Lap Winding Research Articles

Study on the performance of multi‐branch modular permanent magnet motor affected by magnetic pole segmentation

To better address the requirements of integrated equipment, here, a multi-branch modular permanent magnet motor using a toroidal winding with reverse turn coils is proposed. High-speed motors have a large winding span, and the use of a toroidal winding with reverse turn coils in place of lap windings can effectively shorten the length of the motor end. Motor modularisation can improve production, assembly efficiency, and the maintenance economy. To innovate the windings from a basic toroidal winding, a modularised toroidal winding with reverse turn coil is proposed which enables the motor to be decoupled in electrical and mechanical structures. The inductance parameter calculation and finite element simulation verification are carried out on the new winding structure and the lap windings. The feasibility of the 60-degree phase toroidal winding with a reverse turn coil structure with reverse turns is also assessed. The no-load back electromotive force of the new winding structure is a square wave, which will bring certain torque fluctuations. To improve the performance of the motor, the method of radial magnetic pole segmentation is used, and the new magnetic pole is analysed and verified by the segmented magnetic circuit. Finally, the combination of magnetic pole segmentation is explored, and the effect of different segmentation methods on the performance of the motor is compared.

중권 및 동심권을 적용한 정수 슬롯 영구자석 동기 전동기의 비교 연구

중권 및 동심권을 적용한 정수 슬롯 영구자석 동기 전동기의 비교 연구

Analysis of Electromagnetic Force on Rotor End Windings of a 300 MW Variable-Speed Generator Motor for Pumped Storage

The variable-speed generator motor (VSGM) for pumped storage has a cylindrical rotor with three-phase lap or wave windings distributed in slots evenly and fed by a converter. For a large-scale VSGM, the electromagnetic force (EMF) on rotor end windings is an important contributor to distortion, vibration, and even damage of rotor end windings. A 3D finite element model of rotor end region of a 300 MW VSGM is set up. The distribution map of EMF density on involute and nose parts of rotor end windings, under rated load and three-phase short circuit at supersynchronous and subsynchronous speed, is drawn. Furthermore, the amplitude of EMF is calculated, and the radial, tangential, and axial components of EMF are analyzed. The results in this paper will lay a foundation for design of rotor end windings and their support structure.

Blower Motor 4 Poles 2 Brushes with 14 Slots Armature for Automotive Heating, Ventilating, and Air Conditioning (HVAC) Applications

This is a discussion on the method of developing a permanent magnet, 4 Pole 2 brushes DC blower motor for use in a vehicle HVAC system. By modifying the magnet orientation in terms of pole alignment, magnetic field intensity, armature winding technique, and brush alignment, the motor mass and volume is reduced 15% to 30%. These improvements are achieved without reducing motor performance, increasing motor cost or increasing motor brush noise. Keywords: 4 Poles 2 Brushes DC motor; Armature Winding; Improved Lap Winding; Weight; Performance;

Optimal Winding Selection for Wound-Rotor Resolvers

Wound-rotor (WR) resolvers are the most commercially used resolvers in industrial applications. In this paper, the effect of different winding arrangements on the accuracy of WR resolvers is discussed. Three windings are proposed for the stator of the resolver that are involved on-tooth overlapping winding, distributed lap winding and distributed concentric winding. Those windings are also applied to the rotor. All the rotor windings are assumed to be single phase and two-phase. Therefore, the effect of damper winding is also studied in the paper. The analysis is done using time stepping finite element method and the most accurate resolver is built and tested. Close agreement between the experimental measurements and the finite element results confirms the obtained results.

Performance Comparison and Applicability Analysis of Different Armature Structures for a Small-Scale HTS Linear Synchronous Motor

High-temperature superconducting (HTS) coils could bear larger current density and produce higher magnetic field compared to permanent magnets. An HTS linear synchronous motor (LSM) with its secondary excitation system made of HTS coils can provide larger thrust force but unavoidable larger normal force. This paper focuses on the analysis and comparison of different armature structures in an HTS LSM to improve the magnetic flux waveform quality, decrease the normal force, and simultaneously maintain the thrust force. Five alternative armature structures are proposed and investigated, i.e., coreless double layer lap winding (DLLW), yokeless DLLW, coreless and yokeless DLLW, and flat winding with and without iron yoke. Three dimensional models of HTS LSMs are built and verified to compare the magnetic field and force performances of various armature structures using the finite element method. Results indicate that armatures without iron components perform better. Furthermore, the yokeless flat winding is recommended for its 81% reduction of magnetic flux harmonic component and 52% increase of thrust force compared with DLLW.

Advanced High Torque Density PM Vernier Machine With Multiple Working Harmonics

In recent years, permanent magnet (PM) vernier machines have gained more and more attention due to their high torque density and simple mechanical structure. However, PM vernier (PMV) machines with lap windings always suffer from long end winding length, and regular nonoverlapping winding may result in torque reduction for PMV machines. In this paper, an advanced PMV machine topology with multiple working harmonics is proposed. With specially designed stator auxiliary teeth, this topology could achieve ∼20% higher torque density than that of a regular nonoverlapping winding PMV machine, with the same magnet usage. Through finite element algorithm and theoretical analysis, the production of additional flux density harmonics and their contributions to back-electromotive force (EMF) are verified. Moreover, the electromagnetic performances of this novel machine topology, such as back-EMF and output torque, are quantitatively investigated with the geometric parameters’ effect considered. Finally, analysis results are verified by experimental test on a 21 Nm prototype, which is designed to have similar volume and weight with a 14 Nm regular commercial PM machine.

A Fractional Slot Multiphase Air-Core Compulsator With Concentrated Winding

Compulsator is a specially designed generator capable of delivering high current pulses to a low-impedance load, such as the electromagnetic railgun. In order to increase the tip speed of the rotor, advanced composite materials have been used in the recent compulsator prototype, which is mentioned as air core instead of the traditional iron core. For typical air-core compulsators, there are no slots and steel teeth to place the armature windings due to the nonmachinability of composite materials. Therefore, concentric windings in racetrack style are often adopted instead of traditional lap winding in most cases, since it is more convenient to be fixed by composite materials. However, overlap occurs at the end winding part for multiphase compulsators, which are not easy to be formed during the manufacture process. In this paper, a fractional slot multiphase air-core compulsator with concentrated windings is proposed and analyzed. The main advantage of fractional slot configuration is that it can offer a concentrated winding structure under certain conditions, which means each coil only spans one “tooth,” and will not cause any intersection between each phase at the end winding. Two referenced fractional slot air-core compulsators with two phases, six poles, and four “slots” or eight “slots” (q = 1/3 and q = 2/3, q is the “slot” per pole per phase) are analyzed and compared with the performance of a traditional integral slot machine. The results indicated that the output voltage and self-excitation performance of a fractional slot compulsator can reach the same level with an integral slot one, and the discharging performance can reach an acceptable level. Thus, the fractional slot multiphase concept can be further used to improve the manufacture process of the winding in the future.

A Large-Scale Superconducting DC Wind Generator Considering Concentrated/Distributed Armature Winding

The rapid development of renewable wind energy asks for new technology and the scheme of superconducting dc generators with superconducting dc transmission cables provides a possible and innovative solution to this trend. This paper designs a 10-MW superconducting dc generator with copper armature winding in the rotor. To find a suitable configuration of the armature winding, distributed winding, namely double-layer lap winding, and concentrated winding are analyzed and compared. The commutation principal of the two types of armature winding is briefly introduced by a simplified case. Electromagnetic performance, including torque, no-load voltage, and coil current, of the two types are calculated and compared based on the finite-element software. The reasons contributing to the performance difference are also elaborated.

Design and Analysis of a New Ring Winding Structure for Permanent Magnet Linear Synchronous Motors

With the quick development of electromagnetic propulsion systems, permanent magnet linear synchronous motors (PMLSMs) have been the focus of research for high-performance propulsion systems. Compared with traditional windings, two ring windings with novel structures and better performance for PMLSMs are proposed: the single-layer ring windings are suitable for high-power systems; the double-layer ring windings can be adopted in low fluctuation systems. This paper first analyzes the electromagnetic parameters of the ring windings based on the equivalent magnetizing current method to verify the availabilities of ring windings. The main parameters of two ring windings are compared to achieve the optimization guides. Then, the magnetic fields and thrust characteristics of ring windings and traditional lap windings are analyzed by the finite-element method, and the independent magnetic field of ring winding ends is verified. And then a prototype motor with double-layer ring windings was manufactured and experimentally tested, the measurement data were matched with the theoretical calculations. The results illustrate that the PMLSM with ring windings has higher thrust density and lower thrust ripple, ring winding structure is more suitable for electromagnetic propulsion systems.

Motor Stator With Thick Rectangular Wire Lap Winding for HEVs

A stator structure with a rectangular wire distributed winding that exhibited high levels of productivity and extremely flexible design was designed for hybrid electric vehicle motors. We devised a method of forming thick rectangular wire diamond coils and determined the best conditions for forming high-density coils. A structure for terminal connections was also devised to achieve a short coil end. The slot-fill rate of a prototype stator was 80.5%, and its total coil end was 42 mm, which is roughly the same motor performance of a stator with segmented coil wave winding. The key advantage here is that the proposed stator had fewer coils and welding points than a stator with segmented coil wave winding and that the possible number of conductors per slot was higher than four, which is the limit for the stator with segmented coil wave winding.

Programing the rewinding of a three-phase induction motor stator using interactive computer-aided design technique

In this paper, a computer program was developed in MATLAB programming language and applied in the refurbishment of defective three-phase squirrel-cage induction motor using the computer-aided design technique/approach. The MATLAB programming language and Computer-Aided Design (CAD) analysis adopted aided the fast computation and convergence of a output result from the developed program that was used in the practical refurbishment of a defective 48-slot 3-phase squirrel-cage induction motor as well as the production of the entire stator winding. The result also revealed the motor as being a 4-pole type which lends itself easily to the lap winding pattern. The winding was practically developed using the program result data, installed, connected and tested. The speed realized from the post-refurbishment workshop test-running using the stroboscopic speed measuring instrument was 1500rpm. This was considered as good performance on no-load condition. The machine was allowed to run for about one hour during the workshop test-running without overheating. The computed output power was 20 kW. The estimated efficiency and power factor by CAD technique were 90 % and 0.9, respectively. These values were considered satisfactory.

Winding topologies of flux-switching motors for in-wheel traction

Purpose – The purpose of this paper is to investigate winding topologies for flux-switching motors (FSMs) with various segment-tooth combinations and different excitation methods. Design/methodology/approach – For the ac winding of FSM, two winding topologies, namely the concentrated winding and the distributed winding, are compared in terms of the winding factor and efficiency. For the field winding of dc-excited FSM (DCEFSM), another two winding topologies, namely the lap winding and the toroidal winding, are compared in terms of effective coil area, end-winding length, and thermal conditions. Analytical derivation is used for the general winding factor calculation. The calculation results are validated using finite element analysis. Findings – Winding factors can be used as an indication of winding efficiency for FSMs in the same manner as done for synchronous motors. For FSMs with concentrated windings, the winding factor increases when the rotor tooth number approaches a multiple of the stator segment number. For FSMs with certain segment-tooth combinations, e.g. 6/8, the theoretical maximum winding factor can be achieved by implementing distributed windings. Furthermore, the toroidal winding can be an efficient winding topology for DCEFSMs with large stator diameter and small stack length. Research limitations/implications – This work can be continued with investigating the variation of reluctance torque with respect to different segment-tooth combinations of FSM. Originality/value – This paper proposes a general method to calculate the winding factor of FSMs using only the phase number, the stator segment number, the rotor tooth number, and the skew angle. Using this method, a table of winding factors of FSMs with different segment-tooth combinations is provided. Principle of design of FSMs with high-winding factors are hence concluded. This paper also proposed the implementation of distributed windings for FSM with certain segment-tooth combinations, e.g. 6/8, by which means a theoretical maximum winding factor is achieved. In addition, different winding topologies for the field winding of DCEFSM are also investigated.

Development of Motor Stator with Rectangular‐Wire Lap Winding and an Automatic Process for Its Production

SUMMARYAimed at providing small high‐power motors with excellent efficiency, a motor stator with rectangular‐wire lap windings and an automatic process for its production were developed. The structure of the windings, namely, two continuous “α‐shaped” coils, and the coil‐production method (involving simultaneous coil forming and coil insertion) enable mass production of this stator. The slot‐fill rate for a prototype stator was 80.5%, and the total height of the coil ends was 60 mm to 72 mm. On the basis of the ratio of the sectional areas of two types of the motors, its efficiency was estimated to be 3.7% higher than the efficiencies of motor stators with round‐wire concentric windings (at a rotation speed of 1000/min). In addition, the number of coil parts and the number of welding points were greatly reduced compared to those of a stator with segmented‐coil wave windings.

Comparison Study of Superconducting Generators With Multiphase Armature Windings for Large-Scale Direct-Drive Wind Turbines

To reduce the cost of energy and increase the reliability, large-scale direct-drive wind turbines are preferred, especially for the rising offshore wind power generation. Compared to traditional generators, superconducting generators offer many advantages, such as higher power density, higher efficiency at all load, less maintenance, and so on. Therefore, they are regarded as very promising candidates for large-scale direct-drive wind generators with power of 10 MW and larger. For such generators, a great challenge is the full-power converters, which are required as an interface with the grid. Multiphase armature windings are usually used to reduce the current stress of power electronic devices. Two 12-MW nine-phase superconducting generators are designed. Both armature windings consist of three sets of three-phase lap windings, and the primary difference is the phase difference between adjacent phase sets. Using finite element method, the characteristics of the two generators are analyzed and compared, from the point of view of torque performance, eddy-current losses on the damping shell, and power conversion system.

Development of Motor Stator with Rectangular Wire Lap Winding and an Automatic Process for its Production

Development of Motor Stator with Rectangular Wire Lap Winding and an Automatic Process for its Production

Induction machine performance with fractional‐slot concentrated windings

Purpose – The purpose of the paper is to investigate the performance of induction machines with fractional‐slot concentrated‐windings.Design/methodology/approach – This paper examines induction machine performance with fractional‐slot concentrated windings using the standard distributed lap windings as reference. Four designs are compared and various performance tradeoffs highlighted. The first machine has integral‐slot distributed 2 slots/pole/phase lap winding and it serves as the reference winding. The second machine has a double‐layer 1/2 slot/pole/phase winding, a workhorse for brushless DC machines. The third machine has double‐layer 2/5 slot/pole/phase winding. Lastly, the fourth machine has single‐layer 2/5 slot/pole/phase windings. The comparison includes torque‐speed curves (including the effects of major space harmonic components), rotor bar losses, and ripple torque levels.Findings – Based on the analysis results presented here, the traditional distributed lap winding is proven to be superior ...

Investigation of winding topologies for permanent magnet in‐wheel motors

Purpose – This paper aims to find the optimal winding topology for a 14‐pole permanent magnet synchronous motor (PMSM) to be used as an in‐wheel motor in automotive applications.Design/methodology/approach – Comparison is first performed among lap windings with different combinations of slot numbers and pole numbers. A general method for calculating the winding factors using only these numbers is proposed, thus the preferable slot numbers resulting in relatively large winding factors for this 14‐pole PMSM are found. With these slot numbers, the Joule losses of armature windings are further investigated, where the impacts of different end‐winding lengths are considered. By this means, the optimal slot number that causes the least Joule loss is obtained. On the other hand, as a competitor to lap windings, toroidal windings are also discussed. The thermal performances of these two types of windings are compared by performing a finite element analysis (FEA) on their 2‐D thermal models.Findings – For the 14‐po...

Effect of Winding Asymmetries and Winding Connection on Small Synchronous Machines

This paper reports on the study of winding asymmetries in small synchronous generators. These types of generator are commonly used in diesel generator or back-up systems and are usually no more than a few or few tens of kilowatts with two, four, or six salient poles. The three-phase winding is 120 deg pitched, but often, lap windings are not used, rather, a hybrid of concentric winding and double layering is utilized. There are sound manufacturing reasons for this, and these are explained. This leads to small asymmetries in the phase-belt inductances and field-induced voltages. This is examined and validated experimentally. This paper discusses the techniques that are used to analyze the machine. These are analytical methods. The methods address the correct positional coil groupings in the slots to obtain back electromotive forces, mutual and self-inductances, and line currents. These are obtained over a varying load range.

Design and Analysis of Star–Delta Hybrid Windings for High-Voltage Induction Motors

In this paper, a Y-Δ hybrid connection for a high-voltage induction motor is described. Low winding harmonic content is achieved by careful consideration of the interaction between the Y- and Δ-connected three-phase winding sets so that the magnetomotive force (MMF) in the air gap is close to sinusoid. Essentially, the two winding sets operate in a six-phase mode. This paper goes on to verify that the fundamental distribution coefficient for the stator MMF is enhanced compared to a standard three-phase winding set. The design method for converting a conventional double-layer lap winding in a high-voltage induction motor into a Y-Δ hybrid lap winding is described using standard winding theory as often applied to small- and medium-sized motors. The main parameters addressed when designing the winding are the conductor wire gauge, coil turns, and parallel winding branches in the Y and Δ connections. A winding design scheme for a 1250-kW 6-kV induction motor is put forward and experimentally validated; the results show that the efficiency can be raised effectively without increasing the cost.