Distributed Winding Research Articles

Advanced Fault Tolerant 3×3-Phase PM Drive With Concentric Winding for EV Application

Fault tolerant machine drive is essential for EV application to ensure uninterrupted operation during fault event. Among various fault modes, inter-turn fault is the most challenging failure for the PM drive which requires special measures to suppress the excessive fault current. In this paper, a novel concentric winding (CW) is analyzed for a 3×3-phase PM drive to restrict the turn fault current. Compared with the conventional distributed winding (DW), the two sub-coils of each phase occupy the same space angle and both align with the phase axis, and the winding factor of each coil is 0.96 which is 4% lower than the DW. Owing to the two aspects, the coil flux linkages are more effectively nullified after applying winding terminal short circuit (TSC) which indicates lower fault current. The two machines’ healthy performance as well as various fault modes’ behaviors are investigated by detailed simulation and test investigation. The results prove the CW machine has the same healthy characteristics as the DW machine, and the maximum inter-turn fault current is up to 17% lower than the counterpart. In addition, the improved turn fault current suppression capability is achieved simply by re-arranging the coil layout without introducing any extra cost.

Improved Design of a Six-Phase Squirrel Cage Induction Motor With Pseudo-Concentrated Windings

Pseudoconcentrated winding seems to be a promising solution for the six-phase induction motors (6PIMs) because it exposes advantages of concentrated windings (CWs) over the distributed windings (DWs). In addition, this winding has an air gap flux density with higher amplitude of the fundamental frequency and lower total harmonic distortion value compared to the conventional CWs, which results in considerably higher performance. In this article, a design algorithm and an analytical model are developed for a 6PIM to cope with pseudoconcentrated winding. Then, a sensitivity analysis is performed to enhance motor performance. The designed motor with pseudoconcentrated winding shows superior performance compared to the baseline motor with the DWs. The designed motor is manufactured to verify the accuracy of the design procedure, performance calculation, and finite element simulation results.

Mechanism Investigation of Ring Type Winding in Linear Permanent Magnet Vernier Machine for Improving Force Density

The linear permanent magnet vernier (LPMV) machines have been paid more attention in railway vehicles because of its simple structure and low cost. In this paper, the ring type winding (RTW) is adopted in both non-modular and modular LPMV machines to improve force density. The configuration and operating principle of two LPMV-RTW machines are presented. The coil connection and mechanism of RTW are explained and compared with conventional distributed winding (DW) and concentrated winding (CW). The back electromotive force and thrust force are investigated by the time-stepping finite-element method. It is found that non-modular LPMV-RTW machine possesses larger force density than non-modular LPMV-DW machine while modular LPMV-RTW machine has higher force density and utilization ratio of winding than modular LPMV-CW machines under the constant copper loss. Finally, the experiment result is obtained on the prototype, verifying the theoretical analysis.

Comparison characteristics of various SynRMs through FEM and experimental verification

This paper presents the loss and efficiency evaluations for synchronous reluctance motors (SynRM) with permanent magnet assisted (PMA), non-PMA, concentrated winding (CW), and distributed winding (DW) using both the coupled transient finite element method (FEM) and Preisach model. In this paper, the performance characteristics are compared according to the stator and rotor types in SynRM. In addition, an efficiency evaluation is conducted to include iron loss, copper loss, and other losses on the basis of rated load conditions. Computer simulations and experimental results for the efficiency and loss evaluations using a dynamometer show the characteristics of each SynRM and enable the selection of an appropriate industrial application field.

PM Synchronous Machine Drive Response to Asymmetrical Short-Circuit Faults

This paper investigates the impact of machine topology and parameters on the fault-mode characteristics of permanent-magnet synchronous machines (PMSMs) exposed to asymmetrical short-circuit (ASC) faults, one of the most dangerous faults in terms of peak current amplitudes and demagnetization risks. Simulations using an equivalent circuit model combined with finite-element (FE) analysis are used to explore the differences between the ASC fault-mode responses of three major types of PM machines. The effects of several different rotor and winding configurations have been studied to identify the key machine parameters that have a major influence on the fault current amplitudes. Results indicate that fractional-slot concentrated winding (FSCW) PM machines tend to exhibit lower peak currents compared to distributed winding (DW) machines during ASC fault events. Finally, the results from three different types of short-circuit faults are summarized and compared for several PM machine configurations to provide information that will be helpful for choosing the best machine for new applications. Experimental results are provided for constrained ASC fault conditions that build confidence in the models and their predictions.

Preliminary Design Analysis of Low Speed Interior Permanent Magnet Machine with Distributed and Concentrated Windings

Abstract – The paper presents a systematic comparison of four topologies of the interior permanent magnet machine (IPMM) designed for low speed applications. This comparative study investigates the suitability of the concentrated winding and distributed winding in the stator and the flat-shaped or V-shaped magnets in the rotor poles. The paper also studies the inductance characteristics of the designs using finite element analysis. Various steps taken to minimize the cogging torque and torque ripple in the studied machines were also discussed in details. Keywords : AC standstill saliency test, Cogging torque, Concentrated winding, Distributed winding, Direct-drive, Interior Permanent Magnet Machine, PM machine, Torque ripple 1. Introduction I n direct drive wind turbine systems, intermediate gear boxes are eliminated to increase the efficiency and reliability of the whole system, as well as reducing maintenances down-time. The generator used in such systems needs to have a low rated speed. This demand for an increase in the number of pole pairs of the generator. A review done in [1], [2] on direct-drive wind turbines suggests that permanent magnet (PM) machines are the most favorable for direct-drive wind turbine. While the most common type of PM machines used in the wind industry is the radial flux surface mounted magnet (SPM) type, an interior PM synchronous machine (IPMSM) offers a number of advantages over the SPM type. The most commonly cited advantages are: the presence of reluctance torque ( ) as shown in (1) in an IPM machine is beneficial in achieving a higher torque with lower magnet volumes and IPMSM has a mechanically and magnetically robust rotor. It should be noted that the presence of saliency in the IPSM results in the reluctance torque and also contributes toward the constant power speed range. A recent study carried out in [3] found that the use of an IPM machine in a small scale direct drive wind turbine can provide quicker return of investment compared to a SPM machine, especially in sites where average wind speed is low. According to [3] the return of investment can be achieved by taking advantage of provision for a constant power speed range available in IPMMs. But cogging torque in an IPMM is generally greater compared to a SPM machine due to the greater variation of reluctance between the stator and rotor [4]. This makes reduction of the cogging torque crucial in a low speed IPM machines [5]. The IPMSM with radially magnetized V-shaped (V-S) magnets has a better flux concentration and higher saliency ratio than its counter-part flat-shaped (F-S) magnet designs which makes it more attractive for traction drives [6]. The torque components of an IPM machine is (1) where, = magnet alignment torque, = cogging torque, and reluctance torque. The majority of IPM machines are designed with distributed windings (DW). Recently, the concentrated winding (CW) for the IPMSM is getting attention from the research community due to its high slot-fill factor, high tolerance to phase fault, simplified manufacturing process, non-overlapping coils resulting in shorter end-windings and reduced copper usage. In spite of having these advantages, the CW was not widely used in the past due to its characteristics in producing EMF and MMF waveforms with unacceptably high total harmonic distortion. However, in recent years, it has been shown that through appropriate choice of slot and pole combinations [7], the CW stator has the ability to produce sinusoidal EMF waveform with high a winding factor, and smooth average torque. In this paper, four design topologies of IPMSM were considered for investigation which includes (a) conventional distributed winding in the stator and flat-shaped IPM structure in the rotor( DW FS-IPMM), (b) distributed winding in the stator and V-shaped IPM structure in the rotor (DW VS-IPMM), (c) concentrated winding in the stator and flat-shaped IPM structure in the rotor (CW FS-IPMM), (d) concentrated winding in the stator and V-shaped IPM structure in the rotor(CW VS-IPMM). Fig. 1 shows the cross-section of the four topologies and no-load flux distribution. The objective of this paper is to present a detailed comparison of the major performance characteristics of all the four topologies illustrated in Fig.1. The selection process of the major dimensions and winding structure of the proposed IPMM is described in Section 2. Section 3 presents the cogging torque and torque ripple minimization of all the four investigated designs.

Comparison of resistance-based and inductance-based self-sensing controls for surface permanent-magnet machines using high-frequency signal injection

This paper presents injection-based self-sensing (position sensorless) control methods for surface permanent magnet (SPM) machines with concentrated windings (CWs) and distributed windings (DWs). Two position-dependent spatial saliency signals are compared. The two signals relate to resistance variation due to high-frequency eddy current losses and to inductance variation due to stator tooth saturation. Finite-element analysis is performed to investigate the properties of two saliency signals in different SPM machines. Implementation methods, as well as advantages for closed-loop control, are discussed. This paper includes experimental evaluation of resistance-based versus inductance-based self-sensing control performance in SPM machines with CWs and DWs.