Main Converter Research Articles

Triple-Level Single-Ended Main Inductor Converter (SeMLC) with regard to Wind-Solar Hybrid Energies

An output from a DC-to-DC converter that can be more or less than its input is called a Single-Ended Main Inductor Converter (SeMLC). Nevertheless, there is more switching stress in this dual-level SEMIC, which raises switching losses. This rise in switching loss causes the power converter's efficiency to drop. This research suggests a Triple stage SeMIC with lower switching losses to get over this drawback. Using a lower rated switch, Triple level SEMIC increases power efficiency. There is a description of a control method that balances the voltage of the capacitor to avoid damaging the power switch. The suggested converter also lessens the ripple in inductor current in the output inductor. Triple level SeMIC uses a hybrid wind-solar energy system as a source. The benefits of the suggested converter are emphasized by discussing the simulation results of both dual- and Triple-level SeMIC.

(MIMO Buck Converter) Multi-Input Multi-Output DC-DC Buck Converter

Abstract: Designs of the power electronics circuitry are nowadays reducing the size, space, and weight of converter and inverter circuits. This is possible because of the availability of new high-switching frequency devices. This paper presents a generalized model of buck converters that is multi-input multi-output(MIMO) fixed and variable. The converter used for stepping down the voltage is called a buck converter. The buck converter is designed, analyzed simulated & developed. The proposed model of this Buck converter consists of two parts: (a) Main converter circuits with the components like switch, inductor, diode, capacitor, and load, (b) A control circuit for controlling the operation of the switch using 10 10-turn potentiometer. This model can accurately give the power output voltage.

A CASE STUDY ON HIGH POWER COMPENSATOR OF THE POWER GRID IRREGULARITIES FOR INDUSTRIAL APPLIANCES

The paper presents a case study on development of the high power compensator of the power grid irregularities. The compensator is dedicated for sensitive industrial installations protection against dips, sags and short duration interruptions in public power network. The energy for compensation will be stored in bank of high voltage stacked supercapacitors. The development of the new high power medium voltage compensator will be based on experience gained during the realisation in The Electrotechnical Institute Gdansk Branch a similar medium power low voltage device. The study includes: main power converter topology considerations with some preliminary simulation results including harmonic components discussion, the solution to the problem of fast identification of the grid voltage disturbances, the solution to the problem of compensator waveforms synchronization with the grid and the description of the main operational algorithm of the compensator.

Design of a versatile Half-Bridge Converter Able to Drive 6x6, 6x4, 8x6, 12x8 Switched Reluctance Generators and Motors Using Arduino

This paper presents the studies required for the design and construction of a versatile Half-Bridge converter. This converter can drive a wide variety of machines - from one to four phases. The converter was designed mainly to drive Variable Reluctance Machines in 6x4, 6x6, 8x6 and 12x8 topologies, working as both motor and generator. The versatility of the proposed converter is its main advantage, as in both academic and industrial applications, this feature can generate financial and production time savings. An analysis was carried out among the main converter topologies to justify the choice of the Half-Bridge topology followed by a project detailing of the chosen converter. For the design and construction of this converter, only commercially available devices were considered. To control the triggering keys, the Arduino platform was used due to its easy access and low cost. After the converter power circuit definition, the circuit for communication between the sensor (encoder), the controller (Arduino), and the switches (IGBT) is presented, and the project assembly is shown at the end.

Correlation between Peptacetobacter hiranonis, the baiCD Gene, and Secondary Bile Acids in Dogs.

Bile acid metabolism is a key pathway modulated by intestinal microbiota. Peptacetobacter (Clostridium) hiranonis has been described as the main species responsible for the conversion of primary into secondary fecal unconjugated bile acids (fUBA) in dogs. This multi-step biochemical pathway is encoded by the bile acid-inducible (bai) operon. We aimed to assess the correlation between P. hiranonis abundance, the abundance of one specific gene of the bai operon (baiCD), and secondary fUBA concentrations. In this retrospective study, 133 fecal samples were analyzed from 24 dogs. The abundances of P. hiranonis and baiCD were determined using qPCR. The concentration of fUBA was measured by gas chromatography-mass spectrometry. The baiCD abundance exhibited a strong positive correlation with secondary fUBA (ρ = 0.7377, 95% CI (0.6461, 0.8084), p < 0.0001). Similarly, there was a strong correlation between P. hiranonis and secondary fUBA (ρ = 0.6658, 95% CI (0.5555, 0.7532), p < 0.0001). Animals displaying conversion of fUBA and lacking P. hiranonis were not observed. These results suggest P. hiranonis is the main converter of primary to secondary bile acids in dogs.

DEVELOPMENT OF DC-DC BUCK CONVERTER FOR SOLAR PANEL ENERGY STORAGE THROUGH LOAD OPTIMIZATION AND FEEDBACK CIRCUIT

Solar panels are crucial components in converting sun radiation into electrical energy through the photovoltaic effect. A solar panels cannot be connected directly to the load due to its low energy conversion efficiency and low output voltage. One of the methods used to control solar cells to operate efficiently at their maximum power point is MPPT. In this paper, we design a DC-DC converter by modifications of the Butterworth filter circuit and feedback circuit in the MPPT system for storing solar panel electrical using the Hill Climbing (HC) method. The device consists of a DC-DC buck converter circuit, two pieces of INA219 sensors, a DS18B20 temperature sensor, a MAX44009 light intensity sensor, a SD card module and a DS3231 RTC. The DC-DC buck converter circuit simulation is carried out to determine the optimal load. The load optimization was conducted by analyzing the AC simulation using Ltspice software. The magnitude of the output voltage ripple in nine different loads was observed. From the simulations performed, it was found that the 50 Ω load has an output voltage ripple of 8.96 mV and is smaller than the other loads. The main DC-DC buck converter circuit is designed using a butterworth low pass filter with a cut-off frequency of 1000 Hz (R = 50 Ω, L = 33.8 mH and C = 750 nF) and a feedback circuit with a cut-off frequency of 500 Hz is added. From the prototype measurement, it was found that the average output power was 3249,7 milliwatts and the average input power was 4779 milliwatts, thus the average efficiency was 68%. With these results, the DC-DC converter circuit configuration is suitable for use in electrical energy storage systems from solar panels that have high efficiency.

Multiple voltage source converters based microgrid with solar photovoltaic array and battery storage

In this paper, a standalone photovoltaic (PV)-battery storage (BS) based microgrid (MG) is presented with a 415V-AC bus. The PV array is linked to the main voltage source converter (VSC1) DC-link to maximize power production in an efficient and cost-effective single-stage structure. This is achieved through an incremental conductance (INC) maximum power point (MPP) tracking approach. Moreover, a secondary converter (VSC2) is connected to BS for power flow management. MG performance is evaluated under various operating conditions. Steady-state and dynamic performances of MG are studied for variations such as changes in solar PV irradiance and load unbalances.

Enhanced Cascaded Converters for Switched Reluctance Motor-Fed Electric Vehicles

This manuscript proposes an optimization technique for electric vehicles (EVs) operated through solar photovoltaic (PV) panels by enabling the drive of a switched reluctance motor (SRM) and an enhanced cascaded converter (ECC). The proposed method is an improved Tunicate Swarm Algorithm (ITSA). The Lévy flight distributions are emerging at the conventional Tunicate Swarm Algorithm (TSA) in the modified Tunicate Swarm Algorithm, which enhances the capabilities of diversification searching and avoids the potential for stagnation. The major objective of the proposed method is to minimize the ripple present in the supply current and give optimal photovoltaic power extraction to the solar module. The proposed enhanced cascaded converter method consists of a single main converter and one auxiliary converter combined as a series structure for the distribution of minimal voltage across the switch to restrict the switch stress of dv/dt. These quantities of error are lessened by the controller of Proportional–integral; the PI gain controller is tuned to the error and provides a reference current signal by using the proposed method. An optimum voltage gain and continuous input current minimize the impact of less solar irradiation in EV applications. Finally, the performance of the proposed method is implemented in the MATLAB platform and compared with existing methods.

Thermal simulation analysis of power module of combined converter for metro vehicle

In order to reduce the occupancy space and equipment cost of the on-board converter, a combined traction-auxiliary converter for subway vehicles is proposed in this paper. The power loss of the main traction converter module (MCM) and the auxiliary converter module (ACM) was calculated according to the speed and power variation of the vehicle running between five consecutive stations, and the flow rate of cooling air was calculated through the heat balance theory. The air volume of MCM and ACM and the plate temperature of the radiator are analysed by step method. Then, according to the instantaneous maximum temperature of the radiator obtained by simulation and the thermal parameters of the IGBT module, the junction temperature of the IGBT and diode chips is calculated by means of the junction temperature equivalent circuit. The results show that the plate temperature of the heat sink and junction temperature meet the design requirements. The design and thermal simulation method in this paper provide theoretical reference for the design of railway vehicle converters.

Coordinated Control and Load Shifting-Based Demand Management of a Smart Microgrid Adopting Energy Internet

High renewable energy penetration worsens systems instability. Balancing consumption energy and generation output energy reduces this instability. This paper introduces coordination control to coordinate the flow of electricity between MG buses and to stabilize the system under variable load, generation conditions. The adopted MG regulates the bidirectional DC/AC main converter using digital proportional resonant controllers in a synchronous reference frame. A maximum power point tracker-based boost DC/DC converter enables the wind turbine and solar photovoltaic to harvest maximum power. Traditional methods such as perturb and observe and incremental conductance maximum power trackers cannot solve nonlinearity and inaccurate responses. This work provides a hybrid maximum power tracker strategy to modify the responses of standard maximum power point techniques based on particle swarm optimization-trained adaptive neuro-fuzzy inference system (ANFIS-PSO) to achieve quick and maximum solar power with minimal oscillation tracking. Concerning the management system, this paper adopts a recent meta-heuristic algorithms-based DSM program to modify consumers’ electricity use by shifting the load appliances to off-peak demand periods. The adopted algorithms for DSM are sparrow search algorithm (SSA), binary orientation search algorithm (BSOA), and cockroach algorithm (CA). Finally, based on energy Internet technology, ThingSpeak cloud-based MATLAB is adopted to gather and display real-time data streams and generate graphical analyses. The simulation results reveal that the recommended coordinating control produces quick grid frequency responsiveness and zero steady-state errors. The optimal demand management program minimizes peak energy consumption from 5.2 kWh to 4.6 kWh. All DSM methods cost 439.1 $ per month, compared to 484.4 $ for the nonscheduling load profile.

A coordinated control scheme for VSC-MTDC system with multiple renewable energy sites based on voltage margin and adaptive drooping control

This paper designs a novel coordinated control scheme to improve the control performance of voltage source converters (VSC) based multi-terminal high voltage direct current (MTDC) transmission network by merging the benefits of adaptive drooping and voltage margin controllers. In this proposed scheme, the droop coefficient is used to manage the DC voltage and maintain power sharing by shifting the control modes of the rectifiers and inverters in the presence of considerable power disturbances. The droop coefficient is planned based on the stability limit of DC voltage. The performance of the designed control scheme is compared to that of existing coordinated control and voltage margin droop control approaches. A ±400 kV five-terminal VSC-MTDC network is developed in PSCAD to verify the planned control method. The simulation results indicate that the proposed control scheme can achieve good performance for controlling the DC voltage and maintaining active power in the MTDC system.

Voltage-Controlled Variable Inductor for Fixed-Frequency Critical Conduction Mode Operation

This study proposes a novel voltage-controlled variable inductor (VI) for fixing the switching frequency of DC-DC converters in the critical conduction mode (CRM). It overcomes the limitations of conventional current-controlled VIs such as complex winding structures, difficulties in control, and high sensitivity to temperature. In the proposed voltage-controlled VI, the primary-side inductance of a coupled inductor is regulated by an auxiliary voltage source on the secondary side. The auxiliary voltage source is implemented by an auxiliary DC-DC converter, which delivers power to the load in parallel with the main converter. The operating principle of the converter system for employing the proposed VI is presented, and a control loop is designed to fix the switching frequency, considering the small-signal model of the auxiliary converter. The validity of the proposed VI is experimentally verified using a prototype CRM boost converter with an output voltage of 400 V and a maximum power of 400 W. The switching frequency is fixed at 100 kHz and the soft switching of the main converter is maintained regardless of the input voltage and output power.

DC-DC Boost Converter with Reduced Switching Losses in Wide Range of Voltage Gain

This article presents the results of research on a new topology of a DC-DC converter in which switching losses are reduced by an auxiliary switching circuit (ASC). The proposed ASC can work as a passive or active circuit depending on the voltage gain of the converter. In both cases, this does not affect the operation of the main circuit and is analogous to a classic boost converter, which allows the use of the same control circuits and methods. The operation of the ASC is synchronized with the control of the main converter transistor. The reduction of transistor turn-off losses over a wide range of converter gain is a unique advantage of the proposed auxiliary circuit. This is evidenced by the comparison of the loss reduction with the classic boost converter and the reference converter with soft turn off. This article presents an in-depth analytical discussion related to the reduction of power losses, supported by simulation results, and verified experimentally.

Novel Resonant Power Feedback DC-DC Converter

In this article, a novel soft-switched isolated dc–dc converter topology is proposed that consists of a main power converter using a standard topology, augmented with a resonant power feedback circuit. The power feedback circuit utilizes a fraction of the output power to regulate the input voltage of the main converter. Input voltage regulation proves to be advantageous in applications where wide range of source voltage variations are experienced, such as in photovoltaic microinverters. The operation of main converter with a regulated input voltage results in a near-constant phase-shift angle and a high-frequency current wave shape with a low root mean square value over the entire range of operating conditions. Moreover, the operation with near constant phase-shift angle and the presence of additional resonant current in the feedback circuit extend the range of soft-switched operation of semiconductor devices in the converter. The proposed converter topology and its theoretical analysis is verified through an experimental prototype.

A Compact Auxiliary Power Supply Design for a Medium Frequency Solid State Transformer

The design of auxiliary power supply (APS) in solid-state transformers (SSTs) is quite challenging. To minimize the isolation requirement, this APS is usually powered by dc-link capacitors. However, it poses voltage unbalance issues when the main converter is not in operation. To address this problem, a compact and cost-effective APS design is proposed, which utilizes the isolation structure of main medium-frequency transformers (MFTs). The proposed APS system also provides half-duplex communication, which replaces the costly optical fiber system. The interference between main and auxiliary power transfer links has been significantly reduced by the decoupled transformer design and the dual-band scheme for inductor-inductor-capacitor (LLC) and inductor-capacitor-inductor-capacitor (LCLC) converters. In addition, a new startup strategy with a low standby power is applied to this APS system. A 3.2-kW SST prototype with a peak efficiency of 97.9% has been built, whose APS is 6 W. The experimental results verify the feasibility and performance of the proposed techniques.

Multiport DC-DC Converter with Differential Power Processing for Fast EV Charging Stations

With the growing interest in owning electric vehicles due to increased environmental awareness and uncertain energy security together with the development of Li-ion batteries, quietness, and trouble-free operation, it is urgent to develop charging stations that are fast enough to supply the vehicles with energy conveniently, as in case of conventional petrol stations. The main reason that hinders the spread of fast charging stations is the installation cost, comprising the infrastructure and converter costs. In this article, a multiport DC-DC converter with differential power processing stages is proposed for Electric Vehicle (EV) fast charging stations, which results in a considerable reduction in the cost of using converters while achieving high efficiency. The proposed topology consists of two paths for the power flow (outer and inner loops) for EV battery charging with main and auxiliary DC-DC converters in the outer loop; all the ports are connected in series with the main supply, where the bulk power is being transferred. The main DC-DC converter injects a series voltage to control the power in the outer loop. The auxiliary DC-DC converters are rated at a fractional power that controls the partial power supplied to each port through the inner loops. Thanks to the fractional power processed by the auxiliary converter with the remaining power fed to the battery through the main converter, the proposed architecture enables simultaneous charging of multiple electric vehicles with better efficiency, lower cost, and the capability of providing a fault tolerance feature. A PWM control scheme for the converters to achieve bi-directional power flow in the partially rated DC-DC converters is discussed for the proposed system. Moreover, a practical down-scaled hardware prototype is designed to validate the functionality, control scheme, and effectiveness of the proposed topology in different case studies being investigated. The efficiency of the proposed converter is compared to the conventional configuration.

Oncogenic role of LMP1 expression in Epstein-Barr virus associated with nasopharyngeal carcinoma: A literature review

Nasopharyngeal carcinoma (NPC) is a malignant carcinoma that appears in the epithelial lining of the nasopharyngeal mucosa. Genetic predisposition, environmental risk factors, nutritional risk factors, and Epstein-Barr virus (EBV) infection are the main risk factors for NPC. Epstein-Barr virus, a human cancer-associated virus, is present in more than 90% of people worldwide. Latent Membrane Protein 1 (LMP1) has been identified as the main Epstein-Barr virus converting oncoprotein. LMP1 was shown to be present in NPC tumor tissues, suggesting a potential role for LMP1 in EBV-mediated carcinogenesis. LMP1 exerts several oncogenic properties and has the ability to transform epithelial cells through the activation of numerous signaling pathways and the control of the expression of different oncogenes and tumor-suppressor genes. the process by which tumor traits such cell proliferation, apoptosis resistance, invasion and motility, and angiogenesis are produced and maintained.

Bidirectional Buck-Boost Converter Using Cascaded Energy Storage Modules Based on Cell Voltage Equalizers

Ordinary modular energy storage systems require cell- and module-level equalizers, in addition to a main bidirectional converter, increasing the system complexity and cost. This article proposes a bidirectional buck-boost converter using cascaded energy storage modules. Each module contains a cell-level equalizer with a half-bridge cell. The half-bridge cell in each module is utilized not only for the cell-level equalizer but also for the cascaded buck-boost converter. Module voltages are equalized by adjusting duty cycles of the half-bridge cells, allowing the elimination of dedicated module-level equalizers. Furthermore, the cascaded structure equivalently increases the switching frequency and reduces the inductor current ripple. An experimental charge-discharge cycling test using the prototype was performed for three electric double-layer capacitor modules. Cell and module voltages were gradually equalized during cycling, demonstrating the bidirectional power conversion and cell- and module-voltage equalization capabilities of the proposed converter.

Evaluation and Performance of Three-Phase Inverter Using Multiple Bidirectional Choppers Intended for 1.5-kVdc PV Systems

This article focuses on the chopper-cell number of a novel three-phase inverter for utility-scale photovoltaic (PV) systems where multiple cascaded bidirectional chopper cells and a three-phase line-frequency transformer with a three-legged core are used. The inverter per phase is composed of a main converter, which is equivalent to the conventional bidirectional chopper, and an auxiliary converter, which is composed of multiple cascaded chopper cells. Although the inverter performance can be improved by increasing the chopper-cell number because of increased switching frequency and reduced voltage steps, the increased cell number may result in increased converter loss and cost. However, no paper has evaluated the chopper-cell number of the inverter to the best of the authors’ knowledge. Further, no paper has carried out experimental verification of the inverter during the power faults. This article evaluates the inverter using two cells per phase (two-cell inverter) with the one using three cells per phase (three-cell inverter) under the same equivalent switching frequency in terms of converter loss, efficiency, and steady/transient state performance. The numerical analysis shows that the two-cell inverter shows superiority over the three-cell inverter in converter efficiency. Further, the experiments using a 1.5-kW downscaled model verify the inverter performance under the normal and fault conditions.

Black-Box Large-Signal Average Modeling of DC-DC Converters Using NARX-ANNs

This paper investigates the use of non-linear autoregressive exogenous (NARX) artificial neural networks (ANNs) to achieve black-box average dynamic models of dc-dc converters capable of capturing the main converter non-linearities. Non-linearities may include, for example, dynamic behavior variations due to changes of operating point or operating mode (e.g., discontinuous conduction mode, continuous conduction mode). This paper presents design guidelines for determining the NARX-ANN architecture and the dataset to be used in the training process. Dataset definition includes the choice of the perturbations for stimulating the aimed system behaviors and optimizations for dataset size reduction. The proposed approach is first derived for a dc-dc boost converter. To verify the generality of the proposed method, the same methodology is also applied to a Ćuk converter. In both cases, the proposed NARX-ANN modeling provided accurate results, with only limited deviations observed in the time-domain responses to step variations of duty-cycle and output current. The proposed model provided accurate small-signal behavior under different operating conditions. The validity of the approach is evaluated experimentally by considering a boost converter prototype.