Question 3 25 Marks Consider a separately-exited DC motor with very large armature and field inductances which has to be driven from 50-Hz, 240-V single phase AC by some form of controlled rectifier. a) If the motor will only be turning in one direction, but requires braking capabilities (i.e. reverse voltage at forward current), draw a quick drawing of operating quadrants required. Then select a circuit topology for the task. What is the main difference between this chosen type, and other single-quadrant circuits? b) Draw the chosen circuit and indicate the equivalent armature and field circuits. c) Draw a labeled sample output voltage waveform with firing angle . Integrate the waveform and average the integral to obtain the equivalent average output voltage as a function of . Given the nominal motor values of Ra= 0.4 ; Rf = 100 ; Kt = 1.1; Kv = 0.9 calculate the following steady-state values: d) Use your result in (b) to calculate the firing angle necessary on the field side to effect an average current of 2 A. e) Calculate the armature current necessary to develop a torque of 100 N-m. f) Calculate the armature back-E.M.F. necessary to effect a steady-state speed of 1000 r.p.m. at the above torque. g) Now use your result in (b) to calculate the firing angle necessary on the armature side to effect the steady-state speed of 1000 r.p.m. (Neglect friction and inertia) h) Calculate the efficiency of the entire motor alone (not the rectifiers) by considering resistive losses vs power to the motor.