FPGA Controller Based Z-Source Inverter for Wind Turbine Driven Permanent Magnet Generator

This paper presents VHDL simulation of controller for Z-source inverter suitable for wind energy conversion system (WECS). The main thrust in wind energy conversion system is to maintain a constant voltage at the output in spite 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 voltage. The controller is designed and VHDL simulation carried out for traditional PWM as well as for the modified PWM employed with Z-source inverter.