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Uncontrolled Rectifiers in MATLAB

Welcome to the introduction of Simscape Electrical in MATLAB/Simulink. This document serves as the course material for understanding uncontrolled rectifiers, specifically focusing on diode rectifiers.

What is a Rectifier?​

Diodes are extensively used in rectifier circuits. A rectifier is an electronic circuit that converts an alternating current (AC) signal into a unidirectional (direct current) signal. Essentially, a rectifier functions as an AC-to-DC converter and can also be considered an absolute value converter.

When an AC input voltage Vs is applied to a rectifier circuit, the output voltage Vo follows the waveform of the input voltage, but with a crucial difference: the negative portions of the input signal are converted to positive values. This relationship can be expressed mathematically as:

Vo = |Vs|

Where |Vs| represents the absolute value of the input voltage.

Classification of Rectifiers​

Rectifiers are classified based on the type of input supply into two main categories:

1. Single-Phase Rectifiers​

These rectifiers operate with single-phase AC input and are further subdivided into:

  • Half-wave rectifiers: Convert only one half of the AC waveform
  • Full-wave rectifiers: Convert both halves of the AC waveform

2. Three-Phase Rectifiers​

These rectifiers operate with three-phase AC input systems and are commonly used in industrial applications requiring higher power conversion.

This content is designed to provide a foundational understanding of rectifier circuits using Simscape Electrical tools in MATLAB/Simulink environment.

Important Notes​

  • Single-phase half-wave rectifiers represent the simplest type of rectifier configuration. However, due to their poor efficiency and high ripple content, they are not commonly used in industrial applications.

  • For the purpose of this course and analysis, diodes are considered to be ideal. This assumption simplifies calculations by neglecting forward voltage drop and reverse leakage current.

Learning Focus​

In this section, we will concentrate on uncontrolled rectifiers, which use diodes as the primary switching elements. Unlike controlled rectifiers that use thyristors or other controllable switches, uncontrolled rectifiers provide a fixed output voltage relationship with the input voltage.