Synchros

P.M.MENGHALFACULTY OF ELECTRONICS

MILTARY COLLEGE OF ELECTRONICS & MECHNICAL ENGINEERING,TRIMULGHERRY,SECUNDERABAD -500 015

ANDRA PRADESH INDIA Mobile: 9440635370

Email:[email protected] [email protected]

TRANSFER FUNCTION

Control Engineering Coursework

DE-93 Control Engg Asst Professor P M Menghal 2

WARNING!

I claim no originality in all these notes. These are the compilation from various sources for the purpose of delivering lectures. I humbly acknowledge the wonderful help provided by the original sources in this compilation.

For best results, it is always suggested you read the source material


SYNCHROS

A synchro is an electromagnetic transducer commonly

used to convert an angular position of a shaft in to an

electric signal. There are six types of synchro, classified

according to functions1. Synchro Transmitter (TX)

2. Synchro Receiver (TR)

3. Synchro Differential Transmitter (TDX)

4. Synchro Differential Receiver (TDR)

5. Synchro Control Transformer Synchro Resolver


SYNCHRO TRANSMITTER


SCHEMATIC DIAGRAM OF SYNCHRO TRANSMITTER

Let Vs1n ,Vs2n, Vs3n be the voltages induced in the stator coils S1,S2 and S3 with respect to neutral terminal. Then the rotor position of synchro transmitter shown in fig., where rotor axis makes an angle θ with the axis of stator coil S2 Vs1n = kVm Sin ωt Cos(θ +120) -------------(1)Vs2n = kVm Sin ωt Cosθ -------------(2)Vs3n = kVm Sin ωt Cos(θ +240) -------------(3)


The three terminal voltages of the stator coils are

VS1S2 = VS1n - Vs2n =√3 k VmSin (θ +240)Sinωt ----(4)

VS2S3 = VS2n - Vs3n = √3 k VmSin (θ +120)Sinωt ----(5)

VS3S1 = VS3n - Vs1n = √3 k VmSinθ Sinωt ----(6)

When θ =0 from eqn.2 voltage induced in stator coil S2 is maximum and from eqn.6 The terminal voltage

VS3S1 is zero.


SYNCHRO RECEIVER


SYNCROS AS ERROR DETECTOR

θR

θC

e(t)


The voltage induced in receiver rotor is proportional to the

cosine of angle between the two rotor axis

e(t)= KVm Sinωt Cos(Ø)

Ø = Angle difference between two rotors.

When Ø =900 i.e. The two rotor are at right angle ,the

voltage induced in the Synchro receiver rotor is zero. This

position is known “Electrical Zero” position of Synchro

receiver used in error detector mode.

The net angle between two rotor

Ø = (90 + θC - θR)

The voltage induced in the rotor of the synchro receiver is

e(t) = KVm Sinωt Cos (90 + θC - θR)

e(t) = KVm Sinωt Sin (θR - θC)


e(t) α (θR - θC)Thus the synchro transmitter-receiver pairs acts as an

error detector because the voltage signal of the rotor

terminal of the synchro receiver is proportional to the

difference in transmitter and receiver rotor shaft

Position.

e(t)= Ks(θR - θC)Ks = Known as sensitivity of synchro (Volt/rad)

E(s) = Ks[θR(s) – θC(s)] θR(s) +

- θc(s)

KS

E(s)


SYNCHRO APPLICATIONS

1.Data Transmission

Electrical DataTransmission

A.C.Supply

TRTX

da

ba

ab

b


2.AZIMUTH POSITION OF RADAR ANTENNA


PotentiometerPotentiometer is a transducer which converts angular

position in to an electrical signals. It is ac as well as dc

ep(t)

E+-

x

Linear PotentiometerThe output is proportional to displacement ep(t) α x(t)

ep(t) =Kp x(t)

Ep(s) = Kp X(s)

Block modeling is

X(s)Kp

Ep(s)


CIRCULAR OR ROTARY POTENTIOMETER

ep(t)α θ(t)

ep(t) = Kpθ(t)

Ep(s)= Kpθ(s)

KP

θ(s) E(s)


POTENTIOMETER AS ERROR DETECTOR

In error detector mode the electrical error signal produced is proportional to the difference in reference and control potentiometer shaft position.

ee(t) α (θR- θC) ee(t) = KP(θR- θC) Ee(s)=KP(θR- θC)

KP

θR(S)

θc(S)

+-

Ee(s)


AMPLIFIER1.Single Input Amplifier

KA

ei(t) eo(t)

2.Differential Amplifier

KA

ei(t)eo(t)

ec(t)

+

-

Eo(s) = KA [Ei(s) – Ec(s)]

KA

Ei(S)

Ec(S)

+-

Synchros

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