The following discussion focuses on the full-wave bridge rectifier but generally
applies to the center-tapped circuit as well.
Resistive Load
The voltage across a resistive load for the bridge rectifier of Fig. 4-1 is expressed as
(4-1)
The dc component of the output voltage is the average value, and load current is
simply the resistor voltage divided by resistance.
(4-2)
Power absorbed by the load resistor can be determined from I
2
rmsR, where Irms
for the full-wave rectified current waveform is the same as for an unrectified
sine wave,
(4-3)
The source current for the full-wave rectifier with a resistive load is a sinusoid
that is in phase with the voltage, so the power factor is 1.
RL Load
For an RL series-connected load (Fig. 4-3a), the method of analysis is similar to
that for the half-wave rectifier with the freewheeling diode discussed in Chap. 3.
After a transient that occurs during start-up, the load current io reaches a periodic
steady-state condition similar to that in Fig. 4-3b.
For the bridge circuit, current is transferred from one pair of diodes to the
other pair when the source changes polarity. The voltage across the RL load is a
full-wave rectified sinusoid, as it was for the resistive load. The full-wave recti-
fied sinusoidal voltage across the load can be expressed as a Fourier series consisting
of a dc term and the even harmonics
where (4-4)
Vo 2Vm
and Vn 2Vm
a 1
n 1
1
n 1
b
v