Question

I've already solved other problems except (d). Although I cannot understand (d). Please solve (d) and give me a detailed explanation.

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This is the real problem. I posted a wrong problem. please solve this problem. sorry.

What are the instantaneous and time-averaged torque under this condition? 4.30 Figure 4.42 shows in schematic cross section a salient-pole synchronous machine having two identical stator windings a and b on a laminated steel core. The salient-pole rotor is made of steel and carries a field winding f connected to slip rings. Because of the nonuniform air gap, the self- and mutual inductances are functions of the angular position 0o of the rotor. Their variation with 0o can be approximated as: Mab L2 sin 20 Lo - L2 cos 26 Lbb Laa = Lo + L2 cos 200 b a O Rotor -b Stator Figure 4.42 Schematic two-phase, salient- pole synchronous machine for Problem 4.30. where Lo and L2 are positive constants. The mutual inductance between the rotor and the stator windings are functions of 6 Maf M cos 0 Mbf M sin 0 where M is also a positive constant. The self-inductance of the field winding, Lf, is constant, independent of 60 Consider the operating condition in which the field winding is excited by a direct current It and the stator windings are connected to a balanced two-phase voltage source of frequency a. With the rotor revolving at synchronous speed, its angular position will be given by 0o = wt. Under this operating condition, the stator currents will be of the form is=21, cos (ot +8) is 21, sin (ot +8) a. Derive an expression for the electromagnetic torque acting on the rotor. b. Can the machine be operated as a motor and/or a generator? Explain. c. Will the machine continue to supply torque if the field current Ie is reduced to zero? Support you answer with an expression for the torque and an explanation as to why such operation is or is not possible. Spring Plunger Ri g

Answer 1

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