IJSRSET184126 | Received : 20 Dec 2017 | Accepted : 07 January 2018 | January-February-2018 [(4) 1 : 33-39 ] © 2018 IJSRSET | Volume 4 | Issue 1 | Print ISSN: 2395-1990 | Online ISSN : 2394-4099 Themed Section : Engineering and Technology 33 Study of Z-Source Inverter Using Different Control Techniques Nikhil J Bodele 1 , Ashutosh Rajurkar 2 1 M.Tech (Power Electronics and Drives) Assistant Prossor, Jhulelal Institute of Technology, Nagpur, Maharashtra, India 2 Assistant Electrical Engineer, MAHATRANSCO, Maharashtra, India ABSTRACT This paper represents study of Z-Source Inverter using different controlling techniques like simple boost control, maximum boost control, maximum constant boost control and space vector control. All the techniques were implemented in MATLAB/SIMULINK, also relation with voltage gain versus modulation index and voltage stress versus voltage gain were analyzed in detail and verified. It was observed that gain of Z-source inverter can be varied by varying its parameters like modulation index and shoot-through duty ratio. The comparison shows that even though simple boost control technique was having higher boost factor, Maximum constant boost control technique is most suitable in PWM technique. Keywords: Z-Source Inverter, Modulation Index, Boost Factor, Space Vector. I. INTRODUCTION In the conventional dc to ac converter, there are some limitations. In most of their application they are used as either buck or boost their output voltage but not both. In traditional method, different pulse width (PWM) control methods are used for three phase voltage source inverter. There are six active vectors for V-source inverter. When the dc voltage is applied across the load, two extra zero states will appear because of short circuiting of lower and upper three devices. Also both the upper and lower devices of V-source cannot be switched together, that will destroy the power device. So dead time is needed for power devices for protection purpose and this will introduce harmonics distortion at the output. Different combinations like ac-dc, dc-ac, dc-dc, ac-ac can be achieved using Z-Source inverter. It provides a special feature that utilizes the shoot through zero state by gating on both upper and lower switches of a phase leg. Output voltage can be greater than available input dc voltage. So reliability of the inverter is improved. Latest application of ZSI is hybrid vehicle [3]. Also used in solar application system. II. THE CONVENTIONAL Z-SOURCE INVERTER Z-source inverter is combination of two inductor (L 1 ,L 2 ) and two capacitor (C 1 ,C 2 ) connected in X shape. The specialty of Z-source inverter is that its output can vary between zero to infinity i.e. it is buck-boost inverter which is having vary wide range of output. Unlike traditional VSI that has eight switching states, the ZSI Bridge has nine permissible switching states. 1. Six active vectors same as VSI when the dc voltage is connected across load. 2. Two zero vectors when the load terminals are shorted through either the upper devices or lower devices. 3. One extra zero state is possible when upper and lower device is shorted with one leg or two legs or all legs. This extra zero state is called as the shoot-through zero state. It can be produced in seven different ways. Output of traditional Z-source inverter can be varied by using two parameters that is shoot-through duty ratio and modulation index [4]. By varying shoot-through duty ratio we can vary voltage boost factor of the ZSI and ac output voltage can be varied by using modulation index. During operation, there is compromise between modulation index and shoot-through duty ratio. If modulation index is large, shoot-through duty ration should be small and vice versa. Strong boost factor can be provided using large shoot-through duty ratio and that will increase the inverter bridge voltage from a very few low voltage. So large shoot through-duty ratio and