DC Energy Research Articles

Diagnostics and Fault Tolerance in DC–DC Converters and Related Industrial Electronics Technologies

The deployment of DC energy systems is an attractive alternative to conventional AC-based energy distribution systems, improving the efficiency of energy supplies and promoting renewable energies [...]

A Dual-Polarized Omnidirectional Rectenna Array for RF Energy Harvesting.

In this paper, a dual-polarized omnidirectional rectenna array using a hybrid power-combining scheme is proposed for the applications of RF energy harvesting. In the antenna design part, two omnidirectional antenna subarrays are created to receive horizontally polarized electromagnetic (EM) waves and a four-dipole subarray is produced to receive vertically polarized incoming EM waves. The two antenna subarrays of different polarizations are combined and optimized, so as to reduce the mutual influence between them. In this way, a dual-polarized omnidirectional antenna array is realized. In the rectifier design part, a half-wave rectifying structure is adopted for converting the RF energy into DC energy. Based on the Wilkinson power divider and 3-dB hybrid coupler structure, a power-combining network is designed to connect the whole antenna array and rectifiers. The proposed rectenna array is fabricated and measured under different RF energy harvesting scenarios. All simulated and measured results are in good agreement, which verifies the capabilities of the designed rectenna array.

Synchronous Switch Energy Extraction Circuit for Motor Regenerative Braking Enhancement

The synchronous switch technique has been utilized as a promising solution to enhance the energy harvesting capabilities of piezoelectric devices. It utilizes a switched inductive branch to compensate for the capacitive source and increase the real power. The synchronous switch technique was also extended to enhance energy harvesting from electromagnetic (EM) sources. This paper introduces a synchronous switch energy extraction (SSEE) circuit and examinates its performance in motor regenerative braking (RB) enhancement. In the SSEE scheme, a switched capacitive branch is connected to compensate for the inductive source of an electromagnetic motor. The output current from a coil is made in phase with the induced voltage source. The braking power is significantly improved. Therefore, the kinetic energy is extracted much faster to brake the motor quickly, while a portion of the extracted energy is harvested into storable electrical dc energy. This paper comprehensively evaluates the SSEE performances, in terms of energy harvesting and motor braking, respectively. Experimental results show that, given a flywheel released from the same speed, the SSEE can recover 182.5% more energy than the diode-bridge rectifier. For the braking performance, the SSEE can reduce the braking time by 35.1%, compared with the short-circuit braking (SCB) case.

Generation of Single Phase Energy from Inverter from Solar Tree

The solar tree is an innovative way to harness solar energy by installing solar panels on a tree-like structure. The energy generated from the solar panels is converted into usable electricity through an inverter. This paper focuses on the generation of single-phase energy from the solar tree with the assistance of charge controller and inverter. The solar tree consists of multiple branches, each with several solar panels installed on them. The solar panels are connected to a central inverter that converts the DC energy generated by the panels into usable AC energy. The inverter is also designed in this paper is used to regulate the output voltage and frequency to ensure that the electricity produced is stable and usable.

Research on the Optimal Design of a New Hybrid DC Energy Dissipation Valve

DC energy dissipation valve is the core equipment of offshore wind power flexible and direct transmission system. It is of great significance for protecting the operation safety of converter valve equipment and restraining the over-voltage of the DC bus in case of an AC fault at the receiving end. However, DC energy consumption device has many topologies and novel structure, and their equipment construction cost and operation reliability are one of the important factors limiting their engineering application. In this paper, the topological structure of a hybrid DC energy consumption device is studied, and the distributed resistance parameters of a hybrid DC energy consumption device are optimized. Based on the optimization scheme, a new switching control strategy and voltage sharing strategy are proposed, which improves the technical and economic efficiency of hybrid DC energy consumption devices. The feasibility of the proposed measures is verified through simulation and experiment, which is of engineering significance.

A Bidirectional Isolated Dual-Phase-Shift Variable-Frequency Series Resonant Dual-Active-Bridge GaN AC–DC Converter

This article presents a novel single-stage series resonant dual-active-bridge (SR-DAB) for grid-con- nected bidirectional ac–dc energy storage applications. The single-phase SR-DAB is connected to the grid with an unfolding bridge on the ac side. Three SR-DABs are utilized to connect to a three-phase grid. A control scheme that combines dual-phase shifts and variable frequency is proposed to achieve zero voltage switching and power factor correction over a wide range of ac and dc voltages and loads. A series of comparisons in terms of inductor root mean square current, turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> current of all transistors are conducted at different loads to prove the advantage of the proposed converter over the traditional dual-active-bridge-based ac/dc converter. A GaN-based hardware prototype connecting the 480Y/240/208 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta$</tex-math></inline-formula> three-phase grid to a 48-V battery was developed with a peak efficiency of 97.2%.

A Clockless Synergistic Hybrid Energy Harvesting Technique With Simultaneous Energy Injection and Sampling for Piezoelectric and Photovoltaic Energy

In this paper, a mutually synergistic hybrid energy harvesting (SHEH) circuit with both AC and DC energy harvesting capability is proposed. Within the proposed hybrid harvester, the vibration period of the piezoelectric transducer (PZT) is served as the switching signal for photovoltaic (PV) energy harvesting so that a dedicated clock generator is saved. Meanwhile, during the sampling phase, a small portion of the PV energy is injected into the PZT as an investment, which enhances the damping force and charge extraction of the PZT. Theoretically, the total synergistically extracted power from the proposed hybrid harvester is more than the sum of the power obtained from each transducer independently. The proposed SHEH circuit is fabricated with a 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process. The buck-boost converter with zero-current switching control achieves a peak efficiency of 82.8%, and the maximum efficiency of piezoelectric energy harvesting can reach 4.5 times that of the full-bridge rectifier.

ANALISIS PERFORMANCE INVERTER FULL BRIDGE SATU FASA

Technological advances are increasingly rapid and cannot be separated from the use of electricity for various types of electronic devices that use electrical energy. The use of electrical energy cannot be separated from DC and AC energy sources. The electric voltage itself can be done by changing or converting electrical energy from DC to AC using an inverter. The inverter itself is a device that can convert DC voltage to AC with a full bridge configuration that uses a transformer to get the best efficiency using a transformer, using an input voltage of 12 VDC to get 220 VAC by changing the value of the duty cycle used to find the results of the PWM wave and get the efficiency value. From these experiments it was then tested with 15W and 30W loads to get good efficiency values and wave output results.

Optimized Bidirectional DC-DC Converter Adapted to High Voltage Gain and Wide ZVS Range

As a key component connecting dc microgrid and energy storage system, dual active bridge (DAB) converter has some inherent problems under high gain conditions. To solve the problems, this article proposes a half-bridge cascaded DAB converter with partial switch sharing. The converter combines the advantages of high voltage gain, wide soft switching range and less reactive backflow loss, under a hybrid modulation strategy based on pulsewidth modulation control and phase-shift control. In this article, the output power, soft switching characteristic and reactive backflow loss are analyzed in detail. By using the Karush–Kuhn–Tucker function method to achieve multiobjective optimization, the system can achieve the zero voltage switch (ZVS) turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and reduce the reactive backflow loss. Moreover, the coupled relationships among variables are clarified clearly, and the system can achieve high voltage gain at low turns ratio. A 500 W, 100 kHz experimental prototype is built to verify the correctness of the theoretical analysis.

Hosting capacity enhancement of hybrid AC/DC distribution network based on static and dynamic reconfiguration

AbstractThe hybrid AC/DC distribution networks will have a crucial role in the future of smart grids due to their adaptiveness to a variety of DC loads and energy resources. Thus, it is necessary to assess and enhance the Hosting Capacity (HC) of these hybrid networks for the integration of Renewable Energy Sources (RESs). One way to increase the HC without further expansion in the grid is using the potential of Network Reconfiguration (NR). This paper proposes an HC enhancement model that includes AC/DC distribution NR. Two types of NR are considered, namely static, that is, embedding the NR capabilities at the planning stage, and dynamic, that is, using remotely controlled switches as an Active Network Management (ANM) scheme. Besides, two unique potential sources of hybrid AC/DC distribution networks that could be used for the HC enhancement are included, that is, reactive power control of Voltage Source Converters (VSCs) and the mesh operation capability. The problem is formulated as a mixed‐integer linear optimal power flow that aims to maximize the RESs HC under thermal and voltage constraints. Also, stochastic programming is utilized for managing the RESs uncertainties. The simulation results show the accuracy and efficiency of the proposed formulation from various perspectives.

Inverter-Less Integration of Roof-Top Solar PV with Grid Connected Industrial Drives

Green energy from Solar PV is getting increased attention in the industries due to the falling price of solar panels in the world market. A grid-tied inverter is one of the major components in such a system, where the DC energy from PV is converted to AC and synchronized with the grid to obtain power sharing between the PV and the grid for the industrial drives. In this paper, a DC link has been proposed instead of an AC link for interconnection between the solar PV system and the grid to run those industrial drives. In most modern industrial applications, induction motors are driven by VVVF (Variable Voltage and Variable Frequency) inverters to achieve efficient speed control. The inverters commonly have a rectifier section at the front end that rectifies the input AC to DC and the DC is then used in PWM mode to generate the required voltage and frequency for the induction motor operating under variable speed and load conditions. Such an inverter can use both AC or DC as the input so long the supply voltage has the right value for the inverter to operate. In our proposition, we eliminate the grid-tied inverter and use a DC link, created from the rectified AC and the regular Solar PV, to obtain the power-sharing between the PV output and the grid. Using the DC link output directly to energize the VVVF inverter has an impact on the performance of the inverter. In the proposed system, the solar PV array is designed in such a way that the grid remains as the supplementary power source only to supplement any shortfall in the PV output due to variable sunshine conditions. The control circuit used in this novel technique is inexpensive, efficient, and simple in design when compared to the grid-tied inverters. The proposed system has been implemented at Niagara Textiles in Gazipur, Bangladesh. The experimental/practical results are presented to validate the basic concept. Around a 20% reduction in the cost of energy has been reported in this paper, with a more than 90% efficient system. This will definitely make solar PV energy more competitive with regular energy and attractive to industries for its simplicity.

Design of advanced Aalborg inverter for extracting maximum power from renewable energy sources tied with autonomous grid system

AbstractOwing to increased energy demand, renewable energy sources have recently reached greater heights in the power industry. In this regard, integrating renewable energy with the power grid system has become essential in meeting consumer's energy demands. The novelty in this article is the design of an advanced Aalborg inverter with a reduced number of switches which results in enhanced system performance by reducing the switching losses. Integrating renewable energy sources with the power grid network has gained massive importance in supplying electric power to consumers. Integrating the power grid with renewable energy has become possible with the implementation of grid tie inverters. The only drawback in implementing renewable energy sources with the power grid is that the output of the resources varies from time to time in nature. Voltage Source Inverter‐based grid system requires two or three‐stage inverters for interfacing power units to transfer DC energy into the power grid network. To reduce the switching frequency across the system, many new excellent inverters have been designed to ensure the healthy operation of the system operating at a higher frequency. This article has been coined with the investigation of a novel buck and boosts converter‐based inverter operation named Aalborg inverter. The inverter operates at a higher frequency and minimum voltage drop across the inductor, where only one power stage has been implied to enhance the system's reliability and efficiency. This novel Aalborg inverter is applied and investigated for photovoltaic application.

A Novel Energy Harvesting Method for Online Monitoring Sensors in HVdc Overhead Line

Due to the lack of alternating electric fields and alternating magnetic fields in HVdc transmission system, there has been no sustainable and stable energy harvesting method compatible with them up to now, hindering the application of HVdc sensors. In this letter, we proposed a novel dc energy harvesting method using corona current, and an energy harvesting circuit is constituted with space ion flow generated by dc corona. The feasibility of the proposed method is increased by adding an artificial corona electrode and placing the load before the corona electrode. In addition, it can flexibly operate at any position in an HVdc transmission system according to actual demand. Then the output power is further maximized by adopting a capacitor with high working voltages. The detailed measurement results based on the experimental system validate the effectiveness of the proposed method, with a stable output power as high as 10.15 mW in a dc system of 22 kV. A detailed discussion of the overall performance is finally carried out.

Synthetic Resilience Exploration and Economic Defense Strategy for Microgrid-Level AC/DC Hybrid Energy System

For the ac/dc hybrid energy system, a resilience-oriented defense strategy is developed for survivability enhancement when subject to severe energy disruptions. On account of heterogeneous components, an integration index of synthetic resilience (SR) is formulated to assess the resilience capability of hybrid energy systems in the event of sudden energy changes. The derived SR is systematically illustrated in this work, which not only reveals its convexity feature but also visualizes the inherent self-healing resources during the ac/dc energy interaction. Based on the proposed resilience index and interlinking bridge of bidirectional converter, an economic defense strategy concerning uncertainties from renewable energies and loads is developed and system resilience is consequently reinforced by dispatching distributed energies according to individual marginal cost. Without the global coordination and mode transition, the system resilience is significantly strengthened and assessed by the proposed index and defense strategy, which formulates an operational paradigm for the microgrid-level energy hybridization considering load variation and renewable energy penetration. To completely demonstrate the effectiveness of the proposed index and defense strategy for the hybrid energy system, the controller-hardware-in-the-loop experiment results have been provided from six aspects of steady-state operation, dc demand variation, ac demand variation, renewable energy fluctuations, dc energy source failure, and ac energy source failure.

Configurable Hybrid Energy Synchronous Extraction Interface With Serial Stack Resonance for Multi-Source Energy Harvesting

Conventional multi-source energy harvesters use the time-division multiplexing (TDM) scheme, where the inductor operates in discontinuous current mode (DCM) and fails to perform well in continuous current mode (CCM). This article presents a single-inductor hybrid energy synchronous extraction circuit with serial stack resonance (SSR) for multi-source energy harvesting. The proposed circuit incorporates a synchronous electric charge extraction (SECE) circuit for ac energy and two buck–boost circuits for dc energy with a single inductor, which can operate either in a TDM mode to harvest energy from different sources separately or in an SSR mode to extract energy from multiple sources synchronously. The proposed harvester is fabricated in a 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process. It is configured with a photovoltaic (PV) cell, a thermoelectric generator (TEG), and two piezoelectric transducers (PZTs), where the number of PZTs is flexible to meet different application needs.

Design and Implementation of an Improved Automatic DC Motor Speed Control Systems Using Microcontroller

Energy wastage is one of the major challenges that is facing the world now as there is insufficient supply of energy and the little ones supplied was not appropriately used. This energy wastage has made many researchers to engage more on the research to stop this energy waste as a result of inappropriate allocation of energy to some devices even when they don’t need it. This research work was able to design and implement an improved automated DC Motor speed controller system using microcontroller successfully. The software used for this research work were Fritzing software and Arduino Nano. This project was able to improve on the working system of the DC Motors and energy was automatically and successfully saved. The system runs entirely on Bluetooth technology which consumes less power than other devices. The Android application is user-friendly with enhanced Wireless communication. This design was successfully developed and implemented with 80% accuracy. The design was able to work effectively by increasing the cutting speed when the softness of the material decreases and as the cutting tool material becomes stronger, the cutting speed increases. This showed that the design is effectively and efficiently developed with less energy/power consumption which is the earnest desire of an Engineer as it reduces cost. Keywords: Microcontroller, Improved Automatic DC Motor, Energy, Arduino, PWM

Modelling of a piezoelectric beam with a full-bridge rectifier under arbitrary excitation: experimental validation

Abstract This paper presents a set of nonlinear differential equations to model a piezoelectric energy harvesting (PEH) system with a full-bridge waveform rectifier (FWR) under arbitrary base excitations. The PEH comprises a piezoelectric element modeled as a current source with a capacitor in parallel, which are connected with an inductor and a resistor. The inductor is proposed to smooth the current generated by the piezoelectric element under rapid mechanical variations and improve the convergence of the set of differential equations. The equations are obtained using piecewise linear modelling for the diodes. The main advantage of this piecewise linear modelling is considering different bias points to represent the nonlinear characteristics of real diodes. Numerical simulations are employed to obtain the optimum inductor value through a comparison with an analytical result, validated with experimental tests. A real case of random acceleration in a bike is applied to the PEH-FWR to evaluate the performance of the proposed equations. They are validated with experiments, a LTspice formulation and a numerical previous one. The proposed formulation can estimate the output DC voltage and energy for a large range of excitation frequencies, including resonant and nonresonant conditions and arbitrary or harmonically externally excited PEHs with FWR.

Optomechatronics OMEGA design project of SSPS with MWPT and omnidirectional scanning antenna

<p indent="0mm">Owing to the difficulties and shortcomings of the OMEGA design of the space solar power station, this study proposes an optomechatronics OMEGA design project. First, a spherical crown (instead of the whole sphere) is utilized to collect the parallel sunlight, which is focused on the top-shaped line feed. The DC energy is sent to the transmission antenna. Thus, the problem of designing a special membrane, which is semi-transmitting and semi-reflecting for the sunlight and meanwhile transparent for the microwave, could be avoided. Then, the electric brush with ultra-large DC power is replaced with the traditional DC transfer method to overcome the critical problem of lower reliability. Next, using the omnidirectional scanning antenna, an electric propulsion technique is introduced to adjust the crown pose to replace the control system of the line-feed moving. Afterward, employing a bionic butterflying technology with topology optimization to radiate the massive heat to the cold space resulted in an innovative cooler, checking for both requirements of a bigger radiation size and an ultra-low selfweight, simultaneously.

High-Gain Circularly Polarized Antenna Array for Full Incident Angle Coverage in RF Energy Harvesting

In this paper, a high-gain circularly polarized (CP) hexagonal antenna array is proposed for RF energy-harvesting applications. The hexagonal antenna array is intended to operate at the frequency of 5.8 GHz. It is composed of 6 multilayer substrate CP antennas excited by an X-shaped aperture-coupling feed structure. A frequency selective surface (FSS) was added to further improve the gain, resulting in a maximum gain of 12.7 dBi per element. The main advantage of the proposed hexagonal antenna array is the ability to cover 360 degrees in the azimuth plane with a high gain in all directions without the use of any additional circuitry, allowing the effective absorption of ambient RF energy. A prototype was fabricated and measured, and a good agreement with the simulation results is achieved. In addition, a rectifier is used to convert RF energy absorbed by the antenna into DC energy at the frequency of 5.8 GHz. The measured RF-to-DC conversion efficiency of 44.5% and a DC output voltage of 423 mV at -10 dBm are observed. The performance of the rectenna array with one and six rectifiers has been demonstrated. With the use of a DC combiner, the total RF to DC efficiency of the array is 67.75%, with a DC output voltage of 1.115 V from -10 dBm has been recorded. Due to the immunity to misalignment of the CP antenna, the proposed rectenna array is very suitable for wireless power transfer (WPT).

Traceability Technology of DC Electric Energy Metering for On-Site Inspection of Chargers

The on-site inspection of high-power DC chargers results in new DC high-current measurement and DC energy traceability system requirements. This paper studies the traceability technology of electric energy value for automotive high-power DC chargers, including: (1) the traceability method of the built-in DC energy meter and shunt of the charger; (2) precision DC high current and small precision DC voltage output and measurement technology. This paper designs a 0.1 mA~600 A DC high current measurement system and proposes a 0.005 level DC power measurement traceability system. The uncertainty evaluation experiment of the DC power measurement calibration system and the high-power DC charger’s on-site calibration experiment results verify the method’s effectiveness and feasibility in this paper. The experimental results show that the combined standard uncertainty of the DC power metering verification system can be 0.0451%.