drives assignment
-
Upload
nalin-lochan-gupta -
Category
Documents
-
view
33 -
download
0
description
Transcript of drives assignment
EE‐664 Assignment No. 1
Submission date: 22nd August 2012
1. A motor‐load system has following details: Quadrants l and II, T = 400 – 0.4N, N‐m; where N is the
speed in rpm. Motor is coupled to an active load torque Tl = ±200, N‐m. Calculate the motor speeds for
motoring and braking operations in the forward direction. When operating in quadrants III and IV,
T=–400–0.4N, N‐m. Calculate the equilibrium speed in quadrant III.
2. A drive has following parameters: J = 1 kg‐m2, T = 15 – 0.01N, N‐m and passive load torque Tl =
0.005N, N‐m; where N is the speed in rpm. Initially the drive is operating in steady‐state. Now it is to be
reversed. For this motor characteristic is altered such that T= – 15 – 0.01N, N‐m for positive as well as
negative values of N. Calculate the reversal time.
Hint: Solve the first order differential equation in involving speed.
3. A drive has following equations for motor and load torques:
T= (1+2ωm) and Tl = ‐3 √ωm
Obtain the equilibrium points and determine their steady‐state stability.
4. A 6 pole, 50Hz, 3‐phase wound rotor induction motor has a flywheel couples to its shaft. The total
moment of inertia of motor‐load‐flywheel is 1000 kg‐m2. Load torque is 1000 N‐m of 10 sec duration
followed by a no load period which is long enough for the drive to reach its no load speed. Motor has a
slip of 3% at a torque of 500 N‐m. Calculate
(1) Maximum torque developed by the motor.
(2) Speed at the end of deceleration period.
Assume motor speed‐torque curve to be a straight line in the operating range.
5. Load diagram of a shearing machine shows a periodic fluctuation of torque with 10000 N‐m required for 10 sec and 1000 N‐m for 20 sec. The combined inertia of motor and flywheel referred to the motor shaft is 1000 kg‐m2. Calculate maximum and minimum values of motor torque. The motor speed torque characteristic is a straight line given by the equation T= 20000 – 20N, N‐m, where N is the speed in rpm.
6. A 3‐phase , 100 kW, 6 pole, 960 rpm wound rotor induction motor drives a load whose torque varies
such that a torque of 3000 N‐m of 10sec duration is followed by a torque of 500 N‐m of duration long
enough for the motor to attain steady‐state speed. Calculate moment of inertia of the flywheel, if motor
torque should not exceed twice the rated value. Moment of inertia of the motor is 10 kg‐m2. Motor has
a linear speed‐torque curve in the region of interest.