a full-bridge rectifier and a half-bridge LLC series-resonant converter (SRC) with a voltage-doubler rectifier (VDR), sharing the lagging-leg switches and integrating the VDR of LLC SRC into the node of the secondary-side rectifier in the PSFB converter. This rectifier structure allows the targeted hybrid-type converter to have the advantages of high efficiency and high power density by the modification of the output voltage of LLC SRC. This paper analyzes the operation principle and power distribution of the targeted hybrid-type converter. Based on the analysis, the optimal design of transformer and the control strategy with frequency and pulse-width modulation are presented. With the precise design and control, the conversion efficiency and power density can be increased. Its validity is confirmed by experimental results involving a 3.3-kW (250–450-V/7.33-A) prototype converter.

A Dual Half-Bridge Converter with Adaptive Energy Storage to Achieve ZVS over Full Range of Operation Conditions

The phase-shifted full-bridge (PSFB) converter is widely employed in high-power applications. However, circulating current, duty-cycle loss, secondary voltage oscillation, and narrow zero-voltage-switching (ZVS) range are the main drawbacks of the conventional PSFB converter. This paper proposes a novel full-bridge converter to improve the performance of the conventional PSFB converter. The proposed converter contains two paralleled half-bridge inverters and an auxiliary inductor on the primary side. The rectifier stage is composed of six diodes connected with the form of full-bridge rectification. This structure allows the stored energy for ZVS operation to change adaptively with duty-cycle. The power can be transferred from the primary side to the secondary side during the whole period. Therefore, the requirement of output filter inductance is reduced and the circulating current is removed. The proposed converter is a good candidate for high power, high voltage and variable input voltage applications. The operation principle and performance are verified on a laboratory prototype.

A Novel PCCM Voltage-Fed Single-Stage Power Factor Correction Full-Bridge Battery Charger

A novel pseudo-continuous conduction mode (PCCM) voltage-fed single-stage power factor correction (PFC) full-bridge battery charger is proposed in this paper. By connecting a freewheeling transistor in parallel with an input inductor, the PFC cell can operate in the PCCM with a constant duty ratio. Thus, the dc/dc stage can be designed using this constant duty ratio and the restriction on the duty ratio of the PFC cell is eliminated. As a result, the input current distortion is less and the dc bus voltage becomes controllable over the wide output power range of the battery charger. Moreover, the operation principle of the dc/dc stage is designed to be similar to that of a conventional phase-shifted full-bridge converter. Therefore, it is easy to implement. In this paper, the operation of the new converter is explained, and the design considerations of the controller and key parameters are presented. Simulation and experimental results obtained from a 1 kW prototype are given to confirm the operation of the proposed converter.

Hybrid DC–DC Converter With Phase-Shift or Frequency Modulation for NEV Battery Charger

This paper suggests a new hybrid dc–dc converter for a neighborhood electric vehicle battery charger. The proposed converter is based on the conventional phase-shift full-bridge (PSFB) converter with center-tap rectifier. By integrating an $LLC$ series resonant converter into the conventional PSFB converter, the proposed converter has many advantages like wide soft-switching range without duty-cycle loss, zero-current-switching operation of rectifying diodes, minimized circulating current, reduced size of filter inductor, and much better transformer utilization than before presented hybrid dc–dc converters. The proposed converter can be modulated in phase-shift manner or frequency variation. The feasibility of the proposed converter has been verified with the experimental results under an output voltage range of 36–72 V dc at 1 kW.

Integrated Dual Full-Bridge Converter With Current-Doubler Rectifier for EV Charger

A novel converter topology for high-power battery charger applications is proposed in this paper. The topology adopts the integration structure of two full-bridge converters, which shares one leg of switching device called center-leg. The two full-bridge converters are placed in parallel on the primary side, and are driven in a phase-shift manner. The integrated form of two current-doubler rectifier is adopted on the secondary side, and it has full-bridge structure. With this structure, the proposed converter can overcome drawbacks of the conventional phase-shift full-bridge converter; narrow zero-voltage-switching range, large duty-cycle loss, and high component counts. The validation of the proposed converter is confirmed by the experiment with a prototype battery charger of 5.7 kW and 13.5 A.

전기자동차 탑재형 충전기 응용에서 위상변조 풀브리지 컨버터 성능 분석과 그 개선에 관한 연구

The conventional phase-shifted full-bridge (PSFB) converter with an LC filter has been widely used for high-power applications of over 1.0 kW. However, the PSFB converter cannot obtain optimal power conversion efficiency during the battery charging in electric vehicle (EV) on-board battery charger applications because of its unique drawbacks, such as a large circulating current and very high voltage stress in the rectifier diodes. As a result, the converters with a capacitive filter, such as LLC resonant converters, replace the PSFB converter in the EV chargers. This study analyzes the problems of the PSFB converter for EV on-board charger applications in detail. Moreover, the newest converters based on the conventional PSFB converter are reviewed. On the basis of the reviews, new PSFB converter topologies are proposed for EV charger applications. The new topologies are formed by connecting the rectifier stage in the PSFB converter with the output of an LLC resonant converter in series. Many problems of the conventional PSFB converter for EV charger applications can be solved and the performance can be more improved because of this structure; this idea is confirmed by an experiment consisting of prototype battery chargers under the output voltage range of 250-450 Vdc at 3.3 kW.

저전압 대전류 LLC 공진형 컨버터를 이용한 그린 PC용 전원공급장치 설계

This paper proposes a low voltage high current LLC resonant converter for Green PC. Green PC is composed of a lot of blade PCs, and it is a centralized system to manage them in computer center. Green PC should require that its power supplies have several characteristics such as low output voltage, high output current, and high power conversion efficiency. Conventional PSFB (Phase Shift Full Bridge) converter is usually used as DC/DC converter for computer power supply because it has high power conversion efficiency thanks to ZVS (Zero Voltage Switching) operation under middle and high load conditions. However, this converter has some problems such as large switching noise and limitation of ZVS operation under light load condition. In order to improve the performance of power supply for Green PC, a new power supply using popular high efficiency LLC resonant converter for low voltage and high current application is proposed in this paper. The proposed power supply has ZVS capability over the entire load range, thus resulting in good efficiency and high switching frequency. Experimental results verify the performance of the proposed power supply for Green PC using 2[kW] (19[V], 105[A]) rated prototype converter.

Wide-Range ZVS Phase-Shift Full-Bridge Converter With Reduced Conduction Loss Caused by Circulating Current

A conventional phase-shift full-bridge (PSFB) converter with two clamp diodes and an additional resonant inductor is widely used for front-end dc/dc stage in the distributed power system. However, the hold-up-time requirement limits its operating duty ratio at normal operation. It results in conduction loss caused by circulating current. Therefore, a wide-range zero-voltage switching (ZVS) PSFB converter with reduced conduction loss caused by circulating current is proposed in this paper. The proposed converter adopts the large resonant inductance and replaces clamp diodes in the conventional PSFB converter with MOSFET switches. With these modifications, the proposed converter can achieve the ZVS operation over wide load range as well as can reduce the conduction loss caused by the circulating current. These advantages result in the improvement of whole load efficiency. The operational principle and analysis of the proposed converter are presented and verified by the 1.2-kW prototype.

A New Phase-Shifted Full-Bridge Converter With Maximum Duty Operation for Server Power System

A new high-efficient phase-shifted full-bridge (PSFB) converter is proposed in this paper. The conventional PSFB converter with an external inductor and clamping diodes is widely used in server power systems due to limited voltage stress on switches and its zero-voltage switching (ZVS) characteristics. However, a hold-up time regulation rule in server systems limits its operating duty ratio in nominal state and it increases the conduction loss of the converter. With simple modification, the proposed converter can be operated in the optimal operating point, 50% duty ratio, both in nominal operating condition and hold-up time condition. The ZVS characteristic is still maintained in the proposed converter. Therefore, conduction loss at the primary side of the converter is reduced and higher efficiency can also be obtained in the proposed converter than the conventional converter. The operational principle and analysis of the proposed converter are presented and verified by the 1-kW prototype.

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.