Research On Switch-inductor Z-source/Quasi-Z-source Inverter

With the development of science and technology, power electronic inverters have a wide range of application. Such as photovoltaic power generation, railway electric locomotive, electric automobile, uninterruptible power supply, power system voltage regulation, and AC motor speed regulation and so on. Inverter is an important component, but the traditional voltage source inverter and current source inverter are disadvantages in theory. Voltage source inverter produced output voltage is lower then the supply voltage, while current source inverter’s voltage is higher than that, so it is very difficult to gain wide output voltage with any simple voltage source inverter or current source inverter. If the output voltage is to obtain wider, it ought to add an extra converter, which will decrease operation efficiency of the system and increase system overhead. What is more, voltage source inverter’s each phase bridge-leg can not be in shoot-through state. Current source inverter’s each phase bridge-leg can not be in open circuit state, which would destroy the circuit and decrease the reliability.For the default of traditional inverter, at the beginning of this article, it provides a brief introduction of Z-source inverter and quasi-Z-source inverter, which can solve this problem but with some flaws, such as low boost factor, high capacitive voltage stress. For all this, this article brings to new types of inverters, improved switched-inductor Z-source inverter and multi-cascaded switched-inductor quasi-Z-source inverter.(1) This paper detailed describes circuit topology of improved switched-inductor Z-source inverter base on the switched-inductor Z-source inverter, how it works, capacitor voltage stress and inductor current stress; it determines briefly the usage of Z-source network parameters. In chapter three, it introduces the control method of raising the pressure directly and raising the pressure to maximum by control of inverter. By the simulations and comparisons, it shows the analyzed results of the improved switched-inductor Z-source inverter.(2) This paper puts forward one multi-cascaded switched-inductor quasi-Z-source inverter, and in detail analyzes circuit topology of this inverter and how it works. It also discusses capacitor voltage stress and inductor current stress under different inductors, and gives simulation results; finally it compares improved switched-inductor Z-source inverter and multi-cascaded switched-inductor quasi-Z-source inverter with getting the merits and demerits of the two inverters.