<s>
Random	B-Algorithm
pulse	I-Algorithm
width	I-Algorithm
modulation	I-Algorithm
(	O
RPWM	O
)	O
is	O
a	O
modulation	B-Application
technique	O
introduced	O
for	O
mitigating	O
electromagnetic	O
interference	O
(	O
EMI	O
)	O
of	O
power	O
converters	O
by	O
spreading	O
the	O
energy	O
of	O
the	O
noise	O
signal	O
over	O
a	O
wider	O
bandwidth	B-Algorithm
,	O
so	O
that	O
there	O
are	O
no	O
significant	O
peaks	O
of	O
the	O
noise	O
.	O
</s>
<s>
This	O
is	O
achieved	O
by	O
randomly	O
varying	O
the	O
main	O
parameters	O
of	O
the	O
Pulse	B-Algorithm
Width	I-Algorithm
Modulation	I-Algorithm
signal	O
.	O
</s>
<s>
However	O
,	O
when	O
size	O
is	O
of	O
great	O
concern	O
like	O
in	O
aircraft	O
and	O
automobile	O
applications	O
,	O
one	O
of	O
the	O
practical	O
solutions	O
to	O
suppress	O
conducted	O
emissions	O
is	O
to	O
use	O
random	B-Algorithm
pulse	I-Algorithm
width	I-Algorithm
modulation	I-Algorithm
(	O
RPWM	O
)	O
.	O
</s>
<s>
In	O
conventional	O
pulse	B-Algorithm
width	I-Algorithm
modulation	I-Algorithm
(	O
PWM	O
)	O
schemes	O
,	O
the	O
harmonics	O
power	O
is	O
concentrated	O
on	O
the	O
deterministic	O
or	O
known	O
frequencies	O
with	O
a	O
significant	O
magnitude	O
,	O
which	O
leads	O
to	O
mechanical	O
vibration	O
,	O
noise	O
,	O
and	O
EMI	O
.	O
</s>
<s>
Hence	O
,	O
depending	O
on	O
the	O
parameter	O
which	O
is	O
made	O
random	O
,	O
RPWM	O
can	O
be	O
classified	O
as	O
Random	O
Frequency	O
Modulation	B-Application
(	O
RFM	O
)	O
,	O
Random	O
Pulse	O
Position	O
Modulation	B-Application
(	O
RPPM	O
)	O
and	O
Random	O
Duty-Cycle	O
Modulation	B-Application
(	O
RDCM	O
)	O
.	O
</s>
<s>
Among	O
the	O
different	O
RPWM	O
techniques	O
,	O
RFM	O
(	O
Random	O
Frequency	O
Modulation	B-Application
)	O
is	O
the	O
most	O
common	O
method	O
of	O
the	O
three	O
major	O
types	O
,	O
used	O
in	O
many	O
power	O
converter	O
topologies	O
to	O
pass	O
the	O
electromagnetic	O
compatibility	O
(	O
EMC	O
)	O
test	O
.	O
</s>
<s>
In	O
this	O
type	O
of	O
modulation	B-Application
,	O
the	O
switching	O
frequency	O
of	O
the	O
PWM	O
signal	O
is	O
varied	O
randomly	O
in	O
order	O
to	O
spread	O
the	O
emitted	O
noise	O
of	O
the	O
power	O
converters	O
in	O
which	O
it	O
is	O
applied	O
.	O
</s>
<s>
This	O
modulation	B-Application
technique	O
also	O
offers	O
significant	O
reduction	O
of	O
the	O
conducted	O
emission	O
and	O
,	O
consequentially	O
,	O
the	O
radiated	O
emission	O
of	O
power	O
converters	O
.	O
</s>
<s>
However	O
,	O
in	O
this	O
modulation	B-Application
scheme	O
,	O
both	O
the	O
switching	O
frequency	O
and	O
the	O
pulse	O
width	O
are	O
fixed	O
so	O
that	O
the	O
converter	O
components	O
like	O
inductors	O
and	O
capacitors	O
can	O
function	O
properly	O
.	O
</s>
<s>
This	O
kind	O
of	O
modulation	B-Application
is	O
less	O
common	O
compared	O
to	O
the	O
previous	O
ones	O
.	O
</s>
<s>
This	O
type	O
of	O
modulation	B-Application
is	O
becoming	O
more	O
common	O
in	O
variable	O
frequency	O
drives	O
of	O
all	O
sizes	O
and	O
applications	O
.	O
</s>
<s>
However	O
,	O
while	O
the	O
term	O
"	O
RPWM	O
"	O
is	O
generally	O
used	O
to	O
label	O
this	O
type	O
of	O
modulation	B-Application
in	O
a	O
technical	O
sense	O
,	O
the	O
technology	O
does	O
not	O
yet	O
have	O
a	O
label	O
in	O
the	O
world	O
of	O
VFD	O
parameter	O
names	O
.	O
</s>
<s>
However	O
,	O
when	O
power	O
converters	O
with	O
this	O
special	O
type	O
of	O
modulation	B-Application
coexist	O
with	O
communication	O
systems	O
,	O
there	O
may	O
be	O
a	O
severe	O
electromagnetic	O
interference	O
conflict	O
between	O
the	O
power	O
system	O
and	O
the	O
communication	O
system	O
.	O
</s>
<s>
This	O
detrimental	O
effect	O
can	O
be	O
observed	O
in	O
power	B-Device
line	I-Device
communication	I-Device
(	O
PLC	O
)	O
systems	O
,	O
where	O
both	O
power	O
converters	O
and	O
communication	O
systems	O
coexist	O
.	O
</s>
<s>
The	O
interference	O
can	O
be	O
worsened	O
when	O
the	O
switching	O
frequency	O
and	O
the	O
bandwidth	B-Algorithm
of	O
the	O
PLC	O
system	O
overlaps	O
with	O
that	O
of	O
the	O
power	O
system	O
.	O
</s>
<s>
This	O
could	O
cause	O
coexistence	O
issues	O
mainly	O
in	O
narrow	O
band	O
PLC	O
systems	O
,	O
(	O
specialized	O
PLC	O
protocols	O
which	O
are	O
being	O
used	O
for	O
smart	B-Architecture
grid	I-Architecture
application	O
,	O
such	O
as	O
Prime	O
PLC	O
and	O
G3-PLC	O
,	O
in	O
frequencies	O
below	O
150	O
kHz	O
.	O
)	O
</s>
<s>
However	O
,	O
In	O
RPWM	O
,	O
the	O
noise	O
is	O
more	O
spread	O
and	O
both	O
the	O
PLC	O
and	O
the	O
noise	O
from	O
power	O
converter	O
shares	O
wider	O
bandwidth	B-Algorithm
.	O
</s>
<s>
Therefore	O
,	O
it	O
is	O
advisable	O
to	O
carefully	O
observe	O
the	O
properties	O
of	O
any	O
coexisting	O
systems	O
in	O
order	O
to	O
choose	O
a	O
switching	O
frequency	O
for	O
randomly	O
modulated	B-Application
power	O
converters	O
that	O
does	O
not	O
overlap	O
with	O
that	O
of	O
a	O
coexisting	O
PLC	O
system	O
.	O
</s>
