Bidirectional Converter Research Articles

A Dynamic Smooth Transition Control Integrated With Hybrid Modulation for Wide Output Voltage Range Bidirectional CLLC Resonant Converters

A Dynamic Smooth Transition Control Integrated With Hybrid Modulation for Wide Output Voltage Range Bidirectional CLLC Resonant Converters

A Novel Single-Capacitor-Based T-Type Bidirectional Converter With Buck–Boost Capabilities

A Novel Single-Capacitor-Based T-Type Bidirectional Converter With Buck–Boost Capabilities

Seamless Operation of an SRG Based WEGS and a Bidirectional Converter Interfaced BES Microgrid Under Polluted Grid Conditions

Seamless Operation of an SRG Based WEGS and a Bidirectional Converter Interfaced BES Microgrid Under Polluted Grid Conditions

Switched Capacitor-Based Bidirectional Power Converter with Enhanced Voltage Boost and Reduced Switching Strain for Electric Vehicle Applications

This research work presents an improved design of a bidirectional converter for EVs, specifically focusing on its buck and boost operations. The proposed design incorporates a switched capacitor-based double switch converter, which offers enhanced performance compared to conventional converters. The utilization of switched capacitors reduces voltage stress on switches and improves overall efficiency, making it well-suited for electric vehicle applications. Moreover, the inclusion of synchronous rectification enables zero voltage switching, further enhancing the converter's performance. The effectiveness of the design is verified through MATLAB simulations, demonstrating improved voltage gain and reduced switch stress in both voltage increasing and decreasing modes.

Strategy for Hydrogen Generation from a Photovoltaic System Using a Boost Converter

This research presents two schemes for hydrogen generation by alkaline water electrolysis using a photovoltaic system and a boost converter as a power source. The first scheme aims to extract the maximum power from the photovoltaic system using the P&O algorithm and use this energy to generate hydrogen. Thus, obtaining the maximum efficiency of the photovoltaic-electrolytic cell system. The second scheme aims to generate hydrogen on demand, eliminating the need for storage and reducing the associated costs and risks. Nevertheless, this approach does not fully maximize the power available in the PV system, resulting in lower overall efficiency. Finally, it concludes with the proposal of an approach that combines on-demand hydrogen generation and maximum energy extraction from solar panels. Any unused energy from the electrolytic reactor is stored in a battery bank through a bidirectional converter. However, the simulation and implementation of this third scheme are proposed as future work.

Fundamental impedance-based digital synchronous rectification scheme for bidirectional CLLC resonant converters

Fundamental impedance-based digital synchronous rectification scheme for bidirectional CLLC resonant converters

A Dynamic Transition Algorithm Integrated with Hybrid Modulation for CLLC Resonant Converters

The CLLC resonant converter is a widely used bidirectional power converter known for its high energy transfer efficiency. To extend its operating range, the converter often employs a hybrid modulation strategy, which is valued for its simplicity and efficiency. However, at the critical transition point between pulse frequency modulation and phase-shift modulation, instability in the output can be observed due to repetitive and unnecessary mode changes caused by noise. In order to address this issue, this paper introduces a dynamic transition algorithm integrated with hybrid modulation. This approach adaptively updates the controller parameters to mitigate oscillations resulting from improper initial parameter settings. Additionally, it incorporates error analysis and hysteresis comparison to prevent false triggers caused by noise, enabling intelligent mode adjustments. Finally, a 1 kW prototype is designed to conduct experiments, demonstrating an approximately 50% improvement in dynamic performance when the converter operates with the dynamic transition algorithm.

Ultracapacitor as selectable energy buffer in electric vehicle application

A method of ultracapacitor integration with a regenerative braking system for use in electric drive trains is presented in this paper. An ultracapacitor (UC) is an intermediary to store and provide energy on the DC bus in certain scenarios, such as during acceleration and regenerative braking. UC is used to avoid direct inrush loading on the battery, which the electric drive system may cause. The energy from UC is injected into the DC bus in compliment to the battery, for which a dedicated power source switch called the “Main Charge Controller” (MCC) is responsible. The charge discharge of UC is done through a bidirectional buck-boost converter (BDBBC). The use of UC to offload high energy demand from the battery and store energy recovered during regenerative braking helps improve the vehicle's life and per-charge range. The stored energy in UC can be obtained from the battery at the start. UC can also be charged at the time of charging. The design and the presented control are ideal for lightweight electric vehicles. The system uses a 39.9 kJ ultracapacitor, formed from market-available 50F 2.7 V units in a 52S configuration, storage, and a 6kWh battery. The simulated vehicle in battery only case provides a minimum of 154 km range in rough conditions, in best case scenario it provides a 200 km range. The proposed design provides an increased extended range compared to simple battery-based regenerative braking, in the case of this work the hybrid solution provides an addition of more than 30 km of additional range compared to a battery-only solution which is simulated for all the same conditions except without the addition of the UC and its control and handling system, resulting in a total range of 230 km. The speed control response achieved by the user is also very fast. Electric Vehicles have range limitations due to storage technology which is a high entry barrier for consumers looking for reliable vehicles without range anxiety, as storage technology progresses adoption will become easier. This work is an attempt at using hybrid storage and selective use of it, for improved range and sharper speed response. However, this work does not explore the aging of the storage components due to increased operational load and thermal stresses or application to alternate battery chemistries. This work is primarily focused on the vehicles that use lithium-based batteries.

Investigation on Energy Flow Performance of a Photovoltaic/Battery-Based Isolated Charging Station for Battery-Powered Electric Vehicles

Researchers are paying attention to the current trend of electric vehicles (EVs), but there are not many places to charge them and serve as electric vehicle charging stations (EVCSs). In order to prevent the lack of EVCS for battery EVs (BEVs) on any road with all modes of operation, this paper proposed the design of a novel configuration and control structures for the isolated charging station (ICS) based on the solar PV system for efficient energy utilization to charge battery EVs (BEVs) with flexible double function cascaded converter (MPPT and DC-link voltage regulation). This was done with the aid of a battery energy storage system (BESS) as a backup/auxiliary source. The PV system is reliant on solar radiation and the daily load profile. Therefore, the BESS is employed to provide continuous power to BEVs and overcome PV’s intermittent nature. The cascaded converter is used to achieve the MPP and to regulate the DC-link voltage to its reference value (100 V), while the buck-boost matching bidirectional DC-DC voltage converters (MBDVCs) are used for charging and discharging mode/buck and boost mode, respectively, of BEVs and BESSs. Additionally, the MBDVCs are used as an interface between the ICS sources with the load through the developed control systems. The outcomes of various operating modes show that the system functions effectively. To verify the system performance, the MATLAB/Simulink application builds the system setup.

Analysis of a novel soft switching bidirectional DC-DC converter for electric vehicle

A bidirectional converter (BDC) designed with high voltage gain and it is incorporated with the soft-switching operations to the insulated gate bipolar transistors (IGBTs). The main dual operating characteristics of this converter are boost and buck modes respectively. In order to achieve the reduced switching losses and improved efficiency, the main IGBTs are operated at zero current (ZC) while the IGBTs commutating from turn-on to turn-off state. The ZC turn-off operation is obtained with the aid of soft- switched cell, which consists of resonant inductor (Lr), capacitor and additional IGBTs. In this work, the design simulation analysis for high-gain BDC was performed by 70/300 V power system with the maximum 800 W output power under the operating frequency of 50 kHz. The efficiency for the high-gain soft-switched BDC was obtained as 96.5% when it is operating in boost mode and efficiency of 97% was achieved for the buck mode operation. The simulation evaluations of the above said converters were performed by using MATLAB/Simulink.

A Direct AC–AC Switched-Capacitor Converter With Input-Series Output-Parallel and In-Phase/Out-of-Phase Capabilities

In this paper, a bidirectional transformerless multi-level direct ac-ac switched-capacitor converter (SCC) is proposed with both in-phase and out-of-phase output voltage capabilities. This converter can be used for series compensator applications, such as dynamic voltage restorers (DVRs), to compensate grid voltage sag and swell phenomena by incorporating its input-output common ground. Its input-series output-parallel capabilities reduce voltage and current stresses of the converter components in multi-level configurations, which lead to higher efficiency and lower manufacturing costs for high-power applications. Furthermore, proper utilization of an interleaving control scheme can provide lower input and output currents ripples values and smaller filter sizes. The proposed SCC operation principle and its mathematical analyses are given, in detail. Additionally, its switching patterns have been developed with a safe-commutation strategy to obtain various output voltages. Subsequently, both single- and two-level SCC prototypes are implemented as series compensators for DVR applications. Moreover, experimental results are given to generate in-phase and out-of-phase regulated output voltages. The experimental results at 2 kW show that the output voltage changes are less than 3% under the steady-state conditions, despite the large input voltage changes from 140 to 300V. The converter maximum efficiency value is equal to 95.4% at maximum output power value.

Design of a battery charging system fed by thermoelectric generator panels using MPPT techniques

Abstract Thermal energy is a renewable energy source to generate electrical energy that is not fully developed. One device that converts thermal energy into electrical power is a thermoelectric generator (TEG). TEGs are available as modules of various sizes and voltage levels. This paper is about the design of a battery charging system powered by a TEG panel. The TEG panel is implemented using 150 TEG modules interconnected in series and parallel. Its power is transferred to a battery using two stages of DC/DC converters. The 1st stage is a Lou converter that is used for maximum power point tracking (MPPT) by a referenced perturb and observe (referenced P&O) algorithm. The 2nd stage is a bidirectional converter based on buck-boost modes of operation. The system is used to charge a 9 V 1.2 Ah battery. The proposed MPPT algorithm’s performance is compared with a traditional P&O algorithm. The TEG panel provided 27.5 W at a ΔT of 30 0C. The designed system is simulated in MATLAB SIMULINK.

MPPT DC-DC Buck-Boost Converter for Off Grid Hybrid Solar-Wind-Battery System in Ikuza Island, Tanzania

Ikuza Island in Tanzania faces lack of electricity. Therefore, this paper undertakes to design hybrid renewable energy sources for the island by specifically focusing on the buck-boost converter for the energy conversion from these renewable resources. The design of the bidirectional buck-boost converter for maximum power point tracking in off-grid hybrid renewable energy systems is multifaceted due to the inhomogeneity nature of the renewable energy sources. The bidirectional buck-boost converter, solar PV, wind-based generator, and energy storage system were designed and simulated in MATLAB/Simulink software. The designed system was tested with varying solar irradiance (750 to 1000 W/m2), temperature (20 to 25°C) and wind speed (150 to 157.5 radians/s) at constant load of 260 A while load variation involved varying the load current from 0 to 260 A at solar irradiance, temperature, and wind speed of 1000 W/m2, 25 °C and 157.5 radians/s, respectively. The variation of DC link bus voltage at different load conditions was reported. The simulation results show that the designed converter is able to maintain DC link voltage at 600 V. Moreover, the DC link voltage showed a maximum drop of approximately 0.67% during the constant load condition. Contrarily, a significant improvement is observed when the designed converter operates with the hybrid system of solar PV, PMSG-based wind generator and with energy storage system.

A Control Design Technology of Isolated Bidirectional LLC Resonant Converter for Energy Storage System in DC Microgrid Applications

This paper presents a new control method for a bidirectional DC–DC LLC resonant topology converter. The proposed converter can be applied to power the conversion between an energy storage system and a DC bus in a DC microgrid or bidirectional power flow conversion between vehicle-to-grid (V2G) behavior and grid-to-vehicle (G2V) behavior. Furthermore, such a converter can be applied to energy storage systems for decentralized renewable energy generation systems, such as solar and wind power. In addition, this converter can be combined with a bidirectional inverter to allow energy storage in the system to improve the safety, stability, and power quality of the microgrid. In the proposed circuit structure, we use a bidirectional DC–DC LLC, which has the advantages of a higher voltage conversion ratio, lower part count, simpler control than similar converters such as DAB, CLLC, and L–LLC converters, and bidirectional power flow and electrical isolation. Specifically, to extend the battery life, it can be employed as a control strategy for discharging the energy stored in the battery (SOC) and reducing the temperature rise generated by the internal solid electrolyte interphase (SEI) when discharging the battery under the variation in distributed energy resource (DER) generation and load demand. To realize the bidirectional power conversion without using any auxiliary inductor and only changing the control strategy, the forward step-down power conversion was based on pulse frequency modulation (PFM) control, and the reverse step-up power conversion was based on pulse width modulation (PWM) control. In this paper, we introduce the bidirectional converter topology and its control strategy for the DC microgrid battery energy storage system. Finally, a 500 W prototype is built to verify the effectiveness of the proposed converter.

Control techniques for operation of roof-top solar photovoltaics based microgrid in islanded mode

This paper presents the control techniques for the operation of roof-top solar photovoltaics based single-phase ac microgrid in islanded mode. The proposed microgrid consists of four roof-top photovoltaics on various buildings, battery energy storage system in each building, and loads. In each building, the roof-top photovoltaic system is connected to the single-phase ac loads and proposed single-phase ac microgrid through the two-stage converter, which consists of dc-dc boost converter and bidirectional single-phase voltage source converter. A bidirectional dc-dc converter is used to connect the battery energy storage system to the photovoltaic system. The control technique of the bidirectional single-phase voltage source converter, using the feed-forward and feed-back control signals, has been suggested into a rotating d-q synchronous reference frame, with the dual controllers, for controlling the power mismatch and rated sinusoidal ac voltage of the microgrid. The control technique of the bidirectional dc-dc converter, used for the battery energy storage system, is implemented with two voltage controllers and one current controller for managing of the power mismatch in the proposed microgrid system. In this work, the power control algorithms have also been developed, which are aimed to manage the power balance in the single roof-top PV based building as well as in the proposed microgrid, under islanded mode, for various operating scenarios including fault condition.

A Bidirectional Grid-Tied ZVS Three-Phase Converter Based on DPWM and Digital Control

In this paper, a bidirectional grid-tied ZVS three-phase converter is proposed. The circuit operation principle in both the rectifier and inverter modes was analyzed. The proposed topology could achieve zero-voltage switching in the six main switches and the auxiliary switch both in the rectifier mode and inverter mode. In addition, the reverse recovery current of body diodes in the main switches was also suppressed. Furthermore, in order to realize the ZVS control scheme under the grid-tied bidirectional power flow condition and reduce the number of switchings, a modified carrier-based discontinuous PWM was proposed to fit the bidirectional switching sequence. Finally, a 3 kW prototype was constructed. Some simulation and experimental results are presented to verify the validity of the proposed circuit topology and PWM control scheme.

Transformerless bidirectional switched-inductor switched-capacitor converter

ABSTRACT This research presents a unique bidirectional converter based on the active switched-inductor and switched-capacitor networks of the ASL-SU2C converter. The converter’s primary advantages are its high voltage gain and reduced switch stress. This was accomplished by the converter using three inductors, two switched-capacitors, two switches, and diodes. Switches are used in place of diodes to enable bidirectional power flow in the proposed work, and synchronous rectification is used to boost efficiency by reducing conduction losses. Two inductors and two switches on the low voltage side of the converter aid in lowering the average switch current and, consequently, the current stress. The control operation is made simpler by the fact that two switches on the high voltage side (HVS) have one duty cycle and the other two switches on the low voltage side (LVS) have a different duty cycle. Consequently, two switches will always have identical duty cycles. In order to validate the theoretical findings, the performance of the transformerless bidirectional switched-inductor switched-capacitor (TBSISC) topology is examined in steady state, compared to that of other bidirectional converters, its efficiency is calculated, and experiments with a 500 W prototype are conducted.

Variable Frequency Isolated Bidirectional CLLC Resonant Converter With Voltage Controlled Variable Capacitors

This paper proposes a novel variable frequency isolated bidirectional CLLC resonant converter with voltage-controlled variable capacitors (VCVCs) and auxiliary clamp circuits (ACCs). By employing the class II ceramic capacitors as VCVCs, the converter's modes in one switching cycle and the transient process to set up the DC voltage bias on VCVCs are analyzed detailly to explain the fundamental principles and lossless characteristics of ACCs in the steady state. Suitable ranges of capacitor voltage stress and current stress and gain characteristics of the converter are also given to design the resonant parameters. The converter's soft-switching characteristics, fast transient process, and high efficiency are well demonstrated by the experimental results obtained on a 500 W prototype. The high-efficiency range of the proposed converter with the VCVCs is 20%∼100%, which is at least 10% wider than the others without VCVCs.

Invariant-set design of robust switched trackers for bidirectional power converters in hybrid microgrids

Invariant-set design of robust switched trackers for bidirectional power converters in hybrid microgrids

Switch-Multiplexed Quasi-Two-Stage Isolated Bidirectional Buck-DAB Converter With Full Load ZVS Range

In this paper, a switch-multiplexed quasi-two-stage Buck-DAB (SMBDAB) and its modulation strategy are proposed. Under the quasi-two-stage Buck-DAB (QBDAB) architecture, one bridge of the primary side of the proposed converter is multiplexed as both the bridge of the Buck circuit and the DAB circuit to reduce the power switches. In addition, with the voltage-matching modulation, multiplexing still ensures that the voltages on both sides of the leakage inductor of the DAB circuit are always matched when the voltage gain of the converter changes. And thus the ZVS of all the switches can be achieved. Furthermore, the partial power transfer characteristics of the buck circuit still maintains, which could reduce the power rating of the inductor for the buck circuit. The working principle, power transfer characteristics, and full range ZVS design are analyzed. Finally, the effectiveness of the SMBDAB converter is verified through experimental results from a 1kW prototype.