THREE-PHASE
6- Consider the problem of ripple in the output current of a threephase square-wave inverter. Assume (VLL )1 = 220 V at a frequency
of 52 Hz and the type of load is as shown in Fig.25a with L = 100
mH. Calculate the peak ripple current defined
Chapter 2
Diode Circuits or Uncontrolled Rectifier
2.1 Introduction
The only way to turn on the diode is when its anode voltage becomes
higher than cathode voltage as explained in the previous chapter. So,
there is no control on the conduction time of the
82 Chapter Two
13- Solve problem 12 if the supply has source inductance of 4 mH.
14- Three-phase full bridge diode rectifier is connected to 380V, 50Hz
supply to feed 10 resistor. Draw the output voltage, diode currents
and supply current of phase a. Then
46 Chapter Two
2.4.5 Effect Of LS On Current Commutation Of Single-Phase Diode
Bridge Rectifier.
Fig.2.15 Shows the single-phase diode bridge rectifier with source
inductance. Due to the value of LS the transitions of the AC side current
iS from a value o
34 Chapter Two
For the period 2 < t < 3 the value of i (2 ) from (2.31) can be
used as initial condition for that period. The differential equation
representing this period is the same as equation (2.28) by replacing t by
t 2 and the solution is given by
SCR Rectifier or Controlled Rectifier
91
An expression for the current through the load can be obtained as
shown below:
When the SCR conducts, the driving function for the differential
equation is the sinusoidal function defining the source voltage. Durin
SCR Rectifier or Controlled Rectifier
103
and the SCRs continue to conduct, with the inductor acting as a source.
When the current through an inductor is falling, the voltage across it
changes sign compared with the sign that occurs when its current is
ri
17- Single phase diode bridge rectifier is connected to square waveform
with amplitude of 200V, 50 Hz. The supply has 4 mH source
inductance. The load connected to the rectifier is 45 A pure DC
current. Draw, output voltage, diode currents and supply curr
196 Chapter Three
To allow control over the fundamental output and to eliminate the
fifth-, seventh-, eleventh-, and the thirteenth-order harmonics, five
notches per half-cycle would be needed. In that case, each switch would
have 11 times the switching f
SCR Rectifier or Controlled Rectifier
Fig.3.27 SCR inverter with a DC voltage source.
Fig.3.28 Vd versus I d in SCR inverter with a DC voltage source.
Fig.3.29 Voltage across a thyristor in the inverter mode.
115
116 Chapter Three
Inverter startup
For sta