Eureka! Institutional Repository

This project is presenting a new solution about phase control in ac electric motors, and their protection from unwanted parasitic reversed voltages which occur due to the switching supply. This phenomenon of unwanted parasitic reversed voltages is taking place mostly in inductive loads, like the electric motors. In AC loads where phase control is being used, e.g AC speed electric motor control, here, the control is carried out throught the Pulse Width Modulation technique (PWM) and the same time, adjustment circuits for reducing the created reversed voltages are being used. As its known, in inductive loads due to self-induction, reversed voltages are created which are dangerous for the safely operation. The project is also referring to the technique that is being used today, phase control with triac and is comparing with the presented one.From this comparison the advantages of the presenting technique are showing off. By the use of an electronics circuit simulation software the operation of the circuit will be examined in detail. Moreover, there is a small introduction on the AC motors, presenting features such as operation principles, advantages and disadvantages.