Manufacturing, Modelling and Control of a High Speed Permanent Magnet Synchronous Machine including a Thermal Analysis
Authors
Mathiasen, Dan Mølgaard ; Olesen, Nicolaj Thomas
Term
4. term
Education
Publication year
2014
Submitted on
2014-06-03
Pages
146
Abstract
This thesis investigates the development, modeling, and control of a high-speed Permanent Magnet Synchronous Machine (PMSM) for a low-pressure water-vapor compressor with individually driven impellers. The objective is to assess a liquid-cooled motor design by manufacturing two prototypes, building a 3D lumped-parameter thermal model, and an electrical dq model that includes a voltage source inverter with space-vector PWM. Insights from the first prototype inform improvements to the second, including vacuum epoxy potting to seal the cooling channels. Tests, however, reveal persistent coolant leakage and higher-than-expected losses—likely due to damage to stator and rotor laminations—preventing full-scale tests with active cooling. The thermal model is compared with a 2D FEM model and experiments and shows acceptable deviations; using the measured (elevated) losses it predicts excessive temperatures, while temperatures are acceptable with the expected losses. The electrical and mechanical models are used to design and test control strategies: a cascaded closed-loop controller is designed but not implemented, whereas an open-loop voltage control is implemented experimentally. Measured and simulated current characteristics agree reasonably and show large current ripple and speed oscillations at high speed with limited switching frequency; analyses indicate that a switching frequency of at least 10 kHz is required to limit these effects. The work highlights the need for further verification of the thermal model and manufacturing improvements to achieve leak-tight cooling and reduced losses.
Dette speciale undersøger udvikling, modellering og styring af en højhastigheds Permanent Magnet Synkronmaskine (PMSM) til anvendelse i en lavtryks vanddampskompressor med individuelt drevne kompressorhjul. Formålet er at vurdere et væskekølet motordesign ved at fremstille to prototyper, opbygge en 3D termisk lumped-parameter-model samt en elektrisk dq-model, der inkluderer en frekvensomformer med rumvektorpulsbreddemodulation. Erfaringer fra første prototype bruges til at forbedre den anden, herunder vakuumindstøbning i epoxy for at forsegle kølesystemet. Forsøg afslører dog fortsatte lækager i væskekølingen og højere tab end forventet—formentlig pga. skader på stator- og rotorlamineringer—hvilket hindrer fuldskalaforsøg med aktiv køling. Den termiske model sammenlignes med en 2D FEM-model og målinger og viser acceptable afvigelser; med de målte (forhøjede) tab forudsiges for høje temperaturer, mens temperaturerne er acceptable med forventede tab. Den elektriske og mekaniske model anvendes til design og test af styringer: en kaskaderegulator designes, mens en åben sløjfe spændingsstyring implementeres eksperimentelt. Målte og simulerede strømkarakteristikker stemmer rimeligt og viser betydelige strøm-rippler og hastighedsoscillationer ved høj hastighed og begrænset switchfrekvens; analyser indikerer, at en switchfrekvens på mindst 10 kHz er nødvendig for at begrænse disse effekter. Arbejdet peger på behov for yderligere verifikation af den termiske model samt forbedringer af produktionen for at sikre tæt køling og reducerede tab.
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Keywords