Enhanced Core Cooling for a Transformer

Broge, Rolf Nyborg

4. term

Electro-Mechanical System Design, Master

2015

2015-09-01

81

Dette speciale omhandler udvikling og afprøvning af et vandbaseret kølekoncept, Enhanced Core Cooling, opfundet af Johnson Controls, til elektriske maskiner. En velfungerende, vandtæt prototype af en transformer blev bygget og brugt som testplatform for den tiltænkte anvendelse: en permanentmagnet-synkronmotor (PMSM), der driver en aksialkompressor i en vanddampskøler (en industriel køleenhed). DC- og AC-tests vurderede, hvor godt systemet fjerner kobbertab (varme i viklingerne) og jerntab (varme i den magnetiske kerne). Temperaturfordelingen i transformeren blev beregnet med fire modelleringsmetoder: en simpel analytisk model, en klumpet parametermodel, en finite element-metode (FEM) model og en computational fluid dynamics (CFD) model. Den analytiske model fangede de overordnede tendenser, men var for enkel til at matche målingerne præcist. Klumpet parametermodellen og FEM-modellen stemte generelt godt overens med temperaturmålingerne og kan bruges som praktiske designværktøjer i den videre udvikling af Enhanced Core Cooling i elektriske maskiner. CFD-modellen overvurderede varmeoverførslen ved tvungen vandkonvektion og var dermed ikke konservativ (den forudsiger mere køling, end der faktisk er). Afslutningsvis diskuteres implementeringen i en PMSM. Det estimeres, at systemet kan bortlede op til 6 kW varme fra motoren; med et forventet tab omkring 1 kW konkluderes Enhanced Core Cooling at være en effektiv løsning til at køle en PMSM og muliggøre højere effekttæthed.

This thesis develops and tests a water-based cooling concept called Enhanced Core Cooling, invented by Johnson Controls, for use in electrical machines. A robust, waterproof transformer prototype was built and used as a test platform for the intended application: a permanent magnet synchronous motor (PMSM) that drives an axial compressor in a water-vapor chiller (an industrial cooling unit). Direct-current (DC) and alternating-current (AC) tests evaluated how well the system removes copper losses (heat in the windings) and iron losses (heat in the magnetic core. The transformer's temperature distribution was predicted with four modeling approaches: a simple analytical model; a lumped-parameter network; a finite element method (FEM) model; and a computational fluid dynamics (CFD) model. The analytical model captured overall trends but was too simplified to match measurements accurately. The lumped-parameter and FEM models agreed well with measured temperatures and are suitable as practical design tools for further development of Enhanced Core Cooling in electrical machines. The CFD model overestimated heat transfer for forced water convection, making it non-conservative (it predicts more cooling than is actually available). Finally, the study discusses integrating Enhanced Core Cooling into a PMSM. It is estimated that the system can remove up to 6 kW of heat from the motor; with an expected loss of about 1 kW, Enhanced Core Cooling is concluded to be an effective solution for cooling a PMSM and enabling higher power density.

[This abstract was generated with the help of AI]

Core ; Cooling ; Transformer ; PMSM

Download
View record in AAU Student Projects