Effect of Annealing on the Properties of Nanocrystalline CdS Thin Films Prepared by CBD Method

The CdS thin films were deposited on glass substrate by chemical bath deposition (CBD). The effect of annealing temperature on the morphological, structural, optical and electrical properties of the crystalline CdS films were investigated for different annealing temperature (as deposited, 300, 400 and 500 °C).The annealing time is 1 h. The materials have been prepared using simple aqueous solutions containing cadmium sulfate, as source of cadmium, and thiourea as source of sulfur and ammonium hydroxide as the complexing agent. The temperature of the bath was maintained at low temperature of 80 °C. The surface morphological properties studied by SEM and AFM respectively. The structural properties of CdS thin film was studied by X-ray diffraction. The optical parameter such as transmittance and energy band gap of the films with thermal annealing temperature was investigated by UV-Visible spectrophotometer. The variation of band gap values of CdS thin film samples were found to be in the range of 2.37 to 2.5 eV. Electrical resistivity measurements were carried out in four-probe Van Der Pauw geometry at room temperature by the Hall measurement. SEM image confirmed that film of smooth surface morphology

Extended Kalman filter based speed-sensorless load torque and inertia estimations with observability analysis for induction motors

This paper aims to introduce a novel extended Kalman filter (EKF) based estimator including observability analysis to the literature associated with the high performance speed-sensorless control of induction motors (IMs). The proposed estimator simultaneously performs the estimations of stator stationary axis components of stator currents and rotor fluxes, rotor mechanical speed, load torque including the viscous friction term, and reciprocal of total inertia by using measured stator phase currents and voltages. The inertia estimation is done since it varies with the load coupled to the shaft and affects the performance of speed estimation especially when the rotor speed changes. In this context, the estimations of all mechanical state and parameters besides flux estimation required for high performance control methods are performed together. The performance of the proposed estimator is tested by simulation and real-time experiments under challenging variations in load torque and velocity references; and in both transient and steady states, the quite satisfactory estimation performance is achieved

Optimization of model reference adaptive system based speed estimation for speed sensorless control of induction motors via differential evolution algorithm

Committee on Adaptive and Learning Systems;Control (IFAC) - TC1.2: Technical;International Federation of Automatic;Signal Processing;TC 1.1: Modelling, Identification and;TC 2.1: Control Design11th IFAC International Workshop on Adaptation and Learning in Control and Signal Processing, ALCOSP 2013 -- 3 July 2013 through 5 July 2013 -- Caen -- 99962This study proposes an optimally tuned Model Reference Adaptive System (MRAS) based speed estimator using back electromotive force (EMF) vector, which does not require pure integration. The PI (Proportional and Integral) gain coefficients in the speed estimator are optimally determined by utilizing Differential Evolution (DE) algorithm. The performance of the speed estimator is tested with both simulation and real-time experiments for a wide speed range. The obtained results verify the desired performance of speed estimation. © IFAC

Adaptive Fading Extended Kalman Filter Based Speed-Sensorless Induction Motor Drive

et al.;IEEE Industrial Electronics Society (IEEE-IES);IEEE Industry Applications Society (IEEE-IAS);The Department of Electrical and Computer Engineering, Democritus University of Thrace;The International Conference of Electrical Machines Association (ICEM);The Ministry of Environment and Energy23rd International Conference on Electrical Machines, ICEM 2018 -- 3 September 2018 through 6 September 2018 -- -- 141471This paper presents an adaptive fading extended Kalman filter (AFEKF) based speed-sensorless induction motor (IM) drive. Conventional extended Kalman filters (CEKFs) assume the system (Q) and the measurement (R) noise covariance matrices as constant, but those matrices are affected by the operating conditions of IMs and deteriorate the estimation performance. To eliminate this adverse effect, an AFEKF algorithm which has the ability to update Q and R matrices according to the operating conditions of IM are proposed, and the stator stationary axis components of stator currents, the stator stationary axis components of rotor fluxes, the rotor mechanical speed, and the load torque including viscous friction term are estimated. To illustrate the superiority of AFEKF-based speed-sensorless IM drive, the control performance of the proposed drive system is compared to that of CEKF-based speed-sensorless drive system under simulations. In addition to the comparison results, the computational burdens of AFEKF and CEKF algorithms are also examined. © 2018 IEEE

Speed-Sensorless Direct Torque Control System Using Bi-Input Extended Kalman Filter for Induction Motors

In this study, a speed-sensorless direct torque control (DTC) system using bi input-extended Kalman filter (BI-EKF) is designed to perform the high performance velocity control of induction motors (IMs). The BI-EKF algorithm estimates stator stationary axis components of the stator fluxes, tpsa and tpsfl, the rotor angular velocity, omega(m) the rotor resistance, R-r', the stator resistance, R-s, the load torque involving the viscous friction term, t(L), and the reciprocal total inertia of the IM and load, gamma(T) =Delta 1/j(T), as well as stator stationary axis components of stator currents, i(s alpha) and i(s beta), which are also measured as output. The simulation results prove very satisfying performances of the BI-EKF algorithm and therefore the speed-sensorless DTC system

The tin precursors and hydrogen peroxide effects on spray-deposited SnO

The oxide semiconductor compounds such as SnO2, In2O3, ITO, ZnO and others brought about a new attention for the metal-insulator-semiconductor structures as photovoltaic converters because of the high values of transmission and conductivity and the possibility of metal replacement in above-mentioned structures. The characteristics of the solar cells based on these oxide semiconductor compounds can be improved with conductivity increasing of the transparent semiconductor films and that is why the purpose of this paper is obtaining of F-doped tin oxide thin films, preparation of SnO2:F-Si solar cells and studying of their properties. The F-doped tin oxide thin films were prepared by spray pyrolysis technique [1–8]. This method was chosen because of the simplicity of the apparatus and relatively low cost. Aqueous solutions containing 0.1 M (TT, BTT or DTD) and 0.07 M NH4F (in the case of doping with F) have been sprayed by an atomizer on Si or glass substrates, heated up to 420 °C by maintaining the spray liquid volume, the spray time and the pressure of the carrier gas. Spray pyrolysis deposition of transparent and conductive SnO2 is a low-cost and very flexible technique applicable to solar cells. For SnO2, the drawback is that polycrystalline films are only obtained at relatively high deposition temperatures, largely above 450 °C. This constraint may cause damage to the photovoltaic junction. In the present work, it will be demonstrated that the photovoltaic parameters can be influenced by adding small amounts of hydrogen peroxide (H2O2) to the source solution

Nickel on porous silicon MSM photo-detector and quantum confinement in nanocrystallites structure as methods to reduce dark current

We propose in this work, contact Schottky Nickel/porous silicon (PSi) system, coupled to nanocrystallites size variation of material for a possible technique to reduce dark current. The device consists of metal- semiconductor-metal photodiode (MSM-PD). Higher barrier ΦΒ enhances the performance of MSM-PD through reduction in dark current (Is), and benefits to resolve noise from signal detection of the devices. In order to reduce much more Is, we proposed different anodization times (5–7–10 min) as method to tune the size of nanocrystallites. As result Is value was reduced to almost two orders of magnitude for 10 min etching time, and the value of Is ≈ 10–10 A. ΦΒ reached the value of 0.882 eV. Among the hypothesis suggested in the reduction of Is was the quantum confinement effects. According to Rhoderick model, the Schottky barrier height is explicitly linked to the band gap energy due to the presence of interface states. The existence of narrow nanocrystallites increased energy band gap of PSi and the Schottky barrier height, which in turn reduces Is. The photoluminescence measurements confirmed our hypothesis. Photosensitivity of the device was established by adopting the MSM configuration, and strong absorption was detected in visible range