Design optimization of a synchronous reluctance motor based on operating cycle

Synchronous reluctance motors are becoming an interesting solution for drives applications requiring high efficiency. The design of those machines is normally based on the optimization of the motor performance at the rated working point in terms of torque production, torque ripple and efficiency, but in many applications the drive will operate for most of the time at partial load and frequent overload may be required, with a speed not necessarily equal to the rated value. In this work we propose an optimized machine design method to maximize the drive efficiency on the total operating cycle, considering a specific speed and torque profile. Four typical working points are selected, each of them maintained by the machine for a different time in the operating cycle. The obtained machine is compared with the one optimized based on the rated conditions only, showing slightly higher losses on a single working point but an improved efficiency on the global operating cycle

Determination of PM Flux Linkage Based on Minimum Saliency Tracking for PM-SyR Machines without Rotor Movement

Permanent magnet assisted synchronous reluctance (PM-SyR) motors often present relevant magnetic saturation, especially if overload capability is exploited. The knowledge of current-to-flux relationship is mandatory for proper motor control, and it becomes even more critical in the case of sensorless applications. Reliable standstill self-commissioning tests have been recently developed for synchronous reluctance (SyR) motors without producing rotor movement. This procedure can be extended to PM-SyR motors, but being at standstill, it does not retrieve the flux contribution related to the permanent magnets (PMs). This article integrates the identification of the flux characteristics including a novel test for estimating the PM flux linkage, obtaining the complete magnetic characteristic of the PM-SyR motor. The identification session is performed at standstill and without a position transducer, independently of the mechanical load being connected or not. Such conditions are considered the most demanding for self-commissioning tests. The machine is first excited with a proper sequence of bipolar high voltage pulses to determine its current-dependent flux components. Then, the estimate of PM flux linkage is retrieved at standstill by evaluating the local saliency along the negative q-axis. The proposed method is supported by detailed finite element analysis and experimentally verified on two PM-SyR motor prototypes, confirming the accuracy of the PM flux linkage estimate

Transient Overload Characteristics of PM-Assisted Synchronous Reluctance Machines, Including Sensorless Control Feasibility

Synchronous reluctance machines are a highefficiency alternative to induction motors for variable-speed applications. To mitigate the well-known downside of their lower power factor, permanent-magnet-assisted topologies, in which either rare-earth or ferrite magnets are inserted into the rotor in suitable quantities, are often adopted. The design and optimization procedures for PM-assisted topologies have been thoroughly discussed in the related literature. This paper compares synchronous reluctance machines assisted with NdFeB and ferrite magnets, focusing on torque overload capability and feasibility of saliency-based position estimation algorithms. Three prototypes were realized and tested. They all have the stator of a commercial induction motor and the same customdesigned synchronous reluctance rotor laminations. Of the three prototypes, one is a pure synchronous reluctance motor, and the other two have NdFeB and ferrite magnets, respectively; both are designed to give the same torque at rated current. Results from simulations and experiments are presented comparing the transient overload capability of the three machines, in terms of torque capability and de-magnetization limit. A dynamic thermal model of the machines was developed within this scope. Moreover, the feasibility of saliency-based sensorless methods was investigated and is presented here for the three machines, both at high- and low-current loads. The results of the paper suggest that the ferrite-assisted solution is the best candidate for replacing induction motors in variable-speed applications, for its optimal tradeoff between performance and cost

Analysis of overload and sensorless control capability of PM-assisted synchronous reluctance machines

Synchronous reluctance machines are a valid alternative to induction motors for industrial applications requiring variable speed regulation. To mitigate the well-known downside of their lower power factor, permanent-magnetassisted topologies are adopted. Both high-strength rare-earth magnets and low cost ferrite magnets can be used in such machines. Their design and optimization procedures have been discussed in related literature. This paper compares synchronous reluctance machines assisted with NdFeB and ferrite magnets, focusing on torque overload capability and feasibility of saliencybased position estimation algorithms. Three prototypes were realized and tested. They all have the stator of a commercial induction motor, and three custom synchronous reluctance rotors with same laminations: one has no magnets, the other two have NdFeB and ferrite magnets respectively, designed to give the same torque at rated current. Results from simulations and experiments are presented, focusing on torque and demagnetization limits in the over-current loading range. Moreover, the feasibility of saliency-based sensorless methods is investigated, both at high and low current loads. The results of the paper suggest that the ferrite-assisted solution is the candidate solution for replacing induction motors in variable speed applications

High-resolution in situ holographic recording and analysis of marine organisms and particles (HOLOMAR)

We report on the development of a fully- unctioning, prototype, underwater holographic camera (holo-camera) for holographic recording of large-volumes of sea water containing marine plankton and seston within the upper water column The overriding benefit of holographic imaging over other measurement techniques is that it allows non-intrusive and non-destructive, in-situ, recording of living organisms and inanimate particles in their natural environment. Because of the inherently high resolution of holography, its threedimensional imaging properties and the ability to perform "optical sectioning" on the image, it allows identification of particular organisms together with the extraction of sue and relative positional information This information, in turn, affords the ability to gain knowledge of the behaviour of marine biological communities, their relationship with each other and with the particles with which they interact

Isolated Semi Integrated On-board Charger for EVs Equipped with 6-phase Traction Drives

The recent trend in road transportation electrification pushes the development of reliable and compact solutions for the traction drives and charging infrastructures. This work proposes an innovative on-board battery charger partially integrated with the powertrain of a road electric vehicle equipped with a 6-phase traction motor drive. The integration permits to exploit the traction inverter and motor as power conversion unit and HF transformer respectively, with remarkable benefits in terms of e-axle compactness and cost of the components. Despite the integrated nature of the proposed system, galvanic isolation is provided, ensuring reliable and safe operation of the charger. Over to the traction drive, the proposed topology only requires a passive diode bridge and three grid inductors. A dedicated control strategy is developed to avoid torque production during charging. The proposal is validated by exhaustive simulations. A full experimental stage is currently ongoing, and promising preliminary results are reported

Mobile payment applications: offer state of the art in the Italian market

Purpose – The purpose of the paper is to provide an initial study on the Italian mobile payment services market, and to identify and assess the main diffusion drivers of mobile payment applications. Design/methodology/approach – The research design integrates an exhaustive census of all Italian mPayment applications and an in-depth analysis of the most significant cases performed through the case studies methodology: ten user companies or “merchants” and six service providers were analyzed through semi-structured interviews given to top managers. Findings – Through the census, 21 mPayment applications and related services were identified. In addition to this, the case studies brought greater understanding of the key diffusion drivers: strong inhibitory factors and adoption barriers are still restricting user adoption despite the many benefits related to these services. Research limitations/implications – The research represents a first, exploratory study of a market at its embryonic stage of development. Nevertheless, given the global magnitude of the Italian mobile telecommunications market and the gradual rise of the mPayment paradigm, the analysis can provide a valuable basis for future studies in the field. Practical implications – The findings can support a wide set of stakeholders – both first movers and newcomers of the mobile payment segment – in their offer definition and market making choices. Originality/value – The paper combines a census and a case study methodology to delineate the offer's state of the art for innovative, mobile channel-based payment services; moreover, its assessment of the applications' core benefits, diffusion drivers and adoption barriers can be tested for generalization to different contexts