356 IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 29, NO. 1, JANUARY 2014 Development of an FPGA-Based SPWM Generator for High Switching Frequency DC/AC Inverters Matina Lakka, Eftichios Koutroulis, Member, IEEE, and Apostolos Dollas, Senior Member, IEEE Abstract—The digital implementations of Sinusoidal Pulse Width Modulation (SPWM) generators have dominated over their counterparts based on analog circuits. In this paper, an FPGA- based SPWM generator is presented, which is capable to operate at switching frequencies up to 1 MHz (requiring FPGA operation at 100–160 MHz), thus it is capable to support the high switch- ing frequency requirements of modern single-phase dc/ac power converters. The proposed design occupies a small fraction of a medium-sized FPGA and, thus, can be incorporated in larger de- signs. Additionally, it has a flexible architecture that can be tuned to a variety of single-phase dc/ac inverter applications. The postlayout simulation and experimental results confirm that compared to the past-proposed SPWM generation designs, the SPWM generator presented in this paper exhibits much faster switching frequency, lower power consumption, and higher accuracy of generating the desired SPWM waveform. Index Terms—DC/AC inverter, field programmable gate ar- ray (FPGA), high frequency, sinusoidal pulse width modulation (SPWM). I. INTRODUCTION T HE dc/ac converters (inverters) are the major power elec- tronic conversion units in renewable energy production, motor drive, and uninterruptible power supply applications [1]–[4]. A simplified block diagram of a single-phase, full- bridge dc/ac power converter (inverter) is depicted in Fig. 1. The Sinusoidal Pulse Width Modulation (SPWM) technique is widely employed in order to adjust the dc/ac inverter output voltage amplitude and frequency to the desired value. In this case, the power converter switches (e.g., MOSFETs, IGBTs, etc.) are set to the ON or OFF state according to the result of the comparison between a high-frequency, constant-amplitude triangular wave (carrier) with two low-frequency (e.g., 50 Hz) reference sine waves of adjustable amplitude and/or frequency [5], [6]. In the unipolar SPWM technique illustrated in Fig. 2, the generated pulses are either positive or negative during each half- period of the SPWM wave. The high-frequency harmonics of the generated SPWM signal, V spwm in Fig. 2, are then filtered using Manuscript received July 19, 2012; revised October 15, 2012 and December 11, 2012; accepted March 12, 2013. Date of current version July 18, 2013. This paper was presented at the 2011 International Conference on Field Pro- grammable Logic and Applications (FPL), pp. 15–19, September 2011. Rec- ommended for publication by Associate Editor K.-B. Lee The authors are with the Department of Electronic and Computer Engineer- ing, Technical University of Crete, Chania, GR-73100, Greece (e-mail: mati- nalakka@gmail.com; efkout@electronics.tuc.gr; dollas@ece.tuc.gr). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TPEL.2013.2253216 Fig. 1. Block diagram of a single-phase, full-bridge dc/ac power converter. Fig. 2. Unipolar SPWM technique. a low-pass LC-, LCL- or LLCL type filter [5], [7], thus producing the high-power and low-frequency sinusoidal waveform V o at the output terminals of the dc/ac inverter. The amplitude of V o (V ) is calculated as follows:  V o = M · V d =  V c  V tr · V d (1) where V d (V ) is the dc input voltage of the dc/ac inverter,  V c ,  V tr (V) are the amplitudes of the reference sine and carrier signals, respectively, and M is the modulation index. Increasing the switching frequency of the triangular wave f c results in a reduction of the dc/ac inverter output filter size and cost [8]. Depending on their nominal power rating, the dc/ac inverters typically operate at switching frequencies in the range of 1–100 kHz [9], [10]. A dc/ac inverter comprised of four cascaded Z -source inverter modules, which have been built us- ing Gallium Nitride devices operating at a 1-MHz switching frequency, is proposed in [11]. This trend of increasing the operating switching frequency is expected to continue in the near future [12], [13] due to the recent development of Sili- con Carbide power semiconductors, such as JFETs, MOSFETs, 0885-8993/$31.00 © 2013 IEEE