CONTROL OF SEIG WITH Z-SOURCE INVERTER

Abstract

For stand-alone power generation Self Excited Induction Generator has several advantages over conventional generators such as cheap, low cost, ruggedness, less• maintenance, self protection and variable speed operation and also when compared to PMSM which requires rare earth metals it is a cheap and well known technology. But SEIG when driven by a variable speed wind turbine it suffers from poor voltage and frequency regulation. Conventional voltage regulators allow only a small variation in speed and frequency regulator suffers from power wastage. To allow large variation of speed and reduce loses a output of SEIG can be rectified and inverted to desired voltage and frequency. A . Z-Source inverter provides attractive solution of single stage DC to AC conversation without any need for intermediate buck boost converter. With its unique structure Z-Source inverter can use shot through state to boost output voltage which improves inverter reliability greatly. This dissertation work starts with analyzing conventional controllers for SEIG and impedance network and modes of operation of Z-Source inverter. And four possible PWM methods are detailed for Z-Source inverter and they are compared with respect to their voltage gain and voltage stress on switches. MATLAB/SEMULINK models for SEIG with this PWM schemes are developed and results obtained by each control technique are detailed. Two closed loop control algorithms for controlling SEIG with Z-Source inverter are proposed and results obtained are analyzed. A SPWM scheme is implemented on hardware with 28335eZdzp controller. This 28335eZdsp is programmed using processor in loop simulation of MATLAB. Thus obtained hard ware results are found to be agreeing with the simulation results shown in this thesis work.