Buck Operation Research Articles

A transformer-less DC-DC converter for grid-connected PV systems using TSTS-ZSI voltage boost-buck technique

This research introduces an innovative design for a grid-connected photovoltaic (PV) system utilizing a transformer-less DC-DC converter. The converter is based on the TSTS-ZSI (Three-Switch Transformer-less Z-Source Inverter) voltage boost-buck technique, which enhances voltage regulation and energy transfer, making it ideal for micro-inverter applications. The primary goal of the study is to improve energy efficiency while ensuring seamless integration with the grid. The proposed system not only boosts voltage but also ensures efficient buck operation, leading to enhanced power injection into the grid under fluctuating conditions. By utilizing advanced control techniques, the converter minimizes power losses, reduces stress on the components, and maintains stability in a wide range of grid scenarios. Simulations performed using MATLAB/Simulink demonstrate that the converter delivers stable and efficient power with minimal energy loss. The results validate its effectiveness in small-scale grid-connected systems, achieving enhanced power management under various operating conditions. The converter's ability to operate efficiently without a transformer reduces magnetic losses and electromagnetic interference, making it a cost-effective and compact solution. The research presents a valuable contribution to the field of renewable energy integration, with its applications extending to both residential and commercial grid-connected PV systems.'

Controlling of Solar Based Electric Vehicle Charging Station Through Intelligence Controller for G2V and V2G Modes

Abstract: Solar based electric vehicle (EV) charging station was proposed in this paper. The maximum power of a PV module varies due to changing temperature, solar radiation, and load. In order to extract the Maximum power point in this work, an MPPT system consisting of a PV module, a DC-DC converter, and a fuzzy logic controller is designed and simulated in Simulink. The EV battery SOC characteristic is observed to be fully charged within short period. In this paper single Phase grid and the PV system with the Fuzzy controller MPPT is connected to the DC link, which is connected to the EV. Also in the absence of solar PV energy, electric vehicle is charged from the grid. A battery of rating 100AH is charged with the solar PV panel using a boost converter which generates output voltage of 400V. Then the voltage is stepped down for buck operation according to 220 V battery requirement. A Bidirectional AC-DC rectifier is connected to the Grid, and the DC-DC boost converter for the MPPT and the DC-DC bidirectional Converter is connected to the EV for the Charging and Discharging of the EV. During charging and discharging modes the battery voltage and current is presented. It is clear that the grid voltage and current are in phase during charging. During discharging they are said to be out of phase indicating the reverse power flow.

Performance Analysis of LLC Resonant and Pulse Width Modulation Direct Current- Direct Current Converters for Buck and Boost Operation

Performance Analysis of LLC Resonant and Pulse Width Modulation Direct Current- Direct Current Converters for Buck and Boost Operation

Design and analysis of a switch fault-tolerant multi-input single-output DC-DC converter for high reliability applications

The DC–DC converters have been used extensively in various industrial applications such as consumer electronics, aerospace, electric vehicles, and renewable energy systems. The reliability ensures that the converter continues to operate safely and efficiently despite the presence of faults. Enhancing the reliability of DC-DC converters is a challenging task, as power switches are the most fragile components that can be affected by faults in the system. Hence, to address these challenges and ensure the safety of the converter, it is vital to implement appropriate fast fault-diagnosis techniques and fault-tolerant strategies. Many new network topologies have been presented in literature, which lead to a shift from single input–single output to multiport converters. These converters are suitable for integrating different energy sources. However, the majority of them are operated using a time-sharing method, in which only one energy source is used at a time, and the others are inactive at any specified duty cycle. Therefore, the converter and input sources are underutilized in the conventional time-sharing approach. This paper proposes a new multi-input single-output (MISO) converter topology with fully integrated switch fault tolerance. It can perform multi-input buck, boost, and buck-boost operations. More importantly, the converter can operate uninterruptedly for single or multiple switch faults. Using simulation and experimental results, a 400 W prototype circuit is designed to analyze the converter's reliability and performance.

Two‐input single‐output converter with preserved output voltage under source fault

SummaryMulti‐input converters (MICs) play a significant role in the aspect of the integration of sources. The reliability of the converter can be enhanced by using a suitable fault tolerance converter design and control algorithm. A dual‐input single‐output (DISO) DC–DC converter with source fault tolerance is proposed in this paper. In the literature, there are many topologies in this area of work; however, most of them are based on time‐sharing control. In this control scheme, one input source is contributed to the load, and others are kept idle in a particular duty interval; hence, this control scheme leads to underutilization of the converter. The proposed converter is designed to circumvent these challenges and can produce boost, buck–boost, and buck operations. And also, it has a source fault feature for achieving the preserved output voltage under source V1 or V2 failure conditions. A 200‐W prototype is designed, and the feasibility of the proposed converter is validated through simulation and experimental results.

A Class of Bidirectional Single-Phase Z-Source AC–AC Converter With Continuous Input Current and Reduced Component Count

In this paper, a class of single-phase Z-source ac-ac converters is proposed. Share ground and continuous input current are the common features of the proposed converters. The proposed converters have unique features that differentiate them from their counterparts. These features include the buck operation in both in-phase and out-of-phase mode, being bidirectional, the minimum component counts, the ability to boost without duty cycle limitation, and reducing total power ratting of switches is known as switching device power (SDP) parameter. Reducing SDP leads to a reduction in the voltage and current rating of the semiconductors and consequently to a reduction in converter' cost. A safe commutation strategy is applied to eliminate voltage and current spikes on the switches without snubber circuits. The experimental results verify the performance of the laboratory prototype of the proposed converters.

A Novel Single/Multiple Output Multilevel Buck Rectifier for EV-Battery Charging

An electric vehicle (EV) charging system is usually implemented in two stages: a power factor correction (PFC) rectifier stage, followed by a DC-DC converter. For such power conversion, multilevel rectifiers (MLRs) offer advantages compared to a two-level rectifier, such as reducing voltage ratings of power switches and yielding high-quality input voltage waveform. In MLRs, one of the most challenging aspects is balancing the capacitors’ voltages. This article proposes a self-balancing five-level PFC rectifier with the possibility of single/multiple outputs. The proposed rectifier performs buck operation and offers a wide output voltage regulation, which is suitable for EV battery charging. The five-level operation of proposed buck rectifier with continuous conduction mode (CCM) leads to elimination of the inductive filter on the DC side and the capacitive filter on the AC side. This article presents the operating principle, modulation strategy, closed-loop control and experimental validation of the proposed topology.

A Buck-Boost Converter with Extended Duty-Cycle Range in the Buck Voltage Region for Renewable Energy Sources

Buck-boost DC–DC converters are useful as DC grid interfaces for renewable energy resources. In the classical buck-boost converter, output voltages smaller than the input voltage (the buck region) are observed for duty cycles between 0 and 0.5. Several recent buck-boost converters have been designed to present higher voltage gains. Nevertheless, those topologies show a reduced duty-cycle range, leading to output voltages in the buck region, and thus require the use of very low duty cycles to achieve the lower range of buck output voltages. In this work, we propose a new buck-boost DC-DC converter that privileges the buck region through the extension of the duty-cycle range, enabling buck operation. In fact, the converter proposed here allows output voltages below the input voltage even with duty cycles higher than 0.6. We present the analysis, design, and testing of the extended buck-boost DC-DC converter. Several tests were conducted to illustrate the characteristics of the extended buck-boost DC-DC converter. Test results were obtained using both simulation software and a laboratory prototype.

Comprehensive Mapping of Continuous/Switching Circuits in CCM and DCM to Machine Learning Domain Using Homogeneous Graph Neural Networks

This paper proposes a method of transferring physical continuous and switching/converter circuits working in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) to graph representation, independent of the connection or the number of circuit components, so that machine learning (ML) algorithms and applications can be easily applied. Such methodology is generalized and is applicable to circuits with any number of switches, components, sources and loads, and can be useful in applications such as artificial intelligence (AI) based circuit design automation, layout optimization, circuit synthesis and performance monitoring and control. The proposed circuit representation and feature extraction methodology is applied to seven types of continuous circuits, ranging from second to fourth order and it is also applied to three of the most common converters (Buck, Boost, and Buck-boost) operating in CCM or DCM. A classifier ML task can easily differentiate between circuit types as well as their mode of operation, showing classification accuracy of 97.37% in continuous circuits and 100% in switching circuits.

A Bidirectional Five-Level Buck PFC Rectifier With Wide Output Range for EV Charging Application

AC-to-DC conversion is integral to the two-stage charging interface of electric vehicle (EV) batteries. For such chargers, the use of multilevel rectifiers (MLRs) reduces voltage ratings of power switches, while achieving a high-quality input voltage waveform. Balancing of capacitors in MLRs, however, is an important challenge. In this work, a power factor correction (PFC) five-level rectifier with self-balanced switched capacitors is proposed. Each leg of the presented topology comprises five power switches and one switched capacitor, where the voltage ratings of power switches are equal to the output dc voltage. It does not require an additional filter capacitor on the dc side, as the load appears in parallel always with a switched capacitor of one of the legs. The five-level operation with continuous conduction leads to the elimination of the capacitive filter on the ac-side and inductive filter on the dc-side. This article presents the operating principle, modulation strategy, closed-loop control, and design aspects of the proposed rectifier. The proposed topology is validated through experimental results and a comparison is made with other topologies. Following three features of the proposed topology make it suitable for EV battery charging applications—buck operation with a wide output regulation, the possibility of bidirectional flow of power needed for vehicle-to-grid systems, and easy realization of its three-phase version by simply adding one more leg. These features too have been demonstrated with experimental results.

Synthesis and Implementation of a Multiport Dual Input-Dual Output Converter for Electric Vehicle Applications

In recent years, multiport DC-DC converters are seen in a variety of power converter applications in electric vehicles. The design of multiport converter architectures plays a major role in DC microgrids and electric vehicle applications. This research examines a modified multiport converter structure interface with dual inputs and dual outputs used in electric vehicles. The versatility of accommodating energy sources with varying voltage and current nature characteristics is the most notable feature of this converter. During operation, the proposed architecture can offer a boost as well as buck operations at the same time. The suggested dual input-dual output (DIDO) converter is built with fewer components and a simpler control technique which makes it more dependable and the converter is cost-effective. Furthermore, this structure allows the power to flow in both directions making it to be utilized in electric vehicle battery charging during regenerative braking. The converter’s steady-state and dynamic behavior are investigated, and a control strategy for regulating the power flow among the varied input energies is proposed. To develop the suggested converter, a small-signal model is modeled. MATLAB simulation and experimental findings are used for the verification of converter design and validated the performance behavior experimentally using a hardware setup.

Switching-Cell Buck–Boost AC–AC Converter With Common-Ground and Noninverting/Inverting Operations

This article proposes a switching-cell-based bipolar buck-boost ac-ac converter that can provide multiple modes of operation, including noninverting buck operation, noninverting boost operation, inverting buck-boost operation, and adjustable noninverting buck-boost operation with two control duty ratios. Each fundamental switching-cell in the proposed converter is composed of a unidirectional buck circuit with no short-circuit or open-circuit problems, increasing its robustness. Hence, safe commutation is naturally realized without the use of RC snubbers or soft-commutation strategies, removing the need for pulsewidth modulation deadtimes. External fast recovery diodes are utilized, avoiding the high-frequency conduction of MOSFET's body diodes and eliminating their slow reverse recovery problem and corresponding power loss. The proposed converter shares a common ground between input and output ports, offers support for reactive loads, draws continuous sinusoidal current from ac mains, and delivers a continuous output current. The converter is suitable for ac voltage regulation applications, notably as a dynamic voltage restorer, compensating extensive magnitudes of both grid voltage sags and swells. Circuit operation and analysis are provided for all the proposed modes of operation. Experimental results obtained using a 400-W laboratory-scale hardware verify the theoretical analysis.

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.

MSVM ‐based hybrid energy‐fed quasi‐Z‐source cascaded H‐bridge inverter for grid‐connected system

Hybrid energy sources are much needed to meet the power demand for various real-time applications, and the desired output level is attained with the help of various advanced power converter topologies. Here, the hybrid energy source-fed quasi-Z-source cascaded H-bridge inverter (QZS-CHI) is implemented for a grid-connected system. The conventional multilevel inverter topologies are suitable for voltage buck operation, but this proposed system includes quasi-Z-source inverter network, which leads voltage buck-boost operation without any additional dc-dc converter. Modified space vector modulation (MSVM) technique is developed to control the QZS-CHI system, which leads to reduced total harmonic distortion(THD), reduced common-mode voltage (CMV), controlled output current, and improved output voltage. The proposed system QZS-CHI is energized using a hybrid energy source with a photovoltaic (PV) system and wind energy conversion system (WECS). With the help of shoot through mode in QZS, the output voltage is boosted without an additional converter and CMV is minimized by the proper utilization of medium and small switching state vectors. To assess the proposed technique, a laboratory prototype model is built and analyzed under different cases. From the obtained results, it is observed that the proposed method reduces THD to 2.15% for output voltage and 2.99% for output current, and common-mode voltage is reduced to Vdc/6 times of applied dc voltage.

A Three-Phase Resonant Boost Inverter Fed Brushless DC Motor Drive for Electric Vehicles

The present article proposes a three-phase resonant boost inverter (TPRBI) to feed a permanent magnet brushless DC (PMBLDC) motor at the requested torque with low ripples due to the sinusoidal current injected into the PMBLDC motor. PMBLDC motors have the highest torque-to-weight ratio compared to other motors and are the best choice for electric vehicle applications. Conventionally, these motors are driven by voltage source inverters (VSI) with trapezoidal current injection, introducing unwanted torque ripples. Moreover, due to the buck operation of VSI, an extra power conversion stage is required to elevate the battery voltage level to desired DC-link voltage. This extra stage increases the number of components used, complexity of control and decreases the efficiency and reliability of the overall system. TPRBI injects sinusoidal current in the PMBLDC motor in the proposed method, thus minimizing the torque ripples. The proposed inverter also has an inherent voltage boost characteristic, thus eliminating the extra power conversion stage. The single-stage conversion from DC to boosted sinusoidal AC enhances the system reliability and efficiency and minimizes the cost and weight of the system. A MATLAB/Simulink model is presented along with simulation results and mathematical validation. A comparative evaluation of the proposed system with the conventional VSI-fed PMBLDC motor is presented in terms of induced torque ripples.

Battery Charger Utilizing Coupled Inductor Based High Gain Bidirectional DC-DC Converter: Analysis, Design, and Implementation

The bidirectional dc-dc converter with high voltage gain and high efficiency plays an important role in the designing of battery charging systems. In this paper, design and development of a battery charging system utilizing coupled inductor based high gain dc-dc converter is presented. The converter uses a clamp capacitor network to recover the leakage energy of a coupled inductor. The converter has inherent soft-switching capability during turn ON, which ensures high efficiency at high switching frequency. Design equations to derive value of different passive components are given and a step-wise exclusive design to construct coupled inductor is presented. A 50 kHz, 500 W laboratory prototype has been designed, which can increase the voltage with 10 gain (boost operation) in one direction and can reduce the voltage at (1/10) gain (buck operation) in other direction. The CCCV battery charging algorithm is implemented using generic ARM Cortex-M4 microcontroller. Extensive experiments have been performed and the experimental results are presented in buck, boost, and battery charging operations.

Control of Three Phase BLDC Motor for Electric Vehicles by using Four Quadrant Operation

In this paper the four quadrant operation implemented for the recovery of electric vehicles. BLDC motor is used in EV, and bi-directional DC-DC converter is connected to the VSI (voltage source inverter). Bi-directional DC-DC converter performed to modes that is, buck mode and boost mode, energy is recovered through this mode. In buck mode utilized the energy for drive the motor and in the boost mode regeneration of energy and charged the battery. This proposal operated in MATLAB\Simulink software. By using this method we can improve the energy management of electric vehicles when vehicles in motoring mode bi-directional converter did buck operation and utilized energy for driving vehicles. During electric vehicles often start and stop, this operation proposes recovery of kinetic energy of motor and stored it in battery through the regenerative braking. Through electric vehicles going on downhill, drive speed develops more than reference speed, controlled speed offer energy and this energy return to battery.

Simple boost PWM controlled cascaded quasi Z-source inverter

In this paper cascaded quasi Z source inverter is used to give desired boosted output. It can derive from the quasi Z source inverter by adding one diode, one inductor, ant two capacitors. Power converters can be used for adjusting the parameters needed for synchronization of the source and load. This converter commonly used as an interface between the DC voltage source and load. The power converters are used to produce constant output by means of adjusting the firing pulses for switches to get variable output which helps in the protection of devices from high voltage or high current. The traditional Quasi Z-source Inverter (QZSI) is utilized for voltage Boost and voltage Buck operation. A QZSI be able to directly convert input dc voltage into buck or boosted AC output voltage based on applications. Further to improve the performance of QZSI, Cascaded QZSI (CQZSI) is presented in this paper with few additional components like capacitor, inductor and diode. The main aim of this paper is to give the efficient output to the load by using Cascaded Quasi Z-Source Inverter (CQZSI) as a result of voltage boost up ability, single stage power conversion, low voltage stress and high boost factor. The simulation result of cascaded quasi Z source inverter is presented with simple boost PWM in simulation part. In hardware part, the cascaded quasi Z source inverter can be analyzed with single phase inverter. The output voltage can be boosted upto two times of input voltage.

A Monolithic GaN-IC With Integrated Control Loop for 400-V Offline Buck Operation Achieving 95.6% Peak Efficiency

Gallium nitride (GaN) transistors enable efficient and compact high-voltage power converters. In the state-of-the-art enhancement mode GaN-on-Si technology, a 650-V power transistor is formed as a lateral structure enabling monolithic integration with a driver and analog control circuits on one die. Offline power converters show a trend toward a higher level of integration, shifting from monolithic silicon (CMOS) to various integration levels in GaN technology. In this article, a monolithic, self-biased GaN buck converter for offline operation is presented, supporting both 110- and 230-V ac line voltage and providing up to 29-W output power. The converter shows a superior efficiency of 95.6 % and a very high level of integration in a 650-V p-GaN gate e-mode GaN-on-Si technology. Analog design techniques for GaN integration, such as an auto-zero comparator and a high-voltage supply regulator, are discussed. Experimental results of stand-alone circuit blocks and the full buck converter confirm the viability of monolithic GaN integration as a path toward compact and efficient offline power converters.

Novel High-Efficiency Frequency-Variable Buck–Boost AC–AC Converter With Safe-Commutation and Continuous Current

In this article, a novel high-efficiency single-phase frequency-variable buck–boost ac–ac converter is proposed. AC input voltage can be bucked and boosted with step-changed frequency operation. In the topology, only six switches and total ten semiconductors are utilized, which is at the lowest level among existing works. Only two of the switches are operating at high frequency and only one switch is switched on and off in each switching period, Therefore, the proposed converter has less power loss and features high efficiency. With simple and flexible control strategy, the converter is immune of commutation problem and thus no additional safe-commutation strategy or snubber circuit is needed. Power density of proposed converter is high considering the volume metric of the energy storage components. Moreover, the input current of proposed ac–ac converter is continuous. Therefore bulky input filter required by other existing works is totally removed, which further improve the power density. Operation principles and circuit analysis is provided. To verify the performance, a 200-W laboratory prototype is constructed and experiments are conducted in operation of buck and boost mode at step-changed output frequency of 30, 60, and 120 Hz.