Bidirectional Buck-boost DC-DC Converter Research Articles

An experimental investigation design of a bidirectional DC-DC buck-boost converter for PV battery charger system

The aim of this paper is to present a bidirectional DC-DC buck-boost converter design that is specifically intended for use with storage batteries in a PV system. The primary purpose of the batteries is to mitigate the unpredictable and intermittent nature of renewable energy sources. To achieve this, a DC-DC converter is used in buck mode during daylight hours to charge the batteries with power derived from the PV system. If the photovoltaic energy source is unavailable, the batteries can discharge to power the DC load through the converter in boost mode. Therefore, the bi-directional DC/DC converter, which has a high-power capacity, manages the power storage system. To this end, the paper describes the design and implementation of both the power circuit board and drive circuit board of the buck-boost converter, taking into account the rated current, voltage, and power. Finally, the effectiveness and efficiency of the designed converter are verified through experimental tests carried out in both charge and discharge modes, with results demonstrating the validity and efficiency of the converter.

Development and Application of an Energy Management System for Electric Vehicles Integrated with Multi-input DC-DC Bidirectional Buck-Boost Converter

The rise in environmental pollution, demand for fossil fuels, and higher fuel economy vehicles has raised concerns about the creation of new and efficient transportation vehicles in recent days. These days, most developments in electric vehicles concentrate on making the vehicles more pleasant to ride in. Nonetheless, the emphasis now should be on energy and its most efficient use. To do this, you must give your attention to the origin of the automobile. The answer to this problem may be found in hybrid energy storage systems (HESS). This work is concerned with the design and implementation of an effective energy management system in electric vehicles (EVs) equipped with an active HESS consisting of a battery and a super capacitor via the incorporation of load sharing into this hybridization under a variety of load demand scenarios. To address the demands of high fuel efficiency vehicles, automotive firms are focusing on the development of diesel-engine operated vehicles, electric vehicles, fuel-cell vehicles, plug-in electric vehicles, and hybrid electric vehicles. A Multi-input Bidirectional Buck-Boost (MIB3) DC-DC converter is proposed in this dissertation to provide a greater conversion ratio to the input DC voltage. The multi-input converter recommended has fewer components and a simpler control method, making it more trustworthy and cost-effective. This converter also has bidirectional power flow functionality, making it suitable for charging the battery during regenerative braking in an electric or hybrid vehicle. Three different energy sources are used in the suggested topology: a photovoltaic (PV) panel, a battery, and an ultra-capacitor

Hybrid Vehicle CO2 Emissions Reduction Strategy Based on Model Predictive Control

This work proposes a hybrid drive controlled configuration, using a minimum emissions search algorithm, which ensures the operation of the Internal Combustion Engine (ICE) in its fuel efficiency range, minimizing CO2 emissions by controlling the power flow direction of the Electric Machine (EM). This action is achieved by means of Power Converters, in this case a bi-directional DC-DC Buck-Boost Converter in the DC-side and a DC-AC T-type Converter as the inverting stage. Power flow is controlled by means of a bi-directional Model Predictive Control (MPC) scheme, based on an emissions optimization algorithm. A novel drivetrain configuration is presented where both, the ICE and the EM are in tandem arrangement. The EM is driven depending on the traction requirements and the emissions of the ICE. The EM is capable of operates in motor and generator mode ensuring the Minimum Emission Operating Point (MEOP) of the ICE regardless of the mechanical demand at the drivetrain. Simulation and validation results using a Hardware in the Loop (HIL) virtual prototype under different operation conditions are presented in order to validate the proposed overall optimization strategy.

A New Continuous Input Current Nonisolated Bidirectional Interleaved Buck-Boost DC-DC Converter

In this paper, a new interleaved bidirectional buck-boost DC-DC converter is proposed. The input current of this converter is continuous and has a low ripple, that cause reduction in the size of the input filter of the converter. Because of these features, this converter is appropriate for renewable applications such as fuel cells and photovoltaic (PV) panels for obtaining maximum power in which the continuity of the input current is essential. The operation principle of this converter is detailed, and its power losses calculation shows the positive effects of the low input current ripple on its efficiency. The input current ripple of the proposed converter and conventional interleaved buck-boost converter has been calculated in detail. In addition, the comparison results of this converter with conventional interleaved buck-boost converters and other similar structures confirm that the proposed converter without utilizing extra components achieves continuous input current with low ripple. Compared with other buck-boost structures, the low input current ripple in the presented converter causes an improvement in its efficiency. An experimental prototype is implemented in the laboratory to confirm the correctness of theoretical analyses.

A Unified Controller for Multi-State Operation of the Bi-Directional Buck–Boost DC-DC Converter

DC grid interfaces for supercapacitors (SCs) are expected to operate with a wide range of input voltages with fast dynamics. The class-C DC-DC converter is commonly used in this application because of its simplicity. However, it does not work if the output voltage (V2) becomes smaller than the input voltage (V1). The non-isolated bi-directional Buck–Boost DC-DC converter does not have this limitation. Its two half-bridges provide a means for controlling the power flow operating in the conventional dual-state mode, as well as multi-state, tri, and quad modes. These can be used for mitigating issues such as the Right Half Plane (RHP) zero that has a negative impact on the dynamic response of the system. Multi-state operation typically requires multi-variable control, which is not easy to realize with conventional PI-type controllers. This paper proposes a unified controller for multi-state operation. It employs a carrier-based modulation scheme with three modulation signals that allows the converter to operate in all four possible states and eight different modes of operation. A mathematical model is developed for devising a multi-variable control scheme using feedback linearization. This allows the design of control loops with simple PI controllers that can be used for all multi-state modes under a wide range of operating conditions with the same performance. The proposed scheme is verified by means of simulations.

Non-Inverting Cascaded Bidirectional Buck-Boost DC-DC Converter with Average Current Mode Control for Lithium-Ion Battery Charger

In order to develop renewable energy, it also needs to enhance the developing of supporting elements. For example, lithium-ion batteries as a component of energy storage. Lithium-ion batteries (Li-ion) have been chosen as energy storage devices for portable equipment, unmanned Aerial Vehicle (UAV) and grid storage systems. But there is a problem such as the process of charging the battery for UAV. Conventional converters used in those chargers have disadvantages such as limited power, lower voltage gain and also high current stress. Therefore, such converters are not efficient to be used for charging the battery. This paper proposes a cascaded bidirectional buck-boost converter for charging the battery. This converter can be operated bidirectional and have better rated power and higher voltage gain. Also, this topology has the same polarity with the input. From the test results, the converter can work in either forward or backward power flow. This converter is working in both buck or boost mode and has an efficiency of 83% in buck mode and 81% for boost mode. The charging process is about 83 minutes until SOC approximately 90 – 95.Keywords: battery charger, cascaded bidirectional buck – boost converter, constant current, li-ion introduction.

Performance Evaluation of Single-Phase On-Board Charger with Advanced Controller

Abstract: The increasing mobility of electric vehicles has inspired vehicle growth to power grid technology. Such as vehicle to grid technology allows to transfer the power from the electric vehicle battery to the power grid. This enable speak load shaving, load leveling, voltage regulation, and improved stability of the power system. To develop the vehicle to grid technology requires a specialized EV battery charger, which permits the bi-directional energy transfer between the power grid and the electric vehicle battery. There is a specific control strategy used for a bi-directional battery charger. The proposed control strategy is used for charge and discharge battery of EV. The charger strategy has two parts: 1) Bidirectional AC-DC Converter in two-way Communication System. 2) Bidirectional DC-DC Buck-Boost Converter. There are two modes of operation for a bidirectional ac-dc converter: for G2V, rectifying mode is used, and for V2G, inverter mode is used. The suggested charge strategy not only allows for two-directional power flow but also provides power quality management of the power grid. Fuzzy logic controller (FLC) transforms linguistic control topology evaluations knowledge into an automated control topology using FLC. The FLC is more stable, has less overshoot, and responds quickly. The operation of a standard PI controller and a FLC was compared in this study using MATLAB and Simulink, and different time domain characteristics were compared as toshow that the FLC had a smaller overshoot and a faster response than the PI controller. Keywords: Bi-directional AC-DC converter, bi-directional DC-DC Buck-Boost converter, electric vehicles (EVs), on-board battery charger (OBC), grid to vehicle (G2V), vehicle to grid (V2G).

Single-Phase Transformerless Line Interactive Uninterruptable Power Supply with Two Independent Control Algorithms

This paper presents the development of two independent control algorithms for an Uninterruptable Power Supply (UPS). It is a mitigation tool to mitigate power interruption. The UPS circuit consists of a bidirectional buck-boost DC-DC converter, a rechargeable battery and a DC-AC/AC-DC converter. The bidirectional DC-DC converter has a function of charging (buck) or discharging (boost) the battery for maintaining DC-link voltage connected to the DC-AC/AC-DC converter. During the normal mode operation, the DC-AC/AC-DC converter supplies voltage to the bidirectional converter by performing AC to DC conversion. Instead, during the backup mode, the converter supplies voltage to the load by performing DC to AC conversion. In this work, a single-loop voltage control algorithm regulates the bidirectional converter. For the DC-AC/AC-DC converter, a multi-loop control algorithm regulates the output current using the inner loop and the output voltage using the outer loop. MATLAB/Simulink simulates the UPS to determine its performance during normal and backup mode operation. From the simulation results, both independent control algorithms can regulate the operation of both converters during both modes of operation. As a result, the UPS system is capable of supplying sinusoidal waveforms with low Total Harmonic Distortion (THD) of output current and output voltage. Both THD values are below 4%.

Low-loss bidirectional buck-boost DC-DC converter

For DC energy systems there is reversible buck/boost pulse converter (RPC) in the classic converter circuit. The maximum efficiency of the RPC without additional mechanisms to reduce the dynamic energy losses in the power semiconductor keys (PSK) during their commutation is about 92%. Improved efficiency is achieved by providing «soft switching» of the transistors RPC, i.e. in zero current/voltage switching. These methods require the introduction of supporting links in the RPC, which have a negative impact on the performance of reversible buck/boost pulse converter. Due to the increase in the number of components, this leads to degradation of mass-size characteristics of the product and decrease in its reliability. New RPC transistors control algorithm RPC provides an opportunity to use transistors at zero voltage without additional elements. Because of the relative novelty of this technical solution, the energy exchange processes in the reactive elements of power semiconductor devices (PSD) are poorly studied. By reason of insufficient studying of power exchange processes in reactive elements of converter, it seems important to study these processes and use the received results for recommendations about reversible buck/boost pulse converter designing. As a result of research it was found out that the recuperation of energy stored in parasitic capacitance of drain-source transistors acting as PSD. At designing of RPC the account of the revealed phenomenon of energy, recovery will allow additionally to raise its efficiency at the expense of decrease in losses of energy on PSK in shutdown state. For this purpose, it is necessary to use transistors with high value of parasitic capacitance of drain-source or include additional capacitors in parallel with PSK.

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.

Perturb/Observe Controller and PI Controller for Battery Charger with Photovoltaic Panel

In this study, the Perturb observe controller and PI controller for a Li-Ion battery charger with photovoltaic panel sourced is proposed. Compared with other batteries, Lithium-Ion (Li-Ion) batteries are featured by high-energy, high-power, long-life and environmental-friendliness and therefore have found wide application in the consumer electronics. The voltage and current of PV panels are nonlinear and variable environmental conditions cause to change voltage and current. They also cause to change maximum available power of PV panels. Maximum power point tracking (MPPT) methods are used to obtained maximum power and to increase efficiency of the photovoltaic panels (PV). The charger topology consists of two-stages: 1) a photovoltaic panel source DC-DC boost converter to obtain the high output voltage, and 2) a half-bridge bidirectional DC-DC buck-boost converter to behave as a charge controller. The perturb and observe (P&O) controller is used to obtained maximum power and voltage of the photovoltaic panel (PV) system. The constant voltage method with PI controller is used for bidirectional DC-DC buck-boost converter to charge of a Li-Ion battery. PI controller is a simple technique and also it provides satisfactory results. The simulation of the 5 kW photovoltaic panel, DCDC boost converter and charger are created by using of computational blocks and design suit blocks in PSIM circuit simulations. Keywords: Photovoltaic panel, Battery charger, MPPT controller, DC-DC boost converter, Lithium-Ion batteries DOI: 10.7176/JSTR/5-12-19

Grid to vehicle and vehicle to grid energy transfer using single-phase half bridge boost AC-DC converter and bidirectional DC - DC converter

A system configuration based on a single-phase unity power factor (PF) half-bridge boost converter and bidirectional DC-DC converter based energy transfer from electrical vehicle to grid(V2G) and grid to vehicle (G2V) is proposed with detailed analysis. The efficiency of this conversion system is high because there is only one series semiconductor on-state voltage drop at any instant. The analytical results are verified through simulation using switched and averaged circuit models of the system at 230V AC input and DC output. The simulation result demonstrates an improved power factor at AC mains. In the second stage, a bidirectional buck–boost DC-DC converter is used to charge and discharge the battery of the PHEV (Plug-in Hybrid Electric Vehicle). In discharging mode, it delivers energy back to the grid at 230V, 50 Hz. A battery with the charging power of 3.6 kW at 240V is used in PHEV. The buck-boost DC-DC converter is used in buck mode to charge and in a boost mode to discharge the battery.Keywords: Plug-in Hybrid Electric Vehicle (PHEV), Half Bridge Boost AC-DC converter, DC-DC converter, Vehicle to grid (V2G), Bidirectional DC-DC converter, Power quality

Improved frequency control of a micro-grid with a genetically tuned fuzzy controlled super-capacitor system

In this paper, genetically tuned fuzzy controlled super-capacitor energy storage system (SCESS) is employed to improve the frequency control of a hybrid wind-diesel system. Super-capacitor is interfaced with the system through voltage source converter and bidirectional DC-DC buck-boost converter. The fuzzy logic controller for SCESS is designed in such a way that the effect of load disturbance is continuously mitigated while considering the operational constraints of SCESS. The membership functions of fuzzy controller are tuned by employing genetic algorithm (GA) for optimal performance. Optimised membership functions are reached out by introducing a regulated variable based on supercapacitor voltage and frequency deviation of the system. To validate the proposed scheme, detailed model is developed and tested in MATLAB/Simulink environment.

High step‐up/step‐down non‐isolated BDC with built‐in DC‐transformer for energy storage systems

A non-isolated bidirectional DC-DC converter (BDC) is proposed for high step-up/step-down bidirectional power conversion applications. A DC-transformer is integrated into a conventional non-isolated buck-boost BDC to achieve high-voltage conversion ratio and wide voltage/power range regulation simultaneously. The switches are shared by the buck-boost BDC and the DC-transformer. Voltage stresses of switches are reduced by connecting the input and output of the DC-transformer in-series. The duty cycles of switches are used to make sure that the voltages on the two sides of the DC-transformer are matched. As a result, the DC-transformer always operates under the highest-efficiency condition. The phase-shift angle between the switching bridges is employed to achieve the power flow regulation. Soft-switching of all the switches is achieved by adopting the pulse-width modulation plus phase-shift control strategy. Operation principles, characteristics and design considerations of the proposed BDC are analysed in detail. Experimental results from a 48 V/400 V-1 kW prototype verify the effectiveness of the proposed converter. The efficiency is demonstrated to peak at 96.6% for both the step-up and step-down modes.

High Step-Up/Step-Down Soft-Switching Bidirectional DC–DC Converter With Coupled-Inductor and Voltage Matching Control for Energy Storage Systems

A soft-switching bidirectional dc–dc converter (BDC) with a coupled-inductor and a voltage doubler cell is proposed for high step-up/step-down voltage conversion applications. A dual-active half-bridge (DAHB) converter is integrated into a conventional buck-boost BDC to extend the voltage gain dramatically and decrease switch voltage stresses effectively. The coupled inductor operates not only as a filter inductor of the buck-boost BDC, but also as a transformer of the DAHB converter. The input voltage of the DAHB converter is shared with the output of the buck-boost BDC. So, PWM control can be adopted to the buck-boost BDC to ensure that the voltage on the two sides of the DAHB converter is always matched. As a result, the circulating current and conduction losses can be lowered to improve efficiency. Phase-shift control is adopted to the DAHB converter to regulate the power flows of the proposed BDC. Moreover, zero-voltage switching (ZVS) is achieved for all the active switches to reduce the switching losses. The operational principles and characteristics of the proposed BDC are presented in detail. The analysis and performance have been fully validated experimentally on a 40–60 V/400 V 1-kW hardware prototype.

Simple and Accurate Circuit Simulation Model for SiC Power MOSFETs

Simple and accurate circuit simulation models for high-voltage silicon carbide power MOSFETs and Schottky barrier diodes are presented and validated. The models are physics-based and consist of minimal number of model parameters that can be easily extracted from simple static I-V and C-V measurements. The models are used in a buck-boost bidirectional dc-dc converter, with and without an antiparallel Schottky diode. The efficiency of the converter was analyzed for synchronous and nonsynchronous operation of the switches. An optimal selection of the antiparallel Schottky diode is proposed to minimize the cost of the converter without compromising its efficiency.

A Bidirectional DC–DC Converter With Overlapping Input and Output Voltage Ranges and Vehicle to Grid Energy Transfer Capability

A bidirectional buck-boost dc-dc converter and its control is presented for vehicle charging as well as for vehicle-to-grid energy transfer. The cascaded buck-boost topology allows overlapping input and output voltage ranges and a higher intermediate dc-bus voltage where the electric drivetrain traction inverter can be connected. The intermediate dc-link capacitor voltage is varied to improve the transient performances of the converter. The reference voltage of this capacitor is set based on the input and output voltage levels, and the power demand. The modularity, control flexibility, and excellent transient performance of the converter have been verified with simulation and experiments.

Modeling, control, and simulation of battery storage photovoltaic-wave energy hybrid renewable power generation systems for island electrification in Malaysia.

Today, the whole world faces a great challenge to overcome the environmental problems related to global energy production. Most of the islands throughout the world depend on fossil fuel importation with respect to energy production. Recent development and research on green energy sources can assure sustainable power supply for the islands. But unpredictable nature and high dependency on weather conditions are the main limitations of renewable energy sources. To overcome this drawback, different renewable sources and converters need to be integrated with each other. This paper proposes a standalone hybrid photovoltaic- (PV-) wave energy conversion system with energy storage. In the proposed hybrid system, control of the bidirectional buck-boost DC-DC converter (BBDC) is used to maintain the constant dc-link voltage. It also accumulates the excess hybrid power in the battery bank and supplies this power to the system load during the shortage of hybrid power. A three-phase complex vector control scheme voltage source inverter (VSI) is used to control the load side voltage in terms of the frequency and voltage amplitude. Based on the simulation results obtained from Matlab/Simulink, it has been found that the overall hybrid framework is capable of working under the variable weather and load conditions.

A? Fuzzy Controller Based High Efficient Pulse Amplitude Modulation Control for a Permanent Magnet Synchronous Motor

A pulse amplitude modulation (PAM) control can adjust the DC-link voltage of a motor drive. A bi-directional buck-boost DC-DC converter is required at the primary side of PWM-VSI to implement PAM control. This paper is proposed PAM control technique for a permanent magnet synchronous motor (PMSM) based on fuzzy control system. The PAM coefficient (K_PAM) is a constant value for a conventional PAM control system. It requires online adjustment to improve overall performance of a PAM control system. The proposed fuzzy controller based PAM control regulates the K_PAM according to online commanded load voltage. This paper deals with different operation modes of a bi-directional buck-boost DC-DC cascade converter, motoring (accelerate and steady state) and braking operations of a PMSM at different load conditions and speeds. The total harmonic distortion (THD) and system efficiency are also shown in this paper. Effectiveness of the proposed method is confirmed by simulation results.

Research on the Bi-directional DC-DC Conversion Characterization of Ultra -capacitor Energy Storage System

To ensure the stability of load voltage, a bi-directional DC-DC converter is usually required in the power buffer application of the ultra-capacitor energy storage system. In this paper, non-isolated Buck-Boost bi-directional DC-DC converter is analyzed to improve the terminal voltage performances. In the light of the requirements of constant terminal voltage when positive and negative bi-directional power flows, the optimal design of power circuit and control parameters increases the operation stability of the whole ultra-capacitor energy storage system. Furthermore, it decreases the fluctuation of load voltage and raises the utilization rate of ultra-capacitors’ energy reserve.