Simplified arrangement of a DC motor drive system is shown in Figure QI. i) Calculate the total loss in the motor and the variable speed drives system. ii) Calculate the efficiency of the system. iii) If the speed is reduced by 50% but load torque is maintained, calculate the efficiency of the system. Given power factor is 0.5 and line current is 16 A. iv) Based on the calculation results you obtained in i) and ii) as an Electrical machine design engineer, identify and explain the methods with appropriate diagrams to improve the overall efficiency . Also looking in to the current technology there are better motors one can use to avoid the issues mentioned above. Name any two other motors and explain their construction details. [10 marks] v) In to-days fast moving world, energy saving plays an important role in every technology development. Based on your view explain with clear sketches how the Variable Speed Drive system can be optimized to save energy. [5 marks] 21A 49A Variable speed Drive 200VDC M. 400V T= 60 Nm 50HZ 0.7 pf N=1470 rpm 18.5 kW DC Motor Figure Q1