Variable Speed Drives for AC machines

ABSTRACT

Industrial drive applications are generally classified into constant-speed and variable-speed drives. Traditionally, AC machines have been used in constant-speed applications and DC machines were preferred for variable-speed. Induction machine with drive systems are widely used in applications such as pumps, paper and textile mills, elevators, electric vehicle, subway transportation, home appliance and wind generation. The three-phase squirrel cage induction motor is the mostly used motor type in the industry because of its good self-starting capability, simple and rugged structure, low cost, easy maintenance and good reliability. The various methods of variable speed drive control of three phase induction motors are under and some of the methods are discussed in this project report are Pole changing, Variable supply frequency, Variable rotor resistance control, Variable voltage supply control, Constant V/f control, Slip recovery and Vector control.

Table of Contents

1     INTRODUCTION.. 3....................................................................................................3

2     SQUIRELL CAGE INDUCTION MACHINE. 3..................................................3

3     VARIABLE SPEED DRIVES. 5................................................................................5

3.1      General5.....................................................................................................................5

3.2      Control Types7..........................................................................................................7

3.2.1       V/f Control7..........................................................................................................7

3.2.2       Vector Control8....................................................................................................8

4     DETERMINATION OF SQUIRREL CAGE INDUCTION MOTOR PARAMETERS. 11................11

4.1      Nameplate Quantities and Constants. 12.......................................................................................................12

4.2      Stator Resistance, R113....................................................................................................................................13

4.3      Leakage and Magnetizing Inductance, X1, X2, Xm. 14...............................................................................14

4.4      Core Resistance, Rfe17......................................................................................................................................17

4.5      Rotor Resistance, R218......................................................................................................................................18

5     CONCLUSIONS. 19..................................................................................................................................................19

6     REFERENCES. 20......................................................................................................................................................20