**Resolver**

source: designworldonline.com |

** **

**sine-cosine generator**and

**synchro-resolver.**

**Working Principle of Resolver**

Fig1. Resolver |

- The resolver consist of stator and rotor. Stator is the stationary part and rotor is revolving part. A shaft is attached to the rotor.
- The rotor carries the primary winding. The stator carry the two secondary winding displaced angularly offset with respect to one another by 90°. These secondary windings are designated as the
**sine winding**and the**cosine winding**. - The basic function of a resolver is to resolve a vector into its sine and cosine components.
- An AC voltage applied to the reference winding in the rotor.
- This inductively couples to the sine and cosine windings, and hence generating an output voltage with a magnitude that varies as the sine or cosine, respectively, of the angular position of the input shaft relative to some zero point.

Fig.2 |

Consider a right triangle defined by the points (x1,y1), (x2,y1), and (x2,y2) as shown in fig.2. For the angle θ, we can define the side opposite θ as y2-y1, the side adjacent to θ as x2-x1, and the hypotenuse as R. Therefore, we can write as

We can define a circle with radius of R in Cartesian coordinates as R2 = X2 + Y2 as shown in fig.3. Using identities in equations 1 and 2, we can express any point (X,Y) on a unit circle (R = 1) as:

Fig.3 |

Fig.4 |

**Classification of Resolvers**

**1. Computing resolver**

It is used for generating cosine, sine and tangent functions. It also solves geometric relationships.

**2. Synchro resolver**

It is used for data transmission. It has same functions as synchro transmitter, receiver and control transformer but with a better accuracy.

**Applications of Resolvers**

1. Phase shifting

2. Vector composition

3. Vector resolution

4. Vector angle & component resolution

5. pulse amplitude control & pulse resolution