Notesale: Turn your study into money

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9/13/2005

Peak Inverse Voltage
...
Yet,
the bridge rectifier use 4
junction diodes, whereas the
full-wave rectifier only uses
2
...

The problem is that the CVD model does not predict junction
diode breakdown!
If the source voltage vS becomes too large, the junction
diodes can in fact breakdown—but the transfer functions we
derived do not reflect this fact!
Q: You mean that we must

rework our analysis and find new
transfer functions!?

Jim Stiles

The Univ
...
of EECS

9/13/2005

Peak Inverse Voltage
...
Breakdown is an undesirable mode for
circuit rectification
...

Recall that the voltage across a reverse biased ideal diode in
the full-wave rectifier design was:
i
vD 2 = −2vS

so that the voltage across the junction diode is approximately:
i
vD = vD + 0
...
7

Now, assuming that the source voltage is a sine wave
vS = A sin ωt , we find that diode voltage is at it most negative
(i
...
, breakdown danger!) when the source voltage is at its
maximum value A
...
E
...
7

Of course, the largest junction diode voltage occurs when in
forward bias:
max
v D = 0
...
of Kansas

Dept
...
doc

3/6

v
vD(t)

A

t

0
...
7

vS(t)

Note that this minimum diode voltage vD is very negative, with
min
an absolute value ( vD = 2A − 0
...

We call the absolute value of the minimum diode voltage the
Peak Inverse Voltage (PIV):

min
PIV = vD

Note that this value is dependent on both the rectifier design
and the magnitude of the source voltage vS
...

Jim Stiles

The Univ
...
of EECS

9/13/2005

Peak Inverse Voltage
...
e
...
The rectifier will operate “properly”!
However, if the PIV is greater than the Zener breakdown
voltage of our rectifier diodes (i
...
, if PIV >VZK ), then we
know that our junction diodes will breakdown for at least
some small amount of time t
...
Use junction diodes with larger values of VZK (if they
exist!)
...
Use the bridge rectifier design
...
of Kansas

Dept
...
doc

5/6

A: To see how a bridge rectifier can be useful, let’s
determine its Peak Inverse Voltage PIV
...
7
= −vS + 0
...
e
...
I
...
,:
min
vD = −A + 0
...
7 V

Jim Stiles

The Univ
...
of EECS

9/13/2005

Peak Inverse Voltage
...
7

−A + 0
...
7 ), approximately equal to the
value of the source magnitude A
...
7
Note that this bridge rectifier value is approximately half
the PIV we determined for the full-wave rectifier design!
Thus, the source voltage (and the output DC component) of a
bridge rectifier can be twice that of the full-wave rectifier
design—this is why the bridge rectifier is a very useful
rectifier design!

Jim Stiles

The Univ
...
of EECS



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