Phase-shifted Full-bridge Converter Research Articles

A Novel Second Harmonic Voltage Suppression Control for PSFB Converter in Dual-Stage Single-Phase Rectifier

The inherent second harmonic power pulse in single-phase grid-connected rectifiers leads to a noticeable output voltage ripple and thus results in the degradation of the system. A novel second harmonic suppression control is introduced in this paper to address this issue. The key point of the proposed control lies in the real-time prediction of the phase-shifted full-bridge (PSFB) converter’s desired duty cycle through accurate PSFB converter modeling. By accurately predicting the ideal duty cycle, the proposed control facilitates a significant enhancement in the control loop’s gain specifically at the second harmonic frequency, thereby improving the overall system performance. To validate the theoretical analysis, a series of simulations and experiments were conducted. The results demonstrate the effectiveness of the proposed second harmonic suppression control in mitigating second harmonic output voltage ripple.

Modulated-Coupled-Inductor-Based ISOP Phase-Shifted Full-Bridge Converter With Wide ZVS Range and Reduced Duty-Cycle Loss

Modulated-Coupled-Inductor-Based ISOP Phase-Shifted Full-Bridge Converter With Wide ZVS Range and Reduced Duty-Cycle Loss

Paralleled Variable Inductor Phase-Shifted Full-Bridge Converter With Full-Load Range ZVS and Low Duty Cycle Loss

This paper presents a new phase-shifted full-bridge topology using a new variable inductor. In this topology, a variable inductor is connected in parallel with a near-ideal transformer. The ZVS of the switches is achieved over the full load range using the parallel current provided by the variable inductor. And the adjustable parallel current reduces conduction losses. Under the orthogonal DC magnetic potential, the variable inductor has similar characteristics to the saturated inductor, which is beneficial to reduce the conduction loss caused by the parallel current. Since the topology has no series inductor and the leakage inductor is extremely small, the proposed converter has the advantages of extremely small duty cycle loss, larger transformer turns ratio, smaller primary current stress, smaller secondary voltage stress, and smaller output current ripple, which are beneficial to improve the efficiency and frequency of the converter. An experimental platform was established. Theoretical analysis and experimental verification were carried out.

Novel Series-Parallel Phase-Shifted Full-Bridge Converters with Auxiliary LC Networks to Achieve Wide Lagging-Leg ZVS Range

Under light load conditions, the phase-shifted full-bridge (PSFB) converter often has difficulty in realizing the zero-voltage switching (ZVS) of the lagging-leg by relying on the energy of its resonant inductor; however, for the series-parallel PSFB converter applied in high-power applications, the lagging-leg still has the problem of difficult realization of ZVS. Based on this, the paper analyzes the reasons why the series-parallel PSFB converter has difficulty in achieving ZVS for the lagging-leg under light and heavy loads. Under interleaved control, the ZVS of the lagging-leg over the full load range is realized by adding an auxiliary LC branch at the midpoint of the lagging-leg of both submodules. Based on the double-bridge input-parallel-output-series (IPOS) PSFB converter, analyzing the working principle of the circuit after adding the auxiliary LC branch and extending it to the series-parallel PSFB converter. The design requirements of the LC auxiliary branch of the dual-bridge series-parallel PSFB converter are given and the effects of the LC auxiliary branch on the module operating state and device stress are analyzed. On this basis, an extension is carried out to give the working principle and design method of the auxiliary LC branch of the N-bridge series-parallel PSFB converter. Finally, a 100 kW Matlab/Simulink simulation model verifies the superior performance of the proposed LC auxiliary branch to realize the lagging-leg ZVS of the series-parallel PSFB converter under light and heavy loads and achieves a 1.09% peak efficiency improvement at rated load.

Multiobjective Design and Benchmark of Wide Voltage Range Phase Shift Full-Bridge DC/DC Converters for EV Charging Application

This paper presents an analysis, multi-objective design, and benchmark of three modified Phase-Shift Full-Bridge (PSFB) converters that are well-suited for Electric Vehicle (EV) battery charging applications, covering both typical battery voltage classes (400V and 800V). These three modified PSFB converters, denoted as the t-PSFB, r-PSFB, and i-PSFB converters, have the ability to reconfigure and provide better efficiency performance in the wide voltage range necessary for public EV battery charging applications. In this paper, the characteristics and design considerations of these reconfigurable PSFB converters are discussed in detail. A multi-objective converter design process is proposed to optimize the average efficiency, normalized cost, and power density of the magnetic components and heat sinks. This design process employs the correlations between the cost and performance indexes of the key components derived based on open and accessible components data to estimate the design objectives. In this way, the design process is not constrained by certain component choices, making it easier to identify the most advantageous design. A benchmark study is conducted among the re-configurable PSFB topologies and the conventional PSFB circuit using the proposed multi-objective design process. To validate the analysis, a close-to-Pareto-front 11kW, 45kHz r-PSFB converter prototype with 640-840V input voltage and 250-1000V output voltage ranges is developed and tested.

A New Zero-Voltage Zero-Current Switching Converter with Minimum Duty Cycle Loss

Zero-voltage zero-current switching (ZVZCS) phase-shifted full-bridge (PSFB) converters have been widely used in high-power applications because of their high efficiency, low price, and easy control. Currently, the biggest problem with PSFB converters in operation is their high duty cycle loss. With the increase in current, duty cycle loss grows and degrades their performance. Focusing on this problem, a new ZVZCS PSFB converter is proposed in this paper. This topology adds an auxiliary circuit to minimize duty cycle loss. Moreover, the lagging-leg switches can obtain zero-current switching (ZCS) easily with the help of the circuit. The auxiliary circuit is built of four metal-oxide-semiconductor field-effect transistors (MOSFETs) and an auxiliary transformer, and extra voltage can be added to the primary coils when the direct-current (DC) voltage is small. This paper discusses its operation principles and characteristics, and an experiment of a 2 kW prototype was conducted, the results of which demonstrate the advantages of the presented circuits.

Efficiency optimization for phase‐shifted full‐bridge converter with variable frequency control

AbstractIn this paper, a control method combined with variable frequency and phase shifting is proposed, the primary purpose of which is to optimize the operating efficiency of the phase‐shift full‐bridge (PSFB) DC‐DC converter. By modeling the losses of the PSFB converter, the optimal switching frequency related to the load conditions is found. A neural network aided variable frequency controller that can work linearly is built to achieve the proposed method. At the same time, the voltage control loop is retained to ensure the stability of the output voltage and the necessary dynamic response of the converter. This paper builds an experimental platform for a 2 kW PSFB DC‐DC converter to verify the effectiveness of the proposed control method. With the control method proposed in this paper, the PSFB converter can always work at the optimum efficiency point under different load conditions. In addition, this paper also analyzes the influence of variable frequency control on PSFB operating states, such as zero‐voltage‐switching (ZVS) constraints, continuous conduction mode (CCM) operating states, and power density, which have an impact on its operating conditions.

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.

Efficiency and dynamic characteristics of improved dual‐stage power converter setup with advanced model predictive controller for electric vehicle battery charging

SummaryThis paper proposes an advanced power converter setup to charge an electric vehicle battery from a renewable energy source, such as solar photovoltaic. An improved Z‐source DC–DC boost converter (IZSBC) is utilized in the first stage. A synchronous rectifier (SR) of a phase‐shifted full‐bridge converter (PSFBC) with continuous conduction mode (CCM) is employed in the second stage using the zero voltage switching (ZVS) technique to provide isolation between the source and the load. To address the disadvantage of undesirable dynamic characteristics of the PSFBC‐SR, an advanced voltage control using the advanced model predictive controller (AMPC) is suggested to improve the dynamic characteristic of the PSFBC‐SR converter and prevent output voltage overshoot. An AMPC‐based new control method is preferred to eliminate body‐diode conduction for improved efficiency at any load conditions. Simulation and experimental designs of 0.5 kW with a 25 V DC input from the SPV, a boosted output of 100 V for a 60 V, 16 Ah battery bank and switching frequencies of 100 and 250 kHz for IZSBC and PSFBC‐SR, respectively, are produced and evaluated. Results show an efficiency of 93.7% with 31.44 W loss in simulations and 93.94% with 30.25 W loss in hardware tests. The preferred system has fast dynamics and is robust to sudden load impedance changes, thereby improving current tracking and reducing converter losses. The AMPC strategy proposed in this paper can increase conversion efficiency and control the output voltage without additional gain tuning.

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.

An Improved Zero-Voltage and Zero-Current- Switching Phase-Shift Full-Bridge PWM Converter With Low Output Current Ripple

In order to improve the performance of traditional phase-shifted full-bridge converters and reduce the output current ripple, an improved zero voltage and zero current switching phase-shifted full-bridge PWM converter is proposed in this article. By adding a simple auxiliary circuit, the leading-leg switches realize zero voltage switching and the lagging-leg switches realize zero current switching. The primary current is reset during the freewheeling period, so the efficiency of the converter is improved. What is more, the improved converter can effectively reduce the output current ripple. The added auxiliary circuit does not include any lossy components or saturable reactors. The improved phase-shifted full-bridge converter has many advantages, including simple circuit topology, easy implementation of soft switching, high efficiency, and low output current ripple. The operational principle and analysis of the proposed converter are presented in this article. An 800 W experimental prototype is built for experimental verification.

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.

Novel integrated three-port DC/DC converter for different operating modes between renewable energy, electrolyser and fuel cell/battery

AbstractDue to the slow dynamic power-regulation characteristics of the electrolyser (EL), a novel integrated three-port DC/DC converter topology based on a phase-shifted full-bridge converter and dual active-bridge converter is proposed in this paper. Especially, the proposed converter can achieve a fast auxiliary response to the EL. This topology has the features of single-stage conversion, high system integration and compatibility with multiple operation modes. The operational principles and a hybrid modulation scheme of the proposed converter are analysed in detail. In addition, the power-transmission characteristics of each port and the soft-switching range are researched. On these bases, six operation modes suitable for a hydrogen energy-storage system are designed. The simulation and a 2-kW scaled-down experimental prototype are established to verify the feasibility and effectiveness of the proposed topology in different operation modes.

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.