A Z-source inverter is a type of power inverter, a circuit that converts direct current to alternating current. It functions as a buck-boost inverter without making use of DC-DC converter bridge due to its unique circuit topology.
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Impedance (Z-) Source networks provide an efficient means of power conversion between source and load in a wide range of electric power conversion applications (dc–dc, dc–ac, ac–dc, ac– ac) [3], [4]. Z-source-related research has grown rapidly since it was first proposed in 2002 by Prof. F. Z. Peng. The numbers of modifications and new Z-source topologies have grown exponentially. Improvements to the impedance networks by introducing coupled magnetics have also been lately proposed for achieving even higher voltage boosting, while using a shorter shoot-through time [6]. They include the Γ-source, T-source, trans-Zsource, TZ-source, LCCT-Z-source (proposed in 2011 by Dr Marek Adamowicz and utilizing high frequency transformer connected in series with two dc-current-blocking capacitors) [16], high-frequency transformer-isolated, and Y-source [5] networks. Among them, the Y-source network (proposed in year 2013 by Dr Yam P. Siwakoti) is more versatile and can in fact be viewed as the generic network, from which the Γ-source, T-source, and trans-Z-source networks are derived [6]. The incommensurate properties of this network open a new horizon to researchers and engineers to explore, expand, and modify the circuit for a wide range of power conversion applications.
Types of inverters
Inverters can be classified by their structure:
1. Single-phase inverter:
This type of inverter consists of two legs or two poles. (A pole is connection of two IGBTs where source of one and drain of other are connected and this common point is taken out).
2. Three-phase inverter:
This type of inverter consists of three legs or poles or four legs (three legs for phases and one for neutral).
But, inverters are also classified based on the type of input source. And they are,
1. Voltage-source inverter (VSI)
In this type of inverter, a constant voltage source acts as input to the inverter bridge. The constant voltage source is obtained by connecting a large capacitor across the DC source.
2. Current-source inverter (CSI)
In this type of inverter, a constant current source acts as input to the inverter bridge. The constant current source is obtained by connecting a large inductor in series the DC source.
Disadvantages
Typical inverters (VSI and CSI) have few disadvantages. They are listed as,
Advantages of ZSI
The advantages of Z-source inverter are listed as follows,
Applications
- Renewable energy sources
- Electric vehicles
- Motor drives