International Journal of Scientific Engineering and Technology (ISSN : 2277-1581) Volume No.2, Issue No.1, pp : 08-12 1 Jan. 2013 IJSET@2013 Page 8 Analysis and Simulation of Z-Source Inverter Fed to Single Phase Induction Motor Drive Vrushali Suresh Neve, P.H. Zope, S.R. Suralkar Department of Electronics & Tele-Communication Engineering, SSBT’s College of Engineering & Technology, Jalgaon, Maharashtra, INDIA. vrushalisneve@gmail.com, phzope@gmail.com, shakhar_srs@rediffmail.com Abstract-The Z-source inverter utilizing a unique LC network and shoot-through states provides unique features, such as the ability to buck & boost voltage with a single stage structure .The output of inverter is used to control the speed of an induction motor. A model of z- source inverter fed to single phase induction motor drive is built in MATLAB/SIMULINK and its performance is analyzed with simple boost PWM control technique. Keywords- Z-source inverter (ZSI), Simple boost PWM (SBPWM), boost factor, modulation index. I. Introduction Z-source inverter can boost dc input voltage with no requirement of dc-dc boost converter or step up transformer, hence overcoming output voltage limitations of traditional voltage source inverter as well as lower its cost. A comparison among conventional PWM inverter, dc-dc boosted PWM inverter and Z-source inverter shows that z- source inverter needs lowest semiconductors and control circuit cost , which are the main cost of a power electronics system [1] this result increasing attention on z-source inverter . II.Z-Sources Inverter The new impedance-source power inverter has been recently invented, eliminates all problems of the traditional V-source and I-source inverters. It is being used in ac/dc power conversion applications. Fig.1 shows the general Z-source converter structure. The power source can be either voltage source or current source. The Z-source inverter consists of a unique impedance network which couple the converter main circuit to the power source, load, or other converter [1], for providing unique features that cannot be observed in the traditional VSI and CSI inverters. The impedance network consists of two inductors and two capacitors connected to each other as shown in the figure forms the second order filter network. The values of both inductor and both capacitor are equal. The two inductors can be two separate inductors or two inductors inductively coupled to each other on a single core. For size and cost reduction film capacitors of desired value and voltage rating can be selected. Fig.1 Z-Source inverter structure III. PWM Control of ZSI The conventional PWM inverter topology imposes high voltage stresses to the switching devices and motor and limits the motor’s constant power speed ratio [7]. The dc/dc boosted PWM inverter topology can alleviate the stresses and limitations, however, suffers from problems such as high cost and complexity associated with the two-stage power conversion. Traditional PWM consists of six active states and two zero states. In traditional zero state either upper two or lower two switching devices of inverter are on and does not provide current to the load so the load voltage is essentially zero in the zero state. In case of Z-source inverter in addition to six traditional active states and two zero state it consists of one more state called as shoot-through state. In a shoot- through state both upper and lower switching devices in a single arm or all the two arms conducts simultaneously, hence producing short circuit across load. Therefore output voltage across the load remains zero in the shoot-through state. Thus the effect of shoot-through state is same as traditional zero state. In Z-source inverter the part of zero state or entire zero state is converted in to shoot-through state, where both upper and lower switching device of one or all the two arm of