Phase-shifted Full-bridge Research Articles

Analysis and Control of Input-Parallel Output-Series Based Combined DC/DC Converter With Modified Connection in Output Filter Circuit

Input-parallel output-series (IPOS)-based combined converter is usually used in the situation with low input voltage and high output voltage to satisfy the requirements in switch voltage stress reduction and power expansion. In such a system, the voltage balance of filter capacitor in the output side or current sharing in the input side usually used to guarantee the control performance of the conversion system. In this paper, a phase-shifted full bridge (PSFB)-based IPOS converter with modified connection of output filter circuit used for the wide variation of input voltage is proposed, which is beneficial to reduce ripple current of filter inductor significantly. A control scheme using the same phase shifting for the two different modules of this IPOS converter is detailedly investigated with both steady state and small signal model-based analysis, it manifests that special voltage balance and current sharing control scheme are not necessary for IPOS system under the common phase shifting control method. And the small signal transfer functions of this topology used for dual loop control system design are also developed. The simulation and experiment results are presented to validate the analysis and control scheme.

Virtual Resistor-Based Integrated DC Bus Voltage Conditioner for Stability Improvement of Cascaded Power Converters

A bidirectional integrated bus voltage conditioner (IBVC) for an isolated phase-shifted full bridge (PSFB) dc/dc converter is proposed to reduce the dc bus voltage oscillations in a cascaded power converter system, where a load converter is controlled tightly with high-control bandwidth. In the proposed method, unlike conventional dc bus voltage stabilization methods for which auxiliary switches are used, the multiplexing utilization of the full bridge switches at the primary side of a PSFB is adopted. In this paper, to improve the dc bus voltage stability, an equivalent virtual resistor is implemented by applying the duty cycle regulation for both legs of the PSFB. The effectiveness of the proposed method on the dc voltage stabilization is examined through simulations and experiments. The achieved results reveal that the dc bus voltage stability is significantly improved with the proposed method.

A New Phase Shift Full Bridge LLC Resonant Converter with Auxiliary Circuit

A New Phase Shift Full Bridge LLC Resonant Converter with Auxiliary Circuit

Design of Charging Module for DC Charging Pile Based on Two Level Power Conversion

In order to to solve the demand of electric vehicle for high power and high performance DC charging pile, this paper presents a design scheme for charging module of DC charging pile based on two stage power transformation. The pre stage part of the scheme is the VIENNA rectifier controlled by hysteresis current and the phase shift full bridge converter controlled by the average current. The parameters of the main circuit and the control circuit are calculated. At last, the simulation research on the three conditions of the rated load, two times overload and load fluctuation is carried out. The results show that the charging module can achieve high power factor, low harmonic distortion rate, zero voltage switch, low loss operation, strong carrying capacity, good dynamic performance, high steady state precision and simple and easy operation.

A Simple SR Gate Driving Circuit With Reduced Gate Driving Loss for Phase-Shifted Full-Bridge Converter

The phase-shifted full-bridge (PSFB) converter with synchronous rectifier (SR) is one of the most attractive dc–dc converters for the server power supply due to its high power capability and small secondary ripple current with the output inductor. Moreover, it can more reduce the secondary conduction loss by using parallel-connected mosfet s in SR. However, due to large input capacitance of the parallel-connected mosfet s in SR, the PSFB converter has large SR gate driving loss, which particularly degrades the light load efficiency. Thus, in this paper, one additional resistor is added to the conventional SR gate driving circuit to recycle the gate driving energy. As a result, the proposed circuit can improve the light load efficiency of the PSFB converter without operation mode change, additional controls, and complex circuits. The most advantage of the proposed circuit is that it is very simple and available to any other SR gate driver IC. The validity of the proposed circuit is confirmed by experimental results from a prototype with 340–400 V input and 12 V/66.66 A output.

A Quasi-Resonant ZVZCS Phase-Shifted Full-Bridge Converter with an Active Clamp in the Secondary Side

A novel Pulse-Width-Modulation (PWM) quasi-resonant active-clamp phase-shifted full-bridge converter is presented and analyzed in this paper. In the proposed topology, an active-clamp switch and a clamp capacitor that resonates with the leakage inductance of transformer are employed at the secondary side. The active-clamp circuit helps all of the primary switches in achieving both zero-voltage switching (ZVS) turn-on and nearly zero-current switching (ZCS) turn-off over the entire load range, and resets the primary current during the freewheeling interval. The operation of the active-clamp circuit eliminates voltage ringing across the rectifier. In addition, the secondary diodes can achieve ZCS turn-off, which removes the reverse recovery problem of diodes, and the active-clamp switch can achieve ZCS turn-on. A 3.5-kW prototype was built to verify the performance of the proposed converter. A maximum efficiency of 97.6% was achieved under a 2-kW load, and an efficiency of more than 96% was achieved even under a light load.

Reducing Common Mode Noise in Phase-Shifted Full-Bridge Converter

The phase-shifted full-bridge (PSFB) converter has been widely used in medium-to-high power applications because of simple topology and ease of achieving soft-switching for power switches. However, with the phase-shifted control, the electric potential variation of the two phase-leg midpoints happens at different times, and the displacement current generated by two midpoints through associated parasitic capacitance (including the parasitic capacitance between two midpoints to ground and the transformer inter-winding capacitance) cannot be cancelled by each other, resulting in a serious common mode (CM) noise. Moreover, the resonant inductor voltage affects the electric potentials of the transformer terminals, which also generates CM noise. To reduce the CM noise in the PSFB converter, this paper proposes a symmetrical resonant inductor together with symmetrical transformer configuration to eliminate the influence of the resonant inductor voltage on the CM noise. Then, a passive cancellation circuit is introduced to cancel the effect of the voltages between the midpoints and the ground on the CM noise. A 1-kW PSFB converter prototype has been fabricated and tested in the lab, and the experimental results are provided to verify the proposed methods.

Improved Modulation Strategy Using Dual Phase Shift Modulation for Active Commutated Current-Fed Dual Active Bridge

This paper proposes dual phase shift modulation (DPSM) for active commutated current-fed dual active bridge for low-voltage (LV) high-power application to improve the performance of the converter at light loads. The proposed DPSM uses an additional control variable to actively control the peak current in the converter that helps to improve the performance as compared to simpler single variable but unregulated peak current control, phase shift modulation (PSM). The control variables are chosen such that the excess current is just enough to achieve zero current switching (ZCS) turn-off of the LV devices. In the reverse direction, the converter is a full-bridge converter with LC filter. The implementation of the conventional PSM to the full bridge, popularly known as phase-shift full bridge is simple but restricted by the zero voltage switching (ZVS) range. The proposed DPSM is implemented in the reverse direction to maintain the ZVS turn-on of the high-voltage (HV) devices even at very light loads by utilizing the LV devices instead of using them only for synchronous rectification. At higher loads where achieving ZVS is relatively easy, the modulation shifts to conventional PSM to reduce the circulating current and the associated duty cycle loss. The improvement in the performance is validated experimentally with a 1-kW prototype developed for a 30 $\%$ variation in the LV voltage (42–56 V) for both directions of operation. The control of the peak current improved the efficiency by 12 $\%$ from the conventional PSM at 10 $\%$ load at the highest current (42 V) in the forward operation. In the reverse direction, the ZVS turn-on for the HV devices is achieved even at 6 $\%$ load by the proposed modulation at the highest voltage (56 V). Thus, the proposed DPSM is a software-only solution that does not require any additional active or passive components, offering an improved performance while maintaining a low component count and simplicity of the power electronics circuit.

Phase-Shifted Full-Bridge Zero Voltage Switching DC-DC Converter Design with MATLAB/Simulink Implementation

Design of phase-shifted full bridge zero voltage switching DC-DC converter has been very challenging due to circuit parasitic effect on the system dynamics. This paper presents steady-state analysis and iterative approach for the systemic design of phase-shifted full bridge DC-DC converter with improved dynamic performance and satisfactory operational requirement in terms of zero-voltage switching range, operating switching frequency and switching resonance. A 3 kW DC-DC converter is designed using the iterative design approach and the system dynamics performance was investigated in the MATLAB/Simulink environment. The converter zero-voltage switching simulation results were satisfactory with 90% efficiency under full load condition.

A ZVS‐ZCS phase shift full bridge DC‐DC converter with secondary‐side control for battery charging applications

SummaryThe output power requirement of battery charging circuits can vary in a wide range, hence making the use of conventional phase shift full bridge DC‐DC converters infeasible because of poor light load efficiency. In this paper, a new ZVS‐ZCS phase shift full bridge topology with secondary‐side active control has been presented for battery charging applications. The proposed circuit uses 2 extra switches in series with the secondary‐side rectifier diodes, operating with phase shift PWM. With the assistance of transformer's magnetizing inductance, the proposed converter maintains zero voltage switching (ZVS) of the primary‐side switches over the entire load range. The secondary‐side switches regulate the output voltage/current and perform zero current switching (ZCS) independent of the amount of load current. The proposed converter exhibits a significantly better light load efficiency as compared with the conventional phase shift full bridge DC‐DC converter. The performance of the proposed converter has been analyzed on a 1‐kW hardware prototype, and experimental results have been included.

An Improved Phase-Shifted Full-Bridge Converter With Wide-Range ZVS and Reduced Filter Requirement

The phase-shifted full-bridge (PSFB) converter is widely employed in high-power applications. However, circulating current, narrow range of zero-voltage switching (ZVS), duty-cycle loss, and secondary parasitic oscillation are the main drawbacks of the traditional PSFB converter. This paper proposes an improved full-bridge converter to solve the drawbacks of the traditional PSFB converter. In the proposed converter, a coupled inductor with three windings is introduced to adjust the available ZVS energy and to transfer power to the output side during freewheeling period. Due to this structure, output filter requirement, circulating current, the required ZVS energy, and secondary voltage oscillation can be reduced. Thus, the proposed converter can obtain higher conversion efficiency than the traditional PSFB converter. In this paper, the detailed operation principles and experimental results are presented.

Research on a novel variable-frequency and phase-shift control method based on a high-voltage and high-power full-bridge converter

This paper presents a new variable-frequency phase-shift control method to improve the conversion efficiency for a high-power wide-range converter based on a phase-shifted full-bridge (PSFB) converter. The proposed converter can adjust the switching-frequency according to the load power to make the input impedance be inductive. The main switches of the converter can achieve zero voltage switching (ZVS) over a wide load range (500 W–50 kW) without any auxiliary circuit. The maximum switching-frequency of high-power insulated gate bipolar transistor (IGBT) is determined by analyzing the influence of collector current on IGBT switching time. The necessary condition for the proposed converter to realize ZVS is given according to the steady-state model of the full-bridge converter. This paper analyzed the influence of voltage, current and temperature on the switching time of high-power IGBT in detail, and obtained the relationship between the load current and the dead time of high-power IGBT. The optimal switching-frequency under different loads was determined by establishing a switching-frequency loss model of the proposed converter. A 50 kW prototype of the proposed converter was developed and the experimental and simulation results verify the effectiveness and efficiency of the proposed method.

Intermediate DC-Link Capacitor Reduction in a Two-Stage Cascaded AC/DC Converter for More Electric Aircrafts

In this paper, an innovative method to minimize the intermediate dc-link capacitance in a cascaded two-stage combination of a three-phase six-switch power factor correction (PFC) and phase-shifted full-bridge (PSFB) dc/dc stage is introduced and analyzed. The proposed strategy has a significant impact on the minimization of the overall system weight and volume. Fundamentally, the method is based on minimizing the switching fundamental component of the dc-link current and is established by imposing a separate constraint on the phase duty ratios without compromising the unity PFC action. Furthermore, the control loop takes care of regulating the intermediate dc-link voltage along with the final output voltage. A 6 kW laboratory prototype of the integrated three-phase PFC and PSFB dc/dc as a part of auxiliary power unit in more-electric airplanes is developed and designed to validate the proposed algorithm. The experimental results show a conversion efficiency of 95.4% at full load, input total harmonic distortion of 4.1%, power factor of 0.998, output voltage ripple of ±1%, and a reduction of dc-link capacitor by 60%.

Fixed Frequency Pulse-Width Modulation Based Integrated Sliding Mode Controller for Phase-Shifted Full-Bridge Converters

The conventional approach to designing controllers for the phase-shifted full-bridge (PSFB) converter is to design a linear compensator based on the small-signal model, which cannot provide the converter with strong robustness against parametric disturbances and consistent transient responses over a wide range of operating conditions. This paper proposed a fixed frequency pulse-width-modulation (PWM)-based integrated sliding mode (ISM) controller for the PSFB converter. By analyzing the phase-shifted modulation of the full bridge, the dynamic state-space model of the PSFB is established based on the simplified circuit model. On this basis, the sliding motion in state space, the existence condition for steady-state operation, and the indirect PWM control function are discussed. Meanwhile, a switch control is introduced to the control function, and a robustness condition for parametric disturbances is analyzed. The designed PWM ISM controller is applied to a 1-kW PSFB converter prototype. Experimental results verify the effectiveness of the proposed controller by comparison with the hysteresis-modulation-based sliding mode controller and the increment PID controller.

ZVS Phase Shift Full Bridge Converter Design with 2kW Output

ZVS Phase Shift Full Bridge Converter Design with 2kW Output

Adaptive delay control for synchronous rectification phase‐shifted full bridge converter with GaN HEMT

An adaptive delay control method for a phase-shifted full bridge converter with a synchronous rectifier is presented. With this control, the delay time between primary and secondary switches can be optimised to reduce dead time, according to output power. Moreover, due to the poor third quadrant conduction of gallium nitride (GaN) high-electron-mobility transistors (HEMTs), the dead time needs to be optimised to utilise the benefits of a GaN HEMT. The experimental results with a 500 W prototype show that the efficiency can be improved by 0.7% with the proposed control.

Quasi-Parallel Voltage Regulator Topology for Powering Laptop Processors

This paper presents a quasi-parallel voltage regulator topology that is suitable as a laptop processor power supply where the input voltage varies over a wide range. It consists of a phase shift full bridge converter and a buck converter, whose inputs are connected in series to divide the total input voltage and the outputs are connected in parallel to share the load current. The output voltage is regulated with fast dynamics against load change and input voltage variation while the input voltage to the buck converter is also regulated at a relatively low value to improve the overall system efficiency. Different methods to improve the converter efficiency further at both light and high loads are also proposed. The efficiency of the converter at different load currents and input voltages are obtained from a laboratory prototype demonstrating a maximum efficiency of 90.8% at an output voltage of 1.2 V. A small signal model of the converter is then presented and a design methodology for a decoupled controller is discussed. Transient performance of the converter using this controller against 50 A load current change is found to comply with the specifications for a laptop processor power supply.

Variable-Switching-Frequency State-Feedback Control of a Phase-Shifted Full-Bridge DC/DC Converter

This paper presents a methodology to control a phase-shifted full-bridge (PSFB) dc/dc converter with variable switching frequency, as a function of the output load power. The main objective of such control is to maximize the conversion efficiency at a wide range of load power levels. By tuning the switching frequency, the net phase of the input impedance of the converter can be manipulated, and thus, at the lower load power operation, the net input impedance can be made highly inductive to achieve zero-voltage switching (ZVS) at the primary-side switches. This paper proposes an efficiency maximization method, which derives an optimum switching frequency based on the load power from a loss-minimization model. In addition, a state-feedback-based control method is proposed for maintaining a tight dynamic regulation over the converter output under a load transient. A 6-kW laboratory prototype of the PSFB converter is developed and designed to validate the proposed control algorithm. The experimental results show a conversion efficiency of 98% at full load and output voltage ripple of ±1%, while ensuring ZVS at all operating points between 100 W and 6 kW.

Control-oriented discrete-time large-signal model of phase-shift full-bridge DC–DC converter

In this paper, a new approach toward large-signal discrete-time modeling of phase-shift full-bridge (PSFB) dc–dc converter for discontinuous conduction mode operation has been introduced. Instead of averaging the circuit elements or state variables, this approach makes use of the inherent characteristics of the dc–dc converter by developing piecewise differential equations of the switching network in different time intervals. Then, these differential equations are analytically solved with appropriate boundary conditions in order to develop the discrete-time nonlinear model of the PSFB dc–dc converter. The developed nonlinear model captures the complete dynamics of state variables within a switching cycle. Another major contribution of this research work is an accurate linear model of PSFB dc-dc converter, which has been acquired by employing small signal approximations and change of variables. The proposed model has been compared to the previously reported large-signal models of the PSFB dc–dc converter. Detailed theoretical results have been included, which show excellent agreement of the proposed model with the original switching network.

Design of a Novel Integrated L-C-T for PSFB ZVS Converters

To enhance the zero-voltage switching (ZVS) range and power density of the phase-shift full-bridge (PSFB) ZVS converters used in geophysical exploration, an additional resonant inductor is used as a leakage inductance and a blocking capacitor which is equivalent to interlayer capacitance is integrat...