Balancing Device Research Articles

Analysis of axial force of double circular arc helical gear hydraulic pump and design of its balancing device

In view of the axial force produced in the working process of double arc helical gear hydraulic pump, the theory of differential equation of curve and curved surface was utilized so that the calculation formula of axial force was obtained and the relationship between the axial force and structure parameters of gears was clarified. In order to balance the axial force, the pressure oil in the high pressure area was introduced into the end face of the plunger to press the plunger against the gear shaft, and the hydrostatic bearing whose type is plunger at the end of the shaft was designed. In order to verify the balance effect of axial force, the leakage owing to end clearance and volume efficiency of gear hydraulic pump before and after the balancing process was analyzed. This paper provides a new analysis idea and balance scheme for the axial force produced in the working process of the double arc helical gear hydraulic pump, which can reduce the leakage owing to end clearance caused by the axial force and improve the volume efficiency of the gear hydraulic pump.

Modelling of transient and steady-state modes of a vertical rotor with an automatic balancing device

The authors of the study work out the differential equations of motion of a vertical rotor model on an elastic-dissipative suspension, balanced by a ball-type automatic balancing device. Often, the cross-section of the cavity of the body of the automatic balancing device is rectangular and during rolling the balls have two points of contact, in one of which the balls slide along the surface of the cavity. To prevent the balls from sliding, the inner surface of the cavity of the automatic balancing device is made in the shape of a torus, which provides one point of contact. The forces of gravity and the forces of resistance to the movement of the correcting weights are taken into account, and the model is drawn up for both viscous and dry friction forces inside the body of the automatic balancing device. The obtained mathematical model of the rotor makes it possible to study the transient and steady-state modes of motion of the rotor system.

Natural Amplification of Soft Defects Signatures in Cables Using Binary Time Domain Reflectometry

In our digital world, energy and data transmission play a major role and often rely on electrical wires. Some of these wires are used in harsh or aggressive environments and may be subject to defects. Security and preventive maintenance require tools to detect and precisely locate such defects. This paper details the Binary Time Domain Reflectometry (BTDR) method, presented earlier, which does not rely on the use of expensive and complex digital to analog and analog to digital conversion components. We explain the role of additive white noise and of the use of the time derivative for the improvement of its performances. The study focuses on BTDR's natural capacity of magnifying soft defects' peaks on the reflectogram. The method takes advantage of phase opposition to cancel the contribution of the extremities of the line under test and saturate the amplitudes of the remaining peaks. This can only be achieved if these contributions are equal or very close to each other. A balancing device is added at the cable's interface to meet this requirement. This low complexity additional system, made of two controlable digital potentiometers, is driven by the programmable logic digital system at the heart of the reflectometer. Direct magnification of very low amplitude peaks of incipient defects is obtained without any data post-processing. The amplification performance depends on the adjustment accuracy of the potentiometers and the hysteresis level of the comparator used to replace the converters.

Influence of operational changes of clearances in pump channels on the work of the automatic balancing device

Automatic balancing devices are used to balance the axial force in many multistage centrifugal pump designs. Despite the obvious advantages of these devices their failure is one of the main reasons for the complete failure of the pump unit. The axial force acting on the pump rotor can be changed under pump operation in a sufficiently large range and up to several tens of tons. Usually the calculation of automatic balancing device is made under pump's operating parameters. At the same time it is possible the changing of value of the axial force generated by the automatic balancing device on the calculated parameters due to the interdependence of hydrodynamic processes in clearances of the flow part of the pump and in the clearances of the balancing device. The analysis of possible causes of the axial force value changes as a result of unbalanced pressure forces acting on pump impellers and counterbalancing of axial forces arising in face gap balancing device is presented. An improved methodology for calculating the estimation of the axial force arising in the balancing device using the example of industrial multistage centrifugal pump is proposed.

Efficiency of the balancing devices to power quality improve

Violation of the symmetrical mode of operation of the electric network causes a deterioration in the quality of electric energy and significantly reduces the reliability of the functioning of electrical equipment and elements of the electric network. A mathematical model of an electrical network with a grounded neutral is proposed аnd a software package that allows us to evaluate the level of voltage asymmetry of a three-phase system depending on the changing unbalanced load was created. The simulation and calculation of the studied parameters for various combinations of loads and the technical means of balancing the operating mode of the electric network (the balancing device – BD) is carried out. Programs for the Matlab graphic editor are compiled and diagrams of changes in electricity quality indicators are constructed. A numerical analysis is carried out and recommendations are given to determine the most appropriate place for connecting the BD in the electrical network to improve the quality of electricity based on the calculation made.

Disaster-Aware Dynamic Routing for SDN-Based Multi-Site Data Center Networks

In recent years, cloud computing technology has been developing rapidly. As a result, the internal traffic of large-scale enterprises’ data centers has increased significantly. It has become important to improve the disaster tolerance capability of data centers to ensure user data security. However, the data center network relies on its physical infrastructure. Large-scale disasters may damage the infrastructure and cause huge data loss or connection interruption. Software-defined network (SDN) is an innovative network architecture that separates the control and forwarding layers of the network. Thus, SDN promotes network programmability and opens up new ways to design disaster-resistant networks. Based on SDN technology, we propose a disaster-aware dynamic routing (DADR) scheme. When a disaster signal is received, the SDN controller notifies the Global Server Load Balance (GSLB) device and stops declaring the IP of the disaster-stricken data center. At the same time, the SDN controller sends the server and client session information and the current traffic information of the disaster-stricken data center to other sites, where the optimal routing path is calculated for the data center based on the traffic characteristics by the proposed Lagrangian Relaxation based Bellman-Ford Parallel algorithm (LRBFP). Our results show that in the event of a disaster, based on the proposed DADR scheme and LRBFP algorithm, the packet loss rate and network delay can be greatly reduced.

Design, development, and calibration of bipedal force-plate for post prosthesis gait rehabilitation

There is a large demand for gait balancing devices for the above knee and below knee amputees after the installation of prostheses globally due to rehabilitation problems associated with prosthesis they occupied. Conventionally various methods used for this purpose those not affordable and not accessible easily and are not feasible generally as they need a lot of space and a well-qualified trainer which is not possible. So for it is required to design and develop an in-house transient force sensing device for lower limb amputees to get balanced in their gait cycle after wearing a prosthesis. Objectives of this research is to design and develop an affordable, accessible, easy to adopt and in-house force-plate for lower limb amputees to balance in gait cycle in four successive stride length after wearing prosthesis and improve their center of pressure line and to get quality of life. A force plate is designed via cad software and fabricated by the author. In this work, researchers passed through all the faces of such as design, modeling, fabrication electronic circuitry, interfacing, programming, and calibration. With the help of this force plate, an amputee can improve their gait cycle in five stride lengths one by one. Finally we have been designed and fabricated an in-house force-plate for lower limb amputees to get balanced in their gait cycle after wearing a prosthesis. A maximum deviation of 0.4 N was found from the tare value after experiments. From this limited study we conclude that the plate designed and fabricate can be used to improve the amputee's gait cycle and it has the potential to get easy access, affordability, less space occupying features.

Effect of front impeller seal leakages on centrifugal stage characteristics

One of the main criteria in designing a pump unit is its economic efficiency and reliability. The efficiency of the pump is impacted by losses which appear in the pump and can be classified into three categories: hydraulic, mechanical and volumetric. Volumetric losses in centrifugal pumps appear in impeller annular seals and throttling gaps of hydraulic balancing devices. Decreasing clearance in annular seals could, undoubtedly, reduce the volumetric losses and lead to an increase in pumps efficiency. In duties close to optimal, a volume of leakages is almost negligible for the main flow passing through the hydraulic passage. On the contrary, impact of leakages becomes significant at underloaded duties. This article deals with effect of leakages in impeller front seal on efficiency and head-capacity curve.

Study on Moving Strategy of Internal Mechanical On-Line Balancing System

Mechanical balancing system driven by the motor can cause wrong adjustment and long balancing time in the controlling process, which will result in lower accuracy of rotation. In order to solve this problem and achieve more efficient online dynamic balance, the optimal moving path of the built-in mass block of balancing device can be determined by us. Four kinds of moving paths for mass block are designed by using for balancing to make experimental verification of spindle dynamic balance movement. By comparing experimental results of balance accuracy and balance efficiency, the optimal dynamic balancing strategy is determined. The results show that the designed moving strategy is reasonable, and the moving optimized path can carry out more accurate control precision and shorter adjustment time to achieve the expected effect. The better control strategy of dynamic balance lays the foundation for the high-precision operation of the spindle system.

FS-MPC Based Thermal Stress Balancing and Reliability Analysis for NPC Converters

Active thermal control has been introduced to regulate the steady state and reduce the transient thermal-mechanical stress in power electronic modules. Specifically, it can equally distribute the temperature among the devices, thereby better distributing the stress among a set of devices and reducing the failure probability in the most thermally-stressed devices. This is of great importance for multilevel topologies and in particular for the Neutral Point Clamped (NPC) topologies, which have an inherent thermal unbalance among devices of the same phase. In hybrid structures, whereby Si and SiC devices are mixed to achieve a better trade-off between efficiency and cost, this problem is even worse due to technology differences. This paper investigates the advantages introduced by using Finite-Set Model Predictive Control (FS-MPC) algorithms designed for achieving a balanced device junction temperature in hybrid NPC and Active-NPC converters. Moreover, a novel setup composed by a hybrid ANPC based power modules is used to experimentally validate the presented FS-MPC algorithm. A lifetime estimation is performed for the two topologies to highlight the long-term benefits of FS-MPC algorithm in these hybrid topologies for UPS applications.

Static and dynamic characteristics analysis of self-balancing motorized spindle

In order to effectively suppress the vibration of motorized spindle caused by unbalance fault, realize online dynamic balance control of motorized spindle unit. A self-balancing motorized spindle with dynamic balancing device is designed and the finite element analysis of self-balancing motorized spindle is carried out. The static analysis is carried out, and the static deformation diagram of spindle is obtained after constraint and load are applied. Then modal analysis and harmonic response analysis are carried out, and the first six natural frequencies, mode shapes and displacement frequency curves of spindle are obtained. The results show that: The deformation of motorized spindle is small and rigidity of spindle meets design requirements: Within the working speed range, the spindle will not resonate and work stably and reliably. The rationality and reliability of structure design of self-balancing motorized spindle are verified.

A Novel DC Bias Suppression Method Considering the Cooperation of Multiple Devices

The dc bias phenomenon caused by the excessive current of the neutral point will pose significant threats to the transformers. The conventional suppression method based on capacitive dc blocking device (BD) can prevent dc bias current from penetrating the transformer winding and is the most widely used. However, due to the high investment cost of the BD, it is not appropriate to install the BD for all transformers around the grounding electrode. Thus the BD may redirect the dc flow from one transformer with a BD to the peripheral transformers without BDs, causing the neutral current to exceed undesirably. To address the problems above, a new type of current balancing device (CBD) is introduced, which can lead to flexible suppression of neutral current. Based on coordination between the BD and CBD, a global optimization configuration method is proposed. Unlike the existing suppression strategy based on dc bias suppression devices, the proposed method optimizes the configuration of suppression devices for each transformer from a global perspective in the planning stage, which is an effective supplement to the current suppression method. MATLAB-based simulation results verify the effectiveness and superiority of the proposed method by numerous comparative case studies.

Modified ball-type automatic balancer for rotating shafts: Analysis and experiment

The automatic balancer is a passive device with masses that are free to move in a shaft-concentric race. At supercritical shaft speeds, the masses automatically re-align to counteract imbalance and reduce vibration. This phenomenon is caused by the phase shift of the shaft bending response that occurs through resonance. The conventional automatic balancer (dual-ball, single race) reduces or eliminates vibration at supercritical speeds given a frictionless race, but increases vibration at subcritical and critical speed transitions. In this work, a fully passive, partitioned-track, automatic balancer with centrifugal clamps is proposed to improve performance during suboptimal operation. Both analysis and experiment are presented to support the novel design. Experimentally, a partitioned-race balancer reduced vibration by 7% during spin up, 83% at supercritical steadystate, and 65% during spin down – a complete improvement over conventional balancers. Model predictions are within 14% of experimental data at steadystate. Additionally, the use of centrifugal clamps reduced vibrations by up to 95% during critical speed transitions in analysis. The vibration reduction capability presented in this research outside of supercritical steadystate operation is a necessary advancement for the practical application of passive balancing devices.

STUDY ON THE SPINE HEALTH MANAGEMENT OF THE ELDERLY USING CENTER OF PRESSURE DATA

This study intends to develop a system for managing the health of the spinal joints of elderly people who mainly live on Korean floor heating (Ondol). The spine health management system consists of a seat cushion-type posture balance device that can measure the sitting posture, an application for smart devices capable of real-time collection of posture balance data, and a database server for analysis and visualized feedback of the data. Each force signal measured with the four load cells installed in posture balance device is wirelessly transmitted to an Arduino-based Android application, and the center of pressure (COP) value of the sitting position is analyzed using the four load cell data. To test the usability of the spinal health management system, the COP values of front, back, left and right torso tilts of healthy adults in a sitting position were measured with the posture balance device and 3D motion analysis program (Visual 3D, USA). After that, the COP values were compared and analyzed. As a result of the analysis, the COP direction data (front, back, left and right) measured with the posture balance device exactly matched the direction analyzed by the 3D motion analysis system.

Development of a control device of the traction battery operation

The necessity of control of charge and discharge modes of lithium-ion traction accumulation battery (TAB) of electric cars and hybrid cars is shown. It is possible to fully realize the capabilities of the traction battery set by the manufacturer only if you strictly ensure the modes of charge and discharge, i.e. maintaining currents and voltages on each element of the battery within acceptable limits. These modes must be provided by a special control system BMS (Battery Manger System). This article is devoted to the practical implementation of a possible use of such a system. Because the TAB elements are connected in series, the current in them is common and is controlled by a battery current sensor. The voltage at each element of the TAB must be monitored individually so that no element has an increase in voltage when the charge is above the maximum allowable, or a decrease in the voltage when the discharge is below the minimum allowable. The onboard charger is practically realized on the microhybrid car on the basis of the Lanos pickup car. TAB of this car consists of 20 cans of lithium-iron-phosphate batteries WB-LYP90AHA, capacity is 90 Ah, maximum charge voltage of one can is 3.6 V. The functional diagram of the onboard charger with balancing and protection system is given. At the input, the charger contains a power factor corrector. The galvanic isolation is made in the form of a resonant half-bridge DC/DC converter. The controller of the onboard charger stabilizes the charging current and voltage. When in the process of charging the TAB voltage reaches a maximum value of 72V, the controller begins to reduce the fill factor, and hence reduce the charging current, preventing further voltage increase. However, before the maximum TAB voltage is reached, the maximum voltage of the individual TAB elements will be reached. For these elements, further charging becomes unacceptable, so the work of the balancing system is necessary. The electric scheme is given and the principle of work of the BMS board is described.Keywords: electric car, hybrid car, traction battery, charger, power factor corrector, battery balancing device, charge and discharge controller.

Principles of a 3D printed mechanical device for total knee balancing

Implant alignment and soft-tissue balancing are important factors in total knee arthroplasty (TKA). The purpose of this study was to design a mechanical balancing device, which measures deflections resulting from forces applied on each condyle to provide numerical data indicating the extent of ligament release needed, or angular changes in the bone cuts required to achieve a balanced knee. Two mechanical devices were designed and 3D printed, Pistol Grip and In-line. The Pistol Grip design consisted of a lever system that indicated the difference between lateral and medial forces with a single pointer. The In-line design allows for the quantification of the absolute force applied on each individual condyle. The two designs were evaluated on a test rig designed to model balance and imbalance conditions in the knee. For the Pistol Grip design maximum pointer deflection indicates a 2 mm change in elevation per condyle and/or a 3 degrees angular change of the condyles which can be corrected by adjusting the ligament lengths equivalent to 2 mm and/or by modifying the proximal or distal femur bone cut by 3 degrees. For the In-line design, maximum pointer deflection represented a 40 N load on the condyle. Our mechanical balancer designs were successful in providing information that can guide surgeons to accurately achieve balance through ligamentous releases and/or modification to bone cuts. The balancer designs are easy to use, do not require any electronics or software, and can be incorporated into the surgical procedure.

72‐3: Influence of Mobility Effect on Top‐Emission Red Quantum‐Dot Light‐Emitting Diode with Weak‐Cavity Structure

Optimization of mobility is critical to achieving carrier balance in quantum dot light‐emitting diodes (QLED) which in turn is essential for high performance devices. In this paper, our red top‐emitting QLED devices possess maximum current efficiency of ~25 cd/A. We find that with appropriate annealing temperature of quantum dots (QDs)/ZMO the charge transfer balance of the device can be improved. We also present a simulation results of carrier mobility V.S. device performance based on the software SETFOS from Fluxim AG. The carrier mobility simulation is agreed with the experimental results. We believe that an applicable annealing temperature is favorable to achieve carrier balance, highly efficient and color saturation devices for display applications.

Quick Design of a Superjunction Considering Charge Imbalance Due to Process Variations

The breakdown voltage, ${V}_{{\text {BR}}}$ , of a superjunction whose pillar parameters, namely doping, length, and width, are optimized to yield the least specific ON-resistance, ${R}_{{\text {ONSP}}}$ , for the specified ${V}_{{\text {BR}}}$ , falls drastically for even small charge imbalances. Hence, a structure fabricated with these target parameter values often has a ${V} _{{\text {BR}}}$ much lower than specified due to the charge imbalance caused by random process variations. We give an analytical solution for alternate target parameter values which yield the specified ${V}_{{\text {BR}}}$ in spite of process variations, with minimum sacrifice in ${R} _{{\text {ONSP}}}$ . The solution is obtained by the method of Lagrange multipliers and a simple equation for the breakdown field versus charge imbalance. It is validated by TCAD simulation. It can either be approximated to a closed-form or can yield the target parameter values accurately with just a few iterations. Apart from eliminating the tedious iterations of prior design methods, our solution provides two new insights: when compared with an optimum balanced device, a device optimized considering typical charge imbalance has significantly lower pillar doping but almost the same pillar length and width; the breakdown field of a balanced device is a power law function of the pillar length alone. Although illustrated for 4H-SiC structures with ${V}_{{\text {BR,target}}}$ of 1–10 kV, our solution should work for any semiconductor after material specific changes.

Balanced Quasi-Elliptic-Type Combline Diplexer With Multiextracted-Pole Junction/Output Sections

A class of coupled-multiline quasi-elliptic-type balanced diplexer device with closely spaced channels and its balanced coupling-routing-diagram formalism to simultaneously model its differential- and common-mode operation are reported. It employs third-order combline-type bandpass filters (BPFs) in its filtering channels, whose resonating lines are connected at one of their extremes to the symmetry plane of the balanced-circuit structure (i.e., virtual grounds for the differential mode), along with a multiextracted-pole/coupled-multiline dual-band BPF junction and single-band BPF output cells. In differential-mode operation, the dual-band BPF junction adds one in-band pole to each diplexer channel and three transmission zeros (TZs) to both channels, whereas the single-band BPF output cells incorporate one in-band pole and two TZs in their corresponding channels. In this manner, increased-selectivity differential-mode BPF transfer functions for the diplexer channels when compared to those of its third-order combline-type BPFs are obtained. Grounded resistors are connected at the symmetry plane of the balanced diplexer for all the resonating lines of the combline-type BPFs, which become detuned with regard to the poles associated with the dual-band BPF junction and the single-band BPF output cells under common-mode excitation. This allows for high common-mode suppression levels in wide spectral ranges to be realized for both channels while maintaining the same TZs as in differential-mode operation. For practical-validation purposes, a 1.6-GHz/1.8-GHz microstrip prototype is manufactured and tested.

Automatic balancing devices of rotors of the knife refiners

The paper considers automatic balancing devices for knife refiner rotors which rotate in a two-phase or three-phase medium. The total imbalance of the mill rotor consists of mechanical, hydraulic and hydrodynamic components. The main component is mechanical imbalance, which changes during operation due to uneven wear of the headset. It is recommended to use automatic rotor balancing devices in the designs of these machines. These devices allow compensating for the mechanical component of the rotor imbalance without stopping the mill. A mathematical model and designs of automatic balancing devices for mill rotors have been developed. The proposed calculation method and design of automatic rotor balancing devices can be used in other machines, for example, in centrifugal pumps.