This question relates mainly to the sixth objective in the course specification.

A 22kW, 440V, 50Hz, 4-pole cage induction motor is part of an adjustable speed drive system. At the base voltage and frequency, the full-load slip is 0.05. It can be assumed that the torque-speed characteristic of the motor is linear in the slip frequency range from -5 Hz to 5 Hz.

Combined moment of inertia of motor and load = 12kgm2.

Load torque in Nm = 5ω where ω is in rad/s.

The steady state operating speed ranges from 900r/min to 1400r/min.

Acceleration is required to be constant at 30rad/s2 and deceleration is required to be constant at 60 rad/s2.

The drive consists of a voltage source inverter with a three-phase diode rectifier at the front end. The supply voltage may be assumed to be 440V.

Estimate-

(a) steady state-slip when speed is 1400r/min.

(b) steady state slip when speed is 900r/min.

(c) required electromagnetic torque during acceleration and during deceleration.

(d) maximum DC input current to the inverter during acceleration (assume efficiency of motorinverter combination is 91%).

(e) acceleration time from zero speed to 1400r/min.

Attachment:- Assignment.pdf