Direct Power Transfer Research Articles

Extended Phase Shift Control of a Novel Bidirectional DC–DC Converter With Direct Power Transfer

Extended Phase Shift Control of a Novel Bidirectional DC–DC Converter With Direct Power Transfer

Comparing costs and climate impacts of various electric vehicle charging systems across the United States

The seamless adoption of electric vehicles (EVs) in the United States necessitates the development of extensive and effective charging infrastructure. Various charging systems have been proposed, including Direct Current Fast Charging, Battery Swapping, and Dynamic Wireless Power Transfer. While many studies have evaluated the charging costs and greenhouse gas (GHG) intensity of EVs, a comprehensive analysis comparing these systems and their implications across vehicle categories remains unexplored. This study compares the total cost of ownership (TCO) and GHG-intensity of EVs using these charging systems. Based on nationwide infrastructure deployment simulations, the change to TCO from adopting EVs varies by scenario, vehicle category, and location, with local fuel prices, electricity prices, and traffic volumes dramatically impacting results. Further, EV GHG-intensity depends on local electricity mixes and infrastructure utilizations. This research highlights the responsiveness of EV benefits resulting from technology advancements, deployment decisions, and policymaking.

Numerical study on a Franchot double-acting heat-driven thermoacoustic-Stirling cryocooler for natural gas liquefaction

Compact heat-driven cryocoolers can harness the thermal energy produced by burning a small quantity of natural gas to accomplish liquefaction. This addresses the requirements of distributed natural gas stations in remote locations. This paper introduces a Franchot double-acting heat-driven thermoacoustic-Stirling cryocooler designed for natural gas liquefaction. It conducts a comparative analysis of the mechanical and electrical systems, focusing on the acoustic field, available energy loss, and performance. Simulation results indicate that the optimized mechanical configuration system achieves peak performance with a piston area ratio of 0.84 and a piston phase angle of 90°. It yields a cooling power of 1964 W@130 K when driven by an 873 K heat source, resulting in an overall system efficiency of 28.3%. This marks a notable enhancement compared to current thermoacoustic systems. While the electrical configuration provides superior stability, the performance is constrained by significant losses in acoustic-electric conversion of linear alternators and compressors. To further enhance efficiency, it is worthwhile to establish direct power transfer between the pistons, for example, by aligning the expansion piston and compression piston coaxially. The evolved duplex configuration eliminates the loss from electrical energy conversion, leading to a remarkable 64.7% increase in overall efficiency. Simultaneously, this evolutionary approach offers a new perspective to elucidate the inherent connections among Stirling heat engines of Franchot double-acting and duplex. It provides valuable theoretical insights for the subsequent analysis and design of Stirling heat-driven refrigerators or cryocoolers.

A Bidirectional DC–DC Converter With Direct Power Transfer

A Bidirectional DC–DC Converter With Direct Power Transfer

A Multilevel Current-Fed DAB Converter With Direct Power Transfer

A Multilevel Current-Fed DAB Converter With Direct Power Transfer

A streamlined and enhanced iterative method for analysing power system available transfer capability and security

Available Transfer Capability (ATC) is a crucial indicator for ensuring the reliable and efficient electric grid as it helps to manage congestion and ensure that the power flows are kept within safe operating limits. This article presents a novel approach named as modified repeated alternating current power flow (MRACPF) with step-size control mechanism and compares it with the existing techniques like direct current power transfer distribution factors (DCPTDF) and repeated alternating current power flow (RACPF) for analyzing the ATC of the power system during bilateral wheeling transactions in MATLAB environment. The study further assesses the ATC in different multilateral wheeling transactions of two standard test systems (IEEE 30-bus and IEEE 118-bus) and evaluates inter-area ATCs for the IEEE 118-bus system under various operational scenarios. The Composite Security Index (CSI) which is based on both line flow limit and bus voltage limit violations is used to identify and rank the most severe (k-1) line contingencies, and is able to differentiate between secure and insecure state of the power system and furthermore, MRACPF with step-size control mechanism is used to assess ATC during the severe (k-1) line outage and generator outage scenarios for various power transactions. The MRACPF method produces comparable results to the RACPF method for obtaining the Available Transfer Capability (ATC), but it takes less time. This time savings can be significant, especially for larger power systems, where the execution time can be reduced by more than 50%.

A Dual-Frequency 3-D WPT System With Directional Power Transfer Capability at Two Separately Regulated Outputs

A Dual-Frequency 3-D WPT System With Directional Power Transfer Capability at Two Separately Regulated Outputs

A novel capacitor‐voltage reduced bidirectional PWM DC‐DC buck‐boost converter for renewable energy battery charge system

SummaryA novel capacitor‐voltage reduced bidirectional (CVRB) PWM DC‐DC buck‐boost converter is presented in this study. Compared to the conventional bidirectional buck‐boost converter, the proposed converter has a lower voltage rating filter capacitor. Accordingly, the given converter has a lower cost and higher power density than the conventional buck‐boost converter. Additionally, the proposed converter is more efficient due to the direct power transfer feature. Besides, the semiconductor switches have no extra voltage/current stress. The theoretical analysis of the converter is made, and its mathematical analysis is presented. The novel converter is experimentally operated in both the buck and boost modes. The experimental waveforms are shown for both operations. The proposed converter is operated in 100 W output power and 20 kHz switching frequency conditions. The efficiency of the proposed converter is 95.6% for the boost mode operation and 95.1% for the buck mode operation at the nominal output power.

Module-to-Panel Modular Differential Power Processing Converter With Isolated DC Bus for Photovoltaic Systems Under Partial Shading

The occurrence of partial shading is known to significantly reduce the energy yield of photovoltaic (PV) panels. Differential power processing (DPP) converters can prevent negative influences of partial shading at a substring level. For PV strings comprising numerous series-connected panels, however, conventional DPP converters face various issues, such as increased converter count, poor extendibility, and cumulative power conversion loss. This article proposes a modular DPP converter with an isolated dc bus for PV strings. The proposed DPP converter is the integration of panel- and module-level DPP converters. Four panels are grouped as a module having a DPP converter, and each DPP converter can handle four panels. PV systems can be scalable with no need to redesign the DPP converter as all modules are connected through the isolated dc bus. The isolated dc bus allows the direct power transfer from unshaded high-voltage modules to shaded low-voltage ones, reducing the cumulative power conversion loss. A field testing for a three-module PV string was performed using a prototype for a four-panel 1-kW module. The experimental results demonstrated 5.6% energy yield enhancement by the proposed DPP converter.

A Nine-Level Transformerless Boost Inverter With Leakage Current Reduction and Fractional Direct Power Transfer Capability for PV Applications

This article describes an integrated voltage-boosting technique, which is essential to achieve compatibility between low-voltage photovoltaic (PV) panels and high-voltage dc links needed for dc-to-ac conversion. To achieve the twin objectives of voltage-boosting and multilevel inversion, this article proposes a transformerless T-type nine-level hybrid boost inverter. To improve the efficiency in the boosting stage of the proposed converter system, a significant portion of the PV energy is directly transferred from the PV source to the load, while the other part is processed through an interleaved converter, which is fused with the inverter. Thus, the proposed converter ensures a higher power density and reduces the power ratings of the semiconductor devices. This article also introduces a modified zone-based pulsewidth modulation (PWM) technique, which achieves a complete elimination of the switching frequency voltage transitions in the total common-mode voltage (TCMV). Thus, this technique mitigates the generation of leakage current while preserving the advantages of conventional multilevel inverters such as low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{d}v/\text{d}t$ </tex-math></inline-formula> and inductive power capability. Besides that, a rigorous mathematical analysis for the common-mode equivalent circuit of the proposed configuration is also presented in this article. Detailed simulation and experimental studies are carried out to validate the feasibility of the proposed configuration.

Direct Electric Vehicle to Vehicle (V2V) Power Transfer Using On-Board Drivetrain and Motor Windings

Vehicle to vehicle (V2V) energy sharing is emerging as an alternate solution to range anxiety and limited charging infrastructure challenges associated with electric vehicles (EVs). The existing off-board dc fast charging options for V2V application found in the literature are not effective due to the additional weight, size and cost of the external charger or interface. In this article, a new V2V interface is proposed in which both EV’s motor winding neutrals and negative rails of on-board drivetrains are directly connected to each other. This further helps in forming an integrated dual bidirectional dc–dc converter to control the direction of power flow. The proposed approach does not require reconfiguration of motor winding or mechanical clutch to arrest the motor from rotating and/or the reconfiguration of drivetrain inverter connections. The major hardware requirement for the proposed approach is, access to the already existing neutral connection of the EV motor phase windings. To achieve dc fast charging, all three-legs of voltage source inverter of energy Provider-EV are switched using interleaved pulsewidth modulation. Furthermore, finite element analysis is presented for 150 kW EV motor model and its performance validation with the high frequency dc current flowing in the motor windings during the V2V operation. A scaled lab prototype is developed to demonstrate the energy sharing between two Lithium-ion battery banks through the proposed direct V2V power transfer concept.

A Power Factor Correction LED Driver With Direct Power Transfer Feature

This article presents an isolated bridgeless single-stage light-emitting diode (LED) driver with high power factor, soft-switching performance, and direct power transfer (DPT) capability. In the proposed circuit topology, a bridgeless boost power factor corrector (PFC) is integrated with an isolated current-driven half-bridge dc/dc converter to achieve a bridgeless single-stage PFC structure. Besides, a direct path is provided using coupled inductors to directly transfer power from the input source to the output. The bridgeless structure and DPT capability result in reduced conduction losses, while the soft-switching operation almost eliminates the switching losses. Therefore, the proposed LED driver benefits from low losses and high efficiency. The proposed LED driver is theoretically analyzed. Also, experimental results for a 150-W prototype supplied from a 120-V/60-Hz utility are presented to verify its performance.

A novel zero voltage transition boost converter and artificial neural network‐based estimation of converter efficiency

AbstractIn this paper, a novel zero voltage transition (ZVT) boost converter is proposed, and the overall efficiency of the converter is predicted with an artificial neural network (ANN) model. In the proposed converter, the main switch is turned on by ZVT and turned off by zero voltage switching (ZVS). Also, the other semiconductor elements operate by soft switching (SS). Besides, the proposed snubber cell has the bidirectional direct power transfer feature. The theoretical analyzes of the converter are verified by an prototype having 50 VDC input voltage, 100 VDC output voltage, 250 W output power, and 100 kHz switching frequency. The overall efficiency of the converter in hard switching (HS) condition is increased from 87.2% to 95.4% thanks to proposed snubber cell. Moreover, the efficiency of converter at HS operation is estimated with ANN. For this estimation, 110 efficiency values are obtained based on the different switching frequency and the output power values. When the actual efficiency measurements and the estimation results obtained with the ANN model are compared, it is seen that the results overlap and is obtained very close result to the truth by ANN. Thus, owing to the ANN model, the semiconductor power elements will not need to be operated at high frequencies and overheating, and the damaging to the elements will be prevented. Finally, the efficiency curve measurement of the converter takes long time in the experimental study when it takes highly short time as a few minutes in the estimation with ANN.

Bidirectional wireless power/data transfer via magnetic field

Recently, inductive power transfer (IPT) system has been used for wireless charging of electric vehicles (EVs). However, most of them only treat the issue of single directional wireless power transfer (WPT). This research proposes a novel bi-directional IPT (BD-IPT) scheme EVs, which can simultaneously transmit power/data via magnetic field when the mutual inductance changes. For power transmission, resonant inverters with phase-shift pulse width modulation (PSPWM) are used to generate carrier waves and alternating current. As for data transmission, a dedicated communication method with the accompanied protocol is proposed. Binary phase shift keying (BPSK) is used to simulate the two-quadrature amplitude modulation (QAM), which generates digital signals for data transmission without the need of extra communication links. Hamming codes are combined with single-error correction and double-error detection (SECDED) to ensure communication quality.

Charging strategy and scheduling algorithm for directional wireless power transfer in WRSNs

Wireless Power Transfer (WPT) technology plays a significant role to prolong the lifetime of wireless rechargeable sensor networks (WRSNs). To achieve stable and reliable energy supplements via wireless charging, the optimization of the trajectory of mobile chargers is crucial. In this paper, a charging strategy and scheduling algorithm for directional wireless power transfer in WRSNs is proposed. Firstly, the charging demand degree is defined to determine the priority of charging requests. Then, to avoid the occurrence of node's energy exhausted, the charger's orientation angle selection algorithm based on charging priority is designed. Finally, we formulate the problem of directional charger's deployment into discrete unit disk cover problem and propose a moving path planning scheme based on improved Genetic Algorithm to optimize the energy charging efficiency. Simulation results illustrate the benefit of our proposed scheme over the benchmark.

Actively controlled asymmetric edge states for directional wireless power transfer.

Wireless power transfer (WPT) has triggered immense research interest in a range of practical applications, including mobile phones, logistic robots, medical-implanted devices and electric vehicles. With the development of WPT devices, efficient long-range and robust WPT is highly desirable but also challenging. In addition, it is also very important to actively control the transmission direction of long-range WPT. Recently, the rise of topological photonics provides a powerful tool for near-field robust control of WPT. Considering the technical requirements of robustness, long-range and directionality, in this work we design and fabricate a one-dimensional quasiperiodic Harper chain and realize the robust directional WPT using asymmetric topological edge states. Specially, by further introducing a power source into the system, we selectively light up two Chinese characters, which are composed of LED lamps at both ends of the chain, to intuitively show the long-range directional WPT. Moreover, by adding variable capacitance diodes into the topological quasiperiodic chain, we present an experimental demonstration of the actively controlled directional WPT based on electrically controllable coil resonators. With the increase in voltage, we measure the transmission at two ends of the chain and observe the change of transmission direction. The realization of an actively tuned topological edge states in the topological quasiperiodic chain will open up a new avenue in the dynamical control of robust long-range WPT.

Interleaved Modulation Scheme With Optimized Phase Shifting for Double-Switch Buck-Boost Converter

Owing to low voltage stresses, wide range of input voltage and the same polarity of output voltage and input voltage, double-switch buck-boost converter (DSBBC) is a popular choice to achieve dc/dc conversion in photovoltaic generations (PV), power factor correction (PFC), portable devices and so on. Combined control (CC) makes DSBBC operate efficiently, but large ripples of output voltage are unavoidable during mode transition. With two equal duties, interleaved modulation (IM) makes the inductor ripple current decrease remarkably compared with synchronous modulation (SM) while inductor average current is still high. By introducing duty offset, inductor average current declines and efficiency is enhanced obviously under interleaved modulation with duty cycle offset (IMDO). However, with 180-degree phase-shifted angle, the ripple current is not low enough in some cases. Thus, to make further improvement on ripple current, an interleaved modulation scheme with optimized phase shifting (IMOPS) is proposed for DSBBC in this paper. Current features, optimal phase-shifted angle (OPSA) and operating region under IMOPS are described meticulously. Besides, theoretical and quantitative comparisons of different modulation schemes are presented, including inductor average current, inductor ripple current and ratio of direct power transfer (DPT). Based on a 150W prototype, the feasibility and effectiveness of IMOPS are demonstrated by experimental results.

New DC–DC Converter With Direct Power Transfer Capability

This article presents a novel isolated dc-dc converter circuit topology, which is able to offer high performance for a wide range of operating conditions. The prominent features of the proposed circuit topology include its direct power transfer (DPT) capability, quasi-rectangular waveform for the input current, and soft-switching performance for a wide range of operating conditions. The amount of power processed by the power switches and transformer is reduced through DPT. In addition, the quasi-rectangular waveform of the input current decreases its peak and root-mean-square values, leading to reduced conduction losses associated with the magnetics and power semiconductors. In the proposed structure, the power switches benefit from zero-voltage-switching characteristics, while the output diodes operate under zero-current-switching conditions. Thus, the proposed topology minimizes both the conduction and switching losses, thereby improving the overall efficiency. Extensive simulation and experimental results are provided to verify the feasibility of the proposed circuitry and demonstrate its superior performance.

Design of a 0.6-V, 429-MHz FSK Transceiver Using Q-Enhanced and Direct Power Transfer Techniques in 90-nm CMOS

A 429-MHz ultra low-power frequency-shift keying (FSK) transceiver (TRX) that is operated at 0.6 V at 200 kb/s is presented in this work. The receiver (RX) used in this work uses a proposed frequency-to-time-based technique that demodulates the output data by discriminating the corresponding date period. The proposed RX provides a sensitivity of −85 dBm at a bit error rate of 0.1% and consumes a power of 146 $\mu \text{W}$ . The 429-MHz FSK transmitter (TX) is also reported in this study. For eliminating circuits that consume high power, in particular power amplifier and phase-locked loop, the proposed TX adopts an oscillator that drives the antenna through an impedance matching network for power conversion. The TX consumes 390 $\mu \text{W}$ , supplies an output power of −8.2 dBm, and achieves a global efficiency of 38.7%. The TRX was fabricated in the TSMC 90-nm CMOS process.

Resource optimization in anti-interference UAV powered cooperative mobile edge computing network

Mobile edge computing (MEC) is a prospective technology to enhance the computing power of mobile devices by offloading the tasks to MEC server. Due to the limited size of mobile devices, the insufficient of battery becomes a serious problem. Wireless power transfer (WPT) and mobile devices cooperation can extend the endurance of mobile devices. Integrating unmanned aerial vehicle (UAV) into wireless powered MEC system, the energy collection efficiency can be improved with the short direct path power transfer. However, mobile devices will interfere with each other by utilizing the same bandwidth during the devices cooperation. In this paper, we proposed an anti-interference UAV powered cooperative mobile edge computing scheme, in which mobile devices utilizes different subcarriers to transmit the information. Moreover, a resource optimization problem is formulated to minimize the transmit energy of the UAV through joint subcarriers and power allocation of mobile devices with the constraints of delay and computing tasks size. Simulation results demonstrate the performance of the proposed scheme.