P9.5 A speed control for a gasoline engine is shown in Figure P9.5. Because of the restriction at the carbu

retor intake and the capacitance of the reduction manifold, the lag τt occurs and is equal to 1.5 seconds.

The engine time constant τe is equal to J b = 4 s.

The speed measurement time constant is τm = 0.6 s.

(a) Determine the necessary gain K if the steady

state speed error is required to be less than 20% of the speed reference setting.

(b) With the gain deter

mined from part (a), apply the Nyquist criterion to in

vestigate the stability of the system.

(c) Determine the phase and gain margins of the system.