Power Flow Diagram Research Articles

Motion, Static Force, and Efficiency Analysis of Planetary Gear Transmission Based on Graph Theory

This paper employs graph theory to analyze kinematic relationships, static force, and power flow for planetary gear systems. We start from the graphs of these trains to determine all the structurally distinct kinematic inversions. We then obtain all the constructive solutions resulting from every possible combination of gear configuration. Based on the kinematic and static force analysis model, related matrices are acquired. Hence, a kinematic and static force analysis of the planetary gear mechanism is achieved. The link power can be determined by the link speed and torque. Power flow diagrams of each gear are acquired. The efficiency is calculated by the transmission ratio method. This analysis is useful in the design of power transmission applications. A planetary gear system of a 6HP26 automatic transmission is further illustrated for the motion, static force, and efficiency calculations by using graph theory technique and matrix equations. This paper provides a guide for engineers in gear transmission fields to easily finish mechanical transmission design.

Enhanced suppression of low-frequency vibration transmission in metamaterials with linear and nonlinear inerters

This study proposes the use of a linear and geometrically nonlinear inerter-based resonator in locally resonant acoustic metamaterials (LRAMs) and evaluates the performance on low-frequency wave attenuation. The LRAM is modeled as a 1D chain system composed of mass-in-mass unit cells connected by springs, and the geometrical nonlinearity is achieved by two lateral inerters linking the resonator and lumped mass symmetrically with respect to the horizontal springs. For the nonlinear inerter-based LRAM, the dispersion relation is analytically derived by a complex Fourier transform and the harmonic balance method. Compared with the linear inerter-based LRAM, the proposed nonlinear inerter-based structure has the property of a low-frequency bandgap with sufficient width for longitudinal wave propagation without being sensitive to changes in the inertance ratio. The nonlinearity can extend the original material parameter restrictions, leading to a lower-frequency bandgap. The results of dispersion properties are validated by wave transmittance and vibration power flow diagrams obtained by using the method of effective mass. It is shown that an adequate number of unit cells can achieve better wave attenuation performance.

Synthesis and Analysis of Three-Port DC/DC Converters with Two Bidirectional Ports Based on Power Flow Graph Technique

This paper presents a systematic topological study to derive all possible basic and non-isolated three-port converters (TPCs) using power flow diagrams. Unlike most reported TPCs with one bidirectional port, this paper considers up to two bidirectional ports and provides a comprehensive analytical tool. This tool acts as a framework for all power flow combinations, selection, and design. Some viable converter configurations have been identified and selected for further analysis.

Power Flow Analysis and DC-link Voltage Control of Hybrid Distribution Transformer

DC-link voltage control is a key issue for the reliable operation of hybrid distribution transformers (HDTs). This article uncovers the basic power flow principle of HDT based on the established dynamic power balance equations and the proposed power flow diagrams. Based on the derived differential equations and the transfer function models, the dc-link voltage control system with PI controller is developed. With the pure PI controller, the grid currents distortion and asymmetry cannot be well eliminated. To address this, an improved controller that includes a low-pass filter and three notch filters is designed. A disturbance feedforward loop is integrated into the improved controller, thus formulating a novel controller. This novel controller not only controls the dc-link voltage and grid currents with better dynamic performance but also eliminates distortion and asymmetry. Simulation and experiment results verify the correctness of the analyses and proposed methods.

Power Flow and Efficiency Analysis of High-Speed Heavy Load Herringbone Planetary Transmission Using a Hypergraph-Based Method

The existing research problem is that the hypergraph-based method does not comprehensively consider the power loss factors of the mechanical transmission system, especially the existing windage power loss. In the power flow diagram, it is difficult to express and calculate the power loss separately, based on the power loss mechanism. Furthermore, the hypergraph-based methods purposed by some researches are not suitable for high-speed and heavy-load conditions. This paper presents a new hypergraph-based method for analyzing the transmission efficiency of complex planetary gear trains. In addition, a formula for calculating transmission efficiency is derived. The power loss model is established for a high-speed heavy-load herringbone planetary transmission pair considering several sources of power losses such as gear meshing friction, windage, and bearing friction. Then, the efficiency of a two-stage herringbone planetary transmission system is calculated using the proposed method. Furthermore, the influence of input speed, input power, and lubrication state on transmission efficiency is investigated. Finally, the proposed method is verified by comparing calculated values with values published in the literature.

Research on Transmission Performance of A Seven-gear Three-degree-of-freedom Planetary Gear Automatic Transmission Based on Graph Theory and Matrix Equation

The transmission performance analysis of planetary gear automatic transmission is helpful for the following structural size optimization, hydraulic design and electric control design. The current graphic method has the disadvantages of low calculation accuracy and lack of intuition in numerical analysis method. This paper proposes a method to analyze the transmission performance based on graph theory and matrix equation. Firstly, a graph theory analysis model is established for the self-designed seven-gear three-degree-of-freedom planetary gear automatic transmission, and the structural characteristics of the transmission are analyzed. Then, on the basis of analyzing the shift actuator worksheet, the motion analysis model and torque analysis model of typical gears are designed by taking the first gear and the reverse gear as examples, and the speed and torque values of all gears of the transmission are calculated by using the corresponding matrix equation. Finally, the power flow diagram of the typical gear is established by taking the first gear and the fourth gear as examples, and the direction and numerical value of power flow are identified on the diagram. The results show that the method can realize the combination of qualitative and quantitative analysis for the transmission performance analysis of the planetary gear automatic transmission with multiple gears and multiple degrees of freedom, which is more intuitive, accurate and efficient.

Accurate active power flow diagrams of Brushless doubly-fed induction machine in motoring and generating modes

The brushless doubly-fed induction machine (BDFIM) shows interesting features for incorporating as wind generator or variable speed drive. The BDFIM operation is based on magnetic flow modulation of two stator winding fields through a special squirrel cage rotor. Hence, the power flow is very different from that of a regular induction machine. Taking into account, accurate analysis of the power flow is very valuable for the comprehension and design of BDFIM as well as the selection of converter capacity. In this paper, the power balance for BDFIM is discussed in the motoring and the generating modes and for both super- and sub-synchronous speed intervals. For this purpose, the power flow equations are extracted and power flow diagrams taking into account all the power loss components are presented. The accuracy of the proposed power flow diagrams is verified by comparing the obtained results with the experimental and finite element ones.

Multi‐channel VSI fed large variable speed asynchronous hydro‐condenser: fault analysis, fault diagnosis and fault tolerant control

Multi-level voltage source inverter (VSI) fed doubly fed induction machine (DFIM) has gained prominence in large rated hydro-generating unit (HU) since it provides part load operation with reduced power converter rating and high dynamic stability. Power converters connected in rotor side control real and reactive power of the unit. This study discusses the condenser operation of variable speed HU (250 MW), to be commissioned in Tehri plant (India), with the power flow diagram. Further, it provides dynamic behaviour and survivability status of the DFIM unit during power converter and control circuit faults where power converter redundancy is not available in large rated DFIM unit. Economic analysis of 250 MW HU under power converter and control circuit failures are also investigated. The present work also explores fault tolerant operation of a 250 MW DFIM unit at open switch fault in converters to increase the continuity of the unit operation which provides additional 2% of reactive power support to the grid compared to the DFIM without power converter redundancy operation. Open switch fault is detected through Park's vector phase currents technique and variation in DC link voltage. The computer simulation results are validated in an experiment carried on 2.2 kW DFIM in the laboratory.

Production of photonic nanojets by using pupil-masked 3D dielectric cuboid

Photonic nanojets can be created via plane wave irradiation of multi-shaped mesoscale dielectric particles, and a waist of full-width at half-maximum (FWHM) smaller than the diffraction limit can be achieved in this process. In this paper, photonic nanojet produced by a pupil-masked 3D dielectric cuboid lens is numerically investigated under the irradiation of 532 nm wavelength plane wave. It is found that a pupil-masked cuboid lens is not only able to produce photonic nanojets with shorter FWHMs, but also increase its maximal intensity at certain masking ratios on the receiving surface. This phenomenon is different from the result of the spherical-lens reported in previous publications, and is attributed to the convergence of power flow and near-field numerical aperture (NA) increase after analysis of simulated power flow diagrams.

Power-Flow Path Analysis of an Existing 8-Speed Bicycle Drive Hub

This paper presents kinematic analysis and power-flow analysis of an existing 8-speed bicycle drive hub by using the fundamental circuit method. First, a planetary gear mechanism, which consists of three basic planetary gear trains connected in series, and its clutching sequence table are introduced. Based on the fundamental circuits, six kinematic equations of the drive hub are derived. Then, the power-flow diagrams at related gears are illustrated based on the clutching sequence table, and the power-flow paths of the bicycle drive hub can be identified. The results of this study are beneficial to the development of multi-speed drive hubs for bicycles.

Efficiency analysis of two degrees of freedom epicyclic gear transmission and experimental validation

A complete method based on constraint analysis and virtual power is developed in this work. The method is applied to a two-dof epicyclic gear transmission for efficiency modelling and prediction. The power flow diagrams are constructed to obtain possible power flow patterns and to verify the balance of normal power flow and virtual power flow within the system. The theoretical efficiency formulas were derived for the full working range, and further verified by experimental data. It was found that two local loss factors are always coupled together in this device under test, and the same speed ratio may yield different efficiencies depending on the directions of the input angular velocities.

Computing the power flow and mechanical efficiency of in-hub bicycle transmissions

Purpose – The analysis of power flow and mechanical efficiency constitutes an important phase in the design and analysis of gear mechanisms. The aim of this paper is to present a systematic procedure for the determination of power flow and mechanical efficiency of epicyclic-type transmission mechanisms. Design/methodology/approach – A novel epicyclic-type in-hub bicycle transmission, which is a split-power type transmission composed of two transmission units and one differential unit, and its clutching sequence table are introduced first. By using the concept of fundamental circuits, the procedure for calculating the angular speed of each link, the ideal torque and power flow of each link, the actual torque and power flow of each link determined by considering gear-mesh losses, and the mechanical efficiency of the transmission mechanism is proposed in a simple, straightforward manner. The mechanical efficiency analysis of epicyclic-type gear mechanisms is largely simplified to overcome tedious and complicated processes of traditionally methods. Findings – An analysis of the mechanical efficiency of a four-speed automotive automatic transmission completed by Hsu and Huang is used as an example to illustrate the utility and validity of the proposed procedure. The power flow and mechanical efficiency of the presented 16-speed in-hub bicycle transmission are computed, and the power recirculation inside the transmission mechanism at each speed is detected based on the power flow diagram. When power recirculation occurs, the mechanical efficiency of the gear mechanism at the related speed reduces. The mechanical efficiency of this in-hub bicycle transmission is more than 96 percent for each speed. Such an in-hub bicycle transmission possesses reasonable kinematics and high mechanical efficiency and is therefore suitable for further embodiment design and detail design. Originality/value – The proposed approach is suitable for the mechanical efficiency analysis of all kinds of complicated epicyclic-type transmissions with any number of degrees of freedom and facilitates a less-tedious process of determining mechanical efficiency. It is a useful tool for mechanical engineering designers to evaluate the efficiency performance of the gear mechanism before actually fabricating a prototype as well as measuring the numerical data. It also helps engineering designers to cautiously select feasible gear mechanisms to avoid those configurations with power recirculation in the preliminary design stage which may significantly reduce the time for developing novel in-hub bicycle transmissions.

Kinematic Analysis of an 8-Speed Bicycle Transmission Hub

A transmission hub is a speed changing mechanism which is an important device in the transmission system of bicycles. This paper presents the kinematic analysis of an 8-speed bicycle transmission hub by using the fundamental circuit method. First, a distributed-flow type planetary gear mechanism, which consists of two parallel-connected transmission units and one differential unit, and the corresponding clutch sequence table of an 8-speed transmission hub are introduced. Based on the fundamental circuits, four kinematic equations of the transmission hub are derived. Then, the speed ratio of each speed is formulated, which is a function of gear ratios of external and internal gear pairs. By submitting the numbers of gear teeth into these formulas, the value of speed ratio at each speed can be calculated. Finally, the power-flow diagrams at related speeds are presented to illustrate the power-flow paths of the transmission hub.

On the classification of dielectric barrier discharge plasma actuators: A comprehensive performance evaluation study

The increasing popularity and maturity of plasma actuators for many flow control applications requires a common standard for plasma actuator performance evaluation. In the present work, a comprehensive comparative study of existing and new evaluation measures is presented, based on results from identical plasma-actuator configurations. A power-flow diagram is introduced that covers the entire range of power stages from the energy source to the flow-control success. All individual power stages are explained, existing controversial definitions are clarified, and an evaluation guideline is applied to previously obtained data. Finally, the defined systematic analysis is applied to the results of a recently conducted plasma-actuator in-flight experiment.

Mechanical Efficiency Analysis of a 16-Speed Bicycle Transmission Hub

This paper proposes an analytical method to evaluate the mechanical efficiency of the bicycle transmission hub. A 16-speed transmission hub, which consists of two transmission units and one differential unit, is presented first. By applying the concept of fundamental circuits, a step by step analysis process is then described to numerically calculate the angular speed, ideal torque and power flow, and actual torque and power flow by considering the gear-mesh loss of each link of the planetary gear train. Based on the power flow diagram, the mechanical efficiency at each speed of the transmission hub can be estimated.

On Performance and Efficiency of Dielectric Barrier Discharge Plasma Actuators for Flow Control Applications

With further maturity and applicability of plasma actuator flow control it becomes increasingly important to classify and quantify the net efficiency of plasma actuators, taking into account their effect on the flow and including a careful analysis and evaluation of the corresponding energy requirements. The present work provides such an evaluation standard with a comprehensive discussion of plasma actuator performance and efficiency. Existing evaluation strategies are reviewed, contradictory definitions presently found in the literature are clarified, and all discussed quantities are ordered into a universal power-flow diagram, serving as a guideline to classify and quantify plasma-actuator performance in flow control applications.

Design, analysis, and construction of a small scale self-excited induction generator for a wind energy application

Abstract This paper proposes the design, analysis, and construction of a three phase, 0.75 kW, 220/380 V, 3.4/2.0 A, Δ/Y connected, 4 poles, SEIG (self-excited induction generator) based on empirical rules. The designed SEIG offers improved high efficiency and power quality. The design takes into consideration a skew effect and power quality. A 2D-FEA (2 dimension finite element analysis) is used to consider core loss, flux density and circuit parameters of the designed SEIG. The designed SEIG has been tested and compared with a standard SEIG under various operating conditions in terms of efficiency and power quality. Consideration of capacitance for the SEIG based on steady-state equivalent circuit model and a power flow diagram is also given. Research results can be guidelines and recommendations for development of small wind induction generators for effective electricity generation.

Design and Performance Considerations of PFC Switching Regulators Based on Noncascading Structures

This paper systematically explores the performances of power-factor-correction (PFC) switching regulators based on noncascading structures in terms of efficiency, input-current harmonic distortion, and load voltage regulation. The investigation begins with simplified power-flow diagrams, which represent the noncascading PFC switching regulators and describe the essential features of the noncascading PFC switching regulators to achieve PFC and voltage regulation. Based on these diagrams, the noncascading PFC switching regulators can be classified into three categories, each offering a different set of performances. The first category permits a tradeoff between the efficiency and the input-current harmonic distortion, the second permits a tradeoff between the efficiency and the size of the storage element for the load voltage regulation, and the third allows a tradeoff among all the performances. With detailed analyses through analytical approaches, simulation results illustrate the performances of these three categories of noncascading PFC switching regulators. An experimental prototype of the third category has been built to validate the analyses.

Ultrasonic field generated by a transducer non axially located at the end of a cylindrical waveguide surrounded by an elastic medium

The calculation of the ultrasonic field generated by a transducer non axially located at the end of a semi-infinite cylindrical waveguide surrounded by an elastic medium is performed. Numerical results representing power flow, waveforms and dispersion diagrams to highlight non-axisymmetric waves are discussed.