Prototype Machine Research Articles

Alternative Surface-Mounted Permanent Magnet Topology for Reducing Voltage and Torque Harmonics in Shaft Generators

Traditional diesel generators on a merchant ship, composed of a wound rotor synchronous generator and a four-stroke diesel engine, supply electrical power for various loads. Recently, shaft generators for merchant ships have been increasingly replacing diesel generators to reduce CO2 emissions through fuel efficiency improvement. In particular, permanent magnet synchronous generators have replaced induction generators due to their high-efficiency characteristics at light loads. The surface-mounted permanent magnet rotor can be a suitable topology owing to the relatively short constant power range. This generator can also operate as a motor according to the propulsion mode, so minimizing the harmonics of the induced voltage with the torque pulsation being essential. This paper proposes an alternative surface permanent magnet topology. Three magnets comprise one pole, with one bread-loaf magnet and two rectangular magnets. It helps to simplify the magnetization and assembly of the rotor because of the flat bottom shape of the magnet. Due to the low remanence of two rectangular magnets at the pole edge, this rotor structure effectively makes the air-gap magnetic flux density sinusoidal with production costs reduced. The step-skew suppresses higher-order harmonics. The total harmonic distortion comparison of the two-dimensional finite element analysis and the no-load test result shows under 6% difference from the interior permanent magnet prototype machine. A comparison of harmonic characteristics with other rotors shows that the proposed modular pole has sufficient competitiveness compared to the tapered bread-loaf type. It can be applied as a substitute for the tapered bread-loaf magnet in direct-drive ship propulsion systems and is expected to shorten the manufacturing process and time.

The rotational movement in solution of fumaramide- vs. succinamide [2]rotaxanes: The influence of intercomponent interactions

Due to their intrinsic topological features, most artificial molecular devices are based on rotaxane molecules. One of the most important characteristics of this class of compounds is the likelihood of performing molecular movements, which are directly correlated with the intercomponent interactions present in these molecules. The tetralactam macrocycle is quite versatile and used in numerous molecular threads, which have stations that work as fundamental parts in the formation, molecular stabilization, and molecular movements performed. Inspired by how these stations may influence molecular movements (e.g., rotational ones), we sought to study two diamides commonly used as rotaxane stations: fumaramide and succinamide. In this context, we explored the change of station in six pairs of [2]rotaxanes. Studies were carried out in solution through NMR experiments with temperature variation techniques. In the crystalline solid state, the quantum theory of atoms in molecules analysis was performed through quantum mechanics calculations using the density functional theory. The rotational movement found for fumaramide-based [2]rotaxanes is, on average, over 14.91 kcal mol−1. In comparison, succinamide-based [2]rotaxanes have values of 12.78 kcal mol−1 (a 14% difference). In solution, fumadamide-based rotaxanes better retain the macrocycle due to the rigidity of the double bond, making its rotation more difficult and consequently leading to higher rotational energy barriers. In the crystalline solid state, the succinamide station, which has greater structural freedom due to the simple carbon–carbon bond, promotes more interactions, having a greater “complementary adjustment” and a higher stabilization energy. Lastly, our findings demonstrated how intercomponent interactions present in the studied stations can be changed to be used as a “lubricant” in solution for these molecular machine prototypes.

Performance Comparison of Tubular Flux-Switching Permanent Magnet Machines Using Soft Magnetic Composite Material and Hybrid Material Magnetic Cores

The magnetic core of a conventional tubular flux-switching permanent magnet machine (TFSPMM) is made of axially laminated silicon steel sheets. The laminated direction is consistent with the motion direction of the mover. According to the flux-switching principle, a large amount of eddy current loss will be generated when the alternating flux passes through the silicon steel sheets vertically. The soft magnetic composite (SMC) material is magneto-thermal isotropy and has low eddy current loss, which can be used in TFSPMM. However, the permeability of SMC is much lower than that of silicon steel sheets, and the hysteresis loss is large at low frequency. When the two materials are used as the hybrid material magnetic core in the machine, their respective advantages can be used to improve the thrust force of the machine and reduce core loss. In order to study the effect of SMC core and hybrid material magnetic core on the machine, the performances of TFSPMM with different kinds of cores are calculated and compared by finite element method (FEM), including magnetic density distribution, permanent magnet (PM) flux linkage, back-electromotive force (EMF), inductance, detent force, thrust force and core loss. Finally, a prototype machine with hybrid material magnetic core is made and experimental verification is carried out.

Optimal Stealthy Attack on Cyber-Physical Systems and Its Application to a Networked PMSM System

This paper investigates the stealthy attack on cyber-physical systems (CPSs) under the stochastic communication protocol (SCP), which is used to avoid data collisions. The attack stealthiness is characterized by the Kullback-Leibler divergence (KLD) and the attack performance is measured by the corrupted error covariance. This paper aims to maximize the attack performance for a certain stealthy level. Different from the existing results, our proposed attack strategy takes the SCP-introduced effects into account and exploits incomplete measurement outputs at each time instant to construct attack model. Then, a non-convex optimization problem is formulated to achieve the desired attack performance for a given stealthy level. By applying the monotonic optimization technique, the non-convex problem is converted to two optimization problems with equality constraints. Then, the analytical expressions of the attack parameters are derived. Finally, simulations on a three-tank system and experiments on a networked permanent magnet synchronous machine (PMSM) prototype system are conducted to validate our proposed theoretical results.

Investigation of Brushless Doubly-Fed Dual-Stator Machines for Traction Applications

Two brushless doubly-fed dual-stator machines with different inner-stator field windings, namely AC and DC field windings, are proposed and investigated. It is shown the proposed machine with AC field windings exhibits advantages of higher torque density and wider flux-regulation range compared with its DC field winding counterpart. Unlike conventional doubly-fed hybrid-excited machines, the proposed machine consists of AC field windings and hence resulting in more flexible field current control. Its armature and field windings are separately placed in two stators, which can alleviate the space competition between the field and armature slots, as well as significantly enhance the space utilization. Consequently, both flux-regulation capability and torque density can be effectively improved. The topology, operating principle, and mathematical model of the proposed machines are introduced. Then, a sectored flux-weakening control method is proposed and elaborated. Based on finite element method (FEM), the main electromagnetic performances of the proposed machines are comprehensively evaluated. The FEM results manifest the proposed machine with AC field windings shows greatly improved flux-regulation range, higher torque and output power under the proposed sectored flux-weakening method over the whole speed range. Finally, prototype machine of the proposed machine is fabricated, and experimental verifications are performed to validate the feasibility of the proposed machines.

Modelling and Analysis of Inter-Turn Short-Circuit Fault of PM Machines With Parallel-Connected Coils

This paper presents a general analytical fault model in a compact matrix form for surface-mounted permanent magnet (SPM) machines with parallel-connected coils, which is useful to study the machine performance under the inter-turn short circuit (ITSC) fault. To simplify the fault model, the multiphase Clarke transformation has been proposed. In the model, the branch currents rather than the phase currents are employed as state variables to describe machine behaviours under fault. Additionally, self- and mutual-inductances are obtained by winding function approach (WFA) plus slot permeance method. The proposed analytical fault model is applied to a 3 kW 96-slot 32-pole SPM machine and validated by time-stepping FE simulations. A small scale 12-slot 4-pole SPM machine prototype has also been built to further validate the accuracy of the proposed fault model.

MXene/perovskite-based bionic human odor sensor array with machine learning

Human identification is crucial in many fields. However, it is challenging to achieve instant and accurate human identification through body odors. In this work, an in-situ growth strategy was utilized to establish a gas-sensitive nanocomposite material library with MXene and perovskite. A plug-and-play bionic sensor array module based on the material library was manufactured and assembled into an instant detection platform (IDP). Machine learning (ML) algorithms were introduced to assist IDP in identifying human odors. Due to its unique Schottky Barrier structure, the material library exhibited higher performance and responded 37 % ∼ 70 % higher than initial MXene. IDP was applied to detect the odors of volunteers’ breaths and clothes with an accuracy rate of 69.2 % and 51.1 %, respectively, with the assistance of ML. In all, an instant, convenient, and accurate human identification prototype machine was fabricated, providing a general solution for more complex application scenarios.

Liquid food feeding machine prototype for seniors with Parkinsons disease

Over 1.6 percent of senior citizens who are 65 years or older in the United States have Parkinson's disease, which leads to economic, psychological, and physical problems for the patient and their families. Parkinson's disease patients usually have tremors in their hands, which takes away their ability to eat independently. According to research, the main food source for seniors is liquid food, since it is easier to digest. To solve this, this research created a prototype of an inexpensive liquid feeding machine for Parkinson's patients that is easy to use and install. This study used 3D-printed parts, laser-cut parts, and off-the-shelf parts. The feeding machine can replace the job of a caretaker so that seniors will be able to eat independently.

Analysis of losses in the high-speed PM BLDC motor with open slot stator core made of amorphous soft magnetic material

PurposeThe purpose of this paper is to verify results related to losses in the core of a brushless DC prototype motor, obtained using its computer FE models, by experimental tests on manufactured machines. The paper focuses on the comparison of losses in the core of a machine with a classical stator core made of an iron–silicon material (Fe–Si) and a new one made of a modern METGLAS material.Design/methodology/approachComputer models of the prototype motors were created using FEM. The designed machines were manufactured, and experimental tests were performed. To achieve high frequencies in rotating magnetic fields, motors with a stator to rotor pole ratio of 9/12 were built. Twin rotor approach was applied, as two identical rotors were built along the two geometrically identical stators made of different core materials.FindingsExperimental studies have shown the superiority of the METGLAS material over the classical Fe–Si material. Material parameters were measured directly on the prepared cores as library data used in the simulation may be incorrect due to technological processes during core production, which was also verified. Problems related to twin rotor approach have been identified. Solution to the problem has been suggested. Necessity of 3D FEM modelling was identified.Originality/valueThe main source of originality is that METGLAS material used in the prototype machines was developed and manufactured by the authors themselves. Original approach to core parameter evaluation based on simplified methodology has been suggested. Another original part is a simplified methodology applied to loss measurement during no-load test.

Design and Evaluation of a Spatially Distributed and Gear-Integrated Transverse Flux Machine

This paper presents a prototype of a planar aligned transverse flux machine with spatially distributed phases. This topology enables a flatter assembly space compared to typical transverse flux machines and, additionally, features a reduction gear. This makes it a suitable solution for low-speed high-torque applications primarily found in medical or industrial robotic surroundings. The exemplary motor is described throughout its design process and evaluated in detail in simulations and measurements. Benefits and challenges of the concept are considered and presented.

Near-Complete Suppression of Harmonic Currents in SPMSMs Caused by Back EMF and Dead Time

This paper introduces a novel algorithm forsuppression of phase current harmonics in three-phase sinusoidal surface mounted permanent magnet synchronous machines (SPMSMs) caused by non-ideal back-emf waveform and dead-time effects. Proposed feedback acquisition chain obtains an exact information on all the relevant harmonics within each period of the fundamental. Design of the harmonic current controller based on the internal model control principle is given. The paper outlines the relevant details of implementation and the results of verification performed by both computer simulations and experimentally, using a laboratory prototype machine. Experimental results, obtained in presence of non-sinusoidal back-emf and with erroneous dead-time compensation, prove the ability of the proposed solution to remove the stator current harmonics quickly, in just two fundamental periods, and thus eliminate torque ripple.

Design of Multi-Phase Combined Windings for Bearingless Machines

A generalized multi-phase (MP) combined winding design procedure for bearingless machines is proposed and developed. Using this procedure, new bearingless motor windings can be designed and conventional motor designs with MP windings can be transformed into bearingless motors by simply modifying the phase currents. The resulting MP winding is excited by two current components – one responsible for torque creation and another for suspension force creation. By applying the appropriate Clarke transformation, independent control of force and torque can be achieved. Although there are numerous papers in the literature studying bearingless machines with MP windings and their advantages, this is the first paper to provide a formal design procedure that can be applied to any MP winding configuration. The proposed approach can be used to realize popular winding designs, including concentrated- and fractional-slot windings, and is applicable to all radial-flux bearingless machines. The paper uses the Maxwell stress tensor to formulate the force/torque model for the MP combined winding and uses the results to derive design requirements. A sequence of winding design steps is proposed and used to design example MP combined windings. Experimental validation is provided using a six-phase bearingless induction machine prototype.

Design and Fabrication of Plastic Shredding Machine

Abstract: Plastic is one of the most common used materials in the world today, but, they cause serious environmental pollution and exhaustion of landfill space. The recycling of waste plastic recovers the material, which can be used to make new plastic products such as containers, plastic lumbers and particle boards. For this to happen, the waste plastic will first be the effect of plastic waste is environment problems such as: chain food disturb, contaminate ground water, air pollution, extinction anima, poisonous soil, and act. One of the handling for plastic waste is recycling. It starts with separating plastic waste by kind of plastic. The next step is crush it until it becomes small flakes. The Small flakes can be directly used for making product such as pot, filler material for mixing with road asphalt or plastic granulate for making a product by injection mold or extraction. In order to handle plastic waste into small flakes, plastic shredder can be used to realize the making of prototype of plastic shredder machine. The concept design of the shredder machine that is currently available is fairly similar. The shaft and blades are the critical components in the shredder machine that determines its performance. The geometry and orientation of the blades that were fitted into the single or double-shafts were found to directly affect the shredding performance. Therefore, this article aims to review the various geometry and orientations of the blades that give direct effect on the shredding performance, as well as identifying the research gaps related to the shredder machine for plastic waste materials.

In‐depth investigation of inter‐turn short‐circuit faults of surface‐mounted permanent magnet machines with series‐parallel coil connections

AbstractA general analytical model is developed in a concise block matrix form for surface‐mounted permanent magnet (SPM) machines with series‐parallel coil connections under inter‐turn short circuit (ITSC) fault. In the model, branch currents are used as state variables and inductances of different series‐parallel coil connections are calculated using an analytical method, namely winding function approach (WFA) together with slot permeance method. Based on the characteristics of the calculated inductances and the developed fault model, the multiphase Clarke transformation has been proposed to simplify the fault model. In the process of model simplification, the healthy machine model using branch currents as state variables have been proven to be equivalent to that using 3‐phase currents as state variables. The proposed fault models of a 3kW 96‐slot 32‐pole SPM machine with different series‐parallel coil connections have been built in Matlab/Simulink and validated by time‐stepping 2D FE simulations. Simulation results show that different series‐parallel coil connections have little influence on the amplitude of the ITSC current. Finally, a small scale 24‐slot 8‐pole SPM machine prototype has been built to further validate the accuracy of the proposed fault model.

An Influence of Spatial Harmonics on an Electromagnetic Torque of a Symmetrical Six-Phase Induction Machine

The analyses of the influence of spatial harmonics on the electromagnetic torque of the multi-phase induction machine and reducing this influence are important tasks to ensure the high efficiency of the induction machine. Designing the machine to consider the influence of spatial harmonics is essential to ensure the desired mechanical and energy characteristics. In the case of the sinusoidal winding supply of the induction machine, the magnetomotive force has high spatial harmonics, which are caused by the machine-winding design. The interaction between the 5th, 7th, 11th and 13th spatial harmonics of the winding function and the first time-harmonic of the winding supply causes the appearance of the 6th and 12th harmonics in the electromagnetic torque of the machine. A prototype of the symmetrical six-phase induction machine and the experimental study for the influence of spatial harmonics on the harmonic content of the stator currents in different machine modes are given in this paper. The mathematical model of the six-phase induction machine has been developed using the average voltages in integration step method. The introduction of the harmonic components into the magnetization inductance in the mathematical model of the six-phase induction machine for taking into account the spatial harmonics of the machine-winding function is proposed in this paper. The adequacy of the mathematical model was confirmed by comparing the simulation and experimental results. The harmonic content of the electromagnetic torque, which is caused by spatial harmonic influence, is analyzed.

Development of an innovative test machine for tyre, wheel and suspension systems for automotive and industrial vehicles

Reliability and efficiency of automotive and industrial vehicles are strongly affected by the behaviour of the components involved in the interaction with the ground. For this reason, components like tyres, wheels and suspension systems are physically tested, for performance and durability assessment. Anyway, standard test machines are generally designed for testing only one specific component.The aim of this work is the design of an innovative test machine, able to perform different kinds of tests, for tyre, wheel and suspension system components, on a unique bench. The machine is a flat track type, better fit than traditional drum types in simulating real tyre-to-ground contact conditions. The core of the machine is a Gough-Stewart platform, where the flat track is fixed, which is moved by six hydraulic actuators to reproduce multiple work configurations, for extended time periods or numerous test block repetitions. After the preliminary design phase, the machine components were subjected to topology optimization and modal analysis by FEM, to reduce weights and avoid any issues related to the expected working frequencies. Given the quality of the results achieved, currently, the software design for closed-loop control configuration is under development, for the machine prototype next construction.

Accelerated Production of Biopharmaceuticals via Microwave-Assisted Freeze-Drying (MFD).

Recently, attention has been drawn to microwave-assisted freeze-drying (MFD), as it drastically reduces the typically long drying times of biopharmaceuticals in conventional freeze-drying (CFD). Nevertheless, previously described prototype machines lack important attributes such as in-chamber freezing and stoppering, not allowing for the performance of representative vial freeze-drying processes. In this study, we present a new technical MFD setup, designed with GMP processes in mind. It is based on a standard lyophilizer equipped with flat semiconductor microwave modules. The idea was to enable the retrofitting of standard freeze-dryers with a microwave option, which would reduce the hurdles of implementation. We aimed to collect process data with respect to the speed, settings, and controllability of the MFD processes. Moreover, we studied the performance of six monoclonal antibody (mAb) formulations in terms of quality after drying and stability after storage for 6 months. We found drying processes to be drastically shortened and well controllable and observed no signs of plasma discharge. The characterization of the lyophilizates revealed an elegant cake appearance and remarkably good stability in the mAb after MFD. Furthermore, overall storage stability was good, even when residual moisture was increased due to high concentrations of glass-forming excipients. A direct comparison of stability data following MFD and CFD demonstrated similar stability profiles. We conclude that the new machine design is highly advantageous, enabling the fast-drying of excipient-dominated, low-concentrated mAb formulations in compliance with modern manufacturing technology.

Implementation and analysis of mono inverter-battery configuration for wind driven doubly fed induction generator

ABSTRACT This paper investigates the controller implementation and analysis of Doubly Fed Induction Generator (DFIG) for powering isolated loads in rural electrification. A simple speed sensorless algorithm-assisted controller for isolated power supply of DFIG has been proposed using a digital controller and voltage source converter at the rotor terminals of the generator. The controller can automatically correct the voltage and frequency of the rotor side inverter pulse to obtain a desired voltage and frequency at stator side despite the variations in the wind speed and load. A hardware prototype of the system has been built and tested on a prototype machine, which is driven by an emulated wind turbine under sub-synchronous and super-synchronous speed operations. The detailed results of both simulated and hardware waveforms are provided in the paper to demonstrate the working of the proposed topology and embedded control scheme. Further, the performance characteristics of DFIG are modeled and verified experimentally. A good agreement exists between theoretical and experimental results.

Design and Simulation of Banana Pseudo-stem Fibre Extracting Raspador (Cylinder) Using FEA Technique

ABSTRACT Development of mechanical fiber extractors without considering engineering knowledge can cause failures of the machine’s components during operations. Therefore, the present study was conducted to examine the structural strength of the banana pseudo-stem fiber-extracting raspador using finite element analysis. For measuring the force required to extract the fibers, a measuring setup along with an embedded system was developed using the ATmega328P microcontroller, DYMH-103 load cell, and 24-Bit ATD converter, and it was found that an average of 99.09 N force was required to scratch the fibers from single pseudo-stem sheath. Three computer-aided design (CAD) models of raspador having tip angles of blades of 25°, 35°, and 45° were developed in the Creo-Parametric software and simulated in the Ansys® software using three material properties, i.e. high-carbon steel, medium-carbon steel, and low-carbon steel. The results of both static structural analysis and explicit dynamics simulation analysis suggested that the CAD model with 45° tip angle of blade having low-carbon steel has a higher value of total deformation and maximum principal stress and a comparatively lower value of equivalent elastic strain than other models and under the yield limit of the parent material. Hence, it may be used for the development of a prototype of a banana pseudo-stem fiber-extracting machine.

An effective approach for non-singular trajectory generation of a 5-DOF hybrid machining robot

By taking a newly developed 5-DOF (degree of freedom) hybrid robot as an exemplar, this paper presents a novel and effective approach for non-singular tool trajectory generation. Based upon singularity analysis via inverse kinematics, an algorithm for the C-axis path optimization is developed using the weighted S-curve. Incorporated singular domain detection with the C-axis angle correction, the algorithm can easily be programmed and embedded into the CNC (computer numerical control) system as a postprocessing module and works in real-time. Then, an offline feedrate scheduling method is proposed by considering the drive and geometric accuracy constraints, allowing the rapid yet smooth movement in the neighborhood of singularity to be achieved. Additionally, it is found that the orientation accuracy can be improved by setting adequate cone angle and feedrate value. The results of both simulations and experiments on a prototype machine show that the C-axis can follow the non-singular tool trajectory well with relatively high rotary speed to pass through the singular domain, thereby verifying the effectiveness of the proposed approach.