Bidirectional Buck-boost Converter Research Articles

A Multiport Bidirectional LLC Resonant Converter for Grid-Tied Photovoltaic-Battery Hybrid System

Distributed power generation plants with combined photovoltaic (PV) systems and integrated energy storage for grid-connected applications have seen an increase in research interest in recent years. However, the combination of multiple energy sources requires numerous DC-DC converters and thus becomes more complex. To address this issue, a multiport bidirectional DC-DC LLC resonant converter for grid connected applications is presented in this research. In order to minimize the control complexity of the proposed system, a zone based controller approach with an integrated modified maximum power point tracking (MMPPT) method, which is based on the incremental conductance method, is also developed. This proposed controller is able to regulate the converter voltage and power flow while either delivering or taking power from the utility grid. The converter presented in this study contains a bidirectional buck-boost converter and an LLC resonant converter in addition to a voltage source grid-tied inverter which are interfacing the PV, the battery and the utility. Extensive simulation analyses through MATLAB/Simulink have proved the operations of the proposed topology.

Lossless Snubber Cell for a Soft-Switched Bidirectional Buck–Boost Converter

In this paper, we propose a lossless snubber cell for a soft-switched bidirectional buck-boost converter (BBC). The proposed snubber cell provides all switches with soft-switching conditions in both the bidirectional power flows of the BBC. In addition, the cell also achieves a relatively low circulating current for the snubber operation over a wide load range. In particular, the reverse recovery problem of the synchronous rectifier can be eliminated with the aid of the snubber inductor. Accordingly, the snubber cell enables high-frequency switching of approximately 60 kHz for all power switches and achieves high efficiency and high power density. Moreover, the proposed snubber cell does not have any auxiliary switch; therefore, complex auxiliary circuits or driving algorithms for the auxiliary switch are not required. Therefore, the proposed snubber cell has a simple structure with high reliability. To confirm the validity of the proposed lossless snubber cell, we provide detailed analyses, design guidelines, and experimental results using a 3-kW laboratory prototype.

Design and Development of Standalone Solar Photovoltaic Battery System with Adaptive Sliding Mode Controller

In this paper, a solar photovoltaic-battery located standalone system is proposed. The configuration of bidirectional buck-boost converter has been proposed for charging (buck) and discharging (boost) the battery storage system. Due to solar energy sources irregular nature and variations in load demand, DC micro grids mostly depend on control methods to overcome with DC link voltage variations and power stability. Adaptive sliding mode controller with washout filter is applied due to its good strength for unexpected change of energy resources and loads. This system includes a solar photovoltaic array basis on maximum power tracking from PV, boost converter to maximize power from the PV. A bidirectional DC-DC buck-boost converter is proposed being charging battery in buck mode and discharging battery in boost mode. Incremental conductance implemented to obtain maximum power from photovoltaic array. In this paper, study of comparison between proportional-plus integral method and sliding mode control method with washout filter has been also simulated in the MATLAB using Simulink and the Sim Power System toolbox.

Analysis, Modeling and Implementation of a Switching Bi-Directional Buck-Boost Converter Based on Electric Vehicle Hybrid Energy Storage for V2G System

This paper presents a switching bi-directional buck-boost converter (SBBBC) for vehicles-to-grid (V2G) system. The topology can provide an energy bi-directional flow path for energy exchange between the Li-battery/supercapacitor (SC) hybrid energy storage system (HESS) of the electric vehicle and the grid. This topology not only has buck-boost capability, but also has the function of energy management. In this paper, the state-space averaging method is used to analyze the stability of the topology in boost and buck modes. The control strategy is given according to the state of charge (SOC) of the energy storage system to ensure that the output voltage and current are stable. And the Li-battery is charged in constant current (CC) and constant voltage (CV) mode. The voltage and current controllers are designed in the frequency domain based on bode plots. Finally, the electrical feasibility of the topology, the suitability of the design controller and control strategy are verified by simulation and experiment.

Microcontroller Based Bi-Directional DC-DC Converter for Automobile Application

This paper presents different topology for non isolating bi-directional dc–dc converter for automotive application. To increase and decrease the voltage level Buck-boost bidirectional converter type is used. This type of converter reduces the switching losses by using less number of switches. Also regenerative concept was introduced. During braking operation the energy stored in the motor was reduced by buck operation of the bidirectional converter and stored into the battery. This Battery will also act as the supply voltage when required. An auxiliary energy storage battery stores the regenerated energy which is obtained during the process of braking and it fed back to the electric machine in the electric vehicle applications. Auxiliary battery provides the power to the bidirectional dc-dc converter to boost the high-voltage bus during vehicle starting. To achieve power transfer between two dc power sources in either direction, the bidirectional dc-dc converters are used since it has the ability to reverse the direction of the current flow and power. This can also be used in multi port systems. In Multi-Port HEVs, two or more voltage source purposes of better performances of the vehicle are used.

Fractional order control for a bidirectional converter operating in a DC

This paper presents the control design of a bidirectional converter used to support a DC microgrid. The chosen topology for this purpose is the bidirectional buck-boost converter, for which its mathematical model is obtained. Next, a brief introduction of fractional order control is presented and the structure of a fractional order PID controller is shown. The tuning process of this controller is obtained by means of an arithmetic method whose parameters are set to control the bidirectional converter. In order to evaluate the performance of the converter and its fractional-order controller, this is simulated under different situations that represent different operating conditions, such as changes in battery voltage levels, climatic conditions, and uncertainty in the parameters. The simulation results of this controller are analyzed and compared with a classical PID. Finally, the conclusions are presented.

High-efficiency Bidirectional Buck–Boost Converter for Residential Energy Storage System

This paper proposes a bidirectional dc–dc converter for residential micro-grid applications. The proposed converter can operate over an input voltage range that overlaps the output voltage range. This converter uses two snubber capacitors to reduce the switch turn-off losses, a dc-blocking capacitor to reduce the input/output filter size, and a 1:1 transformer to reduce core loss. The windings of the transformer are connected in parallel and in reverse-coupled configuration to suppress magnetic flux swing in the core. Zero-voltage turn-on of the switch is achieved by operating the converter in discontinuous conduction mode. The experimental converter was designed to operate at a switching frequency of 40–210 kHz, an input voltage of 48 V, an output voltage of 36–60 V, and an output power of 50–500 W. The power conversion efficiency for boost conversion to 60 V was ≥98.3% in the entire power range. The efficiency for buck conversion to 36 V was ≥98.4% in the entire power range. The output voltage ripple at full load was <3.59 Vp.p for boost conversion (60 V) and 1.35 Vp.p for buck conversion (36 V) with the reduced input/output filter. The experimental results indicate that the proposed converter is well-suited to smart-grid energy storage systems that require high efficiency, small size, and overlapping input and output voltage ranges.

Zero-Voltage Switching Control of an Interleaved Bi-Directional Buck–Boost Converter With Variable Coupled Inductor

This paper investigates an approach for achieving zero-voltage switching of an interleaved bi-directional buck–boost converter over a wide input–output voltage operating range by utilizing a coupled inductor with a variable coupling coefficient. The approach is based on regulating the value of the coupling coefficient by means of a direct current depending on the converter conversion ratio, thereby controlling the amplitude and duration of the resonant voltage transition. The impact of the controllable value of the coupling coefficient on the equivalent inductance, the zero-voltage transition period, and the resonant amplitude is analyzed in detail by applying analytical modeling. In comparison to the converter with a fixed coupled inductor operating over a wide input–output voltage span, the variable coupled inductor significantly improves the soft-switching range and reduces the circulating energy. Outside of the controllable resonant amplitude region, the converter with a variable coupled inductor still achieves reduction in the duration of the resonant transition period. To validate theoretical analysis, experimental results are recorded on the gallium nitride interleaved bi-directional buck–boost converter prototype. Improvements in efficiency at both full and half loads in comparison to the prototype with a fixed coupled inductor are achieved.

Regulation Performance of Multiple DC Electric Springs Controlled by Distributed Cooperative System

DC electric springs (DCESs) have been recently developed to improve the voltage stability of a DC microgrid. A lately proposed DCES topology is comprised of a DC/DC three port converter (TPC), a bi-directional buck-boost converter (BBC) and a battery, and is arranged as follows: The TPC input port is fed by a renewable energy source (RES) whilst the two TPC output ports supply a non-critical load (NCL) and a critical load (CL) separately; in turn, BBC together with the battery constitutes the DCES energy storage unit (ESU) and is connected in parallel to CL. In this paper, a set of DCESs with such a topology and with their CLs connected to a common DC bus is considered. The control of the DCESs is built up around a distributed cooperative system having two control levels, namely primary and secondary, each of them endowed with algorithms committed to specific tasks. The structure of the control levels is explicated and their parameters are designed. The control system is applied to a DCES set taken as a study-case and tested by simulation. The results of the tests show the excellent performance of the control system in both regulating the CL DC bus voltage and keeping the state-of-charge of the battery within predefined limits.

Design and Implementation of a New Transformerless Bidirectional DC–DC Converter With Wide Conversion Ratios

A new transformerless bidirectional buck-boost converter is proposed in this paper. The proposed converter has a simple circuit structure, low component count, low voltage stress on the power transistors, and a wide voltage gain range. This makes it applicable in the energy storage charge/discharge systems, such as electric vehicles (EV), microgrids and nanogrids with energy storage units, and uninterruptible power supplies. In addition, synchronous rectification between the complementary transistors is employed to improve the converter efficiency. A comprehensive analysis of the steady-state operation, small-signal model, component parameters design, and efficiency analysis of the proposed converter operating in a continuous conduction mode is given. Finally, a 1.6-kW scaled-down prototype was built using Silicon Carbide MOSFET S to validate the effectiveness and feasibility of the proposed converter.

Stability and Dynamic Response of Analog and Digital Control loops of Bidirectional buck-boost Converter for Renewable Energy Applications

This article presents the stability and dynamic response of open loop and closed loop control of Bidirectional buck-boost converter(BBC) using PID and PIDN controllers through transfer function model implemented in MATLAB code. In order to ensure the stability of switch mode power supplies the control loop behaviors need to be characterized. Improvement of stability of BBC using PID/PIDN compensators is demonstrated in both analog and digital domains by plotting bode plots. Step response of BBC using PID /PIDN controllers are plotted that defines the dynamic behavior of the system.PIDN compensator is proposed to maintain a healthy balance between the stability and transient behavior since both are indirectly proportional.

High-Efficiency Bidirectional Buck–Boost Converter for Photovoltaic and Energy Storage Systems in a Smart Grid

This paper proposes a new bidirectional buck–boost converter, which is a key component in a photovoltaic and energy storage system (ESS). Conventional bidirectional buck–boost converters for ESSs operate in discontinuous conduction mode (DCM) to achieve zero-voltage switching turn- on for switches. However, operation in DCM causes high ripples in the output voltage and current, as well as low power-conversion efficiency. To improve the performance of the conventional converter, the proposed converter has a new combined structure of a cascaded buck–boost converter and an auxiliary capacitor. The combined structure of the proposed converter reduces the output current ripple by providing a current path and the efficiency is increased. A prototype was built and tested to verify the effectiveness of the converter. The proposed converter has a maximum efficiency of 98%, less than ${\text{5.14}}{ \text{V}}_{{\text{p.p}}}$ of output voltage ripple, and less than ${\text{7.12}}{ \text{A}}_{{\text{p.p}}}$ of output current ripple. These results were obtained at an input voltage of 160 V, switching frequency of 45 kHz, output voltage of 80–320 V, and output power of 16–160 W. The experimental results show that the proposed converter has improved performance compared to the conventional converter.

Inductor Current Estimation Method for Three-phase Interleaved Bidirectional Buck-Boost Converters using a Current Sensor on a DC Bus

Inductor Current Estimation Method for Three-phase Interleaved Bidirectional Buck-Boost Converters using a Current Sensor on a DC Bus

An anfis converter control approach of grid connected wind/PV/battery system

The major objective of this task is a control technique for power flow management of a network associated hybrid PV-wind-battery based system with multi-input transformer coupled bidirectional DC-DC converter using ANFIS controller is introduced. The proposed system intends to fulfill the demand of load, deal with the power flow from the distinctive sources, injects surplus power into the network and charge the battery from framework as and when required. A transformer coupled boost half-bridge converter is used to tackle power from wind, while bidirectional buck-boost converter is used to outfit control from PV alongside battery charging/releasing control. A single stage full-bridge bidirectional converter is used for ac loads and collaboration with grid. The proposed converter has reduced number of intensity change stages. This enhances the effectiveness and unwavering quality of the framework. In this article Adaptive Neuro Fuzzy interference System (ANFIS) is proposed for better performance of the system. Neural system has many inputs and also has multiple outputs but the fuzzy logic has multiple inputs and single output, so the combination of this two is known as ANFIS which is utilized for nonlinear applications. The proposed paper of simulation results acquired using MATLAB/Simulink demonstrate the execution of the proposed control procedure for power stream the executives under different methods of activity.

HM/PWM Seamless Control of a Bidirectional Buck–Boost Converter for a Photovoltaic Application

The versatile buck–boost dc/dc converter is found suitable for a particular photovoltaic application that requires either a voltage step-up or a voltage step-down operation injecting the maximum available current into an intermediate-voltage battery. It is proposed to implement the converter control stage providing seamless changes between the step-up (boost) and step-down (buck) operating modes. Based on the sliding-mode control technique, a hysteretic-modulation-based (HM) controller is designed allowing the tuning of the switching frequency around either of the two possible operating points. The introduction of minor modifications into the HM implementation results in a pulsewidth modulation controller that preserves the seamless changing features between buck and boost working modes while providing a fixed switching frequency. Experimental results demonstrate that both solutions allow the converter input voltage control by showing a perfect tracking of 1-kHz square-type references, similar to those provided by a classical perturb-and-observe (P&O) MPPT algorithm but much faster.

Autonomous Battery Storage Energy System Control of PV-Wind Based DC Microgrid

: This paper describes the simulation and modelling of a DC microgrid. The proposed microgrid system comprise of a wind turbine, solar PV array, battery storage systems and control and dc loads. The wind turbine is interfaced to the microgrid with MPPT to extract maximum power and PV array is connected via boost converter to the dc grid. A constant dc bus voltage is maintained with the help of controlled Battery Energy Storage System (BESS) which is connected via bidirectional buck-boost converter. The system is designed and analyzed in MATLAB-SIMULINK under different operating conditions of wind speed and solar irradiation and the results have been studied.

Design and simulation of bi-directional DC-DC converter with dual switch forward snubber

A novel isolated bi-directional buck-boost converter is presented for energy storage application. Isolated boost bi-directional DC-DC converters are required to meet the wide voltage variation demand. The conventional isolated boost converters have some auxiliary circuits to provide an auxiliary path for mismatch current between source inductance and leakage inductance of the transformer. The dual switch forward snubber circuit is adopted as auxiliary circuits along with dual active bridge (DAB) converter in the proposed converter. The proposed converter has distinct advantages like zero voltage switching starting (ZVS), no voltage stress on main switches, no additional conduction losses and improved efficiency as compared to RCD snubber-based converter system. The wide voltage variation in output side for 45V to 320V bi-directional DC-DC converter has been simulated with PSIM. The charging mode and discharging mode with energy storing mode has been explained in detail. The simulation results show the effective performance of proposed converter system. The loss comparison has been shown between RCD snubberbased converter and dual switch forward snubber which proves that dual switch forward snubber has high efficiency compared to RCD snubber circuit.

Design and simulation of bi-directional DC-DC converter with dual switch forward snubber

A novel isolated bi-directional buck-boost converter is presented for energy storage application. Isolated boost bi-directional DC-DC converters are required to meet the wide voltage variation demand. The conventional isolated boost converters have some auxiliary circuits to provide an auxiliary path for mismatch current between source inductance and leakage inductance of the transformer. The dual switch forward snubber circuit is adopted as auxiliary circuits along with dual active bridge (DAB) converter in the proposed converter. The proposed converter has distinct advantages like zero voltage switching starting (ZVS), no voltage stress on main switches, no additional conduction losses and improved efficiency as compared to RCD snubber-based converter system. The wide voltage variation in output side for 45V to 320V bi-directional DC-DC converter has been simulated with PSIM. The charging mode and discharging mode with energy storing mode has been explained in detail. The simulation results show the effective performance of proposed converter system. The loss comparison has been shown between RCD snubberbased converter and dual switch forward snubber which proves that dual switch forward snubber has high efficiency compared to RCD snubber circuit.

A Model Predictive Control for Renewable Energy Based AC Microgrids Without Any PID Regulators

This letter presents a novel model predictive control strategy without involving any proportional-integral-differential regulators for practical renewable energy based ac microgrids. The proposed method consists of a model predictive power control (MPPC) scheme and a model predictive voltage control (MPVC) scheme. By controlling the bidirectional buck-boost converters of the battery energy storage systems based on the MPPC algorithm, the fluctuating output from the renewable energy sources can be smoothed, while stable dc-bus voltages can be maintained as the inverters' inputs. Then, the parallel inverters are controlled by using a combination of the MPVC scheme and the droop method to ensure stable ac voltage output and proper power sharing. Compared with the traditional cascade control, the proposed method is simpler and shows better performance, which is validated in simulation on MATLAB/Simulink and on real-time laboratory platform.

Modular Regenerative Emulation System for DC–DC Converters in Hybrid Fuel Cell Vehicle Applications

This paper proposes a novel emulation system for emulating the power system in the fuel cell electric vehicle. The major purpose of the proposed emulation system is to test the dc-dc converter between the fuel cell and high-voltage powertrain. The bidirectional buck-boost type dc-dc converter is applied in the emulation system as the basic elements. A modularized approach is presented for easily scaling up and down the power level of the emulation system. Meanwhile, an energy loop structure is implemented in the proposed emulation system for power capability boosting purpose. Because of the proposed energy loop configuration, the emulation system offers long-term running capability with high power rating without the grid connection. A neutral current control mechanism is applied in this paper to further enhance the long-term testing capability as well as extending the lifespan for the battery packages. The simulation studies are proposed in this paper to validate the control mechanisms of the emulation system. A 10 kW hardware prototype has been built and the experimental tests are presented for validating the functionalities of the emulation system.