Water pumping using a photovoltaic d.c. solar pump without energy storage

A model for the simulation of photovoltaic d.c. solar pumping plants is presented. The model also includes simple meteorological data simulations. The computations are based on an energy balance at the pump input and take into account the effect of meteorological data on the array efficiency and the effect of the configuration instantaneous state on the subsystems efficiency. The results allow explanation of the morning/afternoon dissymmetry of the flow and show that the price of a cubic meter of water can be optimized to improve the benefit/cost ratio. The dissymmetry and the variation of the cubic meter price are explained as follows: small-sized plants are affected by the threshold effect of the pump, and large-sized plants work under a higher manometric head in the afternoon.     

Analysis and development of a low-cost permanent magnet brushless DC motor drive for PV-array fed water pumping system

This paper deals with the analysis and development of a permanent magnet brushless DC (PMBLDC) motor drive coupled to a pump load powered by solar photovoltaic (PV) array for water pumping system. A simple low-cost prototype controller has been designed and developed without current and position sensors which reduces drastically the overall cost of the drive system. This controller is used to test the dynamic behavior of the PMBLDC motor drive system. The mathematical model of the system is developed with a view to carry out a comparison between experimental and simulated response of the drive system. A simple filter circuit incorporated in between PV-array and an inverter to reduce ripples and to improve the performance of the PV-array. The necessary computer algorithm is developed to analyze the performance under different conditions of varying solar insolation for a pump load.     

Integrated solar pump design incorporating a brushless DC motor for use in a solar heating system

Most solar thermal hot water heating systems utilize a pump for circulation of the working fluid. An elegant approach to powering the pump is via solar energy. A “solar pump” employs a photovoltaic module, electric motor, and pump to collect and convert solar energy to circulate the working fluid. This article presents an experimental investigation of a new integrated solar pump design that employs the stator of a brushless DC motor and a magnetically coupled pump that has no dynamic seal. This design significantly reduces total volume and mass, and eliminates redundant components.The integrated design meets a hydraulic load of 1.7 bar and 1.4 litres per minute, equal to 4.0 watts, at a rotational speed of 500 revolutions per minute. The brushless DC motor and positive displacement pump achieve efficiencies of 62% and 52%, respectively, resulting in an electric to hydraulic efficiency of 32%. Thus, a readily available photovoltaic module rated 15 watts output is suitable to power the system.A variety of design variations were tested to determine the impact of the armature winding, pump size, pulse width modulation frequency, seal can material, etcetera. The physical and magnetic design was found to dominate efficiency. The efficiency characteristics of a photovoltaic module are such that over-sizing is wasteful.The integrated design presents a robust, efficient package for use as a solar pump. Although focus has been placed on application to a solar thermal collector system, variations of the design are suitable for a wide variety of applications such as remote location water pumping.     

Performance evaluation of a.c. and d.c. direct coupled photovoltaic water pumping systems

Photovoltaic (PV) water pumping systems have been widely tested and assessed in Indonesia because of the deficiency of potable water in remote areas. Several different PV water pumping systems, such as a.c./d.c. with/without battery and various pumps, have been tested in the field. Further study, evaluation and classification of optimized PV water pumping systems is needed. Three of those pumping systems were installed in Sumba Island in 1983, in three adjacent villages with similar climate and environment conditions. Two of the installations had a.c. direct coupled systems and the other had d.c. The a.c. systems used a 3.65 kW_p PV generator each and the d.c. system used 5.76 kW_p. After comparing the performance data of both systems, it can be concluded that the a.c. system performs better and needs less maintenance on the pump. In May 1987, as a result of this evaluation, the 5.76 kW_p d.c. system was replaced by an a.c. one, and its capacity was increased to 9.22 kW_p. Meanwhile, the 3.65 kW_p a.c. system was increased to 3.88 kW_p.     

Analyses and compensation of rotor position detection error in sensorless PM brushless DC motor drives

In a permanent-magnet (PM) brushless DC motor, the waveform of back electromotive force (EMF) is related to the rotor position; hence, the back EMF can be used for position sensorless control. However, in practical implementation, the terminal voltage or phase voltage is used instead, as the back EMF is difficult to be sensed directly. Thus, detection error of the rotor position can occur. This paper documents the calculations and analyses on the detection error and the motor commutation angle, and presents an error compensation circuit to ensure proper commutation. Finite-element field simulation and experimental results are also given to verify the calculations as well as the compensation circuit.     

Performance optimization of a photovoltaic induction motor pumping system

The performances of a photovoltaic pumping system based on an induction motor are degraded once insolation varies far from the value called nominal, where the system was sized. To surmount this handicap, an improvement of these performances by the optimization of the motor efficiency is described in this paper. The results obtained are compared with those of similar work pieces presented in the literature where the motor effeciency and air gap flux where optimized separatly. The simulation results show that the proposed system allows at the same time to combine the performances of the system with constant efficiency and the simplicity of implementation provided by the system with constant airgap flux.     

Experimental Study of the Viscous Pump with a Helical Channel Rotor： Torsion Effect of the Channel

The viscous pump, which has a rotor with a helical square channel, is studied experimentally. The non-dimensional channel curvature is taken to be about 0.1. Three types of torsion of the channel are made to investigate the torsion effect on the flow characteristics. We measure the flux through the channel at a constant rotor speed by changing the pressures at the entrance and exit of the pump. We also observe the secondary flow at a crosssection of the channel. Some of the results obtained are shown as follows： The friction factor along the channel to get the same flux is large for large channel torsion at a constant rotation, and becomes small when the favorable rotation of the rotor to the flow is applied. As for the secondary flow in a cross-section, there appear several types of vortex. When there is no rotation, the secondary flow is almost a symmetric two-vortex type for small flux as is the ordinary Dean vortex, but it changes to a four-vortex type when the flux is large. The secondary flow becomes asymmetric as the rotation is applied. We have unsteady flow patterns at large flux and rotation.     

Torque ripple analysis of a PM brushless DC motor using finite element method

Three-phase permanent magnet brushless DC motors are widely used. As a function of the rotor position, the torque produced by these machines has a pulsating component in addition to the DC component. This pulsating torque has a fundamental frequency corresponding to six pulses per electrical revolution of the motor. The shape of the torque waveform and, thus, the frequency content of the waveform can be influenced by several factors in the motor design and construction. This paper addresses the various factors that influence the torque waveshape. It is shown that in addition to the basic induced electromotive force (EMF) waveshape, the magnetic saturation in the stator core, and the accuracy in the skewing are also key factors in determining the torque waveshape. Computer simulation using finite element technique has been conducted to study the torque waveform. Simulation results successfully duplicated the torque waveforms measured in experiments under different excitation currents.     

Energy efficiency improvement of water pumping system using synchronous reluctance motor fed by perovskite solar cells

Perovskite solar cells (PSCs) are in the forefront of third-generation of photovoltaics and gained a lot of attention as a very promising green technology toward direct solar energy conversion to electricity. PSCs are fabricated following solution-processed techniques at low temperature and they present high power conversion efficiency exceeding 25%, enabling them to be attractive alternative to the silicon-based devices. This research work proposes an efficient and cost-effective photovoltaic (PV) pumping system based on PSCs. For this purpose, lab-scale PSCs were fabricated and their characteristics were determined. In parallel, the geometry of a synchronous reluctance motor (SynRM) driving a 350 m³/day water pump was optimized for maximizing the output power, while minimizing the torque ripple simultaneously. In addition, a perovskite solar array feeding the SynRM via an inverter was designed and implemented. The inverter was properly regulated by a control system which optimized the maximum available power of the PSCs solar array and the SynRM characteristics. Finally, laboratory measurements were performed, including a power generator simulating the behavior of the PSCs array feeding the SynRM. The obtained results confirmed the experimental validation of the proposed approach.     

Performance analysis of d.c.-motor-photovoltaic converter system—I separately excited motor

The performance of a solar-electrical system composed of a solar cell array, d.c. separately exicted motor and a mechanical load was analysed. The system operating points in the mechanical plane, (n, T) were transferred to the photovoltaic converter plane (I, U). The relative position of the load line to the maximum power output line of the photovoltaic converter indicates its utilization. The venitlator type load (centrifugal pump) fits very well the converter in contrast to a constant load. The speed variation of the ventilator type load-motor link remains in reasonable limits during the day. For a centrifugal pump, this characteristic corresponds to an almost constant pumping rate during most of the day.     

Water pumping analysis and experimental validation of beach well infiltration intake system in a seawater source heat pump system

Based on energy conservation equation and Darcy’s law, a model of beach well infiltration intake system applied in a seawater source heat pump system was established. The model consists of the seawater seepage and the heat transfer process. A porous medium model in a software named FLUENT was applied to simulate the seepage and the heat transfer process. This model was also validated by field experiment conducted on the seashore in Tianjin, China. The maximum relative error between simulation results and experimental results was 2.1% (less than 5%), which was acceptable in engineering application. The porosity and coefficient of thermal conductivity of the aquifer soil were determined to be 0.49 W/(m·K) and 1.46 W/(m·K), respectively in the simulation. In addition, the influencing factors of pumping water of beach well were also analyzed. The pumping water was found to increase when the distance between the beach well and the impervious boundary becomes longer, when the distance between the beach well and the supplying water source shortens, when the diameter of the beach well enlarges, and the drawdown enlarges.     

Performance analysis of PV pumping systems using switched reluctance motor drives

A PV pumping system using switched reluctance motor (SRM) is thoroughly investigated in this work. This motor is supplied by a d.c. voltage through a simple switching circuit. This drive circuit is much simpler than the normal d.c./a.c. inverter required to supply the induction motor. The efficiency of this motor is considerably higher than that of the equivalent d.c. or induction motors. In addition, because of the simple construction, SRM is cheaper than these conventional drives. Because of the above advantages of the SRM, the proposed system has higher efficiency and lower cost as compared with other systems.A design example is studied in detail to explore the advantages of PV pumping systems based on this new drive. The study of the performance of the proposed system showed that the operating efficiency of the motor is about 85% during most of its working time. The matching efficiency between the PV array and the proposed system approaches 95%. The major part of the losses takes place in the pump and the riser pipes, this loss represents one-third of the total available energy.     

Numerical investigation and optimization of the thermal performance of a brushless DC motor

A computational study of a brushless DC motor is presented to determine the thermo-flow characteristics in the windings and bearings under the effects of heat generation. The rotation of the rotor blades drives an influx of ambient air into the rotor inlet. The predicted inflow rates were higher at the front inlet than at the rear inlet due to non-uniform pressure distribution. A recirculation zone appeared in the tiny interfaces between windings. The poor cooling performance was caused by flow separation near the groove threshold by the inclination angle of the bearing groove and by a relatively slow velocity near the bearing and between windings. Based on these results, design parameters for the inlet location and geometry, and for the bearing groove geometry, were determined and optimized to enhance the cooling performance up to 24%.     

风力提水系统专用水泵设计与试验

介绍了与小型独立运行的立轴式风力机械相匹配的水泵设计和试验.通过优化设计计算,确定了水泵的几何参数和性能参数,当风力提水机转速n为72 r/min,水泵叶轮转速为512 r/min时,能够达到最满意的泵水效果.风力提水机的风力机额定转速为70 r/min.     

Control of a linear permanent magnet brushless DC motor via exactlinearization methods

The author develops a position controller for permanent magnet brushless DC motors (PMBDCMs) which systematically determines control laws for operation in both the transient and steady-state with consideration of reluctance force. The controller design is based on a differential geometric approach which assists the motor in overcoming its inherent deficiencies, such as effects of torque ripples and reluctance torque. This is achieved by transforming the nonlinear state equations into an exact linear model. Computer simulations of the resulting closed-loop system were performed to demonstrate the effectiveness of the proposed control laws. Simulation results of the control variables were injected into the actual nonlinear system in an experimental open-loop setup to validate the design procedure     

Automatic diagnosis and location of open-switch fault in brushless DC motor drives using wavelets and neuro-fuzzy systems

The faulty performance of permanent-magnet (PM) brushless dc motor drives is studied under open-switch conditions. The wavelet transform is used to extract diagnostic indices from the current waveform of the motor dc link. An intelligent agent based on adaptive neuro-fuzzy inference systems (ANFIS) is developed to automate the fault identification and location process. ANFIS is trained offline using simulation results under various healthy and faulty conditions obtained from a lumped-parameter, network model. ANFIS testing shows that the system could not only detect the open-switch fault, but also identify the faulty switch. Good agreement between simulation results and measured waveforms confirms the effectiveness of the proposed methodology.     

Performance evaluation of a commercial positive displacement pump for wind-water pumping

This paper presents the experimental performance test evaluation of a commercial wind-driven positive displacement pump type JOBER of 3 in diameter. Results of the behaviour of pump lift rod peak force, in relation with the lift rod elasticity and the piston valve closure delay are presented. The pump performance is analysed in terms of its volumetric and overall efficiencies. Evidence about a possible effect of the piston valve closure delay over the pump overall efficiency is also discussed.     

Operating modes of the brushless DC motor with a 120° inverter

An analysis of the brushless DC motor with a 120° inverter is presented. It is shown that the brushless DC motor-120° inverter system has several distinct operating modes. The status of the motor phase current in which the inverter transistors are not conducting (gated off) is used to classify the modes of operation. These modes are identified and their relationship to the speed and the advance in the firing angle is established     

Evaluation of a rice drying system using a solar assisted heat pump

The use of a combined solar-heat pump rice drying system is being developed as an alternative to conventional mechanical dryers. The experimental equipment developed is a modified 7 kW R-22 air conditioning unit and is combined with a solar colector for a more precise control of temperature and humidity.     

Passive Control of an Impulsive Wave Using a Cavity／Helical Vane System

INTRODUCTIONUnsteadycompressiblegasflowthroughaductisoftenencoullteredinmanyengineeringapplicationsandhasbeeninvestigatedbymanyresearchers.Whenapressurewavegeneratedinsideaductisdischargedfromanopenendoftheduct.animpulsivewave,whichcanbefrequentlycha...