Improvement of starting characteristic and speed control of three-phase induction motor using microprocessor

In this paper a new method for improving the starting characteristics of three-phase induction motor is presented. The developed method employs only one IGBT as a chopper circuit with a diode bridge rectifier connected with the stator windings. The feeder impedance is taken into consideration. The IGBT is used as a phase controlled for chopping the input voltages to the motor. This is simple and less costly than the other methods. A microprocessor is used to generate the gating signals for the IGBT for open and closed-loop speed control systems. The power circuit and the required interface circuit are built. The digital simulation of the system is proposed and applied to obtain transient and steady state performance. The parameters of the Proportional Integral (PI) controller can be obtained using the proposed digital simulation for any operating point. The simulation results for starting, steady-state and closed loop speed control are proved good agreement when compared with the experimental results.