Engineering, Technology & Applied Science Research Vol. 8, No. 1, 2018, 2452-2458 2452 www.etasr.com Nouaiti et al.: Experimental Implementation of a Low-Cost Single Phase Five-Level Inverter for … Experimental Implementation of a Low-Cost Single Phase Five-Level Inverter for Autonomous PV System Applications Without Batteries Ayoub Nouaiti Abdallah Saad Abdelouahed Mesbahi Mohamed Khafallah Laboratory of Energy and Electrical Systems (LESE) Superior National School of Electricity and Mechanical (ENSEM) University of Hassan II Casablanca Casablanca, Morocco Laboratory of Energy and Electrical Systems (LESE) Superior National School of Electricity and Mechanical (ENSEM) University of Hassan II Casablanca Casablanca, Morocco Laboratory of Energy and Electrical Systems (LESE) Superior National School of Electricity and Mechanical (ENSEM) University of Hassan II Casablanca Casablanca, Morocco Laboratory of Energy and Electrical Systems (LESE) Superior National School of Electricity and Mechanical (ENSEM) University of Hassan II Casablanca Casablanca, Morocco Abstract—This paper presents the design and the implementation of a low-cost single phase five-level inverter for photovoltaic applications. The proposed multilevel inverter is composed of a simple boost converter, a switched-capacitor converter, and an H-bridge converter. An efficient control method which associates a closed-loop regulation method with a simple maximum power point tracking (MPPT) method is applied in order to allow the proposed multilevel inverter to transfer power energy from solar panels to autonomous load with no storage batteries. An experimental prototype of this inverter is fabricated at the laboratory and tested with a digital control system. Obtained results confirm the simplicity and the performance of the proposed photovoltaic system. Keywords-Multilevel inverter; Boost converter; Switched capacitor converter; MPPT; PV I. INTRODUCTION Power inverters are mostly used in photovoltaic systems to convert the DC power energy from solar panels to an AC form while respecting the standard criteria for voltage, frequency, and total harmonic distortion (THD). Classical power inverters structures present many problems such as high switching losses, high level of THD, output filters with high sizes [1]. Multilevel inverters present many advantages compared to classical ones [2]. Classical multilevel inverters are systematized in three categories: Flying Capacitor, Neutral Point Clamped Inverter, and Cascaded H-Bridge Inverter [3]. Several structures of multilevel inverters can be deduced from these categories by using, hybrid, symmetric, and asymmetric adjustment [4]. From hybrid adjustment, an important structure is derived: the switched-capacitor converter (SCC) used in two ways: either as a step-up converter or as a multilevel converter tied with classical inverters to get multi-level AC waveforms [5]. Non-isolated DC-DC converters such as classical boost converters (BC) are frequently used between solar panels and multilevel converters structures for low and medium power- levels applications in order to increase the used DC-Bus voltage. These converters are chosen for their simplicity, low manufacturing cost, and low weight [6]. This paper presents the design and experimental test of a simple single phase five-level inverter for Photovoltaic (PV) system applications. An efficient control method which incorporates an MPPT method with a closed-loop regulation method is used. The key part of this inverter is the SCC which is used to tie a BC with a classical H-bridge converter (HBC). By utilizing this structure, the duty cycle of the control signal of the BC will be smaller, thus reducing the switching losses across its power switch, the total number of power switches with their gate-drivers power supply is reduced compared to conventional multilevel inverters. The proposed inverter is tested experimentally under industrial values of voltage and frequency by feeding power energy from solar panels to a 130W single phase induction motor driving a water pump. II. DESCRIPTION OF THE PROPOSED MULTILEVEL INVERTER The topology of the proposed PV multilevel inverter is shown in Figure 1. It’s composed of a single DC voltage source from solar panels (Vpv), a DC-DC BC circuit, a DC-AC five- level converter (FLC) circuit, and an AC single-phase load. Fig. 1. Topology of the PV multilevel inverter.