Simple Three-Input Single-Output Current-Mode Universal Filter Using Single VDCC

This paper presents a second-order current-mode filter with three-inputs and single-output current using single voltage differencing current conveyors (VDCC) along with one resistor and two grounded capacitors. The design of presented filter emphasizes on the use of a single active element without the multiple terminals VDCC which is convenient to implement the VDCC using commercially available IC for the practical test. Also, it can reduce the current tracking error at current output port and can reduce the number of transistor in the VDCC. The proposed filter can realize all the five generic filter responses, namely, band-pass (BP), band-reject (BR), low-pass (LP), high-pass (HP), and all-pass (AP) functions from the same configuration under various conditions in terms of three input current signals. Furthermore, the natural frequency and quality factor are electronically controlled. The output current node exhibits high impedance. Besides, the non-ideal case is also investigated. The simulation and experimental results using VDCC constructed from commercially available IC can validate the theoretical analyses

Simulation and Analysis of Variable Gain DVCC Based Active Inductance and its Application in Constant K Prototype and Resonance Filter

The inductor is an essential component in many electronic systems. But the passive inductance is not suitable due to its dimension and magnetic interference. To overcome these issues, active inductance is preferred. Active inductance is simulated using the RC network connected with an active device(s). Here, VG-DVCC (Variable Gain Differential Voltage Current Conveyor) is proposed as an active device. The VG-DVCC with two external R and one C component forms the Impedance Converter which converts Active RC network into Active Inductance. This paper gives an overview of the design-simulation of Active Inductance and the frequency range analysis of its linearity. Also, it highlights applications in the realization of constant k-prototype and resonance filters

Tunable Fractional-Order Capacitance Multiplier Using Current Gain Adjustment

This paper brings new solution of linearly adjustable fractional-order capacitance multiplier. The adjustable current gain, linear in wide range of input current and with linear dependence on driving voltage, serves for these purposes and offers one-decade variation of equivalent capacity (pseudo-capacitance) between 24 and 429 F/sec^0.75 . The operational range was tested by PSpice simulations and by measurement using RC approximant of constant phase element of the order 0.25 in bandwidth from 20 Hz up to 1 MHz

Analog Implementation of Fractional-Order Elements and Their Applications

With advancements in the theory of fractional calculus and also with widespread engineering application of fractional-order systems, analog implementation of fractional-order integrators and differentiators have received considerable attention. This is due to the fact that this powerful mathematical tool allows us to describe and model a real-world phenomenon more accurately than via classical “integer” methods. Moreover, their additional degree of freedom allows researchers to design accurate and more robust systems that would be impractical or impossible to implement with conventional capacitors. Throughout this thesis, a wide range of problems associated with analog circuit design of fractional-order systems are covered: passive component optimization of resistive-capacitive and resistive-inductive type fractional-order elements, realization of active fractional-order capacitors (FOCs), analog implementation of fractional-order integrators, robust fractional-order proportional-integral control design, investigation of different materials for FOC fabrication having ultra-wide frequency band, low phase error, possible low- and high-frequency realization of fractional-order oscillators in analog domain, mathematical and experimental study of solid-state FOCs in series-, parallel- and interconnected circuit networks. Consequently, the proposed approaches in this thesis are important considerations in beyond the future studies of fractional dynamic systems

Design and Development of FPGA based Controllers for Photovoltaic Power System

In the recent years owing to increased energy consumption and consequent rise in crude oil price and global climatic change have motivated researchers to focus towards harnessing power from renewable energy resources such as photovoltaic (PV), fuel cell, biomass and wind energy systems. Among the different renewable resources, PV technology is one of the fastest growing technologies, because of abundance availability of solar irradiance and it has no adverse environmental impacts. But, the cost of PV energy is higher than the other conventional sources owing to its low PV conversion efficiency. Therefore, research opportunities lie in applying power electronics and control techniques for harvesting PV power at higher efficiencies for appropriate utilization. For simulation, analysis and control design of a PV power system, an accurate model of the PV cell is essential because PV cell is the basic bulding block of a PV power system. To maximise the power generation of a PV system it is necessary that the PV array should be operated at the maximum power point. A maximum power point tracker (MPPT) is required in the PV system to enable it to operate at the MPP. The output current-voltage (I-V) and power-voltage (P-V) characteristics of a PV vell are non-linear and hence its power fluctuates in accordance with the variation in solar irradiance and temperature. During the last decade, a lot of research has been directed to develop efficient MPPT schemes. But, research opportunities are still promising for designing new MPPT algorithms and to address their digital implementation issues. Further, there lies challenge to design MPPTs that can handle partial shading conditions. The thesis first proposes development of new MPPT algorithms and different pulse width modulated-voltage source inverter control strategies for a PV system. Firstly an integral sliding mode MPPT controller (ISMC) has been proposed for achieving an effective MPPT scheme, and then a modified P&O MPPT controller is developed which is implemented using a real-time digital simulator called Opal-RT. The performance of the modified ISMC is compared with that of the conventional proportional integral (PI) MPPT controller using both MATLAB simulation and real-time experimentation. The performance of the modified P&O MPPT controller with fixed step size is compared with that of the conventional incremental conductance (Inc Cond) and P&O MPPT controllers, and these are validated by using Opal-RT and subsequently through FPGA implementation. A modified incremental conductance MPPT controller with variable step size is then proposed for handling partial shading conditions. The tracking performance of the proposed modified Inc Cond MPPT controller is also compared with that of the conventional Inc Cond MPPT controller, from the obtained results by using Opal-RT. Further, an experimental prototype PV set-up is developed in the laboratory to implement the proposed MPPT algorithms on the physical hardware. After having developed efficient parameter extraction algorithms for a PV panel, the thesis subsequently proposes five new MPPT algorithms such as Integral sliding mode MPPT, modified P&O MPPT, modified Inc Cond MPPT, Model predictive MPPT, and modified Inc Cond variable step size MPPT controllers. All these developed MPPT algorithms have been implemented on a Solar array simulator (SAS) PV system, in MATLAB/SIMULINK, OPAL-RT and on a prototype hardware PV set-up. From the obtained results, it is found that these MPPTs adjust the power of a PV system effectively to its maximum power value smoothly with fast response and accuracy whilst reducing the fluctuations in its power. Tracking performance of all these proposed MPPT algorithms are found to be superior to some of the existing MPPTs such as perturb and observe (P&O), incremental conductance (INC), HCC and adaptive HCC. Further more, a PV system is observed to be stable with all these proposed MPPTs. From the results obtained it is also confirmed that the proposed modified P&O MPPT exhibits better MPP tracking performance in terms of quick settling time and least steady state error. Further, less voltage fluctuation and less maximum overshoot are observed in the case of the proposed modified Inc Cond MPPT among all the proposed MPPT algorithms. The proposed controllers are also well suited to all weather conditions. A grid connected PV system involves a power conversion from DC power into AC power. Due to high switching frequencies of this conversion by inverter, there is a power loss. An efficient control scheme needs to be developed for integrating the PV system to the grid. The thesis then proposes a Model Predictive Control (MPC) for integrating a PV system to the grid. The performance of the MPC is compared with conventional hysteresis current controller (HCC) and also with that of an adaptive HCC (AHCC) through a real-time simulatin using the Opal-RT then through FPGA implementations. FPGA implementation of the controllers such as HCC, AHCC and MPC were also performed by using LABVIEW configured with NI-cRIO-9014 platform. For elimination of current harmonic and reactive power of the grid connected PV system, there is a need of designing a filter. The PV system based shunt active power filter (SAPF) with modified incremental conductance MPPT controller with variable step size is then designed. From the MATLAB simulation and real-time digital simulation studies it is envisaged that the proposed PV based SAPF exhibits good harmonics compensation