Soft Switching Of Three Phase Induction Motor

Abstract

Induction motor is the workhorse of an industry. It has its uses in a full power range, from limited watt to megawatts. By giving power to the induction motor, it faces some problems. Due to which high switching current goes into the windings. This current causes a dip in the voltage of that line and may damage the equipment connected on the line. Moreover motor starts with a jerk which causes mechanical wear and tear. In order to cope with this problem we have to reduce the switching current so that our equipment is being protected from any damage and motor starts smoothly without any jerk. Many methods are in practice in the industry. These methods in- clued addition of a resistor with the windings so that the switching current can be lowered, star-delta conversion technique, DOL method etc. These methods are not efcient because the inrush current cannot be smoothed by these methods. In other words transients are always there, which can cause damage. Therefore to tackle these problems, we use soft switching. In soft switching applied voltages are controlled. By controlling the voltages, the switching current and switching torque will be controlled, hence the motor will run smoothly without having any transients.