TABLE OF CONTENTS As described in Chapter 3, all AC/DC rectifiers are treated as a zero-order-hold (ZOH) element in digital control systems. We will discuss this model in various circuits in this Chapter.
AC/DC rectifiers are the first group of the power switching circuits applied in industrial applications. In the 1940s, Mercury-arc rectifiers were very popular in DC power supply. In 1960s, semiconductor manufacture development brought power devices, such as power diode, thyristor (or silicon controlled rectifier, SCR), gate turn-off (GTO), Triac, bipolar transistor (BT), insulated gate bipolar transistors (IGBT) and metal-oxide semiconductor field effected transistor (MOSFET) and so on, into the DC power supply. The DC power supply equipment is totally changed. The corresponding control circuit is gradually changed from analog-to-digital control system since 1980s. The mathematical modeling for all AC/DC rectifiers is discussed widely in worldwide. Finally, a ZOH is generally accepted to be used to simulate the AC/DC rectifiers used.
In this Chapter we assume that the input voltage is a sinusoidal wave with the frequency f = 50 Hz. The transformer is used in the rectifiers with the following turn s ratio: 1:1 for Y/Y connection, 
:1 for ?/Y connection, 1 : for Y/ ? connection and 1:1 (or using : ) for ?/ ? connection in convenient analysis. The parameters used to describe the characteristics are listed below:
v( t): instantaneous phase voltage:
V rms: root-mean-square (rms) voltage
V m: maximum (amplitude) voltage:
V O: average...
