Simulation based analysis of quasi Z-source converter for wireless power transfer

Abstract

Implementation of Wireless Power Transfer (WPT) allows avoid connection by using wires to transfer energy between the power source and load. This allows development of devices that are more users friendly and easy in the exploitation. Elimination of the galvanic connection between the charging station and the energy consumer simplifies the charging process and removes safety concerns. In this paper an insight is given into basics of WPT theory to show why often an additional DC-DC converter at the WPT converter input is used and why the Z-source converter can be useful for this application. It is explained why application of an additional converter can give additional increase of the efficiency. The paper presents deeper analysis of scientific papers about Z-source network application in WPT systems that allows eliminate utilization of the additional converter but allows to regulate the input voltage. In the paper simplified explanation of quasi Z-source converter operation in boost mode is given. Based on this explanation it is easier to understand operation of the quasi Zsource converter and usefulness of application of this topology in WPT applications. Simulation of the quasi Zsource based WPT converter is performed and the simulation resulting waveforms show that it is possible to regulate the DC bus voltage and supply the energy to the system output with Z-source based WPT simultaneously, without adding extra semiconductor devices and very complex control circuitry to the conventional WPT system. These simulation results show that the quasi Z-source converter for WPT can regulate the DC bus voltage and transfer power to the load with relatively simple control. The waveforms of the control signals and current, and voltage waveforms are given. The Z-source topology analysed in this paper offers significant benefits, therefore, scientific research to improve and optimize this topology is needed further in order to meet the EMI standards, reduce switching losses with implementation of soft switching, optimize passive components, develop new control strategies and to increase the system efficiency. By overcoming these issues, the Z-source topology can become very attractive for WPT systems.