Electric Power Systems Research 86 (2012) 51–60 Contents lists available at SciVerse ScienceDirect Electric Power Systems Research jou rn al h om epage: www.elsevier.com/locate/epsr Vector-based reference location estimating for space vector modulation technique Lütfü Saribulut ∗ , Ahmet Teke, Mehmet Tümay C ¸ ukurova University, Department of Electrical and Electronics Engineering, Balcalı, Adana, Turkey a r t i c l e i n f o Article history: Received 14 June 2011 Received in revised form 30 November 2011 Accepted 2 December 2011 Available online 5 January 2012 Keywords: Space vector modulation technique Reference location estimating Multilevel inverter Generalized SVM algorithm a b s t r a c t Space vector modulation (SVM) has become a popular pulse width modulation technique (PWM) for multilevel inverters. In SVM technique, the determination of the angular position of the reference voltage vector is very important to generate the required output voltage by the inverter. The switching time and switching sequence of SVM are calculated by vector location. The calculation of vector location and switching time become difficult and more complex when the numbers of output voltage levels increase for a given number of inverter levels. In this paper, a new SVM method is developed to determine the actual vector location. The proposed method can increase RMS value of the inverter output voltage; can reduce the algorithm complexity and computation time when compared to conventional SVM methods. In addition, the calculation of switching times for two-level inverter is generalized for N-level inverters. PSCAD/EMTDC simulation program is used to create the test system and to perform the case studies. Extensive simulation results are given to validate the performance of the proposed algorithm. © 2011 Elsevier B.V. All rights reserved. 1. Introduction The recent developments of the power electronics industry resulted in a considerable increase of the power that can be manip- ulated by semiconductor devices. In spite of that, the maximum voltage supported by these devices remains the major obstacle in medium and high voltage applications. For such applications, multilevel inverters have been proposed [1]. Multilevel inverters offer many benefits for higher power applications. They present low harmonic distortion when compared to two-level inverters at the same switching frequency and DC voltage [2,3], provide conve- nient means for the regulation of the real and reactive power flow, voltage support and improvement of the dynamic performance of the power systems [4]. The cascaded inverter and neutral-point clamped (NPC) inverter are well known multilevel inverter topologies [5]. They were inves- tigated with the requirement of quality and efficiency in high power systems. They offer many advantages such as increased power rat- ing, minimized the harmonic effects and reduced electromagnetic interference (EMI) emission [6]. Pulse width modulation (PWM) techniques are showing popularity to control multilevel inverters for multi-megawatt industrial applications. The output waveforms ∗ Corresponding author. E-mail addresses: lsaribulut@cu.edu.tr, lutfusaribulut@hotmail.com (L. Saribulut), ahmetteke@cu.edu.tr (A. Teke), mtumay@cu.edu.tr (M. Tümay). of multilevel inverters can be generated at low switching frequen- cies with high efficiency and low distortion. The harmonics are shifted towards higher frequency bands and large voltages are eas- ily shared between the series devices. Such techniques are applied independently for three phases. Many different PWM techniques have been developed to achieve the following aims [7]: • wide linear modulation range, • less switching loss, • less total harmonic distortion (THD) in the spectrum of switching waveform, • easy implementation and less computation time. Space vector modulation (SVM) is one of the most popular PWM techniques gained interest recently. This technique reduces the switching losses and provides better utilization of DC supply voltage. Hence, the utilization of DC bus voltage can be further increased using certain over modulation approaches. In sinusoidal PWM (SPWM) method, the determination of switching time and sequence are obtained comparing the reference signal with a carrier (triangle) signal [8]. The switching time and sequence for each state are calculated by determining the projection vector of reference vector. SVM technique can be examined under two main headings. One of these heading is the determination of vector location. It can be obtained by using the phase angle of the system derived from the Clarke (–) transformation [9]. 0378-7796/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.epsr.2011.12.004