2014 IEEE Students’ Conference on Electrical, Electronics and Computer Science 978-1-4799-2526-1/14/$31.00©2014 IEEE Solar PV Stand-Alone Water Pumping System Employing PMSM Drive Menka Dubey, Shailendra Sharma, Member IEEE and Rakesh Saxena Electrical Engineering Department Shri G.S. Institute of Technology & Science 23 Park Road, Indore-452003, India menkadubey@gmail.com, ssharma.iitd@gmail.com, rakeshsaxena@hotmail.com Abstract - This paper deals with the stand alone solar PV (Photo Voltaic) supplied PMSM (Permanent Magnet Synchronous Motor) drive for water pumping system. An interlink Boost converter is used between solar PV panel and DC bus of PMSM drive. The DC bus voltage of PMSM drive is maintained constant by controlling the duty cycle of boost converter. Three phase VSI (Voltage Source Inverter) is controlled to supply PMSM under change in solar irradiation to regulate discharge of water. Solar PV stand–alone water pumping system employing PMSM drive is modelled in MATLAB/SIMULINK environment using the sim power system toolboxes. The performance of the proposed system is obtained under wide variation in PMSM speed with change in solar irradiation. Keywords- DC to DC boost converter; PMSM drive; photo voltaic; vector control; water pumping system I. INTRODUCTION Renewable energy penetrations are increased in power sector to reduce dependency on fossil fuels [1]. Solar PV (Photo-Voltaic) systems are now well recognized for trapping solar energy. Solar energy has the greatest availability compared to other energy sources. It has been estimated that the amount of energy supplied to the earth in one day is sufficient to cater energy needs of the earth of one year [2]. For such solar PV systems, maximum power point tracking control is preferred for efficient operation [3]-[5]. Matsui et. al have presented a MPPT control system for solar PV system by utilizing steady state power balancing condition at DC link [6]. It has further improved by Mikihiko for sensorless application [7]. Integration of PV system with the grid fulfil standard power quality requirements and it have been reported in [8]-[10]. The solar PV system has found many potential applications such as residential, vehicular, space air craft and water pumping system [11]. PV water-pumping is highly competitive compared to traditional energy technologies and best suited for remote site applications that have small to moderate power requirements. Most of the existing photovoltaic irrigation systems offer a mechanical output power from 0.85 kW up to 2.2 kW. The efficiency of Induction motors are less compared to permanent magnet motors, whereas DC machines are not suitable for submersible installations [12]. In recent years, the use of PMSM (Permanent Magnet Synchronous Motors) are increased for drives applications due to its high efficiency, large torque to weight ratio, longer life and recent development in permanent magnet technologies [13]-[15]. It need power processor for effective control [16]. PMSM become a serious challenger of induction motors in hybrid electric vehicle applications [17]-[18]. This paper presents a stand alone solar PV supplied PMSM drive for water pumping system. Pumping water is a universal need for agriculture and the use of PV panels is a natural choice for such applications. In the proposed system, duty cycle of boost converter is controlled to maintain the DC link voltage at required level. The speed of a PMSM drive is a function of solar irradiation. Three phase VSI (Voltage Source Inverter) is controlled to supply PMSM under change in irradiation in vector oriented mode. II. SYSTEM CONFIGURATION AND PRINCIPLE OF OPERATION Fig.1 shows schematic diagram for the stand-alone solar PV based PMSM drive for water pumping system. The proposed system consists of solar PV panel, a boost converter, a three phase VSI (Voltage Source Inverter)and a PMSM coupled with a centrifugal water pump. A PV or solar cell is the basic building block of a PV system. An individual PV cell is usually quite small, typically producing about 1 or 2W of power. To increase the power output of PV cells, these cells are connected in series and parallel to assemble larger unit called PV module. The PV array is connected to the DC to DC boost converter to increase the output voltage level. An IGBT (Insulated Gate Bipolar Transistor) based VSI is used for DC to AC conversion and connected to the PMSM drive. The constant DC voltage is converted to the AC output using a VSI. Reference speed of PMSM is a function of solar irradiation. III. DESIGN OF PV BASED PMSM DRIVE The design of a PV based PMSM drive consists of PV array, a DC to DC converter, a DC link capacitor and a VSI. Ratings of selected parameters are given in Appendix. The designs of various components of drive system are as follows,