DESIGN OF SWITCHING SCHEMES FOR VOLTAGE SOURCE INVERTER

Abstract

DC-AC Inverters are key components in various industrial applications that include power supplies, motor drive systems and power systems. Now-a-days dc-ac inverters (both 1- phase & 3-phase) are finding more attention in renewable energy systems also. These inverters are big source of harmonics, which leads to various other problems like heating of instruments, faulty operation of protection devices etc. The harmonics generated by inverter can be controlled and minimise by controlling the switching of the device. Several approaches has been made already to deal with this problem like as carrier based PWM (pulse width modulation), selected harmonic elimination, Random PWM etc. Although the methods named above have been succeeded in improving the quality of power by reducing the harmonics but the problem is still not solved completely, so it still required attention. The Proposed project work is to design new switching schemes for single phase H-bridge Voltage Source DC – AC inverter. The motive of new switching technique is to further improve the quality of output by reducing total harmonic distortion. Two switching scheme are proposed for the project work. One is ―modified hysteresis switching scheme‖ and another one is ―wavelet modulation techniques‖. Both schemes are considered for voltage source inverter. Modified hysteresis switching scheme as well as wavelet based modulation technique would be studied, analysed and applied for switching of single phase and three phase voltage source inverters to produce significantly improved fundamental components and low harmonic contents. The inverter along with its switching technique would be simulated using MATLAB software and results would be analysed.