Vorlesung GEET

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  • Title: Leistungselektronik

  • Professor: Prof. Dr.-Ing. Holger Hirsch, Universität Duisburg-Essen.

  • Responsibilities: Energietransport und -speicherung.

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  • Subject Coverage: Grundlagen der elektrischen Energietechnik.

  • Key Topics:

    1. Wechselstromrechnung

    2. Drehstromsysteme

    3. DC-Systeme

    4. Hochspannungsfelder

    5. Hochstromfelder

    6. Einphasen-Transformatoren

    7. Leitungen

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  • Copyright © 2024 Prof. Dr.-Ing. Holger Hirsch.

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  • Title: Leistungselektronik

  • Professor: Prof. Dr.-Ing. Holger Hirsch, Universität Duisburg-Essen.

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Wechselstromrechnung

  • Development: Transition from direct current (DC) to alternating current (AC) systems due to various advantages:

    • Simpler generation through electrical machines.

    • Simpler transition between different voltage levels (using transformers).

    • Better switching behavior (archs can be extinguished due to current zero crossings).

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1.1 Harmonische Vorgänge (1)

  • AC voltage generated in generators is sinusoidal (ideal).

  • Key Parameters:

    • Amplitude:

    • Peak Value:

    • Period Duration (T) / Frequency (f):

    • Formulas involved:

      • [ u(t) = \hat{u} * \sin(\omega t) ]

      • [ i(t) = \hat{i} * \sin(\omega t - \phi) ]

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1.1 Harmonische Vorgänge (2)

General Relationships in Trigonometric Functions:

  • Various relationships including:

    • [ \sin(a \pm b) = \sin(a).\cos(b) \pm \cos(a).\sin(b) ]

    • Identity derivations such as [ \sin^2(a) + \cos^2(a) = 1 ].

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1.2 Effektivwert (1)

  • The average ( R) associated with instantaneous values is determined by:

    • [ u(t) = \hat{u} * \sin(\omega t) ]

    • Applying the formula:

      • Power at time: [ p(t) = \hat{u} * \hat{i} * \cos(\omega t) ]

      • Resulting in average power equations based on AC variables.

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1.2 Effektivwert (2)

  • Definition of the effective value of voltage and current, stating:

    • [ U_{eff} = \frac{U_{peak}}{\sqrt{2}} ]

    • Common measurement neglects "eff" in AC specifications, e.g., [ U=230V ].

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1.3 Zerlegung in Komponenten, Zeigerdiagramme (1)

  • Every harmonic oscillation can be uniquely decomposed into sine and cosine components:

    • Describes AC voltage as a combination of sine and cosine waves.

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1.3 Zerlegung in Komponenten, Zeigerdiagramme (2)

  • Parameters represented as vectors in a coordinate system.

    • Visual representation of sine and cosine components.

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1.4 Addition von Zeigern

  • Kirchhoff’s principles applied to vector addition of phasors in AC analysis.

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1.5 Verhalten von Kapazitäten und Induktivitäten in Wechselstromkreisen

  • Describes leading and lagging relationships between current and voltage in capacitive and inductive circuits, emphasizing phase differences of 90°.

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  • Copyright © 2024 Prof. Dr.-Ing. Holger Hirsch.

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  • Title: Leistungselektronik

  • Professor: Prof. Dr.-Ing. Holger Hirsch, Universität Duisburg-Essen.

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1.6 Komplexe Rechnung (1)

  • Introduction of the Euler’s formula and complex numbers in AC analysis, used for phasor representation in electrical circuits.

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1.6 Komplexe Rechnung (2)

  • Descriptive equations regarding the behavior of circuit elements in AC networks.

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1.6 Komplexe Rechnung (3)

  • Specific descriptions of resistive and reactive components using phasors.

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1.6 Komplexe Rechnung (4)

  • Analysis of inductance behavior with special attention to reactances.

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1.6 Komplexe Rechnung (5)

  • Example calculations for mixed circuits and the passive components impacting performance.

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  • Copyright © 2024 Prof. Dr.-Ing. Holger Hirsch.