Simulation of Switched Reluctance Generator in Low and Medium Speed Operations for Wind Energy Application

This paper provides a new approach to maximize the amount of power generated by the switched reluctance generator (SRG) in the low and medium speed operations. There are many control variables which affect the power generated such as: firing angles, reference current, speed and voltage. It will incur high costs and time consuming to modify the variables using experimental set up. Hence, to minimize time, cost and aid in the manufacturing industry, a simulation model of the overall SRG drive is developed. The objective of the work is to identify the optimal parameters and characterize them under closed loop control. The study indicates that there is an optimal voltage, firing angles and reference current at each speed range. Also, the percentage of the power generated can be categorized as a function of dwell angle and speed at optimal voltage level. The optimal dwell angle is determined using the least square method. Within the closed loop system, the high percentage of power generated can be maintained by adjusting the voltage level. It allows operation in single pulse mode as opposed to the conventional current chopping during the low and medium speed.13 page(s

A Comprehensive simulation platform for switched reluctance generator system

A Switched Reluctance Generator (SRG) system normally encompasses three main components: SR machine, controller and converter. On-going research on simulation and modelling of SRG system has focused on one component. There is a lack of a more comprehensive approach which integrates all three components into one simulation platform. We have developed a simulation model comprising SR machine, control and converter using MATLAB/Simulink. The main advantage of a simulation model is to reduce time and cost by having to perform changes on the prototype machine. In this paper, the work is focused on developing the optimal control algorithm for the platform. Optimal parameters are identified and characterized in terms of highest percentage of power generated. From simulation, the most influential parameters affecting the power generated are the firing angles and voltage level. So, a function relating the optimized parameter with machine performance was developed. The proposed control technique will provide easy implementation and ensure high machine performance. The effectiveness of the proposed method is demonstrated by simulation results. The work will aid in development of SRG by providing a platform to determine the best generating operation before real implementation, reducing manufacturing time and cost.11 page(s

Development and evaluation of portable low cost testing system for phthalates

A portable low-cost microcontroller based testing system was designed and constructed to detect phthalates in aqueous media. Phthalates, especially di (2-ethylhexyl) phthalate is the most ubiquitous endocrine disrupting compound (EDC) posing highest reproductive toxicity threat to all living species on earth. Frequency response analyser (FRA) approach was used to develop the rapid response, non-invasive electrochemical impedimetric system for detection. A smart thin film gold interdigital electrodes capacitive sensor with enhanced penetration depth was used with the proposed system for detection of the said EDC. The performance of the developed system was evaluated by comparing the results to the commercially available electrochemical Impedimetric frequency response analyzer equipment. Complex nonlinear least square (CNLS) curve fitting algorithm was used to deduce the equivalent circuit for the developed system. The DEHP detection results by the developed system were validated using high performance liquid chromatography (HPLC) diode array detection confirming that the proposed system was able to detect the concentration of phthalates in aqueous medium.7 page(s

Rapid and molecular selective electrochemical sensing of phthalates in aqueous solution

Reported research work presents real time non-invasive detection of phthalates in spiked aqueous samples by employing electrochemical impedance spectroscopy (EIS) technique incorporating a novel interdigital capacitive sensor with multiple sensing thin film gold micro-electrodes fabricated on native silicon dioxide layer grown on semiconducting single crystal silicon wafer. The sensing surface was functionalized by a self-assembled monolayer of 3-aminopropyltrietoxysilane (APTES) with embedded molecular imprinted polymer (MIP) to introduce selectivity for the di(2-ethylhexyl) phthalate (DEHP) molecule. Various concentrations (1–100 ppm) of DEHP in deionized MilliQ water were tested using the functionalized sensing surface to capture the analyte. Frequency response analyzer (FRA) algorithm was used to obtain impedance spectra so as to determine sample conductance and capacitance for evaluation of phthalate concentration in the sample solution. Spectrum analysis algorithm interpreted the experimentally obtained impedance spectra by applying complex nonlinear least square (CNLS) curve fitting in order to obtain electrochemical equivalent circuit and corresponding circuit parameters describing the kinetics of the electrochemical cell. Principal component analysis was applied to deduce the effects of surface immobilized molecular imprinted polymer layer on the evaluated circuit parameters and its electrical response. The results obtained by the testing system were validated using commercially available high performance liquid chromatography diode array detector system.8 page(s

Introducing molecular selectivity in rapid impedimetric sensing of phthalates

This research article reports a real-time and non-invasive detection technique for phthalates in liquids by Electrochemical Impedance Spectroscopy (EIS), incorporating molecular imprinting technique to introduce selectivity for the phthalate molecule in the detection system. A functional polymer with Bis (2-ethylhexyl) phthalate (DEHP) template was immobilized on the sensing surface of the inter-digital (ID) capacitive sensor with sputtered gold sensing electrodes fabricated over a native layer of silicon dioxide on a single crystal silicon substrate. Various concentrations (10 to 200 ppm) of DEHP in deionized MilliQ water were exposed to the sensor surface functionalized with molecular imprinted polymer (MIP) in order to capture the analyte molecule, hence introducing molecular selectivity to the testing system. Impedance spectra were obtained using EIS in order to determine sample conductance for evaluation of phthalate concentration in the solution. Electrochemical Spectrum Analyzer algorithm was used to deduce equivalent circuit and equivalent component parameters from the experimentally obtained impedance spectra employing Randle's cell model curve fitting technique. Experimental results confirmed that the immobilization of the functional polymer on sensing surface introduces selectivity for phthalates in the sensing system. The results were validated by testing the samples using High Performance Liquid Chromatography (HPLC-DAD).6 page(s

Sensor and instrumentation for progesterone detection

The reported research work uses a real time and noninvasive method to detect progesterone hormone concentration in purified water using Electrochemical Impedance Spectroscopy (E.I.S.) technique. Planar capacitive sensor, consisting of inter-digitated microelectrodes, is designed and fabricated on silicon substrate using thin-film Microelectromechanical system (MEMS) based semiconductor device fabrication technology. The sensor in conjunction with EIS is used to evaluate conductivity, permeability and dielectric properties of reproductive hormone progesterone and its concentration quantification in purified water. Impedance spectrums are obtained with various concentrations of the hormone in purified water by using an electric circuit in order to extract sample conductance. Relationship of sample conductance with progesterone concentration level is studied in this research work. The ability of E.I.S. to detect progesterone concentration is aimed to be used in dairy farming industry in order to obtain better reproductive performance of the dairy cattle.6 page(s

Development of electrochemical impedance spectroscopy based sensing system for DEHP detection

This research work presents a real time and non invasive technique to detect Di(2-ethylhexyl) phthalate (DEHP)content in purified water and quantify its concentration by Electrochemical Impedance Spectroscopy(E.I.S.). Planar Inter-digital capacitive sensor is employed to evaluate conductivity, permeability and dielectric properties of material under test. This sensor, consisting of inter-digitated microelectrodes, is fabricated on silicon substrate using thin-film Microelectromechanical system (MEMS) based semiconductor device fabrication technology. Impedance spectrums are obtained with various concentrations of DEHP in purified water by using an electric circuit in order to extract sample conductance. Relationship of sample conductance with DEHP concentration is studied in this research work which enables us to show the ability of E.I.S. to detect DEHP concentration in water and hence can be applied in water treatment process for contamination quantification.9 page(s

Electrochemical impedance spectroscopy based MEMS sensors for phthalates detection in water and juices

Phthalate esters are ubiquitous environmental and food pollutants well known as endocrine disrupting compounds (EDCs). These developmental and reproductive toxicants pose a grave risk to the human health due to their unlimited use in consumer plastic industry. Detection of phthalates is strictly laboratory based time consuming and expensive process and requires expertise of highly qualified and skilled professionals. We present a real time, non-invasive, label free rapid detection technique to quantify phthalates' presence in deionized water and fruit juices. Electrochemical impedance spectroscopy (EIS) technique applied to a novel planar inter-digital (ID) capacitive sensor plays a vital role to explore the presence of phthalate esters in bulk fluid media. The ID sensor with multiple sensing gold electrodes was fabricated on silicon substrate using micro-electromechanical system (MEMS) device fabrication technology. A thin film of parylene C polymer was coated as a passivation layer to enhance the capacitive sensing capabilities of the sensor and to reduce the magnitude of Faradic current flowing through the sensor. Various concentrations, 0.002ppm through to 2ppm of di (2-ethylhexyl) phthalate (DEHP) in deionized water, were exposed to the sensing system by dip testing method. Impedance spectra obtained was analysed to determine sample conductance which led to consequent evaluation of its dielectric properties. Electro-chemical impedance spectrum analyser algorithm was employed to model the experimentally obtained impedance spectra. Curve fitting technique was applied to deduce constant phase element (CPE) equivalent circuit based on Randle's equivalent circuit model. The sensing system was tested to detect different concentrations of DEHP in orange juice as a real world application. The result analysis indicated that our rapid testing technique is able to detect the presence of DEHP in all test samples distinctively.12 page(s

MEMS based impedimetric sensing of phthalates

Phthalate esters are known ubiquitous teratogenic and carcinogenic environmental and food pollutants. Their detection and quantification is strictly laboratory based, time consuming, expensive and professionally handled procedure. Presented research work describes a real time non-invasive detection technique for phthalates detection in ethanol, water and drinks. The new type of inter-digital sensor design incorporating multiple sensing gold electrodes were fabricated on silicon substrate based on thin film micro-electromechanical system (MEMS) using semiconductor device fabrication technology. A passivation layer of Silicon Nitride (Si₃N₄) was used to functionalize the sensor. Various concentrations (0.1 to 20ppm) of DINP (di-isononyl phthalates) in ethanol and di (2-ethylhexyl) phthalate (DEHP) in deionized MilliQ water were subjected to the testing system by dip testing method. Electrochemical impedance spectroscopy (EIS) technique was used to obtain impedance spectra in order to determine sample conductance for evaluation of its dielectric properties. The impedance spectra so obtained showed that the sensor was able to detect the presence of phthalates in the samples distinctively. Electrochemical Spectrum Analyser was used to model the experimentally obtained impedance spectra by curve fitting technique to figure out Constant Phase Element (CPE) equivalent circuit. Locally available energy drink and juice was added with phthalates in concentrations of 2, 6 and 10ppm to observe the performance of the sensor in such products. Experimental results showed that the new sensor was able to detect different concentrations of phthalates in energy drinks.6 page(s