Single-phase Full-bridge Converter Research Articles

Power Quality in the Hybrid Grid PV-Wind-Battery by the Multi-Input Transformer-Coupled Bidirectional DC-DC Converter

Abstract: A control strategy for power flow management of a grid-connected hybrid photovoltaic (PV)–wind-battery- based system with an efficient multi-input transformer-coupled bidirectional dc–dc converter is presented. The proposed system aims to satisfy the load demand, manage the power flow from different sources, inject the surplus power into the grid, and charge the battery from the grid as and when required. A transformer-coupled boost half-bridge converter is used to harness power from wind, while a bidirectional buck– boost converter is used to harness power from PV along with battery charging/discharging control. A single-phase full-bridge bidirectional converter is used for feeding ac loads and interaction with the grid. The proposed converter architecture has reduced number of power conversion stages with less component count and reduced losses compared with existing grid-connected hybrid systems. This improves the efficiency and the reliability of the system. Simulation results obtained using MATLAB/Simulink show the performance of the proposed control strategy for power flow management under various modes of operation. The effectiveness of the topology and the efficacy of the proposed control strategy are validated through detailed experimental studies to demonstrate the capability of the system operation in different modes.

Simulation and implementation of a harmonics suppression technique for a single-phase full-bridge converters

ABSTRACT This paper presents a harmonic suppression technique for a single-phase full-bridge converter, and the mathematical principles underlying a modified PWM technique are discussed. To verify the effectiveness of the proposed technique, voltage and current sensor circuits in a single-phase full-bridge converter connected to a digital signal processor controller with an analog-to-digital converter were analyzed experimentally. The output voltage harmonics of the converter were examined, and the frequency spectra of the output voltage were analyzed. Furthermore, a digital control system with a TMS320F2808 digital signal microcontroller was realized. The experimental results verified the effectiveness of the proposed technique in suppressing low-frequency harmonic in a prototype of a converter.

A Novel DC Bias Suppression Strategy for Single-Phase Full-Bridge DC-DC Arc Welding Converter

The high frequency transformer in single-phase full-bridge DC-DC converter is prone to saturation because of the asymmetry of circuit parameters. Transformer saturation will increase power consumption, accelerate the aging of winding insulation, and even damage power switches. In order to prevent this risk, a DC bias suppression strategy is presented in this article, and the main advantage of this strategy is that the problem of transformer saturation can be completely eliminated. In this article, firstly, the DC bias and saturation mechanism of single-phase full-bridge DC-DC converter are analyzed in detail, and the Maximum Integral Value of Volt-Second Product error (MIVVSPE) is derived. Secondly, aiming at the saturation problem of single-phase full bridge DC-DC converter, a new digital integral circuit is designed to evaluate the DC bias state of transformer, and a DC bias suppression strategy is constructed to suppress the saturation of transformer. Furthermore, different from the traditional current feedback control strategy, the DC bias suppression strategy based on volt-second product error integral can be triggered before the transformer enters the saturation state, and the transformer saturation can be completely suppressed. Finally, a 30 kW single-phase full-bridge DC-DC converter for arc welding is established in lab. The experimental results show that the new DC bias suppression strategy can effectively prevent the transformer from entering the saturation state and improve the operation stability of single-phase full-bridge DC-DC arc welding inverter.

Performance evaluation and load demand management of grid connected hybrid wind-solar-battery system

<div data-canvas-width="325.8629661358597">In this paper, Performance of the grid connected hybrid wind-solar energy</div><div data-canvas-width="38.15327554928442">system and load demand response of the battery integrated single phase voltage source inverter is presented. The wind energy conversion system is</div><div data-canvas-width="397.2481505744809">generating AC power and the solar PV system is generating DC power and</div><div data-canvas-width="240.71571255795203">both are integrating with battery in the common DC bus. The output voltage</div><div data-canvas-width="284.91922495464627">of the wind and solar system are controlling using dc-dc converters and it</div><div data-canvas-width="397.2100987704092">achieved more than the battery voltage. P&O algorithm used MPPT based</div><div data-canvas-width="188.4705855674259">voltage controller is driving the dc-dc converter with a reference voltage</div><div data-canvas-width="37.43029127192098">value of the battery. The single-phase full-bridge converter is converting DC</div><div data-canvas-width="397.2735184438622">to AC power and feeding into the standalone AC loads and distribution grid</div><div data-canvas-width="180.08650473694817">with IEEE 519 standard. The bi-directional converter is controlling the directions of power flow and it operates two modes namely inverter mode and rectifier mode based on a voltage level of the battery. In this bi-directional converter is controlling by the PI controller with the reference value of the DC bus voltage and load current. The power quality and demand response of the inverter is observing at various types of load conditions in standalone mode and grid-connected mode using experimental results.</div>

Hybrid PV-Wind-Battery Based System for Household Applications Using DC-DC Converter

In this project, a control strategy for power flow management of a grid-connected hybrid PV-wind-battery based system with an efficient multi-input transformer coupled bidirectional dc-dc converter is presented. The proposed system aims to satisfy the load demand, manage the power flow from different sources, inject surplus power into the grid and charge the battery from grid as and when required. A transformer coupled boost half-bridge converter is used to harness power from wind, while bidirectional buck-boost converter is used to harness power from PV along with battery charging/discharging control. A single-phase full-bridge bidirectional converter is used for feeding ac loads and interaction with grid. The proposed converter architecture has reduced number of power conversion stages with less component count, and reduced losses compared to existing grid-connected hybrid systems. This improves the efficiency and reliability of the system.

Grid-Connected PV-Wind-Battery-Based Multi-Input Transformer-Coupled Bidirectional DC-DC Converter for Household Applications

In this paper, a control strategy for power flow management of a grid-connected hybrid photovoltaic (PV)–wind-battery-based system with an efficient multi-input transformer-coupled bidirectional dc–dc converter is presented. The proposed system aims to satisfy the load demand, manage the power flow from different sources, inject the surplus power into the grid, and charge the battery from the grid as and when required. A transformer-coupled boost half-bridge converter is used to harness power from wind, while a bidirectional buck-boost converter is used to harness power from PV along with battery charging/discharging control. A single-phase full-bridge bidirectional converter is used for feeding ac loads and interaction with the grid. The proposed converter architecture has reduced number of power conversion stages with less component count and reduced losses compared with existing grid-connected hybrid systems. This improves the efficiency and the reliability of the system. Simulation results obtained using MATLAB/Simulink show the performance of the proposed control strategy for power flow management under various modes of operation. The effectiveness of the topology and the efficacy of the proposed control strategy are validated through detailed experimental studies to demonstrate the capability of the system operation in different modes.

Comparison of Different Phase-Shift Control Methods at Isolated Bidirectional DC-DC Converter

In this study, the operation, design and comparison of single, extended and dual phase shift control methods on bidirectional DC-DC converters are discussed. The major components (DC link capacitors and inductors) are derived for different phase shifting methods in order to obtain maximum efficiency. Triggering signals, voltages and current waveforms are compared for buck-boost conditions through PSCAD simulation results on the single-phase full-bridge converter topology with isolation transformer.

Control Strategy to Naturally Balance Hybrid Converter for Variable-Speed Medium-Voltage Drive Applications

In this paper, a novel control strategy to naturally balance a hybrid converter is presented for medium-voltage induction motor drive applications. Fundamental current of the motor is produced by a three-level quasi-square-wave converter. Several single-phase full-bridge converters are connected in series with this quasi-square-wave converter to eliminate harmonic voltages from the net output voltage of this hybrid converter. Various novel modulation strategies for these series cells are proposed. These lead to a naturally regulated dc-bus voltage of series cells. These also optimize the number of series cells required. Variable fundamental voltage and frequency control of induction motor is adopted with a constant dc-bus voltage of the three-level quasi-square-wave converter. Experimental results are also produced here to validate the proposed modulation strategies for induction motor drives using low-voltage protomodel. Based on the aforementioned, a 2.2-kV induction motor drive has been built, and results are also produced in this paper.

Application of shunt active power filter for harmonic reduction and reactive power compensation in three‐phase four‐wire systems

This study deals with the analysis and implementation of compensation algorithms applied to a shunt active power filter, which uses three single-phase full-bridge converters sharing the same dc-bus voltage. The shunt filter is applied to three-phase four-wire systems, performing harmonic current suppression, reactive power compensation and power factor improvement. In addition, load unbalances compensation is also carried out. Two different control strategies are presented. In the first strategy, which is called independent current control, the currents of the three-phase power source are independently compensated performing harmonic suppression and load reactive power compensation, that is, the three-phase four-wire system is treated as three independent single-phase systems. In the second strategy, in addition to harmonic suppression and load reactive power compensation, the shunt filter also performs load unbalance compensation, resulting in sinusoidal and balanced source currents. The compensating algorithms are evaluated by means of several experimental test conditions, in order to validate the theoretical development and analyse the performance of the shunt filter.

Design of a bidirectional power interface for V2G technology with smaller DC-link capacitance

A configuration of a single-phase full-bridge AC-DC converter and dual active bridge (DAB) converter used in V2G (vehicle to grid) and G2V (grid to vehicle) technology is proposed in this paper. It can well realize the bi-directional energy fluidity. The numerous controllers can be designed by MATLAB SISOTOOL easily and quickly. And PLECS software is used to validate the function of the proposed system. In addition, a power decoupling method for this power interface is presented and verified. The simulation results show this configuration works well in V2G application and the DC-link capacitance could be reduced remarkably using proposed method.

Integrated higher‐order pulse‐width modulation filter–transformer structure for single‐phase static compensator

A power filter is necessary to connect the output of a power converter to the grid so as to reduce the harmonic distortion introduced in the line current and voltage by the power converter. Many a times, a transformer is also present before the point of common coupling. Magnetic components often constitute a significant part of the overall weight, size and cost of the grid interface scheme. So, a compact inexpensive design is desirable. A higher-order LCL-filter and a transformer are increasingly being considered for grid interconnection of the power converter. This study proposes a design method based on a three-winding transformer, that generates an integrated structure that behaves as an LCL-filter, with both the filter inductances and the transformer that are merged into a single electromagnetic component. The parameters of the transformer are derived analytically. It is shown that along with a filter capacitor, the transformer parameters provide the filtering action of an LCL-filter. A single-phase full-bridge power converter is operated as a static compensator for performance evaluation of the integrated filter transformer. A resonant integrator-based single-phase phase locked loop and stationary frame AC current controller are employed for grid frequency synchronisation and line current control, respectively.

Transformerless Hybrid Topology for Medium-Voltage Reactive-Power Compensation

In this paper, natural sinusoidal hybrid converter is presented for medium-voltage reactive-power control applications. Main high-voltage inverter that produces fundamental reactive current is a square-wave inverter. Several single-phase full-bridge converters are connected in series with this square inverter to eliminate harmonic voltages from the net output voltage of this hybrid converter. DC bus voltages of these cells are naturally controlled. Two different switching strategies are proposed for these series cells in this paper-one is pulse width modulation (PWM) type and the other is non-PWM type. Dc bus voltage of main high-voltage inverter is varied to have variable reactive power. Finally, experimental results are produced here to validate this hybrid topology and its proposed control strategies from a scale-down proto model.

Single-Phase to Single-Phase Full-Bridge Converter Operating With Reduced AC Power in the DC-Link Capacitor

This paper presents a control technique based on input and output AC power synchronization to reduce the low frequency AC power and the DC-link voltage fluctuation of a single-phase full-bridge converter. The control technique is based on a technique in which the load voltage is synchronized with the input grid voltage for both constant (Mode I) and variable (Mode II) phase angle. Such approach allows for a reduction in the capacitor size. A capacitor bank design approach is also proposed. The technique has been achieved for the same input and output converter frequency. Simulated and experimental results are addressed.

Improving the voltage dip immunity of converter-connected distributed generation units

Voltage dip immunity of converter-connected distributed generation units will become increasingly important. This paper focusses on the relation between the voltage-dip ride-through capability of converters and their current-control strategy. A comparison is made between a recently proposed control strategy with programmable damping resistance and the classical sinewave control algorithm. The first-mentioned control structure will prove to yield an improved voltage dip immunity. Experimental tests on a single-phase full-bridge bidirectional converter are carried out and validate the aforementioned postulations.

A Bidirectional Isolated DC–DC Converter as a Core Circuit of the Next-Generation Medium-Voltage Power Conversion System

This paper describes a bidirectional isolated dc-dc converter considered as a core circuit of 3.3-kV/6.6-kV high-power-density power conversion systems in the next generation. The dc-dc converter is intended to use power switching devices based on silicon carbide (SiC) and/or gallium nitride, which will be available on the market in the near future. A 350-V, 10-kW and 20 kHz dc-dc converter is designed, constructed and tested. It consists of two single-phase full-bridge converters with the latest trench-gate insulated gate bipolar transistors and a 20-kHz transformer with a nano-crystalline soft-magnetic material core and litz wires. The transformer plays an essential role in achieving galvanic isolation between the two full-bridge converters. The overall efficiency from the dc-input to dc-output terminals is accurately measured to be as high as 97%, excluding gate drive and control circuit losses from the whole loss. Moreover, loss analysis is carried out to estimate effectiveness in using SiC-based power switching devices. Loss analysis clarifies that the use of SiC-based power devices may bring a significant reduction in conducting and switching losses to the dc-dc converter. As a result, the overall efficiency may reach 99% or higher

Voltage dip ride-through capability of converter-connected generators

Voltage dips have been proven to be one of the most important aspects of power quality. In order to avoid major economical damage, grid-connected equipment should be designed with a good voltage dip immunity. This holds as well for converter-connected loads as for converter-connected distributed generation (DG) units. This paper presents a control strategy for grid-connected DG converters yielding an improved voltage dip ride-through capability. Due to the implementation of the proposed control strategy, shutdown of DG units due to voltage dips is avoided, resulting in a stronger utility grid. Experimental tests on a single-phase full-bridge bidirectional converter are carried out and validate the aforementioned postulations.

次世代3.3kV/6.6kV電力変換システムのコア回路としての双方向絶縁形DC/DCコンバータ

This paper describes a bi-directional isolated dc/dc converter considered as a core circuit of 3.3-kV/6.6-kV high-power-density power conversion systems in the next generation. The dc/dc converter is intended to use power switching devices based on SiC and/or GaN, which will be available on the market in the near future. A 350-V, 10-kW and 20kHz dc/dc converter is designed, constructed and tested in this paper. It consists of two single-phase full-bridge converters with the latest trench-gate Si-IGBTs and a 20-kHz transformer with a nano-crystalline soft-magnetic material core and litz wires. The transformer plays an essential role in achieving galvanic isolation between the two full-bridge converters. The overall efficiency from the dc-input to dc-output terminals is accurately measured to be as high as 97%, excluding gate drive circuit and control circuit losses from the whole loss. Moreover, loss analysis is carried out to estimate effectiveness in using SiC-based power switching devices. The loss analysis clarifies that the use of SiC-based power devices may bring a significant reduction in conducting and switching losses to the dc/dc converter. As a result, the overall efficiency may reach 99% or higher.