The Significance of Fourier Analysis

Fourier Analysis

The switch action in a conversion circuit is most often periodic. The waveforms themselves are rather choppy and sometimes discontinuous. We must form an approximate DC output of a rectifier, for instance, by piecing together ‘chunks’ of the AC input. Given the strange waveforms and the periodic action, how can we determine whether a conversion operation is successful? What filtering is […]

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Review of Fourier Series

Fourier Series

Nearly any periodic function of time , such that , can be written as a sum of sinusoids known as the Fourier Series. where the radian frequency is defined as . This result applies to signals with jump discontinuities which are often encountered in the world of power electronics. While there are few very special periodic functions without Fourier Series […]

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Characteristics of Power Semiconductor Devices

Diode, IGBT, and MOSFET silicon carbide power semiconductors.

Diode – Current ratings from under 1 A to more than 5000 A. Voltage ratings from 10 V to 10 kV or more. The fastest power devices switch in less than 20 nanoseconds, while the slowest require 100 microseconds or more. The function applies in rectifiers and DC-DC circuits. BJT – (Bipolar Junction Transistor) Conducts collector current (in one direction) when […]

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Kirchhoff’s Voltage and Current Laws

Kirchhoff's Voltage Law

Granted, a switch circuit can perform power conversion, and granted, it can be described as a switch matrix. How do we make the choices of switch operation? Consider first the simple circuit shown to the right – something we might try for AC-DC conversion. This circuit has problems. Kirchoff’s Voltage Law (KVL) tells us: The sum of voltage drops around a […]

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Introduction to Switches

Switches

We have seen that circuits involving switches and energy storage can be operated to give energy conversion functions. Switches come in a huge variety including mechanical and semiconductor styles. It is important to develop a systematic way to identify appropriate power electronic circuits, and to find out how they can be controlled to give the desired performance. Consider, for example, […]

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