- Q2 A Discuss Why There Is A Need To Use Three Phase And Single Phase Converters In Electrical Drives Also Discuss Ho 1 (146.98 KiB) Viewed 60 times
Q2. (a) Discuss why there is a need to use three phase and single phase converters in electrical drives. Also discuss how the function of a DC machine's commutator compares with a power electronics converter. [4 marks] (b) The slip of an induction motor in a Tesla high-performance electric vehicle is 200rpm. The rate Torque of the motor is Tem = 200 Nm. New safety regulations require that the slip speed at the rated torque is reduced to 100rpm. You know that the cost of the rotor assembly will determine the actual resistance of the material in the rotor bars. Assuming that nothing else changes, determine if the rotor cost would go down and by how much. [4 marks] (c) You are required to design a few components for an electrical machine. The starting point for the design is a magnetic core with the following dimensions: length Im = 0.45 m, width w = 0.008 m, depth d = 0.007 m. You must now design a coil, by specifying the number of turns N and by selecting an appropriate relative permeability Mr for the core material, so that the system can achieve a current of 3.5 A and a flux density of 0.19 T. The resulting coil must be of inductance L = 88.4 pH. [8 marks] (d) You are supervising a junior engineer, who has designed a cascade control structure for an electrical drive, and when you inspect the design, the torque loop seems to be the slowest (lowest bandwidth). Discuss if this is appropriate and justify your answer. [4 marks]