A dual-memory permanent magnet brushless machine for automotive integrated starter-generator application

This paper presents a dual-memory permanent magnet brushless machine for automotive integrated starter-generator (ISG) application. The key is that the proposed machine adopts two kinds of PM materials, namely NdFeB and AlNiCo for hybrid excitations. Due to the non-linear characteristic of demagnetization curve, AlNiCo can be regulated to operate at different magnetization levels via a magnetizing winding. With this distinct merit, AlNiCo can provide the assistance for online tuning the air-gap flux density. Firstly, the configuration of proposed machine is presented. Secondly, the finite element method (FEM) is applied for the field calculation and performance verification. Finally, both simulation and experimental results confirm that the proposed machine is very suitable for the ISG application. © 2012 IEEE.published_or_final_versio

Electric vehicle possibilities using low power and light weight range extenders

Electric cars have the disadvantage of a limited range, and drivers may experience a range anxiety. This range anxiety can be solved by adding a range extender. But, the range extender should be light so as not to significantly increase the weight of the original vehicle. In urban areas with dense traffic (usually developing countries), the average speed around cities is typically lower than 50km/h. This means, the rolling resistance losses are more important than aerodynamic losses, and a weight reduction results in a bigger electrical range. Therefore, smaller and lighter range extenders are of much interest. The contribution of this paper is to indicate the possibility of range extenders with less than 25 kg with a capacity of 150 to 200 cc to suit a condition where weight counts. In this paper, the cost, environmental and grid impacts of going electric are also discussed. The effect of high altitude and driving style on the performance of an electric vehicle is assessed. The challenges and opportunities of vehicle electrification between countries with decarbonated power generation and fossil fuel dominated power generation are highlighted. Throughout the article, the case of Ethiopia is taken as an example

IPM Machine Drive Design and Tests for an Integrated Starter-Alternator Application

Abstract\u2014This paper deals with an integrated starter\u2013 alternator (ISA) drive which exhibits a high torque for the en- gine start, a wide constant-power speed range for the engine speedup, and a high-speed generator mode operation for electric energy generation. Peculiarities of this ISA drive are thus its \ufb02ux- weakening capability and the possibility to large torque overload at low speed. The focus on the design, analysis, and test of an interior permanent-magnet motor and drive for a prototype of ISA is given in this paper. In details, this paper reports on the design of stator and rotor geometries, the results of \ufb01nite-element com- putations, the description of control system, and the experimental results of prototype tests

IPM Machine Drive Design and Tests for an Integrated Starter-Alternator Application

This paper deals with an integrated starter-alternator (ISA) drive able to satisfy the requirements of exhibiting high torque, driving start, and a wide constant-power speed range driving generation. It illustrates the design, analysis and test of an interior permanent magnet (IPM) motor and drive for an ISA, developed for the IEEE International Future Energy Challenge (IFEC) 2007. The paper reports the design of the stator and rotor geometry, the results of finite elements computations, the description of control algorithms and the experimental results of the tests on the prototype

Caratterizzazione di alcuni motori campione per la sperimentazione di azionamenti elettrici

Lo scopo perseguito nella tesi è la misura, il collaudo e la caratterizzazione di alcune diverse tipologie di macchine elettriche presenti in laboratorio. Nello specifico sono state presi in considerazione tre differenti motori,un motore asincrono e due motori sincroni a magneti permanenti

Multi-phase Starter-Generator for 48 V Mild-Hybrid Powertrains

Transportation electrification has experienced a significant growth in recent years, and the electrification of the powertrain – namely hybridization – is considered the most viable solution seen by car manufacturers to achieve the challenging emission targets. Among the hybrid electrical powertrain topologies, the mild-hybrid configuration with the 48 V battery system offers the best ratio cost versus CO2 improvements. In particular, the 48 V technology does not require electrical shock protection whilst allows to leverage a variety of fuel saving functions such as electrical boost and regenerative braking. The thesis is focused on the electromagnetic and thermal design of a Belt-driven Starter Generator, BSG, for 48 V mild-hybrid powertrains. In the BSG layout, the starter-generator replaces the conventional alternator with a low impact on the engine compartment layout, even if a redesign of the belt tensioner is required. It is noteworthy to keep in mind that the electrical machine shall provide high starting torque and wide constant power speed range, both in motor and generator mode. Furthermore, the application imposes the adoption of low cost materials and the electrical machine is located in a harsh environment. As a consequence, the design is challenging from the electromagnetic, thermal and mechanical point of view. The novelties of the research lie in the 48 V automotive applications, by describing the practical difficulties to fulfill the design specifications through a suitable material selection, the identification of the cooling system and the available technological solutions. The first section of the thesis reports results from a literature review on electrical machine for mild-hybrid application aiming to highlight different criteria for the selection of the electrical machine. In this context the advantages in terms of fault tolerance and stator current splitting of multiphase drives are investigated. Furthermore, in this section the required performances and the constraints imposed by the specific application are analyzed. Among the different motor technologies, a dual three-phase induction machine having two stator winding sets shifted by 60 electrical degrees is selected as a suitable candidate. The second part of the thesis reports electromagnetic and mechanical issues addressed during the design stage, with special focus on stator winding layout, pole number and rotor slot. The adopted six-phase machine uses a four-layer bar stator winding that has been demonstrated as a good solution to improve the slot fill factor and thermal behavior. In addition, the thesis reports a comparison supported by experimental tests between open and closed rotor slots solutions; the focus is to maximize the machine electromagnetic performance according to the mechanical limits imposed by the rotating speed. Finally, predicted and measured performance of the prototypes are reported and discussed for validation purposes. The third part of the thesis deals with the thermal assessment of the BSG with particular emphasis on accurate winding temperature prediction as well as the cooling system selection. Since the stator-winding region is very sensitive to thermal issues and is usually attributed as being the main heat source within the machine body, its thermal modeling is of major importance. In these regards, a simplified stator winding thermal model was developed for the temperature prediction during transient condition. Moreover, considering that the driving cycle is characterized by time variable loss distribution, an effective cooling system must be mandatorily adopted together with high temperature class insulation material. In this context, the development of heat extraction through forced convection is experimentally investigated on the BSG prototype. As a main outcome of this research activity, it has been demonstrated the feasibility of the proposed design solution with respect to electromagnetic and thermal requirements

Caratterizzazione sperimentale di un motore sincrono a magneti permanenti mediante la misura dei flussi in presenza di saturazione incrociata

Guida all'esecuzione delle prove sperimentali di flusso tenendo conto anche dela cross-saturation e guida a tutte le prove di flusso e coppia esegubili su un motore IPMopenEmbargo per motivi di segretezza e di proprietà dei risultati e informazioni sensibil

Design and modelling of permanent magnet machine's windings for fault-tolerant applications

The research described in this thesis focuses on the mitigation of inter-turn short-circuit (SC) faults in Fault tolerant Permanent Magnet (FT-PM) machines. An analytical model is proposed to evaluate the inter-turn SC fault current accounting for the location in the slot of the short-circuited turn(s). As a mitigation strategy to SC faults at the design stage, a winding arrangement called VSW (Vertically placed Strip Winding) is proposed and analysed. The proposed analytical model is benchmarked against finite element (FE) calculation and validated experimentally. The results demonstrate that the proposed winding arrangement in the slot improves the fault tolerance (FT) capability of the machine by limiting the inter-turn SC fault current regardless the fault location in the slot. Electromagnetic and thermal studies are conducted to verify the merits and drawbacks of the proposed winding compared to the conventional winding using round conductors (RCW). The study shows that the proposed winding scheme, in addition to being fault-tolerant, has an improved bulk radial conductivity, can achieve a good fill factor, but has a significantly higher frequency-dependent AC copper loss. To predict the AC losses an analytical model based on an exact analytical 2D field solution is proposed. This model consists of first solving the two-dimensional magneto-static problem based on Laplace’s and Poisson’s equations using the separation of variables technique. Then, based on that solved solution, by defining the tangential magnetic field (Ht) at the slot opening radius, Helmholtz’ equation is solved in the slot sub-domain. Subsequently, an FE and MATLAB® coupled parametric design is undertaken to maximise the VSW wound machine’s efficiency whilst maintaining its FT capability. The proposed analytical models for prediction of the SC fault current and AC copper losses are integrated into the coupled optimisation. It is shown that the effective losses of the VSW can be minimised through the parametric design while maintaining the required level of machine performance. Using an existing FT-PM machine of which the rotor is kept unchanged two stators were designed, manufactured and wound with RCW and VSW respectively and experimental tests are carried out to validate the analytical models and the new winding concept