1 Abstract—Nowadays power inverter serves as an important emergency power supply system in events of mains power supply failure. The AC output voltage of a power electronic inverter is usually non-sinusoidal and hence has a high harmonic content. Sinusoidal Pulse Width Modulation (SPWM) scheme is normally used to convert the DC power supply into AC power supply by comparing the reference voltage waveform with the triangular waveform known as carrier. SPWM provides a way to reduce the total harmonic distortion of load current. The objective of this paper is to demonstrate a SPWM switching by using Altera DE2 board. In this SPWM, a sinusoidal reference voltage waveform is compared with the triangular carrier voltage to generate the on and off switching scheme. These switching schemes will trigger the gate of the power switch. In this paper, the SPWM switching strategies will be develop using Altera DE2 (Cyclone II EP2C35F672C6) with 16 bit serial configuration devices. The switching between reference and carrier waveforms of SPWM is obtained by using Matlab software. Simulation on the design pulses is conducted using Quartus II software tools provided by Altera. The output frequency of SPWM is 50 Hz and the design is limited to two levels of modulation index which are 0.5 and 0.75. Keywords: SPWM-Sinusoidal Pulse Width Modulation, FPGA- Field Programmable Logic Array, VHDL- Very High Description Language. I. INTRODUCTION ulse width modulation (PWM) is the most popular switching method used to several types of converter with an appropriate switching scheme to produce a desired switching pattern. PWM is one of the switching techniques used for converter to produce an AC output signal fed from DC input [1]. PWM makes the inverter output waveforms made up of many pulses with certain rules and goals through . supplying DC voltage for the inverter [2]. The on and off scheme based on the intersection of the carrier signal (triangular) and reference signal (constant DC). PWM still contains a harmonics and another approach is SPWM switching technique [3]. This paper presents work carried out in developing control signal using bipolar SPWM to produces a switching scheme which only a single sinusoidal waveform (reference) used with the triangular (carrier) [4]. In SPWM a fixed triangular is compared with sinusiodal waveform and the amplitude can be varied from [1]. The on and off switching scheme will be produce when the instantaneous value of the reference signal is larger than the triangular carrier, the output is at positive and when the reference is less the carrier output is at negative as shown in figure 1. In order to demonstrate SPWM switching using Altera DE2 board, the switching interval between each crossing obtained using Matlab software. The crossover of the signal then transferred into a table. The switching scheme should be able to be implemented to the four switches at the inverter with a different timeline. This project presents the implementation of FPGA technology in designing the SPWM switching signal. Altera Cyclone II FPGA is used in this project. It aslo provide a wide range of density, memory, embedded multiplier, and packaging options in a customer-defined FPGA feature set optimized for low-cost applications. Besides that, Cyclone II FPGA also supports a wide range of common external memory interfaces and I/O protocols common in low-cost applications. The use of FPGA will produce better control signal for single phase full bridge inverter. The modulation index, number of pulses over a period and the output frequency can easily changed using the program. The designed of the switching pulse can be altered without any changes in hardware. This is the main advantages of this project that applied the FPGA technology where there is the flexibility of any changes on the switching parameter and directly eliminates the complexity of the hardware. Figure 1: Single phase full-bridge inverter. Design of FPGA Based SPWM Single Phase Inverter Afarulrazi Abu Bakar, Md Zarafi Ahmad and Farah Salwani Abdullah P Proceedings of MUCEET2009 Malaysian Technical Universities Conference on Engineering and Technology June 20-22, 2009, MS Garden,Kuantan, Pahang, Malaysia MUCEET2009 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by UTHM Institutional Repository