This dissertation deals with the magnetic analysis of an outer-rotor DC brushless motor. The motor, called BL42, is one of the DC brushless configuration available in the MAE (Motori Apparacchiature Elettriche) catalog. Its 6-pole/9-slot configuration derives from a previous AC brushless, from which it retains the sinusoidally-magnetized rotor-ring. This motor is usually applied in blower applications. MAE’s engineers aim at making it suitable also in other applications, by increasing its performances and reducing the inevitable torque ripples caused by its “AC-derived” magnetic design. MAE required this goal to be reached by changing only the rotor structure and magnet arrangement, while maintaining the existing stator structure from BL42 motor. This constraint is justified by economic and standardization reasons across MAE production and supply chain, especially as far as the stator laminations are concerned. It is also worth mentioning that “AC-derived” DC-brushless topologies are in fact not so unusual in appliances, and similar solutions were found in motor catalogues from MAE competitors. The benchmark motor magnetic behaviour is studied through a variety of techniques, starting from simple analytic models and then moving to Finite Element Analysis with 2D models created in COMSOL Multiphysics. Building on the analysis results of the benchmark motor, new magnetic configurations for the rotor are suggested and examined. Some modifications have then been implemented in new motor prototype tested in the laboratory.
Questa tesi si occupa dell'analisi magnetica di un motore brushless DC a rotore esterno. Il motore, chiamato BL42, è una delle configurazioni DC brushless disponibili nel catalogo MAE (Motori Apparacchiature Elettriche). La sua configurazione a 6-poli/9-cave deriva da un precedente AC brushless, di cui conserva l'anello magnetico magnetizzato sinusoidalmente. Questo motore è solitamente utilizzato come soffiatore. Gli ingegneri di MAE mirano a renderlo adatto anche in altre applicazioni, aumentandone le prestazioni e riducendo gli inevitabili ripple di coppia causati dal design magnetico derivato dal modello in “corrente alternata". MAE ha richiesto di raggiungere questo obiettivo cambiando solo la struttura del rotore e la disposizione dei magneti, mantenendo la struttura dello statore esistente. Questo vincolo è giustificato da ragioni economiche e di standardizzazione in tutta la catena di produzione e fornitura di MAE, soprattutto per quanto riguarda le laminazioni dello statore. Vale anche la pena menzionare che le topologie DC-brushless "derivate dall'AC" non sono in effetti insolite negli elettrodomestici, e soluzioni simili sono state trovate nei cataloghi dei motori dei concorrenti MAE. Il comportamento magnetico del motore di riferimento viene studiato attraverso una varietà di tecniche, partendo da semplici modelli analitici per poi passare all'analisi agli elementi finiti con modelli 2D creati in COMSOL Multiphysics. Basandosi sui risultati dell'analisi del motore di riferimento, vengono suggerite ed esaminate nuove configurazioni magnetiche per il rotore. Alcune modifiche sono state poi implementate in nuovi prototipi di motore che sono stati testati in laboratorio.
Magnetic analysis and experimental characterisation of an outer-rotor DC brushless motor
Rolla, Marco
2020/2021
Abstract
This dissertation deals with the magnetic analysis of an outer-rotor DC brushless motor. The motor, called BL42, is one of the DC brushless configuration available in the MAE (Motori Apparacchiature Elettriche) catalog. Its 6-pole/9-slot configuration derives from a previous AC brushless, from which it retains the sinusoidally-magnetized rotor-ring. This motor is usually applied in blower applications. MAE’s engineers aim at making it suitable also in other applications, by increasing its performances and reducing the inevitable torque ripples caused by its “AC-derived” magnetic design. MAE required this goal to be reached by changing only the rotor structure and magnet arrangement, while maintaining the existing stator structure from BL42 motor. This constraint is justified by economic and standardization reasons across MAE production and supply chain, especially as far as the stator laminations are concerned. It is also worth mentioning that “AC-derived” DC-brushless topologies are in fact not so unusual in appliances, and similar solutions were found in motor catalogues from MAE competitors. The benchmark motor magnetic behaviour is studied through a variety of techniques, starting from simple analytic models and then moving to Finite Element Analysis with 2D models created in COMSOL Multiphysics. Building on the analysis results of the benchmark motor, new magnetic configurations for the rotor are suggested and examined. Some modifications have then been implemented in new motor prototype tested in the laboratory.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/183201