Phase-shifted Full-bridge Research Articles

Current-Fed Phase-Shifted Full-Bridge Converter With Secondary Harmonic Current Reduction for Two-Stage Inverter in Energy Storage System

For the low voltage, high current, isolated DC-DC converter applications, current-fed type converter has the chance to achieve higher efficiency due to the lower transformer root mean square current compared with other well-known converters such as dual active bridge or LLC. A current-fed phase-shifted full-bridge, CFPSFB converter has the advantages of nearly full range zero-voltage-switching and soft-commutating without large size of passive or active snubber circuit because the phase-shift of secondary full-bridge is controlled to be proportional to the input current. However, as a front-end stage of a single phase inverter, the input secondary harmonic current (SHC) propagating from the output AC load may cause large voltage spike to damage the primary MOSFETs due to losing the soft-commutating property. SHC may also reduce the conversion efficiency and the lifespan of battery intensely. This paper proposes a simple control scheme based on virtual series impedance method with a notch filter in control loop to reduce the SHC and maintain good dynamic performance. A small-signal model of CFPSFB for a reliable controller design is derived and verified by simulation. A 48 V/3 kW maximum output power inverter prototype is built to verify the theoretical analysis. The maximum efficiency of the DC-DC stage is 97.4% and the peak to peak SHC is less than 10% of the average input current.

Stability Analysis and Control Strategy Optimization of a Paralleled IPOS Phase-Shifted Full-Bridge Converters System Based on Droop Control

The application of high-power DC equipment further increases the power supply scale of DC systems. But, it is difficult for a single converter to support high transmission power, so multiple converters must operate in parallel for efficient power transmission. In a parallel system comprising many IPOS phase-shifting full-bridge converters, current sharing can be realized via droop control. However, the stability of the parallel system using current-sharing control will appear poor in light load conditions, so it is necessary to analyze the stability of parallel systems in light load conditions. Firstly, a single IPOS phase-shifted full-bridge control system is modeled; on this basis, the state space model of the n-module paralleled IPOS phase-shifted full-bridge converters system is derived. Then, the influence of load power and the number of parallel IPOS phase-shifted full-bridge converters on the system stability is analyzed via eigenvalue analysis, and an optimal control strategy based on a particle swarm optimization algorithm is proposed. The control parameters are optimized for the parallel system of eight IPOS phase-shifted full-bridge converters. Finally, the above results are simulated to verify the accuracy of the stability analysis and the feasibility of the optimized control strategy.

Parameter Optimization of Magnetic Components for Phase-Shifted Full-Bridge Converters Using a Digital Twin

Due to their significant performance, Phase-Shifted Full-Bridge Converters (PSFBCs) have gained widespread adoption in medium- and high-power applications. The performance of a PSFBC is greatly influenced by its magnetic components, namely the transformer and resonance inductor. To address these challenges, this paper proposes a parameter optimization of magnetic components for PSFBCs, specifically the transformer turns ratio and resonance inductor value, to enhance conversion efficiency and minimize operational loss. A digital twin of PSFBCs enabling a more accurate loss estimation is proposed to achieve this objective. The proposed loss estimation method precisely calculates the effective and circulation intervals and the corresponding current points of the primary-side transformer current, resulting in improved accuracy. By leveraging the digital twin, the effects of transformer turns ratio and resonant inductor value on the conversion efficiency of a PSFBC can be efficiently simulated. This facilitates the parameter optimization of magnetic components, thereby minimizing operational losses across different application scenarios. This paper also designs and implements a PSFBC prototype with a rated input voltage of 380 V, output voltage of 24 V, and output current of 20 A. The experimental results show the influences of transformer turns ratio and resonant inductor value on the PSFBC and validate the proposed digital twin. The proposed parameter optimization of magnetic components is further evaluated across two application scenarios with varying utilization rates. The simulation results indicate a reduction of approximately 14% in operational loss per hour after applying the parameter optimization of magnetic components for the PSFBC used as a battery charger. The results demonstrate the effectiveness and practicality of the proposed digital twin in designing PSFBCs.

Analysis and Suppression of Rectifier Diode Voltage Oscillation Mechanism in IPOS High-Power PSFB Converters

Parasitic oscillations in the rectifier diode voltage of phase-shifted-full-bridge (PSFB) converters limit their application in high-voltage and high-power situations. The conventional analysis method for parasitic oscillation in rectifier diode voltage in PSFB converters treats the filter inductor as a constant current source and fails to consider the impact of changes in filter inductor current on the rectifier diode’s parasitic oscillation. Consequently, this approach does not apply when analyzing the rectifier diode voltage’s parasitic oscillations in high-power PSFB converters employing an input-parallel output-series (IPOS) configuration with interleaved drive. This research paper introduces an innovative equivalent circuit model for analyzing the parasitic oscillations of rectifier diode voltage in IPOS high-power PSFB converters. The model takes into account the mutual influence of rectifier diode voltage oscillations between submodules under interleaved control, considering the influence of changes in filter inductor current on rectifier diode parasitic oscillation. Based on the circuit model, we explain the mechanism of multiple oscillations of the rectifier diode voltage and the reason for the high peak of the first oscillation. Consequently, the interplay of rectifier diode voltage oscillations in IPOS high-power k-module PSFB converters under interleaved control is analyzed. To mitigate the adverse effects of rectifier diode voltage parasitic oscillation, a buffering strategy involving the connection of a resistor capacitor diode (RCD) circuit in parallel after the rectifier bridge is adopted, considering the structure of the IPOS high-power PSFB converter. The study provides a detailed analysis of the circuit’s operation mechanism upon incorporating the RCD buffer circuit and establishes the relationship between buffer capacitance, resistance, and spike voltage. Furthermore, a design method for buffer capacitors and discharge resistors in buffer circuits is presented. Finally, a 100 kW prototype is tested to verify the rectifier diode voltage oscillation mechanism of the IPOS high-power PSFB converter and the rationality of the buffer capacitor and discharge resistor design method under the interleaved drive approach.

Reliability Analysis of Multi-Level PFC Converter-Based Charger for Light EV Charging Application

Electric vehicle (EV) charging architectures with two stages consist of rectification and a DC–DC conversion stage. Multi-level rectifiers are emerging as better alternatives in the rectification stage of EV charging applications. As they possess minimum voltage stress on switches, better harmonic profile at the grid side, lower dv/dt stress, and higher voltage capability. In this article, a five-level rectifier in conjunction with a phase shift full bridge converter is implemented for EV charging applications. The rectifier has the inherent capacitor voltage balancing capability and maintains unity power factor at the source side under varieties of operating conditions. The reliability of power electronic converters can be estimated by accessing the reliability of each component in converters. To establish the suitability of the implemented system for real-time EV charging applications, comprehensive performance analysis has been carried out including reliability assessment, the impact of parametric variations on reliability, calculation of losses and efficiency. The battery charger is mathematically modeled and validated experimentally in laboratory. The comparative analysis of the rectifier with state-of-the-art literature has been also carried out.

Development of Phase-Shift Full-Bridge Converter With Integrated Winding Planar Two-Transformer for LDC

This study proposes a new phase-shift full-bridge (PSFB) converter with an integrated winding planar two-transformer for a low-voltage dc–dc converter (LDC). An LDC is a dc–dc converter that supplies power to a 12-V auxiliary battery (A_BAT) and loads from the main battery (M_BAT) of electric vehicles (EVs), used in low-voltage and high-current output applications. PSFB converter is widely used as a suitable topology for such systems. In order to improve the power density, the integrated planar magnetics is designed in the proposed PSFB converter. Furthermore, the size of the transformer is optimized considering the footprint and core loss of components. To confirm the validity of the proposed converter, a 2.1-kW prototype LDC with an input voltage range of 400–800 V and an output voltage of 14 V is analyzed, and the operating characteristics are described. The proposed converter achieves a maximum efficiency of 95.4% and a power density of 5.2 kW/L.

Design and Implementation of a Reconfigurable Phase Shift Full-Bridge Converter for Wide Voltage Range EV Charging Application

This article analyzes, designs, and tests a reconfigurable phase shift full-bridge (r-PSFB) isolated dc/dc converter well suited for a wide voltage operating range. By controlling the auxiliary switches, a series or parallel connection can be realized on the secondary side of the converter. As a result, the r-PSFB converter can operate in an extremely wide voltage range without compromising the system efficiency. In this article, the characteristics of the r-PSFB converter and its design considerations are discussed in detail. An 11-kW r-PSFB converter prototype with 640–840-V input voltage and 250–1000-V output voltage ranges is developed and tested to validate the analysis and efficiency of the designed converter. A comparative study against a conventional PSFB converter is conducted for benchmark purposes to prove the advantages of the studied r-PSFB converter.

Design of a Dynamic Hybrid Compensator for Current Sharing Control of Parallel Phase-Shifted Full-Bridge Converter

The phase-shifted full-bridge (PSFB) converter has been widely used in power supply modules due to its simple control and high output power. However, with the market’s increasing demand for higher power sources, the PSFB converter needs to face challenges in increasing its output power level. Compared to redesigning a larger power module or a larger single converter, it will be more cost-effective to achieve a higher power output by paralleling the existing converters. However, due to the manufacturing differences in circuit components, the output imbalance in parallel PSFB converter systems may damage the power modules. Thus, the influence of differences in circuit components is analyzed in this paper, and it is found that the leakage inductance and transformer ratio are the main factors resulting in errors in current sharing control. Consequently, a dynamic hybrid compensator (DHC) is proposed in this paper, that can significantly reduce the error in current sharing control via the compensation of the duty cycle of a slave module. Furthermore, the DHC is verified on an 800 W two-phase PSFB converter, which shows that even when the difference in components is as large as 20%, the proposed method can still reduce the error in current sharing control to less than 2% under both half and full load conditions.

Integration of SiC Devices and High-Frequency Transformer for High-Power Renewable Energy Applications

This paper presents a novel structure of Integrated SiC MOSFETs with a high-frequency transformer (I-SiC-HFT) for various high-power isolated DC–DC converters. Several resonant converters are considered for integration in this paper, including the phase-shift full-bridge (PSFB) converter, inductor–inductor–capacitor (LLC) resonant converter, bidirectional PSFB converter, and capacitor–inductor–inductor–capacitor (CLLC) resonant converter. The applications of I-SiC-HFT are focused on V2G EV battery charging systems, energy storage in DC and AC microgrids, and renewable energy systems. SiC devices, including MOSFETs, Schottky diodes, and MOSFET modules, are used in this novel structure of I-SiC-HFT. The high-frequency magnetic structure uses distributed ferrite cores to form a large central space to accommodate SiC devices. The optimized architecture of I-SiC-HFT and heatsink structure is proposed for thermal management of SiC devices. To prove the concept, a small-scale 1.5 kW prototype I-SiC-HFT is used to demonstrate the basic structure and various performance indicators through the FEM based electromagnetic simulation and DC–DC converter experiments.

Active Damping Control and Parameter Design Method for ISOP-Based Load Converter in DC Distribution System

To meet the diversified requirements of active damping configuration in a dc distribution system, the input-series-output-parallel (ISOP) load converter based on phase-shifted full-bridge (PSFB) modules is investigated in this article. The reduced-order impedance model of the PSFB-based ISOP converter with common-duty-ratio control is established first, and then the active damping control strategies using the primary- and secondary-side voltages are proposed, respectively. By reformulating the stability criterion in the form of impedance-frequency curves and using the impedance sensitivity, the sensitivity of resonance frequency is derived to develop a method for designing the parameters of active compensators. Finally, the experimental results demonstrate the effectiveness of the proposed active damping control strategies and parameter design method.

Research on Establishment and Application of Digital Twin for a Phase-Shift Full-Bridge Current Doubling Rectifier Converter

In order to improve the safety and reliability of airborne power supply and distribution system, a digital twin of a phase-shift full-bridge current doubling rectifier converter based on gallium nitride metal-oxide-semiconductor field-effect transistor (GaN MOSFET) is built. The digital twin can be regarded as virtual symmetry of the real converter. The particle swarm optimization (PSO) algorithm is applied to compare the voltage and current waveforms of the real converter with relative waveforms of its digital model established in simulation software, and the interior parameters of the model are constantly updated until the waveforms of the digital twin coincide with that of the converter. Applications of this digital twin are discussed through experimental verification, and the results show that the digital twin can deduce the parameter value of key components of the converter in the case of soft faults. In the case of hard faults, a back propagating artificial neural net (BP ANN) is trained by data collected from the digital twin, and the BP ANN is able to identify different running states of the converter. The outcomes of this paper present a non-intrusive and high real-time method of condition monitoring and fault diagnosis, which is beneficial to improve the reliability of airborne HVDC power supply system.

Phase-Shifted Full Bridge DC–DC Converter for Photovoltaic MVDC Power Collection Networks

The connection of photovoltaic sources to a medium voltage dc collection network requires a dc-dc converter having specific grid-connected converter capabilities. This article presents the application of a phase-shifted full bridge (PSFB) converter for medium voltage dc collection networks suited to photovoltaic power plants. The unidirectional structure of the converter is beneficial in terms of cost and simplicity of hardware implementation of the MV circuit components. The design of the PSFB converter is presented considering ratings of 250 kW power, 1.2 kV input, and 20 kV output. A converter model and a novel PSFB input voltage control regulating the dc-link voltage are developed and verified. A tuning method is given taking into account the effect of different transformer leakage inductance values. The behaviour of the PSFB under the PV power production profile and MV network faults is studied in simulation and verified against a reduced-scale prototype with ratings of 30 kW and 350 V / 600 V operating at 20 kHz. The experimental verification of the control is performed considering a real PV power profile. The experimental results under faults show the same response as in simulations. The PSFB fault response is observed to be superior compared to other dc–dc topologies with capacitive output filter only, making it suitable for grid-connected operation.

A Three-Port PSFB/DAB-MMC PET With Inertia Enhancement Under LVDC Disturbance

DC distribution system has been popular in research and industry applications in recent years. The topology of the three-port modular multilevel converter (MMC) was proposed to interconnect the medium voltage DC (MVDC) distribution system, the medium voltage AC (MVAC) distribution system and the low voltage DC (LVDC). Compared to classical two-port MMC, a three-port MMC substitutes the tranditional submodules with bidirectional isolated converters. There are two kinds of existing three-port MMC topologies. One topology uses dual active bridge (DAB) converters to transfer power from the medium voltage side to the LVDC system, which is called DAB-MMC. The other topology utilizes bidirectional phase shift full bridge (PSFB) converters as submodules, which is called isolated MMC (I-MMC). Compared to the DAB-MMC, the I-MMC reduces the cost of the submodule capacitors and the power switches. But the LVDC inertia of the I-MMC is low due to the common submodule capacitors, especially during disturbances. In this article, a hybrid three-port MMC topology with inertia enhancement is proposed. With the combination of the PSFB and DAB submodules, the proposed MMC increases the equivalent inertia of the LVDC system using a novel virtual control method. The simulation results in MATLAB/Simulink and real-time RT-LAB prove the feasibility and the accuracy of the proposed inertia enhancing method.

Design and Implementation of an Isolated Bidirectional Phase-Shift Full-Bridge Converter With High Transformation Ratio

In this paper, a bidirectional full-bridge phase-shift converter with high transformation ratio scheme is proposed. The main architecture of this converter is dual active full-bridge circuit. By using phase-shift modulation, the energy can be transmitted between high-voltage-side and low-voltage-side, and also can make the power switches have the function of soft-switching. This converter is designed with the transmission power of 1kW and the digital signal processor TMS320F28335 is utilized as the main system controller core. Finally, it realizes the bidirectional power conversion mechanism between battery 50 Vdc and DC grid 400 Vdc. The experimental results show that the maximum conversion efficiency of this converter when operating in the forward charging mode (G2V mode) is up to 92.25 %, and in the reverse discharging mode (V2G mode), the maximum conversion efficiency is up to 93.02 %. In comparison with the related studies for dual active full-bridge converters, the conventional transformation ratio is lower or equal to 4. This study with high transformation ratio can reach 8 for practical high-low voltage bidirectional applications. After the validation for both modes, the proposed concept is practical in the high transformation scenarios.

M-ary Amplitude Shift Keying Power and Information Synchronous Transmission Based on Phase-Shifted Full-Bridge

This paper proposes an M-ary amplitude shift keying (MASK) power and information synchronous transmission system based on phase-shifted full-bridge (PSFB) for applications in wireless power transmission (WPT). The Pulse Width Modulation (PWM) waveform uses different phases to control the MOSFET in the full-bridge inverter for MASK modulation. The inverter voltage generates M amplitude transformation, forming a comprehensive power information flow. The demodulation circuit processes the information transmitted to the secondary side, following the power supply with a differential amplifier, to realize synchronous transmission of power supply and information. Compared with conventional amplitude modulation, the system’s volume is significantly reduced, and the DC-DC modulation circuit has no filtering effect. It transmits comprehensive high-level data and improves the information transmission rate from the perspective of bit width. In the experiment, 16-bit width data are transmitted, and the bit rate is increased by four times compared to conventional amplitude modulation. Combined with DSP, the designed demodulation circuit reduces the voltage amplitude fluctuation at the receiving end to 5% and minimizes the impact of amplitude modulation voltage fluctuation on the system.

High Power ZVZCS Phase Shift Full Bridge DC–DC Converter With High Current Reset Ability and No Extra Electrical Stress

Zero-voltage zero-current switching (ZVZCS) phase-shift full-bridge (PSFB) dc–dc converters are candidate converters for high-power switching mode power supply because of their low cost and high efficiency. However, these converters still have some definite weaknesses, e.g., resetting obstacles of high-value currents, extra electrical stress on the power devices. Hence, customers seldom adopt these topologies in high-power applications. This article proposes a new ZVZCS PSFB dc–dc converter to solve the above problems. A clamping circuit with two <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s, two diodes, and a resetting transformer ensures ZCS of the lagging-leg switches over a wide load range, and no extra electrical stress arises on the primary or secondary components. The clamping circuit has a high current reset ability and can break through the power limitation of conventional ZVZCS PSFB dc–dc converters. The volume of the resetting transformer is small because of the low voltage-second product, and the added <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s cause low power loss because of the wide soft-switching load range and low on-resistance. The experimental results from a 12-kW prototype prove the rightness and advantages of the proposed converter.

Dual-Transformer-Based Hybrid Phase-Shift PWM DC-DC Converter With Wide ZVZCS Range

This brief proposes a dual-transformer-based hybrid phase-shift full-bridge (PSFB) converter. Instead of adopting auxiliary components, the proposed hybrid PSFB converter widens the zero-voltage switching (ZVS) range with the help of the current generated by additional transformer and additional half-bridge. Unlike the conventional method utilizing auxiliary circuit, the additional transformer and half-bridge can also transmit a large part of the power to reduce the burden on the main transformer. Meanwhile, the circulating current on the primary side can be effectively reduced due to the structure of hybrid bridge, and the additional half-bridge can achieve zero-current switching (ZCS) with reduced switching loss. The proposed converter can obtain a wide ZVZCS range with simple phase-shift pulse width modulation under fixed switching frequency. The operating principle, ZVZCS performance, and parameter design are analyzed in this brief. Finally, a 1 kW experimental prototype was built to verify the effectiveness of the proposed solution.

Research on ZVS Phase-Shifted Full-Bridge Broadband Inverter Based on Auxiliary Current Source

Phase-shifted full-bridge topologies are widely used in medium- and high-power DC/DC converters due to their small size and high switching frequency. However, there are few studies on the application of broadband inverters. In the traditional phase-shift full-bridge inverter with a fully resonant load, the problem of current commutation which leads to hard switching is often encountered, to overcome such an issue, an auxiliary current source network is introduced to realize the zero-voltage turn-on of the lagging bridge arm. The working modes of the converter are analyzed in detail, and the parameters of the auxiliary current source network are designed. The simulation verification is carried out by MATLAB/Simulink in a wide frequency range from 10 kHz to 500 kHz. Finally, an experimental circuit board is designed, and the experimental results show that the topology can achieve soft switching in a frequency range from 10 kHz to 200 kHz and has a certain applicability.

Variable Saturation Inductor-Based Full Bridge Converter With Wide ZVS Range and Reduced Duty Cycle Loss

A phase-shifted full-bridge (PSFB) converter is widely used in various applications due to its soft-switching characteristics. However, one of the recognized shortcomings of the PSFB converter is that it cannot simultaneously have a wide soft switching range and a small secondary-side duty cycle loss. The shortcoming hinders the high frequency and high efficiency of the converter. In this article, the change of the energy demand of the converter on the external series inductor with input voltage and load is analyzed. On this basis, a variable saturation inductor with controllable energy is proposed to meet the energy demand and solve the problem of core heating. The controllable change characteristics of the inductor energy are studied directly instead of the controllable change of the inductance value. By adjusting the inductor energy, the PSFB can not only achieve soft switching under light loads, but also reduce duty cycle loss under heavy loads. Theoretical analysis and experimental verification are carried out on the soft switching and duty cycle loss of the converter. Since the transformer ratio can be increased due to thesmaller duty cycle loss. The efficiency of the converter can be further improved.

An Improved Control Scheme for Reducing Circulating Current and Reverse Power of Bidirectional Phase-Shifted Full-Bridge Converter

Phase-shifted full-bridge (PSFB) converter is widely adopted in electric vehicle and energy storage applications. However, it suffers from serval technical drawbacks such as voltage overshoot, hard switching, severe circulating current, and large reverse power. To address such issues, an improved control scheme is proposed to enhance the performances of bidirectional operation in the PSFB converter. In this method, the precharge stage and the co-charge stage are added by adjusting the phase shift angle and duty ratio. The reverse power, circulating current and transformer Root Mean Square (RMS) Current can be reduced with the co-charge stage. Due to the precharge stage, this method can constrict voltage overshoot, while achieving zero current switching (ZCS) on the large current side devices and zero voltage switching (ZVS) on the high voltage side devices nearly along all the load range. The proposed method is described, analyzed, and validated in a 1 kW prototype which presents 96.1% peak efficiency and improves average efficiency by about 2% in the experimental results.