<s>
A	O
resolver	B-Algorithm
is	O
a	O
type	O
of	O
rotary	O
electrical	O
transformer	B-Algorithm
used	O
for	O
measuring	O
degrees	O
of	O
rotation	O
.	O
</s>
<s>
It	O
is	O
considered	O
an	O
analog	O
device	O
,	O
and	O
has	O
digital	O
counterparts	O
such	O
as	O
the	O
digital	O
resolver	B-Algorithm
,	O
rotary	O
(	O
or	O
pulse	O
)	O
encoder	O
.	O
</s>
<s>
The	O
most	O
common	O
type	O
of	O
resolver	B-Algorithm
is	O
the	O
brushless	O
transmitter	O
resolver	B-Algorithm
(	O
other	O
types	O
are	O
described	O
at	O
the	O
end	O
)	O
.	O
</s>
<s>
On	O
the	O
outside	O
,	O
this	O
type	O
of	O
resolver	B-Algorithm
may	O
look	O
like	O
a	O
small	O
electrical	O
motor	O
having	O
a	O
stator	O
and	O
rotor	O
.	O
</s>
<s>
The	O
stator	O
portion	O
of	O
the	O
resolver	B-Algorithm
houses	O
three	O
windings	O
:	O
an	O
exciter	O
winding	O
and	O
two	O
two-phase	O
windings	O
(	O
usually	O
labeled	O
"	O
x	O
"	O
and	O
"	O
y	O
"	O
)	O
(	O
case	O
of	O
a	O
brushless	O
resolver	B-Algorithm
)	O
.	O
</s>
<s>
The	O
exciter	O
winding	O
is	O
located	O
on	O
the	O
top	O
;	O
it	O
is	O
a	O
coil	O
of	O
a	O
turning	O
(	O
rotary	O
)	O
transformer	B-Algorithm
.	O
</s>
<s>
This	O
rotary	O
transformer	B-Algorithm
induces	O
current	O
in	O
the	O
rotor	O
without	O
wires	O
or	O
brushes	O
to	O
provide	O
a	O
direct	O
electrical	O
connection	O
.	O
</s>
<s>
The	O
rotor	O
houses	O
a	O
coil	O
,	O
which	O
is	O
the	O
secondary	O
winding	O
of	O
the	O
turning	O
transformer	B-Algorithm
,	O
and	O
a	O
separate	O
primary	O
winding	O
in	O
a	O
lamination	O
,	O
exciting	O
the	O
two	O
two-phase	O
windings	O
on	O
the	O
stator	O
.	O
</s>
<s>
The	O
primary	O
winding	O
of	O
the	O
transformer	B-Algorithm
,	O
fixed	O
to	O
the	O
stator	O
,	O
is	O
excited	O
by	O
a	O
sinusoidal	O
electric	O
current	O
,	O
which	O
by	O
electromagnetic	O
induction	O
induces	O
current	O
in	O
the	O
rotor	O
.	O
</s>
<s>
As	O
these	O
windings	O
are	O
arranged	O
on	O
the	O
axis	O
of	O
the	O
resolver	B-Algorithm
,	O
the	O
same	O
current	O
is	O
induced	O
no	O
matter	O
what	O
its	O
position	O
.	O
</s>
<s>
Resolvers	B-Algorithm
can	O
perform	O
very	O
accurate	O
analog	O
conversion	O
from	O
polar	O
to	O
rectangular	O
coordinates	O
.	O
</s>
<s>
Resolvers	B-Algorithm
with	O
four-lead	O
rotors	O
can	O
rotate	O
 [ x ] 	O
and	O
 [ y ] 	O
coordinates	O
,	O
with	O
the	O
shaft	O
position	O
giving	O
the	O
desired	O
rotation	O
angle	O
.	O
</s>
<s>
Resolvers	B-Algorithm
with	O
four	O
output	O
leads	O
are	O
general	O
sine/cosine	O
computational	O
devices	O
.	O
</s>
<s>
When	O
used	O
with	O
electronic	O
driver	O
amplifiers	O
and	O
feedback	O
windings	O
tightly	O
coupled	O
to	O
the	O
input	O
windings	O
,	O
their	O
accuracy	O
is	O
enhanced	O
,	O
and	O
they	O
can	O
be	O
cascaded	O
(	O
"	O
resolver	B-Algorithm
chains	O
"	O
)	O
to	O
compute	O
functions	O
with	O
several	O
terms	O
,	O
perhaps	O
of	O
several	O
angles	O
,	O
such	O
as	O
gun	O
(	O
position	O
)	O
orders	O
corrected	O
for	O
ship	O
's	O
roll	O
and	O
pitch	O
.	O
</s>
<s>
For	O
the	O
position	O
evaluation	O
,	O
resolver-to-digital	O
converters	O
are	O
commonly	O
used	O
.	O
</s>
<s>
Basic	O
resolvers	B-Algorithm
are	O
two-pole	O
resolvers	B-Algorithm
,	O
meaning	O
that	O
the	O
angular	O
information	O
is	O
the	O
mechanical	O
angle	O
of	O
the	O
stator	O
.	O
</s>
<s>
Other	O
types	O
of	O
resolver	B-Algorithm
are	O
multipole	O
resolvers	B-Algorithm
.	O
</s>
<s>
Some	O
types	O
of	O
resolvers	B-Algorithm
include	O
both	O
types	O
,	O
with	O
the	O
2-pole	O
windings	O
used	O
for	O
absolute	O
position	O
and	O
the	O
multipole	O
windings	O
for	O
accurate	O
position	O
.	O
</s>
<s>
Two-pole	O
resolvers	B-Algorithm
can	O
usually	O
reach	O
angular	O
accuracy	O
up	O
to	O
about	O
±5	O
,	O
whereas	O
a	O
multipole	O
resolver	B-Algorithm
can	O
provide	O
better	O
accuracy	O
,	O
up	O
to	O
10	O
for	O
16-pole	O
resolvers	B-Algorithm
,	O
to	O
even	O
1	O
for	O
128-pole	O
resolvers	B-Algorithm
.	O
</s>
<s>
Multipole	O
resolvers	B-Algorithm
may	O
also	O
be	O
used	O
for	O
monitoring	O
multipole	O
electrical	O
motors	O
.	O
</s>
<s>
In	O
practice	O
,	O
the	O
resolver	B-Algorithm
is	O
usually	O
directly	O
mounted	O
to	O
an	O
electric	O
motor	O
.	O
</s>
<s>
The	O
resolver	B-Algorithm
feedback	O
signals	O
are	O
usually	O
monitored	O
for	O
multiple	O
revolutions	O
by	O
another	O
device	O
.	O
</s>
<s>
This	O
allows	O
for	O
geared	O
reduction	O
of	O
assemblies	O
being	O
rotated	O
and	O
improved	O
accuracy	O
from	O
the	O
resolver	B-Algorithm
system	O
.	O
</s>
<s>
Because	O
the	O
power	O
supplied	O
to	O
the	O
resolvers	B-Algorithm
produces	O
no	O
actual	O
work	O
,	O
the	O
voltages	O
used	O
are	O
usually	O
low	O
(	O
<	O
24VAC	O
)	O
for	O
all	O
resolvers	B-Algorithm
.	O
</s>
<s>
Resolvers	B-Algorithm
designed	O
for	O
terrestrial	O
use	O
tend	O
to	O
be	O
driven	O
at	O
50	O
–	O
60Hz	O
(	O
utility	O
frequency	O
)	O
,	O
while	O
those	O
for	O
marine	O
or	O
aviation	O
use	O
tend	O
to	O
operate	O
at	O
400Hz	O
(	O
the	O
frequency	O
of	O
the	O
on-board	O
generator	O
driven	O
by	O
the	O
engines	O
)	O
.	O
</s>
<s>
Other	O
types	O
of	O
resolver	B-Algorithm
include	O
:	O
</s>
<s>
Receiver	O
resolvers	B-Algorithm
These	O
resolvers	B-Algorithm
are	O
used	O
in	O
the	O
opposite	O
way	O
to	O
transmitter	O
resolvers	B-Algorithm
(	O
the	O
type	O
described	O
above	O
)	O
.	O
</s>
<s>
Differential	O
resolvers	B-Algorithm
These	O
types	O
combine	O
two	O
diphased	O
primary	O
windings	O
in	O
one	O
of	O
the	O
stacks	O
of	O
sheets	O
,	O
as	O
with	O
the	O
receiver	O
,	O
and	O
two	O
diphased	O
secondary	O
windings	O
in	O
the	O
other	O
.	O
</s>
<s>
A	O
related	O
type	O
is	O
also	O
the	O
transolver	O
,	O
combining	O
a	O
two-phase	O
winding	O
like	O
the	O
resolver	B-Algorithm
and	O
a	O
triphased	O
winding	O
like	O
the	O
synchro	B-Algorithm
.	O
</s>
