Modeling and implemention of variable frequncy drive based on open-loop volt/hertz

A single or three -phase squirrel cage motors are one of mostly used in many industrial applications this motors consuming more than half of the total generated electrical energy .The Induction motors can run only at their full speed when they are attached to the AC supply. However, speed control of squirrel cage motors is important to many industrial applications that require variable flow control of fluid (air, water and chemical liquid). Speed control method that has been developed with voltage-source inverter become a popular method for the speed control of induction machines. The purposes of this thesis are to model and implement an AC-Drive, by three type inverter switching techniques as Sinusoidal Pulse width Modulation (SPWM), Third Harmonic Injection Pulse Width Modulation (THIPWM), and Space Vector Pulse Width Modulation (SVPWM). These techniques are based on Voltage-Source Inverter (VSI) and open- loop speed controller, with principle (Volt/Hertz). The three switching techniques and open-loop (Volt/Hertz) control are compared with each other's. The mathematical model has been developed for AC-drive system. Also, the model has been simulated by a software to evaluate the performance of open-loop speed control system with three switching techniques. The results indicate that the mathematical model is accurate and practicable, also achieved to satisfy the requirements of the users. Moreover, in the thesis, a practical model of AC-Drive with SPWM technique has been realized. The practical model imitates to conceptions of power electronic module, (HY-DQ Inverter v 2.0) module used to control and drive of the three phase squirrel cage induction motor. This practical model has quality of completely implemented and exact results are obtained. The experimental results are based on the voltage measured in load side and rotor speed with actual load (1-hp IM). These results have shown satisfactory performance of the system from output voltage waveform and rotor speed.