AC-DC Converter Research Articles

Self-Sustainable IoT-Based Remote Sensing Powered by Energy Harvesting Using Stacked Piezoelectric Transducer and Thermoelectric Generator.

We propose a self-powered remote multi-sensing system for traffic sensing which is powered by the collective energy harvested from the mechanical vibration of the road caused by the passing vehicles and from the temperature gradient between the asphalt of the road and the soil underneath. A stacked piezoelectric transducer converts mechanical vibrations into electrical energy and a thermoelectric generator harvests the thermal energy from the thermal gradient. Electrical energy signals from the stacked piezoelectric transducer and the thermoelectric generators are converted into usable DC power to recharge the battery using AC-DC and DC-DC converters working simultaneously. The multi-sensing system comprises an embedded system with a microcontroller that acquires data from the sensors and sends the sensory data to an IoT transceiver which transmits the data as RF packets to an ethernet gateway. The gateway converts the RF packets into Internet Protocol (IP) packets and sends them to a remote server. Laboratory and road-testing results showed over 98% sensory data accuracy with the system functioning solely powered by the energy harvested from the alternative energy sources. The successful maximum transmission distance obtained between the IoT, and the gateway was approximately 1 mile, which is a considerable transmission distance achieved in an urban environment. Successful operation of the self-powered multi-sensing system under both laboratory and road conditions contributes considerably to the fields of energy harvesting and self-powered remote sensing systems. The energy flow chart and efficiency for the steps in the system were found to be mechanical power from vehicles to the energy harvester of 0.25%, stacked PZT transducer efficiency was found to be 37%, and for the TEGs the efficiency is 11%. AC-to-DC and DC-to-DC converters' efficiencies were found to be 90% and 11%. The wireless communication RF transceiver efficiency was found to be 62.5%.

Design and Implementation of Single-Phase Boost PFC Converter

In this paper, a single-phase boost type ac-dc converter with power factor correction (PFC) technique is designed and implemented. A current mode control at a constant switching frequency is used as a control strategy for PFC converter. The PFC converter is a single-stage singleswitch boost converter that uses a current shaping technique to reshape the non-sinusoidal input current drawn by the bulky capacitor in the conventional rectifier. This technique should provide an input current with almost free-harmonics, comply with the IEC61000-3-2 limits, and a system operates with near unity power factor. The other function of the boost converter that should beaccomplished is to provide a regulated DC output voltage. The complete designed system is simulated in MATLAB/SIMULINK and a hardware prototype has been built using analog devices. Simulation results and experimental results are presented to validate the proposed system.

Artificial Intelligence and Agent based Modeling for Power System Engineering

The fields of power electronics and fuel cells have emerged as key players in the development of sustainable power sources. The prevailing demand for fuel cells is projected to increase as they become the principal source of energy for portable electronics. A high-efficiency converter is a crucial component of the whole system and an absolute must for this specific use case. This is because the converter has a huge impact on the portability of the system as a whole in terms of size, efficiency, cost, and reliability. Choosing appropriate converter architecture is a key and important aspect of increasing the network of fuel cells for embedded systems since the converters alone accomplishes such as significant role in determining the overall efficiency of the system in this study, we take a look at the many topologies configurations of AC inverters and DC converters that are employed in the installation of fuel cells for autonomous and portable. The techniques of switching used in fuel cell energy conditioning are also analyzed in this research. The current issue with DC converters and AC inverters is also discussed at the end of this paper.

A Single-Stage Charger for LEV Based on Quadratic Buck-Boost AC-DC Converter Topology

A single-stage AC-DC converter, which uses a quadratic buck-boost voltage gain, for LEVs' (Light Electric Vehicles) battery charging is presented in this work. Unlike conventional BCs (Battery Chargers), which employ transformer (low or high frequency) based approaches to charge low voltages LEVs' batteries, the presented charger utilizes transformerless single-stage power architecture. In order to realize desired charging of LEVs and to maintain proper transformerless voltage gain, the presented quadratic buck-boost AC-DC converter ensures high step-down gain characteristics between AC mains and low voltage battery packs. Besides realizing desired battery charging profile, the presented single-stage BC ensures high PQ (Power Quality) indices (low input current distortions and unity power factor operation) at the supply side. Notably, the presented quadratic buck-boost AC-DC converter exhibits an intrinsic power factor correction (PFC) feature at the AC input mains under discontinuous inductor current mode (DICM) operation, thereby, incurring minimum complexities during the control implementation, which further reduces the cost of the charger. The DICM operation facilitates negligible switch turn-on and diode reverse recovery losses, and therefore, ensures an improved conversion efficiency of the BC. Even if, the presented AC-DC converter employs two switching devices, the simultaneous switching of both switches shrinks the cost and complexity of driving circuitry even further. Finally, a comprehensive operational analysis, component selection criteria, and modelling of the presented quadratic buck-boost AC-DC converter-based LEVs BC are carried out and its performance is validated through a test bench set-up in a laboratory environment. Relevant results are presented to validate the efficacy of the presented quadratic buck-boost AC-DC converter for LEVs charging applications.

Three-Phase Multiport DC–AC Inverter for Interfacing Photovoltaic and Energy Storage Systems to the Electric Grid

Distributed renewable energy sources (RES) in combination with hybrid energy storage systems are capable to smooth electric power supply and provide ancillary services to the electric grid. In such applications, multiple separate DC-DC and DC-AC converters are utilized, which are configured in complex and costly architectures. In this paper, a new non-isolated multiport DC-AC power inverter is presented, which comprises less passive components and less high-frequency power semiconductors. The proposed grid-connected multiport converter (MPC) enables the integrated power management of a photovoltaic (PV) array, a battery unit, a supercapacitor bank and the battery of an electric vehicle. The power circuit of the proposed MPC inverter is based on a new version of a split-source inverter topology to support bidirectional power flow and enables to connect the PV source directly to the DC-link. The proposed design is accompanied by a specifically developed control method which enables to implement the maximum power point tracking (MPPT) process without the need of any extra power converter, regulate the power flow at each port independently, as well as to control the power flow between its ports. An experimental prototype of the proposed MPC inverter has been constructed and its operation has been validated experimentally under various power flow scenarios.

Robust Integral Sliding Mode Control for Transient Voltage Support From Bidirectional Converter-Based Active Filters in Microgrids

The DC-AC conversion in microgrids leads to second-order oscillations in the DC side voltages and source currents. These oscillations are mitigated using either active or passive filters. Active filters are preferred, as they mitigate oscillations with lesser component size than passive filters. The active filters are regulated to absorb the harmonic ripples at the ripple frequency, and do not provide any voltage support during DC bus voltage fluctuations due to load changes. In this paper, a Robust Integral Sliding Mode Control (RISMC) is proposed to regulate Bidirectional Converter (BDC) based DC active filters to facilitate voltage conditioning along with reduction of second-order harmonics which are caused due to DC-AC conversions. The proposed RISMC enhances capability of the BDC active filters to provide DC bus voltage conditioning in case of transience during load variations and uncertain voltage fluctuations. The proposed control consists of a nominal dual-loop PI control which regulates the voltage of the storage capacitor of BDC and a non-linear integral sliding mode control which regulates DC bus voltage. The proposed control mitigates voltage and current ripples hence preventing them to propagate towards the sources while providing additional voltage support functionality. The proposed control is verified through simulations and experimentation.

A Multi-Port DC Power Flow Controller Integrated With MMC Stations for Offshore Meshed Multi-Terminal HVDC Grids

Multi-terminal dc (MTDC) systems have the potential to facilitate the integration of offshore wind farms. A dc power flow controller (DPFC) is necessary for meshed multi-terminal high voltage dc (HVDC) grids to regulate the power flow in dc lines. However, DPFCs based on modular multilevel converters (MMCs) require two dc-ac conversion stages and an extra ac transformer, which increases the cost and loss for offshore platforms. This paper proposes a multi-port DPFC that is integrated internally into the offshore MMC station, eliminating the need for an extra transformer and reducing dc voltage ripple. Additionally, the full bridge submodules (FBSMs) in the DPFC can further reduce the number of FBSMs required in the MMC station for dc fault blocking. The proposed DPFC is composed only of cascaded FBSMs connected to the arms of the offshore MMC station, which can exchange power directly with the MMC valve to achieve power balance. By using the MMC station, the proposed DPFC requires a small kVA rating, approximately 1%-5% of the total system power rating. The performance of the proposed DPFC is validated through simulation of a hybrid system of the IEEE 39 bus and the Cigre HVDC benchmark, and also through down-scale experimental testing.

3상 DC-AC 컨버터용 필름 커패시터 내부 상태 추정 기법 및 전해 커패시터와 비교 연구

Metalized polymer-film capacitors have acquired a distinctive position among a variety of capacitor types due to their self-healing ability. Therefore, these devices are appropriate for critical power applications that demand reliability and durability. Nevertheless, as converters are increasingly being used for transmissions in networks, it is essential to improve stability to ensure the safety of system operations. Therefore, it is necessary to have a monitoring process that enables predictive maintenance to evaluate the health status and ensure the stability of electrical systems. However, the research in this field concentrates on electrolytic capacitors; and the characteristics of electrolytic and film capacitors differ. Hence, the need for further investigation into film capacitors is evident. This research proposes a condition monitoring approach that employs frequency signal analysis to assess the health status of capacitors in a three-phase AC-DC converter. The capacitor current is subjected to discrete wavelet transform and normalized by various indices, which serve as the input for learning algorithms. In addition, for comparison, capacitor voltage, output current, and output voltage are investigated using the discrete wavelet transform and fast Fourier transform. In this study, various indexes including root-mean-squared value, variance, average, and median, are utilized as inputs for artificial intelligent models to investigate factors affecting film capacitors. Eight learning algorithms are implemented to monitor the health status of film capacitors. The results show that utilizing the discrete wavelet transform combined with indexes for capacitor current yields a high accuracy of approximately 99.85%. These findings offer valuable insights into monitoring film capacitors using advanced techniques, and are anticipated to be informative for practical applications of film capacitor monitoring.

Multi‐port single‐phase inverter considering battery‐alone mode for stand‐alone applications

SummaryThis paper presents a new single‐phase multi‐port DC–AC converter with high voltage gain in low duty cycle. The operation of the proposed converter consists of four modes, especially battery‐alone mode, which makes it appropriate for stand‐alone renewable applications. Using a suitable boosting method, this converter can achieve high voltage gain in all modes. The high gain performance of the converter occurs at both low shoot‐through duty cycle and high modulation index. Therefore, the output voltage and current harmonics as well as the filter size are reduced. In addition, the converter transfers the power with a continuous current through its input ports and has a common ground between the input sources and the inverter bridge. The positive features of this converter are the result of the appropriate design and localization of the bidirectional port that connects the battery to the converter. The proposed configuration includes an impedance network that protects the converter in the shoot‐through states and takes the advantage of the shoot through in its boosting performance. Another advantage of the proposed converter is that the voltage stress on the power switches on the DC side is considerably low. In order to validate the feasibility and effectiveness of the converter, a prototype rated at 110 V is prepared and tested.

Predicting the stability of smart grid for improving the sustainability using distributed generation technology

Distributed Generation balances the supply in the grid effectively. Numerous distributed power generation technologies need more efficiency, cost, and power output to meet the energy requirements. Hence, this paper has aimed to provide an efficient DG system by integrating a PV module with a smart grid through a 3-phase AC-DC converter. Numerous PV modules are combined through DC linking, and different inverter control strategies are used to control the network. The ANN algorithm is used to optimize the demand and supply in the network. PV modules are included in the network to boost up the renewable energy source for the network. The power generated from the PV module is converted to DC through 3 phase AC-DC converter. A DC-link modeling is carried out between various converters and PV modules. It helps balance the variation in the DC input from the PV modules converted by AC-DC converters. The input current is again sent into a closed-loop inverter system to control the input current appropriately based on the demand. The problems between demand and supply are sorted through an ANN algorithm that optimizes the whole model based on supply and demand. The whole is simulated, and the results obtained are discussed in detail. The results are compared with similar Distributed power generation technologies to compare their efficiency. The comparison clearly shows that the proposed model provides better environmental sustainability and expandability to the system.

Primary-side control for the flyback AC–DC converter

Graphical AbstractThis is a figure. Schemes follow the same formatting.

ITBC Controlled IPWM for Solar Based Wide Range Voltage Conversion System

This paper presents an isolated tiny or micro-bidirectional DC–AC converter (ITBC) that operates in a single-phase, single-stage, bidirectional, and isolated configuration. The converter utilises a voltage-in-phase PWM (IPWM) control scheme to regulate the potential conversion ratio of the converter, enabling it to handle a wide voltage range. The converter also enables smooth power flow direction changes and can achieve soft switching, resulting in high efficiency. A unidirectional current controller can be used for both DC–AC and AC–DC modes. The paper provides detailed information about the micro-inverter's working principles, design procedure, characteristics, and control strategy. The proposed solution is verified by a 500-watt test bench model with a voltage input range of 30 volts to 50 volts.

A Modulation Strategy With Transformer Leakage Inductance Energy Management for a Three-Phase Matrix-Based Isolated AC–DC Converter

Three-phase matrix-based ac-dc power conversion has recently gained popularity, considering its higher conversion efficiency and power density compared to the conventional two stage solutions. In the literature, several modulation strategies have demonstrated improved total harmonic distortion (THD) of the ac current in the matrix converters through independent control of the anti-series combination of active devices that form a matrix switch (i.e., two gate drivers per matrix switch). In this paper, a matrix-based ac-dc power converter that utilizes only one gate driver per matrix switch is proposed without compromising the quality of ac current. Managing energy stored in high-frequency transformer’s leakage inductor is an issue while utilizing single driver per matrix switch. An additional short-circuit leg is proposed to circulate stored energy in the leakage inductance during zero vector periods of the proposed converter, thereby ensuring continuous path for the leakage inductor’s energy flow. Steady-state analysis of the proposed ac-dc converter along with its loss modelling are presented with necessary mathematical expressions. The presented analysis and design of the proposed converter are experimentally validated on a 2 kW hardware prototype in the laboratory environment. A pertinent comparison of the proposed matrix-based conversion methodology with the conventional matrix-based conversion strategy is also provided.

Capacitor-Voltage-Balancing Control for Isolated Medium-Voltage AC-DC Modular Matrix Converter

This paper presents a capacitor-voltage-balancing control scheme for an isolated medium-voltage AC-DC converter using level-shifted PWM control of a modular matrix converter (MMxC). The proposed isolated AC-DC converter is composed of the primary MMxC with level-shifted PWM control, high-frequency transformer, and secondary H-bridge circuits. The high-frequency transformer of the proposed circuit can be downsized because the level-shifted PWM control scheme makes the rated frequency of the high-frequency transformer equal to the switching-frequency. The proposed capacitor-voltage-balancing control can compensate for the capacitor voltage imbalance of the MMxC using the positive-sequence and negative-sequence circulating-currents with a power supply frequency and high-frequency voltage. In the proposed control system, the three feedback control systems with DC control variables can be developed to compensate for the capacitor voltage imbalance. The effectiveness of the proposed capacitor-voltage-balancing control scheme and the control systems is verified by experiments using a 200V, 5-kW laboratory prototype.

Zero-Vector-Regulation-Based Closed-Loop Power Distribution Strategy for Dual-DC-Port DC–AC Converter-Connected PV–Battery Hybrid Systems

The dual-dc-port dc-ac converter-connected photovoltaic (PV)-battery hybrid systems present high-efficiency and low-cost features with single-stage power conversion as PV and battery are connected to the grid directly. However, it is challenging to achieve flexible power distribution in this configuration due to its coupled features in grid-side current tracking and power distribution. To deal with this issue, this paper proposes a zero vector regulation-based closed-loop power distribution strategy for the dual-dc-port dc-ac converter-connected PV-battery hybrid systems. By modeling the dual-dc-port dc-ac converter as an equivalent two-level one, an extra control freedom for power regulation is accessible and a closed-loop power control is adopted for flexible power distribution by zero vector regulation. With the proposed power distribution strategy, the desirable quality of the grid-side current is achieved without complicated voltage vector synthesis, along with good adaptivity to different modes/voltages and flexible power control. Besides, detailed power distribution discussion and analysis with different proportions of zero vector are carried out. Finally, the islanded microgrid experimental tests are conducted to verify its effectiveness and feasibility.

Robust current-mode control of bridgeless single-switch SEPIC PFC converter

In this paper, the nonlinear model of the bridgeless single-switch ac-dc single-ended primary-inductor converter (SEPIC) in discontinuous conduction mode is derived. In addition, a robust control method is introduced to accommodate the variations in input voltage and load current. The current-mode controlled power converter is designed to operate in buck and boost modes. The proposed closed-loop SEPIC converter is simulated in MATLAB to validate the design approach. The current-mode control scheme is also compared with the conventional voltage-mode controller. It is confirmed that the proposed control scheme exhibits precise tracking performance and enhanced transient response under large disturbances.

An Integrated Three-Phase AC–DC Wireless-Power-Transfer Converter With Active Power Factor Correction Using Three Transmitter Coils

Three-phase AC-DC converters are more commonly used for high-power applications compared to single-phase converters. For high-power wireless power transfer (WPT) applications, such as wireless electric vehicle chargers, usually a two-stage topology is applied, which consists of a three-phase AC-DC rectifier with power factor correction and a DC-DC converter for WPT. Recently, there are several studies on three-phase single-stage WPT solutions being proposed to reduce power conversion stages, and furtherly increase overall efficiency and reduce system cost. In this paper, an integrated three-phase AC-DC WPT converter topology with active power factor correction is proposed. The count of power semiconductor devices is significantly reduced compared to state-of-the-art three-phase single-stage topologies. Moreover, three transmitter coils are used to enhance the system power capacity. Topology description, operation analysis, control method, power loss analysis, and reference design guideline of the proposed topology are presented in detail. Finally, a laboratory prototype is built and evaluated. The functionalities, performances, and advantages are demonstrated by the corresponding experimental results.

Build a DC to AC Inverter Circuit with IOT Based Load Monitoring

Abstract: The boost inverter or boost DC-AC converter is a new voltage source inverter (VSI) that is suggested in this research. The novel inverter topology's key feature is that, depending on the instantaneous duty cycle, it produces an AC output voltage that is greater than the DC input voltage. This characteristic is not present in the conventional VSI, which consistently generates an AC output instantaneous voltage lower than the DC input voltage. A sliding mode controller is suggested to optimize the boost inverter dynamics while guaranteeing proper functioning under any working circumstance. The primary benefit of sliding mode control over traditional control strategies is its resistance to changes in plant parameters, which results in invariant dynamics and steady-state response in in the best scenario. This study covers operation, analysis, control technique, and experimental outcomes. When an AC voltage greater than the DC link voltage is required, the new inverter is designed to be employed in UPS and AC driver systems without the requirement for a second power conversion stage

PERFORMANCE EVALUATION OF AC-DC ACTIVE-PFC BASED CHARGING DEVICE FOR TWO-WHEELER EV APPLICATION

Fossil fuels emit greenhouse gases during their usage process. The emission of greenhouse gases leads to global warming. Alternative energy resources with zero pollution are a viable option in these modern days to protect the environment. Vehicular pollution contributes more to global warming and Electric vehicles (EVs) driven from a battery source can control this condition. Due to limitations in the storage system, electric vehicles are not much popular but to reduce the pollution from vehicles, EVs are a must and is recommended for (public/personal) transportation. EV (battery) is charged through a DC source (converting the available AC supply to DC). The conversion process diminishes the input source power factor and is a worrying factor. This paper addresses the power factor issue while charging the battery of EVs. The paper focuses on maintaining the unity power factor on the source side while charging the battery of the EV from AC-DC conversion. The model is developed and the results are discussed (for three different battery levels) using MATLAB/SIMULINK software.

Sliding Mode Regulation of a Boost Circuit for DC-Biased Sinusoidal Power Conversion

The boost converter is mostly used as a DC–DC converter, but two boost converter power stages can be configured to perform the DC–AC conversion. In this case, the control system of the power stage must be designed for trajectory tracking (instead of regulation), which brings interesting challenges. This work deals with the design of a higher-order sliding mode output regulator for a DC-biased sinusoidal power conversion problem on a single boost converter stage of a boost inverter for asymptotic trajectory tracking of the voltage capacitor. The steady-state reference signal for the inductor current is proposed as an approximated solution of the well-known Francis–Isidori–Byrnes equations. The used approach is the direct control of the output, where the nonminimum phase variable, i.e., an adequate sliding function, stabilizes the current through the inductor. Lastly, by means of real-time experimentation, the good performance of the proposed control strategy is verified.