Modelling and Implementation of Active Thermal Controls for the Power Electronics System for Motor Drive Applications
Author
Vernica, Ionut
Term
4. term
Education
Publication year
2016
Pages
49
Abstract
Denne afhandling undersøger, hvordan aktiv termisk kontrol kan begrænse den termiske cykling i effekthalvledere i motordrev, med fokus på en permanentmagnet-synkronmaskine (PMSM) drevet af en back-to-back spændingskildeomformer. For at forstå årsagerne til temperatursvingninger er motoren, feltorienteret styring med PI-regulatorer, og en trefaset inverter med diskontinuerlig PWM modelleret; derudover er et detaljeret tabsschema for lednings- og koblingstab med temperaturafhængighed kombineret med et Foster RC-termisk netværk til estimering af knudetemperatur. På basis af denne model foreslås og implementeres tre aktive kontrolmetoder – justering af koblingsfrekvens, injektion af reaktiv strøm og tilpasning af decelerationshældning – med særligt henblik på belastningsskift under opbremsning, hvor termisk cykling er kritisk. En missionsprofil-emuleringsalgoritme for en tre-niveaus NPC H-bro er udviklet for at afprøve strategierne, og simulationsresultaterne er valideret gennem laboratorieforsøg. Resultaterne viser konsistens mellem model og målinger og indikerer, at de foreslåede metoder er egnede til at påvirke knudetemperaturens dynamik under deceleration og dermed adresserer problemstillingen omkring levetid i effektelektronikken.
This thesis examines how active thermal control can limit thermal cycling in power semiconductor devices within motor drives, focusing on a permanent-magnet synchronous machine (PMSM) driven by a back-to-back voltage source converter. To analyze the origins of temperature swings, the machine, field-oriented control with PI regulators, and a three-phase inverter with discontinuous PWM are modeled; a detailed conduction and switching loss model with temperature dependence is combined with a Foster RC thermal network to estimate junction temperature. Building on this model, three active control methods—switching frequency adjustment, reactive current injection, and deceleration slope adjustment—are proposed and implemented, with particular attention to load changes during deceleration where thermal cycling is most severe. A mission profile emulation algorithm for a three-level NPC H-bridge is developed to exercise the strategies, and simulation results are validated through laboratory experiments. The results show agreement between simulations and measurements and indicate that the proposed methods can influence junction-temperature dynamics during deceleration, thereby addressing reliability concerns associated with thermal cycling in power electronics.
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