0885-8993 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/TPEL.2018.2830401, IEEE Transactions on Power Electronics Switched-Capacitor Based Single Source Cas- caded H-bridge Multilevel Inverter Featuring Boosting Ability Hossein Khoun Jahan, Mehdi Abapour, Kazem Zare Abstract-cascaded multilevel inverter (CMI) is one of the most popular multilevel inverter topologies. This topology is synthe- sized with some series connected identical H-bridge cells. CMI requires several isolated dc sources which brings about some difficulties when dealing with this type of inverter. This paper addresses the problem by proposing a switched capacitor (SC) based CMI. The proposed topology, which is referred to as switched capacitor single source CMI (SCSS-CMI), makes use of some capacitors instead of the dc sources. Hence it requires only one dc source to charge the employed capacitors. Usually, the capacitor charging process in a SC cell is companied by some current spikes which extremely harm the charging switch and the capacitor. The capacitors in SCSS-CMI are charged through a simple auxiliary circuit which eradicates the mentioned current spikes and provides zero current switching condition for the charging switch. A computer-aid simulated model along with a laboratory-built prototype are adopted to assess the performances of SCSS-CMI, under different conditions. Index Terms—multilevel inverter, CMI, switched capacitor. NOMENCLATURE m I Maximum value of load current f Frequency of the output voltage  2 f   Load current angle Number of levels dc v Voltage value of dc source cs os v On-state voltage of the charging switch cd os v On-state voltage of a charging diode fd o v On-state voltage of the freewheeling diode m t Starting instance of the m th level at the first quar- ter of a cycle b n t  Starting instance of the (b+n) th level at the second quarter of a cycle n T Time duration of the n th level n Du Time duration in which the n th capacitor takes part in developing a voltage level 1 c v Voltage of the capacitor participating in the first level 1 c v  Highest voltage drop in a capacitor ( 1 C ) () k v t Voltage in k th H-Bridge cell (0) k v Initial voltage of the capacitor in the k th H-bride cell at the starting instance of a cycle ( ) k v  Initial voltage of the capacitor in the k th H-bride cell at the end of a half cycle k v  Highest voltage variation of the capacitor in the k th H-bride cell R Load resistance k C Capacitance of capacitor in the k th H-bridge cell ch T Charging time duration ch  2 ch T  cs R Resistance of the charging switch d ch R Resistance of a the charging diode d f R Resistance of the freewheeling diode l R Resistance of the charging inductor ch i Charging current ch L Inductance of the charging inductor FCS loss P Total power loss of the charging stage in the presence of the first charging structure SCS loss P Total power loss of the charging stage in the presence of the second charging structure I. INTRODUCTION Multilevel inverters are one of the state-of-the-art con- stituents in modern electrical power systems. They take part in many applications such as renewable energy sys- tems, machine drives, electrical vehicles, and etc. [1-3]. The main advantages related to them are: i) realizing volt- age of lower total harmonic distortion (THD), ii) requiring components of lower voltage stress, and iii) Mitigating electromagnetic interference (EMI). On the contrary, re- quiring extra number of components is the fatal demerit of these kinds of converters [4]. However, to the end of less- ening the mentioned drawback several topologies are intro- duced so far [5-7]. Diode-clamped converter (DCC), Flying-capacitor con- verter (FCC), and Cascaded multilevel inverter (CMI), are the most well know topologies of multilevel inverter [8- 10]. Among these three topologies CMI stands out for its modular structure which makes it easy to be designed, syn- thesized, and repaired. However, this topology does suffer from requiring several isolated dc sources. This issue, apart from bringing about some physical problems like increas- ing cost and volume, arises some fatal difficulties to appear in its different applications. Hence, addressing this problem is of particular importance. However, some researchers have taken the advantage of needing some isolated dc sources to adopt CMI in photovoltaic (PV) applications [1][11]. As shown in these papers employing this inverter in PV applications calls for some individual dc-dc convert- ers and an elaborate controlling system. Furthermore, CMI is considered to be workable in STATCOM application. In this application the dc sources are replaced with some ca- pacitors [12-13]. Same as the PV application, CMI in STATCOM application requires a versatile controlling system to balance the voltage of the capacitors. We also encounter to some researches that attempt to reduce the number of dc sources in CMI. One solution is using low frequency transformers instead of several dc source [14- 15]. Using transformers in CMI structure has its own pros and cons. By choosing proper transformer ratio, transform- ers can offer an arbitrary voltage value from a given input voltage value, they provide a galvanic isolation as well. On the contrary, they are bulky, expensive, and wasteful. The other solution is using a high frequency link and transform-