FPGA Control of the Neutral Point Clamped Quasi-Z-Source Inverter S. Stepenko 1,2 , O. Husev 1,2 , D. Vinnikov 1 , S. Ivanets 2 1 Department of Electrical Drives and Power Electronics, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia, E-mail: dmitri.vinnikov@gmail.com 2 Department of Industrial Electronics, Chernihiv State Technological University, Shevchenko street 95, 14027 Chernihiv, Ukraine, E-mail: stepenko.sergey@gmail.com ABSTRACT: The three-level neutral point clamped quasi- Z-source inverter has been proposed recently. Due to its features the neutral point clamped quasi-Z-source inverter is especially suitable for renewable energy sources. This topology requires special control methods and respectively new element basis can be used for control implementation. Current paper describes the control system implemented, based on FPGA for a three-level neutral point clamped quasi-Z-source inverter and the control signals obtained. KEYWORDS: FPGA, control system, three-level inverter, neutral point clamped inverter, quasi-Z-source inverter. 1 Introduction A new modification of the quasi-Z-source inverter, a three-level neutral point clamped quasi-Z-source inverter, has been proposed recently [1]. Its topology is shown in Fig. 1. This topology is a combination of the quasi-Z-source inverter (qZSI) and the three-level neutral point clamped inverter (3L-NPC). The new converter comprises advantages of both of these topologies: it can buck and boost the input voltage, it has excellent short circuit immunity and due to the multilevel topology, high energy density is attainable [2]. Fig. 1. Neutral point clamped quasi-Z-source inverter Each leg of the neutral point clamped quasi-Z-source inverter consists of two complementary switching pairs of transistors and four anti-parallel diodes (Fig. 1). This topology has also such advantages as continuous input current, the possibility to use shoot-through, lower switching and balanced neutral-point voltage losses in comparison with the traditional two-level voltage source inverter [1]. Due to the above features the neutral point clamped quasi-Z-source inverter is especially suitable for renewable energy sources. To manage the 3L-NPC qZSI eight control signals applied to the gates of power switches (e.g. MOSFETs, IGBTs) and a shoot-through separately formed signal are required. Finally, the generated shoot-through vector will be mixed with other control signals. These signals should be shifted and have different shape. To satisfy such requirements using microcontroller will be quite difficullt and therefore new element base for control is necessary. 2 Basis for Control Implementation In recent years implementations based on Field Programmable Gate Arrays (FPGAs) have become common in different areas of electronics. There are many studies devoted to embedded systems (Systems-On-Chip) that cover the main problems of their usage, both in the industry and academia. Accordingly, each year at the most prestigious conferences numerous papers describing the newest features of FPGAs have been reported. For example, in some cases if we need, it is possible now to emulate large systems that cannot even be placed into existing FPGA [3]. In turn, the possibilities of FPGAs (due to their advantages, such as fast prototyping, reprogramming, high operating frequency, and parallel processing capabilities) are increasingly used in power electronics to control the DC/AC converters (inverters) in order to achieve the desired output voltage. The implementation of control for various types of voltage source inverters (VSI) using FPGA was proposed in [4], [5] and several practical examples of its application demonstrate the utility of such approaches. In addition to the above features of FPGAs, there is also the possibility to use the Nios II embedded processor, which can be built by a designer through a software [6]. 263 2012 13th Biennial Baltic Electronics Conference (BEC2012) Tallinn, Estonia, October 3-5, 2012 978-1-4673-2774-9/12/$31.00 ©2012 IEEE