Non-isolated Bidirectional DC-DC Converter Research Articles

Isolated bidirectional DC-DC Converter: A topological review

Bidirectional DC-DC converters (BDCs) are certainly an important power electronic converter for managing bidirectional power flow in various applications. It offers the ability to flow power in both directions, which is useful in systems with renewable energy sources and energy storage. BDCs are becoming increasingly important in various applications, including renewable energy systems, electric vehicles, and energy storage. The development of new BDC topologies and control strategies is expected to further improve their efficiency and performance. Non-Isolated Bidirectional DC-DC Converters (NBDCs) and Isolated Bidirectional DC-DC Converters (IBDCs) are the two main types of BDCs with different isolation properties and trade-offs in terms of size, cost and performance. Topological classification of BDCs further distinguishes various BDC types based on their configurations and voltage-boosting techniques. IBDCs are preferred over NBDCs due to high-power applications, and wide voltage range with higher efficiency; the performance of IBDCs is improving day by day. To provide a framework for comparison in implementing novel configurations or identifying the best converter for a given application, this study is concentrated on each topology and its usual applications. Soft switching converters are also discussed pointed to Resonant Power Converters (RPCs) for the application into Electric Vehicles (EVs). It is worth noting that the choice of BDC depends on the specific requirements of the application, such as power level, voltage range, efficiency, and cost. A detailed comparison, application, advantage and disadvantage table can be useful in comparing the characteristics of different BDCs and selecting the most suitable one.

A Novel Soft Switching Non-Isolated Bidirectional dc–dc Converter Without Any Extra Auxiliary Switch

In this paper, a new zero-voltage-switching (ZVS) non-isolated bidirectional DC-DC converter without any extra auxiliary switch is introduced. In the proposed converter, by applying an auxiliary circuit, soft switching condition is provided for all semiconductor elements regardless of the power flow direction and without any extra voltage stress. Each of the main switches provides soft switching conditions for the other switch. Additionally, each of the switches can be used as a synchronous rectifier switch in both power flow directions. The auxiliary circuit only consists of two coupled inductors with the converter main inductor and two diodes, which operate with a zero-current-switching (ZCS) condition. Since, all of the converter inductors are implemented on a single core, the presence of coupled inductors doesn’t increase the converter volume considerably. The detailed operating analysis of the proposed bidirectional converter and the design method of the main circuit is presented. Also, the theoretical analysis of the proposed bidirectional converter is verified with a 100W experimental prototype converter.

Dual-Stacked Bidirectional Boost/Buck DC–DC Converter

A new non-isolated bidirectional DC-DC converter with low voltage and current stresses across the semiconductor devices is presented in this paper. The proposed converter is a combination of a dual-stacked bidirectional boost converter. The converter presents different operations modes, such as: synchronous and asynchronous. These modes can reduce the current ripple of the voltage source. Besides that, in this paper, the modeling and control of the proposed converter are done. To validate the theoretical evaluations of the proposed converter, a 1 kW, 144 V/ 400 V prototype was built to verify its performance where the peak efficiency is 96.33 % and 96.87 % for step-up and step-down modes, respectively.

Analysis and Control of an Input-Parallel Output-Series Connected Buck-Boost DC–DC Converter for Electric Vehicle Powertrains

Many electric vehicle powertrains use a boost type dc-dc converter to step-up the battery voltage for optimization and improving vehicle performance. The converter allows variation of inverter dc-link voltage to further reduce losses. By focusing on boost operation only, previously proposed drivetrains have not fully utilized the benefits of variable dc-link. This paper describes a new non-isolated bidirectional dc-dc converter capable of voltage step-down as well as high-gain voltage step-up operation. Such wide voltage range operation can lead to improved efficiency of electric vehicle drivetrains. The proposed converter comprises two non-inverting buck-boost modules, configured to operate in various optimized modes depending on the load requirement. Compared to existing bidirectional buck-boost converters, the proposed converter offers lower switch stress, reduced converter size and better efficiency. The operation of the converter in different modes is described in detail, followed by small-signal modeling and an outline of the control scheme. Experimental results obtained in an all-SiC 5 kW prototype show stable operation while the converter emulates the behaviour of the dc-dc stage in a variable dc-link EV powertrain under the ECE 15 drive cycle. The prototype demonstrated peak efficiencies of more than 98.5% and 98% for voltage step-up and step-down operations, respectively.

PV System with Battery Storage Using Bidirectional DC-DC Converter

With the increase in demand for generating power using renewable energy sources, energy storage and interfacing the energy storage device with the load has become a major challenge. Energy storage using batteries is most suitable for renewable energy sources such as solar, wind etc. A bi-directional DC-DC converter provides the required bidirectional power flow for battery charging and discharging mode. The duty cycle of the converter controls charging and discharging based on the state of charge of the battery and direction of the current. In this paper, a nonisolated bi-directional DC-DC converter is designed and simulated for energy storage in the battery and interfacing it with the DC grid. The power extracted from the solar panel during the daytime is used to charge the batteries through the DC-DC converter operating in buck mode and when solar power is unavailable, the battery discharges to supply power to DC load through the converter operating in boost mode. Solar arrays connected through a DC bus to a load. Due to the instantaneous changes of solar irradiance and temperature, maximum power point tracking (MPPT) is integrated in the inverter control. The technique of maximum power point tracking (MPPT) is used in photovoltaic systems to extract the maximum power. The most popular MPPT techniques are reviewed and studied, such as: Perturb and Observe, Increment of Conductance and control based on fuzzy logic (LF). The simulation is done in matlab/simulink and results are presented.

フライングキャパシタ変換器をベースとした非絶縁形DC-DC変換器の電流制御法比較

This paper presents a bidirectional non-isolated dc-dc converter based on three-level flying-capacitor converters. The converter uses multiple auxiliary converters, each of which is based on cascaded chopper cells and an inductor, which enables active control of the inductor current. This paper compares the following two current control methods: conventional sinusoidal-wave current control method and proposed trapezoidal-wave current control method, in terms of ac-current peak values, dc-current values, current root-mean-square (RMS) values, voltage ripples in dc-capacitor voltages, current ripples in dc currents, and converter efficiency. The validity of the comparison and trapezoidal-wave current control method is verified in a simulation using MATLAB and experimentally using a 2-kW downscaled model.

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 novel non-isolated three-port bidirectional DC-DC converter for off-grid solar-powered charging for electric and hydrogen vehicles using STM32 microcontroller

A novel non-isolated three-port bidirectional DC-DC converter for off-grid solar-powered charging for electric and hydrogen vehicles using STM32 microcontroller

Design and Implementation of Real-Time Simulation Module for Non-Isolated Bidirectional Half-Bridge Dc-Dc Converter

Design and Implementation of Real-Time Simulation Module for Non-Isolated Bidirectional Half-Bridge Dc-Dc Converter

A multi-port non-isolated bidirectional DC-DC converter

A multi-port non-isolated bidirectional DC-DC converter

A multi-port non-isolated bidirectional DC-DC converter

A multi-port non-isolated bidirectional DC-DC converter

Efficiency and Power Density Evaluations of Bidirectional Non-Isolated DC-DC Converter based on Flying-Capacitor Converters

This study carries out the efficiency and power density evaluations of a bidirectional non-isolated dc-dc converter based on flying-capacitor converters using Pareto optimization method. The converter comprises a main converter with four power devices and an auxiliary converter, each of which is formed by cascaded chopper cells. A converter design procedure based on Pareto optimization method is proposed, followed by the discussions how the carrier frequencies of the main and auxiliary converters, and the chopper-cell count affect the efficiency and power density of the converter. Consequently, it is revealed that the maximum power density can be achieved when using four cells in the auxiliary converter. The validity and effectiveness of the design method presented in this paper are verified using a 200-V, 1-kW down-scaled model. Further, the efficiency and power density evaluations of an actual dc-dc converter system rated at 100 kW are carried out using numerical analysis based on the MATLAB software package.

High Gain and High-Efficiency Bidirectional DC–DC Converter With Current Sharing Characteristics Using Coupled Inductor

Application of coupled inductor in designing nonisolated bidirectional dc-dc converter provides flexibility to attain high voltage conversion ratio both in buck and boost mode of operation. In this article, a new coupled inductor bidirectional converter is designed with low winding turns ratio (n = 1). The proposed topology uses two current path inductor structure which improves voltage conversion ratio and shares current in all operating modes. All the active switches in the proposed topology are soft switched utilizing synchronous rectification concept. Higher efficiency operation is possible as no extra circuit elements are required to achieve soft switching. Leakage energy of coupled inductor is successfully stored in a clamped capacitor which is utilized in the circuit topology. The voltage stress and current stress level of main active switches are low. The proposed circuit is simulated and performance parameters are verified through hardware results. Both simulation and experimental results performed on a 250 W prototype confirm to attain a high efficiency of the proposed converter with simple hardware requirement for practical implementation.

Modelling and control of a non-isolated half-bridge bidirectional DC-DC converter with an energy management topology applicable with EV/HEV

Energy management strategy is gaining much popularity due to the involvement of conventional/non-conventional power sources with an efficient energy storing solution to offer un-interruptible power demand. Thus, in this work a simpler logic control circuit based nonisolated bi-directional DC-DC converter with both battery and super capacitor topology is proposed. For the proposed topology, first its mathematical modelling in ideal-case with parasitic in every mode of actions is presented. To control the bidirectional DC-DC converter topology, its small signal model for individual buck and boost operation is obtained by using averaging and linearization technique. Then, a unified logic circuit-based controller is designed for the obtained systems to analyze the performance of the converter in the buck and boost mode operation. The performance of the proposed topology is verified through MATLAB/Simulink environment.

Control and Experimental Verification of a Bidirectional Non-isolated DC-DC Converter Based on Three-level Flying-Capacitor Converters

Control and Experimental Verification of a Bidirectional Non-isolated DC-DC Converter Based on Three-level Flying-Capacitor Converters

Control and Experimental Verification of a Bidirectional Nonisolated DC–DC Converter Based on Switched-Capacitor Converters

This article presents a bidirectional nonisolated dc-dc converter based on switched-capacitor converters intended for electric railway system applications. It consists of plural main converters with two power devices per converter, plural auxiliary converters each of which is formed by cascaded chopper cells, and small-sized inductors for current control. The dc-dc converter can achieve zero-current switching (ZCS) for all power devices used in the main converters under arbitrary load conditions and an arbitrary voltage ratio of high-voltage-side voltage and low-voltage-side voltage. Consequently, square-wave currents can be removed from both the high- and low-voltage sides of the converter. The validity of the operating principles as well as the control methods proposed in this article is verified by experiments using a 200-V, 2-kW downscaled model.

Control and Experimental Verification of a Bidirectional Non-isolated DC-DC Converter Based on Three-level Flying-Capacitor Converters

Control and Experimental Verification of a Bidirectional Non-isolated DC-DC Converter Based on Three-level Flying-Capacitor Converters

An Improved Mode Transition Technique for a Non-Isolated Bidirectional DC-DC Converter

This brief presents the design and analysis of improved mode transition and startup techniques for a DC-DC bidirectional converter (BDC) for battery charging/discharging applications. The BDC inductor current is controlled in such a way that the current reaches its steady state value naturally without any control effort during the transient operation of the converter. The improved mode transition method ensures suppression of large transient currents in either direction by adopting simple control methodology simultaneously reducing the time of mode transition significantly, to the order of time constant of the inductor employed in the converter. This technique is implemented by sensing the direction of inductor current and generating appropriate PWM switching to the bidirectional switches. The startup technique is essential to suppress the current transient during initial response of the BDC for either modes of operation. The start-up and mode transition logic are very effective and easy to implement. A 400 W BDC is designed, analyzed, simulated and experimentally verified for improved mode transition and smooth startup techniques.

A Novel Topology for Bidirectional Converter with High Buck Boost Gain

In non-isolated bidirectional DC-DC converters (NIBIDC), voltage output of buck/boost mode is incongruous at lower and higher end due to the existing gain. In this paper, a novel NIBIDC is designed in such a way that it enhances the gain in both buck and boost mode of operation. The proposed NIBIDC is employed with four power switches (MOSFET) with an anti-parallel diode embodied, four inductors and three capacitors used as passive elements. The current flow in parallel connected inductor improves the circuit competence. Voltage gain of NIBIDC in buck operation is lower than conventional cascaded bidirectional buck/boost converter (CCBBC) whereas the voltage gain is higher than CCBBC in boost mode. The switching stress is same while the efficiency of NIBIDC is more than CCBBC. The topology structure of the NIBIDC is simple and easy to control. The performance analysis under steady-state condition of the novel converter is carried out and a detailed comparison with CCBBC is done in connection to switching stress, converter efficiency and duty ratios to output power, etc. The operation details for proposed NIBIDC in both mode is verified/validated by experimenting with 20[Formula: see text]V input for different duty ratios in charging and discharging state of a battery and the results infer to be identical with theoretical analysis.

Bidirectional Resonant DC-DC Converter for Microgrid applications

This paper presents a non-isolated bidirectional soft-switching dc-dc converter for DC microgrid energy storage synchronization. To assist the soft switching of switches and diodes, the LCL resonant circuit is applied and an input end half-bridge boost converter is enforced. Using the voltage doubler circuit introduced on the output side, a voltage gain of 2X is achieved. Through the non-isolated circuit, the total voltage gain is obtained. The capacitive divider halves the voltage on the greater hand. The circuit performs a high frequency ripple of low output voltage. Diodes guarantee zero voltage Turn ON for switches and zero current turn ON and turn OFF during buck / boost operation Although no internal snubber circuits are available, the circuit ensures low voltage stress across semiconductor systems.