Research On Z-Source Inverter

The traditional voltage source inverter (VSI) belongs to Buck inverter. In some specific application fields, there must be an additional Boost circuit to obtain higher output voltage. This topology reduces the reliability and efficiency of the system, with increased cost. In addition, affected by factors such as electromagnetic interference (EMI), switching devices may act falsely, which resulting in bridge arm straight up and down can cause the switch tube to be damaged by the impact of the short circuit current. Therefore, dead time is usually set in the PWM control signal, which may result in the distortion of output waveforms.To overcome the shortcomings of traditional inverters, the Z-source inverter is researched in this paper. A Z-type impedance network is joined in between the DC power supply and the inverter bridge, which makes the shoot through state be a kind of normal working states and realizes Buck/Boost function. As dead time is not needed, waveforms of the AC output voltage and current are optimized.The main researches of this paper are as follows,1.The topology, working principle and state of Z-source inverter;2. Modulation strategies and simulation implementation of Z-source inverter;3.The design of main circuit parameters of the Z-source inverter, including the design of Z-source network capacitances and inductances, voltage stress analysis of switch devices and the input diode and the design of AC side capacitances and inductances;4.Building simulation models of the Z-source inverter system with different modulation strategies in the Matlab/Simulink environment and analyzing the simulation results to verify the correctness of theories;5. The application of Z-source inverter in photovoltaic (PV) grid system with the function of active power filter (APF) and building simulation model to verify the feasibility of the theory through simulation results.