Analysis Method for the Uniformity of a-Si-Based Multijunction Thin-Film Solar Module Using Ideality Factors

Flexible thin film silicon solar modules on heat-resistant transparent flexible substrates are promising to achieve high efficiency by a combination of high-quality silicon thin films and fully monolithic series integration. In this work, performance of superstrate hydrogenated amorphous silicon (a-Si:H) thin film solar cells and modules on flexible glass using boron-doped zinc oxide (BZO) front electrode have been investigated. Compared with conventional glass, BZO thin films on flexible glass exhibited mixed structure of large-sized pyramid and small-sized grain, preferential crystalline orientations of (100) and (110), relatively lower surface roughness and scattering ability. Accordingly, compared with conventional BZO glass, a-Si:H thin film solar cells on flexible BZO glass exhibited a relative increase in open-circuit voltage, fill factor, and efficiency of 2.0, 5.5, and 3.4%, respectively. Finally, ∼50 cm2 flexible a-Si:H thin film solar modules were prepared by fully monolithic series integration using laser scribing, and relatively higher efficiency was achieved by improving thin films uniformity.

Parameter estimation of solar cells and modules using an improved adaptive differential evolution algorithm

This paper describes the design and implementation of a computer controlled active load for characterization of the steady-state and the dynamic behaviours of polymer electrolyte membrane (PEM) fuel cell systems. The active load converter is based on a linear regulator topology. The non-switching converter is ideal for steady-state measurements. The control of the converter is implemented in Simulink and dSpace and uses a PI feedback loop. The active load is designed for characterization of a fuel cell system, and therefore an electric circuit model for fuel cells is introduced. The circuit model contains a highly non-linear voltage source describing the activation polarization and the concentration polarization, two resistors for the ohmic polarization and the membranes double layer capacitor for the dynamic behaviour. The circuit model parameters are obtained from the measured data. Test results show good similarity with the fuel cell theory and confirm that the fuel cell circuit model can be used for modelling commercially available fuel cell systems, and uncontrolled fuel cell stacks.

Power supply is an important part of the design of any lighting devices with light emitting diodes (LEDs), which provides stable operation of LEDs and, at the same time, stable electrical and lighting parameters of the lighting device as a whole. The purpose of this work was to create a model of the power supply circuit for a luminaire with LEDs and analyse its operation. Modelling of the circuit was carried out in the calculation for an allowable load of no more than 70 W. This value was chosen according to its versatility and the greatest demand in the market of power supplies for lighting devices with LEDs. The simulated circuit of the power supply source, based on the power factor corrector for a light device with LED using the program “Micro-Cap”, is presented in the article. The analysis of the circuit operation in working and emergency modes is carried out. The simulation results are presented in the form of graphs of the time dependence of the main circuit parameters. The principle of controlling the current of the LED and the purpose of functional units of the circuit and outputs of the microcircuit (type MS33262) are described. The purpose of each structural element used in the circuit is specified. The modelled circuit has a power factor which is at least 0.98. The protection device PS triggers normally and the power factor corrector together with the appropriate electronic harness provides stable operation of the circuit for a light device with a 70 W LED.

This article presents a method for characterization of common-mode chokes aimed at constructing accurate virtual prototypes of electromagnetic interference filters. This method is based on a general modal analysis that identifies the natural modes of a symmetric four-port network in a power line. Natural modes excited in the setups defined in the CISPR-17 norm to characterize filtering devices are determined. From this analysis, two simple measurement setups particularly suitable for characterizing common-mode chokes are identified, and a decision-making algorithm is presented to determine the parameters of a configurable circuit model of the common-mode choke. This circuit model is especially devised so that each one of its different circuit blocks can be associated with a single modal response of the common-mode choke. This, along with the use of physical criteria to define the basic schematic of each circuit block, ensures the simplicity, accuracy, and generality of the final circuit model. Characterization of many commercial common-mode chokes with different core materials and winding configurations has been carried out to demonstrate that this circuit model is able to accurately account for the actual response of different types of common-mode chokes in a wide frequency range.

Solar cell/module modeling involves the formulation of the non-linear current versus voltage (I-V) curve. Determination of parameters plays an important role in solar cell/module modeling. This paper presents an application of the improved PSO search method and Particle Swarm Optimization technique for identifying the unknown parameters of solar cell and photovoltaic module models, namely, the series resistance, shunt resistance, generated photocurrent, saturation current, and ideality factor that govern the current-voltage relationship of a solar cell/module. For the confirmation of accuracy of the proposed method, a measurement data of 57 mm diameter commercial (R.T.C. France) silicon solar cell and a module consisting of 36 polycrystalline silicon cells (Photowatt-PWP 201) has been selected and the best optimal value of each parameter has been obtained using Improved PSO. Comparative study among different parameter estimation techniques is presented to demonstrate to verify the accurateness and the effectiveness of the proposed approach.

The intra-layer no-insulation (LNI) coil, which has the advantages of self-protection and high magnetic field homogeneity, is of great potential in HTS NMR and MRI applications. Compared to the more commonly-used double-pancake coils, the transient characteristics are more complex due to additional axial current. While the present circuit model cannot accurately describe the geometry of the LNI coil and the internal characteristics of each turn of the coil, a helical grid equivalent circuit model with consideration of types of mutual inductances is proposed in this paper. In the circuit model, details of the coil are characterized with subdivided helical surface elements in each turn, and each helical surface element can be equivalent to corresponding circuit parameters. The circuit model is verified by a comparison experiment with an intra-layer insulation coil. And elaborate current distributions in each turn of the LNI coil can be obtained with this circuit model. Analysis results demonstrate that the azimuthal current and the axial current are always symmetrically distributed about the middle plane, and the radial current is always anti-symmetrically distributed about the midplane. The circuit model can be used to simulate the quench electromagnetic characteristics of the LNI coil in the future.

In this paper, an equivalent circuit model of a V-shaped linear ultrasonic motor is developed, considering the contact characteristics between the stator and the slider, as well as the piezoelectric coupling characteristics of the ultrasonic motor. The relationship between the mechanical parameters and the electrical parameters during the operation of the motor is studied. The admittance circle of the stator is obtained through experimental methods, and the relationship between the admittance circle and the electrical parameters of the equivalent circuit model of the stator is studied and analyzed. The Rf, Cf, Lm1, Rm1, and any other key parameters of the contact equivalent circuit model of the stator/slider are identified by the energy method. The dynamic contact characteristics between the stator and the slider during the operation of the motor are characterized by the method of comparing the magnitude of the branch current of the stator and the slider and selectively turning on or off the switching transistor. A complete equivalent circuit of the V-shaped linear ultrasonic motor is constructed in the Simulink environment of MATLAB and verified through numerical simulation and experimental verification. The results show that the circuit model can accurately reflect the mechanical characteristics of the motor and the dynamic output characteristics of the motor can be predicted from the changes in the electrical parameters, which can provide theoretical guidance for the regulation and control of the motor when it is used in high precision instruments.

In recent years, battery chargers are not only capable of charging a battery, but also can measure the internal impedance spectrum of a battery in real-time. Measured battery impedance represents electrochemical characteristics, which are used to analyze the internal conditions of a battery and can be represented by a circuit model. This paper presents an equivalent circuit parameter extraction algorithm based on the impedance spectrum measurement of a battery. The proposed algorithm is designed using the Nyquist theory and is applicable to lithium ion batteries specifically. The circuit simulation, ac perturbation, and parameter extraction are processed with the measured circuit parameters, which are obtained from electrochemical impedance spectroscopy (EIS) test of a 1000mAh Li-ion battery. It shows 0.0216mΩ difference for Ohmic resistance extraction based on the proposed simulation results and the selected parameters from experiment. The presented algorithm could be applicable to the battery charger, which is capable of obtaining on-line electrochemical impedance spectrum. The algorithm could be useful for a battery management system as well.

Electrical parameters of metal doped n-CdO/p-Si heterojunction diodes

In inductive power transfer (IPT) systems, it is usually desirable to have an adjustable output voltage. This paper proposes a pulsewidth modulation scheme for active class-E rectifier based IPT systems. The output voltage is regulated by the duty cycle of the active rectifier. Utilizing the proposed modulation scheme, the active MOSFET is turned on at the zero crossing point of its drain-source voltage. Thus, the power MOSFET of the rectifier is achieved with zero-voltage-switching (ZVS) condition over a wide output range. Detailed circuit analysis, modeling and parameters design are presented. The experimental results match well with the circuit modeling and validate the soft-switching operation and the output voltage regulation capabilities. The efficiencies of overall system and rectifier reach 90.22 % and 95.45 % at 120 W output respectively.

In this work, we demonstrate that partial shading of one solar cell in a state-of-the-art monocrystalline photovoltaic module with three bypass diodes results in hot cells with critical peak temperatures of 164 $^\circ$ C. We examine two solar modules in the IEC 61215-2 MQT 09 hot-spot endurance test, one with 367.3 W $_\text{P}$ featuring 72 full-cells and the other with 388.6 W $_\text{P}$ featuring 144 half-cells. For the solar module with 72 solar cells, we measure a maximum temperature of 164 $^\circ$ C, which results in a degradation of the encapsulation material and increases the risk of solar module failure. The high temperature results from the hot cell effect due to the power dissipation in the reverse-biased solar cell caused by partial shading. Our experiments show that the half-cell solar module is advantageous in terms of solar cell shading compared to the full-cell solar module. Although the half-cell solar module has a higher power output than the full-cell solar module, we measure a cooler peak temperature of 150 $^\circ$ C. However, under certain shading conditions, the half-cell solar module can exhibit similar temperatures as the full-cell solar module. Based on our experimental results, we develop an electrical and a thermal model to predict the temperature of novel high-power solar modules with solar cells from larger silicon wafer formats in case of partial cell shading. Our predictions consider the trends of further increasing solar cell and module efficiencies, larger silicon wafer formats, and larger solar modules. We simulate a maximum peak temperature of 176 $^\circ$ C at the solar module's surface, which significantly increases the risk of solar module failure. Our results show that new high-power solar modules employing solar cells that are made from larger silicon wafer formats need a new protection against overheating. Three bypass diodes per solar module are no longer sufficient.

In this paper, a genetic-based algorithm is proposed and implemented to extract diode circuit model parameters. Saturation current, ideality factor, and series resistance are extracted without a need for initial conditions. The proposed technique is found to be robust and capable to reach a solution that is characterized to be global and accurate. Compared with existing conventional techniques, the proposed one shows superior performance in terms of accuracy and being generic and applicable to extract parameters of other devices. The proposed technique performance has been tested using theoretical data, and used to extract real device parameters from its measured I-V characteristics.

Genetic Algorithm Based Diode Model Parameters Extraction

In this work, data transmission in transmission lines containing textured ground planes in the power distribution network is investigated. A lumped element model is developed to generate eye diagrams and circuit simulations are compared with measurements. A circuit model for a transmission line with an EBG ground plane is introduced. The circuit model for the EBG structure is developed based on using LC components and considering each patch as a parallel-plate transmission line. This modeling strategy allows including two important features to the individual LC stages representing the EBG surface: coupling to the signal line, and transverse loading of adjacent patches in the EBG structure. The circuit model parameters are calculated by using closed-form relations and applying the physical dimensions of the structure-under-test. The proposed model is employed to generate the scattering-parameter graphs and eye diagrams, which are compared with full-wave simulations and measurements to ensure validation of the results in both frequency and time domains.