Impedance Source Inverter for Wind Turbine Driven Permanent Magnet Generator

Abstract

This paper presents a Z-source inverter for wind energy conversion system. The main thrust in wind energy conversion system (WECS) is to maintain a constant voltage at the output in spite of variation in wind velocity. The Z-source inverter has been identified to exhibit in steady-state, both voltage buck-and boost-capabilities. It employs a unique impedance network included between the dc power source and converter circuit. The power conversion efficiency of Z-source inverter is appreciably improved because of the traditional three-stage conversion system, consist of rectifier, boost chopper and inverter, replaced by a two stage conversion systems comprising of rectifier and Z-source inverter. All the traditional pulse width-modulation (PWM) schemes can be used to control the Z-source inverter. When the dc voltage is high enough to generate the desired ac output voltage, normal PWM is used. While the dc voltage is not enough to directly generate a desired output voltage, a modified PWM with shoot-through zero states is employed to boost the voltage. The proposed Z-source inverter with PMG and wind turbine is modeled and simulated using MATLAB/SIMULINK.