Modular Machine Research Articles

Fault-Tolerant Modular Stator Concentrated Winding Permanent Magnet Machine

This paper studies a modular permanent magnet synchronous machine (MPMSM) converted from a traditional single-core 24-slot 20-pole tooth-coil winding permanent magnet synchronous machine (TCW PMSM). The performance of the TCW PMSM is compared with the performance of the MPMSM (rearranged from this TCW PMSM) by the finite element method (FEM). It is found that if an electrical machine with a modular structure is designed, the efficiency of the MPMSM may be degraded compared with the conventional structure, especially, if a solid rotor yoke is used. However, the advantages of the proposed MPMSM are related to an option to scale up the machine by applying a certain number of modules, or removing faulty modules (while keeping the healthy modules working). This makes this type of a motor design applicable in certain life-critical applications, or in applications where scaling of the motor power might be needed. As a prototype, a low-power, low-speed generator added to a hook block of a hoist to supply power to measurement electronics is studied.

Development of means of mechanization of fodder production

Annotation Purpose.Establishing the main directions of development of technical means for the preparation of feed for the current state of development of technology in Ukraine and the world. Methods.Monographic, analytical, systematic analysis of the transformation of technical objects and technological processes of harvesting and storage of stem feeds and prospects for their development. Results. Prospects for the development of dairy farming in Ukraine are identified, the main machines for stem fodder harvesting are identified, the characteristics of domestic and foreign production machines are analyzed, their differences are determined, examples of innovative developments in some types of technical means for fodder harvesting are given. Conclusions. Feed harvesting machines produced by Ukrainian producers do not meet the needs of milk producers with more than 120–150 cows, are produced irregularly, in separate batches. Domestic manufacturers of machines for forage harvesting do not produce the entire list of necessary machines. Only the simplest machines of low productivity are issued, use of means of automation of the executed processes is absent. Based on the research of NSC “IAEE”, some samples of innovative forage harvesters and their promising working bodies have been developed and tested. In most types of machines there are noticeable signs of modularity, unification. To provide livestock producers with feed preparation machines, it is necessary to organize (program) the production of standard-sized rows of modular machines agreed with each other on productivity (working speed, width of capture) in accordance with the available energy resources. Keywords: dairy cattle breeding, fodder stem, mower, mower-shredder, stirrer, rake, press-sorter, forage harvester, standard-size range, modular structure.

Modularity and Integrability-based Energy Minimization in a Reconfigurable Manufacturing Environment: A Non-linear Mixed Integer Formulation

Abstract Nowadays, manufacturing environment is characterized by the necessity of customized flexibility as well as responding rapidly and cost-effectively to changing market demands while minimizing impacts on environment and society. To reach these goals, a key paradigm called sustainable manufacturing can be coupled with reconfigurable manufacturing systems (RMSs). The coupling of RMS characteristics and sustainability concerns is a basis to develop a new generation of sustainable production systems. This paper outlines sustainability in a reconfigurable environment from an energy consumption point of view. A nonlinear mathematical model is developed to optimize the energy consumption of a RMS through a redefinition of its core characteristics—modularity and integrability. The objective is to minimize the energy consumption of the system by selecting the most suitable modular machines from a set of candidate machines. The optimization problem is addressed using an exhaustive search heuristic. Finally, the applicability of the proposed approach is illustrated through a simple numerical example and the discussion of the obtained results.

Determining and Evaluating Trajectories of a Modular Machine End-Effector in a Manufacturing Environment using a Game Engine

The University of Stuttgart’s Institute of Industrial Manufacturing and Management (IFF) has proven the feasibility of using a game engine for modelling, visualizing and controlling highly complex production modules in a user-friendly and effective way. This paper describes the extended use of this game engine, its integrated physics engine and path-finding algorithms to determine different possible trajectories of a multi-axis machine. Similarly to a navigation system, the calculated trajectories have been evaluated according to their lead time, movement smoothness and recalculation time. The results were stored as capability descriptions in a machine model ontology.

Determination of the Sound Power Level of Modular Machines with Cyclic Operation Mode – Case Study

Determination of the Sound Power Level of Modular Machines with Cyclic Operation Mode – Case Study

Comparative Study on Two Modular Spoke-Type PM Machines for In-Wheel Traction Applications

This paper focuses on the comparative analysis of modular spoke-type permanent magnet machines with two magnetization modes, which are referred to as M-I and M-II types. The analytical models of the proposed machines are built based on the simple magneto-motive-force-permeance method. With the help of finite element analysis and the analytical models, magnetic fields in machines with different magnetization modes are compared. Then, taking as a base an existing commercial in-wheel machine used in an electric motorcycle, two proposed machines with different magnetization modes are designed as in-wheel traction machines and compared with respect to electromagnetic torque, flux-weakening performance, over-load capability, etc. The machines are prototyped and experimentally tested to verify the prediction that the M-II machines exhibit a higher torque output whereas the M-I machines have a wider speed range.

Novel Modular Fractional Slot Permanent Magnet Machines With Redundant Teeth

In order to ease the manufacture process of very large permanent magnet (PM) machines, such as direct drive wind power generators, modularity technique is usually adopted. Although conventional fractional slot PM machines with all teeth wound windings show good performance, the coils located at the end part of each segment could be easily damaged because of being exposed to the air. In addition, the local winding faults could easily proliferate to the whole machine due to the physical touch of adjacent coils. Thus, a novel modular fractional slot PM machine with redundant teeth is proposed in this paper, while three phases within each set of winding are still balanced. The construction of the proposed modular PM machine having 42-slots/32-poles (42S/32P) combination is described in detail as an example, which can be treated as the integration of six 6S/5P segments and a redundant 6S/2P machine. The reason for using 6S/2P machine is to get rid of the undesirable unbalanced magnetic force (UMF), which usually exists in rotating asymmetric machines, such as 3S/2P PM machine. Since the end part of each segment in the proposed modular PM machine can be covered by half redundant tooth during the production, more protection can be provided for coils located in these regions. Furthermore, the separation of six segments can improve the fault-tolerant capability of the machine. The electromagnetic performance predicted by finite-element analysis (FEA) also demonstrates that the proposed modular machine will perform better if dual three-phase winding is adopted. Finally, the experiments on the prototyped machine validate the analysis in the paper.

Using a novel modular continuous restricted Boltzmann machine to SSVEP-based BCIs for amyotrophic lateral sclerosis

The communication of a patient with amyotrophic lateral sclerosis is limited and then the quality of lives would be greatly reduced. The patients still maintain the cognitive ability, thus developing an assistive communication interface would greatly help them in daily live. Recently, steady state visually evoked potential (SSVEP) based brain computer interfaces (BCIs) had been successfully developed to help patients. Increasing the accuracy of SSVEP-based BCIs is able to realize the assistive communication interfaces in practical applications. In this study, a modular continuous restricted Boltzmann machine (MCRBM) is proposed to improve the performance of SSVEP-based BCIs. To precisely represent the characteristics of elicited signals of SSVEP, the frequency magnitude, the coefficients of canonical correlation analysis, and the correlations of magnitude square coherence are selected as the features. In the first layer of MCRBM, the continuous restricted Boltzmann machine based neural networks are used as the basic units and applied to accurately estimate by using different types of features. In the second layer of MCRBM, a CRBM is then designed to fuse the decisions and find the final results. The experimental results showed that MCRBM produce higher accuracy compared to CRBM. Therefore, the proposed approach can be adopted in practical applications and then help patients in communicating with others.

An Online Global Fault-Tolerant Control Strategy for Symmetrical Multiphase Machines With Minimum Losses in Full Torque Production Range

The high fault-tolerant ability of multiphase drives is favored in safety-critical applications. Under open-phase faults, to guarantee ripple-free torque, stator current references should be revised. In this paper, a global fault-tolerant control strategy based on an online current optimization algorithm (OCOA) is proposed for symmetrical multiphase machines (SMMs) to achieve both the maximal torque production range (TPR) and minimal stator winding losses under all possible OPFs. The OCOA can calculate the minimum losses current references covering the full TPR online, regardless of the number and locations of faulty phases. With the online-optimized references, ripple-free torque and minimum losses in full TPR can be achieved under faulty conditions. Additionally, the proposed method can be adopted to SMMs with arbitrary phase numbers. Simulation and experiments demonstrate that the online optimization can be completed in a short time, meanwhile, achieves the same TPR and loss reduction compared with an existing offline strategy based on prestored look-up tables. Due to the flexible online calculation ability and excellent extensibility, the proposed method is especially favored in modular multiphase converters and machines with high phase numbers, where converters can adapt to machines with different phase numbers or the number of possible faulty conditions can be extremely large.

Comparative Study of Modular Dual 3-Phase Permanent Magnet Machines With Overlapping/Non-overlapping Windings

For modular permanent magnet (PM) machines with overlapping (OLP) windings widely employed in wind power generation, the large torque ripple and long end winding are major issues. In order to solve these problems, PM machines with non-overlapping (NOLP) windings and redundant teeth for easy modularity are proposed in this paper. The comparative study between modular machines with these two kinds of windings is necessary and is the major focus of this paper. For the sake of clarity, two modular dual 3-phase machines with 42-slots/32-poles (42S/32P) and 192S/32P combinations are chosen as examples to show the differences in terms of machine performance. The proposed 42S/32P modular machine adopts NOLP winding, while the conventional 192S/32P one uses the OLP type. Based on the results, it is found that the modular machine with NOLP winding has comparable average torque and efficiency. In the meantime, much lower torque ripple exists for the proposed modular machine regardless of the current value. The shorter and simpler end windings are beneficial to manufacturability. Moreover, the proposed modular machine with NOLP winding will be more fault tolerant due to smaller mutual inductances between phases and larger d -axis inductance. Finally, the proposed 42S/32P modular machine is prototyped and the experiments validate the correctness of the analyses in this paper. Despite two specific examples being used, the conclusion should be generic and can be employed to modular machines with other slot and pole number combinations.

A Novel Modular Stator Hybrid-Excited Doubly Salient Synchronous Machine With Stator Slot Permanent Magnets

This paper presents a novel modular stator hybrid-excited synchronous machine with stator slot permanent magnets (PMs). By regulating the field current, the magnetic field, and consequently the back electromotive force, as well as the average torque can be controlled. The existence of stator slot PMs alleviates the magnetic saturation and improves the flux regulation ratio. The frozen permeability method is employed to investigate the torque contributions by different magnetic sources. Possible stator and rotor pole combinations are illustrated, and the corresponding electromagnetic performances are evaluated with the finite-element method. It is revealed that 12-stator pole machines with 11- and 13-rotor poles exhibit superior average torque and lower torque ripple due to even-order harmonics elimination. Finally, a prototype with modular stator segments is manufactured to validate the analyses and simulations.

Configuration design of scalable reconfigurable manufacturing systems for part family

Intense global competition, dynamic product variations, and rapid technological developments force manufacturing systems to adapt and respond quickly to various changes in the market. Such responsiveness could be achieved through new paradigms such as Reconfigurable manufacturing systems (RMS). In this paper, the problem of configuration design for a scalable reconfigurable RMS that produces different products of a part family is addressed. In order to handle demand fluctuations of products throughout their lifecycles with minimum cost, RMS configurations must change as well. Two different approaches are developed for addressing the system configuration design in different periods. Both approaches make use of modular reconfigurable machine tools (RMTs), and adjust the production capacity of the system, with minimum cost, by adding/removing modules to/from specific RMTs. In the first approach, each production period is designed separately, while in the second approach, future information of products’ demands in all production periods is available in the beginning of system configuration design. Two new mixed integer linear programming (MILP) and integer linear programming (ILP) formulations are presented in the first and the second approaches respectively. The results of these approaches are compared with respect to many different aspects, such as total system design costs, unused capacity, and total number of reconfigurations. Analyses of the results show the superiority of both approaches in terms of exploitation and reconfiguration cost.

Modelling and evaluation of multi-state reliability of repairable non-series manufacturing system with finite buffers

The capacity and capability of flexible manufacturing system varies with different market demands. To satisfy the requirements of performance expressions, avoid the problem of combinatorial explosion and consider the influence of intermediate buffer stations, a new reliability modelling and evaluating methodology for repairable non-series hybrid flexible manufacturing systems with finite buffers is proposed using an extended vector universal generating function technique. For repairable modular machines, the Markov models of modular machines are established using stochastic process analysis and the corresponding theoretical steady-state probability in various states is obtained. Furthermore, the original system in combination with multi-state reliability measures of buffer stations is equivalent to a system with independent machines which can be expressed by vector u-functions. Based on the probability distributions of the states of subsystems, the composition operators for series connections and parallel connections are defined. Consequently, the entire system is simplified to one component represented by the polynomial universal generating function. In particular, reliability indicators and measurement models are given to assess the system’s reliability through promoting the basic ones. Finally, a practical case of engine head machining line is utilized to verify the effectiveness of the method. The results demonstrate that the use of vector universal generating functions can describe the system structure and states more appropriately while providing efficient assessment.

Finite element analysis of a modular brushless wound rotor synchronous machine

This study presents a comparative study of different modular brushless wound rotor synchronous machines (MB-WRSM) using non-overlapping fractional slot double-layer concentrated windings. The goal of the study is to highlight the structure which offers the best fault-tolerance capability and the highest output performance. The fundamental winding factor is calculated by using the method based on voltage phasors as a significant criterion to select the preferred numbers of phases, stator slots, and poles. With the limited number of poles for a small machine (3.67 kW/7000 rpm), 15 different machines for different phase/slot/pole combinations are analysed using two- dimensional (2D) finite element method and compared according to three criteria: torque density, torque ripple, and machine efficiency. The seven-phase/seven-slot/six-pole machine is chosen with the best compromise of high torque density, small torque ripple (3.89%), and high nominal efficiency (95%). This machine is then compared with a reference design surface-mounted permanent magnet synchronous machine (SM-PMSM). The simulation results are discussed and demonstrate that the MB-WRSM presents interesting performance features, such as extended field weakening range, with overall performance closely matching that of an equivalent SM-PMSM.

Model Predictive Thrust Force Control of a Linear Flux-Switching Permanent Magnet Machine With Voltage Vectors Selection and Synthesis

To reduce the thrust force ripple of a complementary and modular linear flux-switching permanent magnet machine, a model predictive thrust force control (MPTFC) is developed and implemented in this paper based on the active voltage vectors selection (AVVS) and two-voltage-vector synthesis (TVVS). First, the active voltage vectors are screened and assigned to the specific sector, instead of traversing all the possible vectors, and consequently, significantly decrease prediction workload. Second, for the elimination of the weighting factor in the conventional MPTFC, the control object is transformed from the thrust force and stator flux to the stator flux only by using the load angle. Third, to achieve the steady-state performance improvement, the TVVS approach is applied in each control period, where the optimal TVVS and its dwell time are simultaneously obtained by only one cost function. Both simulated and experimental results verify that the steady-state performance improvement can be realized by the developed MPTFC through comparing with normal hysteresis current control and conventional MPTFC strategies.

Influence of Armature Windings Pole Numbers on Performances of Linear Permanent-Magnet Vernier Machines

Linear permanent-magnet vernier (LPMV) machine has attracted more and more attention for several advantages including high power density and low cost. Both magnets and windings are located on the short mover, while the long stator is only consisting of iron, which is very suitable for long stroke applications. This paper investigates the influence of armature windings pole-pair numbers on the electromagnetic performances of LPMV machine by using an analytical method based on the finite element. The aim of this paper is to make a comprehensive comparative study of the machine with different armature windings pole-pair numbers while keeping slot number as a constant, select the topology of high performances and recommend suitable application areas. The performances of machines with the armature windings pole-pair numbers $P_{\mathrm {w}}= 1$ , 3, 6 are analyzed in detail. Finally, a new modular LPMV machine with $P_{\mathrm {w}} = 6$ , which possess higher thrust force, lower thrust force ripple, and high fault-tolerant capability, is prototyped and experiments are conducted for validation.

Coupled Electromagnetic-Thermal Optimization of a Separate-Stator Modular Machine With Biased Flux

A separate-stator modular machine with biased flux is proposed in this paper. In this machine, the windings and the permanent magnets are located in two separate parts of the stator, which favors the heat dissipation and magnetic saturation reduction of the machine. With the specially designed stator structure, a biased flux can be introduced to flexibly regulate the excitation field by injecting a zero-sequence current into the phase windings, so that a wide operation speed range can be achieved. Moreover, a modular structure is adopted to simplify the automated manufacture assembly. In this paper, the machine configuration and the working principle are first illustrated. The effect of the design parameters on its torque capability is then investigated. A coupled electromagnetic-thermal optimization method based on the genetic algorithm and finite-element method is proposed to improve the torque performance of the machine.

Effect of tooth tips on the electromagnetic performance of PM fractional‐slot modular machines using grain‐oriented electrical steel

The effect of tooth tips on the performance variations due to using grain-oriented electrical steel (GOES) stator laminations in permanent magnet fractional-slot modular machines is studied in this work. It is concluded that the electromagnetic performance is further improved using GOES in machines with tooth tips compared to machines without tooth tips. This is due to a higher increment on the flux density in the airgap. The acoustic behaviour variations due to using GOES are predicted by analysing several mechanical- and acoustic-related parameters. It is predicted that implementing GOES improves the acoustic behaviour in machines without tooth tips. Furthermore, the effects of GOES in machines with tooth tips are slightly improved compared to machines without tooth tips. However, in order to determine the real mechanical and acoustic behaviours, further analysis is needed.

Performance comparison between consequent‐pole and inset modular permanent magnet machines

This paper proposes some consequent-pole (CP) modular permanent magnet (PM) machines with different flux gap (FG) widths and slot/pole number combinations. The corresponding inset modular PM machines having the same magnet volume are also presented for comparison. It has been demonstrated that the output torques of the consequent pole modular machines are always higher than those of the inset modular machines regardless of FG widths and slot/pole number combinations. Other electromagnetic performances such as back-EMF, cogging torque, and iron losses etc. are calculated by 2D FEA software and compared as well. The advantages and disadvantages of consequent and inset modular PM machines are summarised here.

Utilisation of grain‐oriented electrical steel in permanent magnet fractional‐slot modular machines

The performance improvement of using grain-oriented electrical steels (GOES) in the stator of PM fractional-slot modular machines is analysed in this study. Several models using a finite element tool are examined and it is concluded the techniques used in the actual software are not accurate for simulating anisotropic behaviour. Consequently, a simplified yet accurate modelling technique is proposed to simulate the performance of this type of electrical machines equipped with GOES. The advantages as well as the drawbacks of using GOES on the electromagnetic performance are investigated for different pole/slot combinations. It is concluded that the use of GOES is beneficial from an electromagnetic point of view mainly due to an increase on the radial component of the airgap flux density.