Bidirectional Buck-boost Converter Research Articles

A Low-Cost Cell-Level Differential Power Processing CMOS IC for Single Junction Photovoltaic Cells

This article presents a cell-level differential power processing IC to maximize the power yield under partial shading and mismatch condition in series-connected single junction photovoltaic (PV) cells. A 3-MHz bidirectional buck-boost converter is employed to realize voltage equalization technique forcing the PV cells to constantly operate close to their maximum power points. A novel and simple low-power low-area analog control circuit is proposed to maintain the high system efficiency at low and high levels of mismatch by obviating the need for power hungry blocks such as analog to digital converters, digital to analog converters, op-amps, saw-tooth generator, and regulators. The voltage of adjacent PV cells is used to drive the high-side switches through bootstrap supplies eliminating the need for voltage regulators. The performance of the proposed IC, fabricated in 130 nm CMOS process, is validated through simulation and experimental results. The converter is capable of processing mismatch currents up to 4 A while the control circuitry consumes less than 40 mW and a system efficiency above 95% is achieved.

Hardware-in-the-loop real-time validation of fuel cell electric vehicle power system based on multi-stack fuel cell construction

This paper proposed a Fuel Cell Electric Vehicle (FCEV) power system model which was validated by Hardware-in-the-Loop (HIL) real-time emulation. Multi-stack Fuel Cell (MFC) system was used to increase the system redundancy. Nickel-metal Hydride (NiMH) battery pack (BAT) was selected as the secondary energy source. Dual-input single-output Boost converters were connected with MFC system to satisfy the voltage requirement of DC bus. Bi-directional Buck-Boost converter was connected with BAT and then both discharging and charging modes were controlled. Close loop control strategies were developed for converters to assure their stabilities. Rule-based Energy Management Strategy (REMS) was proposed to distribute the required power among Proton Membrane Exchange Fuel Cells (PEMFCs) and BAT. The proposed model was evaluated by HIL real-time emulation, using the Supplemental Federal Test Procedure US06 (SFTP-US06) driving cycle. MicroLabBox, in which real-time processor and Field Programmable Gate Array (FPGA) were embedded, was selected as the HIL real-time validation platform. The MFC system, BAT model, REMS and low-level controllers were executed by real-time processor while the converter general models were built in FPGA. According to the results, the proposed model and method effectively driven MFC system operating in high efficiency region and successfully kept BAT State of Charge (SOC) in the desired range.

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.

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%.

Design and implementation of a power smoothing system for cross-flow current turbines

This study presents an efficient system that smooths fluctuations in electrical power from a cross-flow (i.e., “vertical-axis”) turbine. The proposed solution is a two-stage approach consisting of a low-pass filter and a bi-directional buck-boost converter. The design and stability characteristics of the system are presented, followed by time-domain simulation and validation against small-scale experiments. When this validated simulation is applied to a full-scale system, we demonstrate a 99% root mean square reduction in fluctuating power output with only a 3% drop in electrical system efficiency. This could allow intracycle control strategies to increase mechanical power output without causing electrical power fluctuations that are incompatible with direct use.

Embedded Bidirectional Buck–Boost Converter in Half Bridge Class-D Audio Amplifier for Suppressing Bus Voltage Pumping

In this article, a half-bridge class-D audio amplifier (HB-CDAA) system with embedded bidirectional buck–boost converter is proposed. The proposed HB-CDAA system consists of a front-end symmetric bipolar output converter, a bidirectional buck–boost converter, and an HB-CDAA. With the help of the embedded bidirectional buck–boost converter, bus voltage pumping on the output of the front-end symmetric bipolar output converter of HB-CDAA can be suppressed. Thus, small ceramic capacitors can be used as bus capacitors to increase power density and to improve audio output quality. Furthermore, ZVS of the embedded bidirectional buck–boost converter can be achieved. The operating principle of the proposed circuit is analyzed and an experimental prototype is built. Experimental results show that ZVS of the embedded bidirectional buck–boost converter is achieved, and bus voltage pumping is successfully suppressed with small bus capacitors.

High-Efficiency Bidirectional Three-Level Series-Resonant Converter With Buck-Boost Capacity for High-Output Voltage Applications

To improve the efficiency and power density of electronic vehicles, battery packs with higher voltage levels have been gradually adopted. This change poses new challenges for conventional battery charger designs based on two-level topologies and low-voltage rating switches. Therefore, in this article, a bidirectional buck-boost three-level series-resonant converter (BBTL-SRC) for high-output voltage applications is proposed. The voltage stress of switches is reduced to only half of the output voltage, so the low-voltage rating switches with lower losses and costs can be used. In addition, the phase shift and pulsewidth modulation strategies are designed to realize buck and boost conversion. All switches can achieve zero-voltage switching, and the reactive current in resonant tank decreases significantly. Hence, the switching and conduction losses are reduced and efficiency is optimized. The operation principles and characteristics are analyzed in detail, and design considerations are provided. A 3.3-kW, 600-840-V output prototype is built and tested. The experimental results verify the effectiveness of the proposed BBTL-SRC.

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.

A Novel Bidirectional Isolated DC-DC Converter With High Voltage Gain and Wide Input Voltage

This article proposes a novel bidirectional isolated dc-dc converter with high voltage gain and wide input voltage, which can be applied to bidirectional power conversion systems. The proposed topology is composed of a bidirectional buck-boost converter and a forward-flyback converter; it has the advantage of higher voltage gain and has continuous current characteristic of the low-side port in step-up and step-down mode. In addition, the proposed topology also has the function of leakage inductance energy recovery, which can improve the efficiency of the converter, reduce the voltage surges on switches, and have the characteristics of zero voltage switching on certain switches. Finally, this paper implements a 500-W bidirectional dc-dc converter to verify the feasibility of the proposed topology. The low-side voltage of the proposed topology is 24, 48, and 55 V; the maximum efficiency in step-up mode are 94.2%, 95.6% and 96.9%, and the maximum efficiency are 92.6%, 94.2% and 94.5% in the step-down mode, respectively.

Kontrol Tegangan pada Sistem Hybrid Panel Surya-Turbin Angin Menggunakan Manajemen Penyimpanan Baterai

The purpose of this paper is to determine the control strategy of the renewable energy systems of hybrid solar panel power and wind turbines in maximizing voltage balance. The voltage control strategy needs to be designed, mainly when different load changes occur. If it is not done, it will affect the balance of power supplied to the load and usually damage the equipment used. Solar and wind energy sources significantly influence the stability of the applied voltage’s quality due to the fluctuating nature of renewable energy. This paper proposes control strategies for the use of PIs and the signal conditioning devices that are modified using the battery charging and discharging modeling while taking into account battery lifetime using PSIM software so that optimal voltage results from hybrid solar panel and wind turbine systems are obtained. The battery will be used as energy storage when the hybrid output power is over, which will then be used again when the hybrid output power is less than the load requirement. The signal conditioning device in this study uses five power converters, one AC to DC converter, two DC-DC boost converters, one bidirectional converter, 1 DC-AC bidirectional converter. Maximum output power uses MPPT, which is applied to the boost converter, whereas to regulate the voltage through charging and discharging the battery through the bidirectional buck-boost converter. This strategy provides the appropriate voltage on the AC side.

Robust non-linear control of a hybrid water pumping system based on induction motor

This contribution presents a non-linear control of a hybrid pumping system supplied with a photovoltaic generator and a battery. This system is employed for delivering a continuous volume of water whatever the climatic conditions. In the DC side, a boost converter is controlled with the indirect double integral sliding mode controller (DISMC) for maximum power point tracking (MPPT). The DISMC is suitable for MPPT because it gives a fast response and reduces the amplitude of power oscillations. Then, a bidirectional buck-boost converter is adopted to ensure the energy management between the battery and the DC-bus, and this converter is controlled with integral sliding mode control (ISMC) theory. The non-linear predictive control (NPC) is chosen to drive an induction motor (IM), the NPC is known by its fast dynamic and high capacity to reject disturbances. The hybrid system is modelled in MATLAB/Simulink software. During simulations, the DISMC-MPPT is compared with other techniques such as sliding mode controller (SMC) MPPT and integral SMC MPPT, the DISMC provides the best tracking performances under different irradiances. Moreover, the designed controller for the bidirectional converter regulates the DC-link voltage with better performances than the classical PI controller. Lastly, the NPC regulates the speed of the IM with high robustness.

PV-Wind-Battery based Bidirectional DC-DC Converter for Grid Connected Systems

The control strategy of solar, wind, battery that connected with bi-directional DC to DC converter are used for grid connected power flow management. Generally all sources of produce the power that should satisfy the load demand without scarifies our basic needs. The power can be acquired from different source and should manage the power flow to the all places in the horizontal level. The surplus power is injected to the grid and the battery should charge from grid, it can be used for latter when it required. A half bridge boost converter coupled with transformer is utilized to collect the power from wind, meanwhile a bi-directional buck-boost converter is utilized to collect the power from solar and battery charging/discharging. AC power is fed to AC load through single phase full bridge bidirectional converter and this helps to communication with grid. The proposed method that reduces the number of switches components losses and mainly the power conversion stage. The simulation results are obtained by using MATLAB/Simulink that shows the performance of control strategy of power flow management in different modes.

Computer Simulation of MPPT Converter to Control PV Panel-Battery System

This research intends to build and simulate a small renewable energy system consists of PV panel, lead-acid battery, and bidirectional DC-DC converter. Bidirectional Buck-Boost converter was used to regulating the voltage and current coming from the solar panels going to the battery and vice versa. It operates a Buck converter which charges the battery from the PV panel when State of charge (SOC) reaches less than 0.4. The battery needs 100 ms to charge from 12.2 V to 13 V with duty cycle 0.5 and 1 A. Also work as a Boost converter when SOC reaches 1 the battery was discharge for 100 ms and SOC decreases from 1 to 0.4.A PSPICE PV panel model (consists of 20 solar cells, 12 V and 60 W maximum power at 25 °C with 1000 W/m2 solar irradiation) has been used as a source of energy to the power circuit. The output of PV panel relates to Boost converter, which is the key for changing the PV’s terminal voltage to track the maximum power, it was rising a PV panel voltage from 10 V to 22 V for all variation of surface temperature from 300 K to 350 K at frequency 10 kHz and ΔVo = 1.1 V.

A Novel Non-Isolated Three-Port Bidirectional DC/DC Converter for Photovoltaic Electric Scooter Charging Stations

This paper proposes a novel non-isolated three-port bidirectional dc/dc converter for photovoltaic (PV) electric scooter (ES) charging stations. The proposed converter combines an improved boost converter and a bidirectional buck-boost converter. When the PV energy is sufficient, the PV module is stepped up to provide dc load energy to the ES through the improved boost converter in order to charge the ES battery. When the PV energy is insufficient, the storage battery is stepped up to provide energy to the ES load dc bus, and the ES load dc bus charges the battery if the battery energy is low. The proposed converter reduces the number of components and circuit cost by using a switch internal diode. Finally, a 400-W modified boost converter and a 120-W/60-W bidirectional boost-buck converter were implemented to verify the three operating modes of the proposed non-isolated dc/dc converter. The results revealed that the highest efficiency levels achieved under PV module step-up, storage battery step-up, and storage battery step-down operation were 97.5%, 96.6%, and 92%, respectively.

Closed‐loop control of a single‐stage switched‐boost inverter in modified DC‐interconnected nanogrids

Switched-boost inverter (SBI) is a single-stage power converter suitable for interfacing between photovoltaic (PV) arrays and loads. Although, it has many advantages such as it's not requiring an expensive complex dead-time circuitry, yet its duty ratio is limited between 0 and 0.5. This means that it has some difficulties in increasing both the DC-link output voltage and its AC-output voltage. So, most researchers proposed it for low-voltage power applications or using with step-up transformers. Accordingly, this study contributes towards improving the performance of the SBI for being used in the modified nanogrid within an open energy system. It introduces a novel approach closed-loop control technique to overcome most of the inverter drawbacks. Also, it enhances both the DC-link and the transformer-less rated AC output voltages to a sufficient value suitable for feeding domestic loads. And in the same time, the proposed robust controller utilizes a hysteresis band for balancing between voltage stability and PV-maximum power achievement. This research also includes a more sophisticated fast-charging slow-discharging control strategy for the battery energy management system that depends on a bidirectional buck-boost converter. Test results ensure the robustness of the proposed controller against sensitivity, nonlinearity, and time-variant parameters of the overall system.

Dynamic Modeling of Battery Energy Storage and Applications in Transmission Systems

In this paper, a Battery Energy Storage System (BESS) dynamic model is presented, which considers average models of both Voltage Source Converter (VSC) and bidirectional buck-boost converter (dc-to-dc), for charging and discharging modes of operation. The dynamic BESS model comprises a simplified representation of the battery cells, which allows to simulate the effects of battery degradation, dc-to-dc converter, VSC, and the dynamics associated with the filter and transformer connecting the BESS to the grid. A decoupled dq-current control is used for the VSC, allowing the operation of the BESS in several modes, i.e., constant active and reactive power, constant power factor, voltage regulation, frequency regulation, oscillation damping, and a combination of the latter two. The proposed model is implemented in DSATools and tested for different contingencies on a benchmark system, and compared with a industry-grade BESS model used in power system dynamic studies. The importance of modeling the current control and dynamics of the dc-to-dc are demonstrated, especially when the battery cells are degraded due to, for instance, aging.

Design, operation and control of a vast DC microgrid for integration of renewable energy sources

DC Microgrid has been a key research area for the last few decades. The development of the DC microgrid system from renewable energy sources is necessary for future energy security for the country. Most of the renewable energy sources are intermittent. Power management and energy management are essential for the stable operation of the system and the high utilization of renewable sources respectively. Power management and energy management rely on the control of the different units of the DC microgrid. This paper presents an Islanded DCMG in which the PV system and the wind system connect with the DC bus through the interfacing devices (DC/DC boost and buck converters respectively) and their duty cycle is controlled by the P&O MPPT algorithm. Its power is fed to AC as well as DC load. DC load varies in steps and AC loads include single-phase linear, non-linear and three-phase inductive load. The sliding mode control technique is used to control the inverter connected to the DC bus to fed AC loads. DC bus voltage is supported by the hybrid energy storage system (HESS) (devices include Battery and Supercapacitor (SC)) with the use of active topology. Storage devices connect with the DC bus through the bidirectional buck-boost converters. A DC dump load is connected with the DC bus to stabilize the DC bus voltage and safety from the overcharging of the battery. The developed DC microgrid model is demonstrated in the MATLAB/Simulink. The results are presented, discussed and validated with the hardware experiment.

Modeling and Control of Solar PV with Battery Energy Storage for Rural Electrification

In rural areas where electric power grid network is rarely available, power generation from renewable energy resource such as solar photovoltaic (PV) is mostly accomplished in standalone mode. The standalone solar PV system requires energy storage device to achieve reliable power supply to the end users. This paper presents modelling and coordination control of solar PV with battery energy storage system (BESS) for rural-electrification applications. The proposed control is accomplished via a bidirectional buck-boost converter with the objective of maintaining voltage at the DC bus constant. Simulation results based-on MATLAB/Simulink platform confirms good performance of the proposed system.

Closed Loop Control of Bidirectional Buck-Boost Converter in A Smart Grid Using Photovoltaic and Energy Storage Systems

A novel closed-loop control bidirectional buck-boost converter, a crucial part of a photovoltaic and energy storage system (PV-ESS), is proposed in this study. To enable zero-voltage-switching turn-on for switches, traditional bidirectional buckboost converters for ESSs run in discontinuous conduction mode (DCM). Nevertheless, low power-conversion efficiency and large output voltage and current ripples are the results of DCM operation. The suggested converter features a new combination construction that combines an auxiliary capacitor with a cascaded buck-boost converter to improve performance over the conventional converter. By offering a current path, the combined structure of the suggested converter increases efficiency while reducing output current ripple. The suggested closed-loop control converter has an output voltage ripple of less than 5.14 Vp.p. and an output current ripple of less than 7.12 Ap.p., with a maximum efficiency of 98%. These outcomes were attained using an input voltage of 160 V, an output voltage of 80 ~ 320 V, an output power of 16 ~ 160 W, and a switching frequency of 45 kHz. According to the experimental findings, the suggested converter performs better than the traditional converter.

Fault Ride-Through Power Electronic Topologies for Hybrid Energy Storage Systems

This work presents a fault ride-through control scheme for a non-isolated power topology used in a hybrid energy storage system designed for DC microgrids. The hybrid system is formed by a lithium-ion battery bank and a supercapacitor module, both coordinated to achieve a high-energy and high-power combined storage system. This hybrid system is connected to a DC bus that manages the power flow of the microgrid. The power topology under consideration is based on the buck-boost bidirectional converter, and it is controlled through a bespoke modulation scheme to obtain low losses at nominal operation. The operation of the proposed control scheme during a DC bus short-circuit failure is shown, as well as a modification to the standard control to achieve fault ride-through capability once the fault is over. The proposed control provides a protection to the energy storage systems and the converter itself during the DC bus short-circuit fault. The operation of the converter is developed theoretically, and it has been verified through both simulations and experimental validation on a built prototype.