A Digital Stochastic Gradient-Ascent Maximum Power-Point Tracking Technique for Photovoltaic Applications

Vol. 1 No. 2

Year: 2013

Issue: Apr-Jun

Title : A Digital Stochastic Gradient-Ascent Maximum Power-Point Tracking Technique for Photovoltaic Applications

Author Name : Yun Chiu

Synopsis :

A digital-domain gradient-ascent algorithm is presented to identify and maintain the peak power operating point of a photovoltaic (PV) source with variable I-V characteristics. The approach employs a low-level dither, realized by a one-bit, 64-sample pseudorandom noise (PN) sequence, to perturb the duty cycle of a boost converter that extracts energy from a PV source for battery charging. The digital-domain optimization process operates continuously in the background, and is robust against measurement noise, offset, jitter, and the inherent large-signal nonlinear dynamics of the boost converter. Acquiring a single sample in each switching cycle, i.e., no oversampling for the analog-to-digital converter (ADC), the digital processor consists of a few adders, flip-flops, and one multiplier, which, in conjunction with the ADC, can be integrated with the driver integrated circuit (IC) of the boost converter for very low cost. Simulation verifies the tracking effectiveness of the proposed technique, and demonstrates a stable operation in presence of large power-on and load transients, with an average output power of ≥ 98.5% of the peak value consistently achieved in steady state.

Flexible optical pulse generation for laser micromachining using FPGA board with integrated high-speed DAC

Vol. 1 No. 2

Year: 2013

Issue: Apr-Jun

Title : Flexible optical pulse generation for laser micromachining using FPGA board with integrated high-speed DAC

Author Name : Chu En Ong, Dr. Teh Peh Chiong , Yeap Kim Ho , Dr. Lee Sheng Chyan

Synopsis :

This paper describes the novel approach of using a custom Field Programmable Gate Array (FPGA) board to generate digital arbitrary waveforms which is subsequently converted into analog waveforms via a high speed Digital-to-Analog Converter (DAC) IC. The FPGA codes are designed and optimized to generate very fast rise/fall times waveforms with the flexibility to vary both the pulse duration and pulse frequency in real time through a microcontroller with serial interface. These custom defined waveforms are then used to generate high intensity laser pulses when connected to a 1064nm fiber laser source. These pulsed laser sources have potential industrial applications in precision laser micromachining, where the high thermal intensity of the laser pulses can be used to perform ablation, cutting, drilling or annealing of processed materials. By able to tailor the shape of the delivered laser pulses, this will lead to reduction in processing time, improves the efficiency of material removal and the quality of the end product. Our custom board can generate arbitrary tailored pulses as short as 10ns and the longest pulse is 150ns. The pulse repetition rate can be tuned from 100kHz to 10MHz.

Autonomous Self Healing Of Reconfigurable Circuits

Vol. 1 No. 2

Year: 2013

Issue: Apr-Jun

Title : Autonomous Self Healing Of Reconfigurable Circuits

Author Name : B HARI KRISHNA, Dr.S.Ravi

Synopsis :

This paper presents an analysis of the fault tolerance achieved by an autonomous evolvable system. By using this method the system may self recover from both transient and cumulative faults. In this paper we present a new technique NSCLB for reconfiguring FPGA circuits. An example of 24 CLBs is tested and results show that it may properly recover more number of faults. The faulty CLB is replaced both structurally and functionally. By selecting the nearest spare the routing path is decreased. The method is implemented using VHDL language in Xilinx10.1 version.

Daubechies, Coiflet, Symlet and Biorthogonal Wavelet Transforms for Effectual Image Compression and Analysis of Fidelity Measures

Vol. 1 No. 2

Year: 2013

Issue: Apr-Jun

Title : Daubechies, Coiflet, Symlet and Biorthogonal Wavelet Transforms for Effectual Image Compression and Analysis of Fidelity Measures

Author Name : siripurapu sridhar, P. Rajesh Kumar , K.V.Ramanaiah

Synopsis :

Wavelet transforms are set of mathematical functions that represent image as a sum of wavelet functions with different locations and scales. Wavelet transformations provide information in both frequency domain and spatial domain as well, standard de-facto images of varying sizes are subjected to two level decomposition using wavelet filter functions like Haar, Daubechies, Biorthogonal, Coiflets and Symlets etc. The transformed approximation and detail coefficients, typically infinite precision real numbers are then quantized such that the more important coefficients are represented with higher accuracy while those with less accuracy are neglected. In quantization input values are mapped to output values, based on particular threshold levels. The quantized coefficients are further coded in a bit stream using recursive splitting Huffman encoding. This study evaluates and compares the merits of selected Wavelet transform techniques for different filter functions graphically to discuss important features of wavelets in image compression. Objective fidelity metrics Peak Signal to Noise Ratio (PSNR), Mean Square Error (MSE) and Compression Ratio (CR) obtained are shown graphically.

Cost Effective, Error Prone and Time Consuming Solution for Digital Energy Meter by using Wireless Prepaid Billing

Vol. 1 No. 2

Year: 2013

Issue: Apr-Jun

Title : Cost Effective, Error Prone and Time Consuming Solution for Digital Energy Meter by using Wireless Prepaid Billing

Author Name : Sheikh Rafik Manihar Ahmed

Synopsis :

The present system of energy billing is error prone and also time and labor consuming. Errors get introduced at every stage of energy billing like errors with electro-mechanical meters, human errors while noting down the meter reading, and errors while processing the paid bills and the due bills. There are many cases where the bill is paid and then is shown as a due amount in the next bill. There is no proper way to know the consumer’s maximum demand, and usage details. The major drawback of a post paid system is that there is no control of usage from the consumer’s side. There is a lot of wastage of power due to the consumer’s lack of planning of electrical consumption in an efficient way. Since the supply of power is limited, as a responsible citizen, there is a need to utilize electricity in a better and efficient way. The distribution company has to receive huge amounts in the form of pending bills, which results in substantial revenue losses. The remedy for this drawback is prepaid energy meter means “pay first and then use”. A wireless billing system in which issue of energy in units (of several categories e.g. 50 units, 100 units and so on) is put for an option to the consumer. Once the consumer recharge its meter then normally they will be mindful of that quota of energy, and so they will consume it accordingly and economically as in the case of mobile. When the finish line is a certain units away, an alarm system will remind them of fresh recharging.

Closed-Loop Approach For Reducing Total Harmonic Distortion In A Flying Capacitor Multilevel Inverter

Vol. 1 No. 1

Year: 2013

 
Issue: Jan-Mar

Title : Closed-Loop Approach For Reducing Total Harmonic Distortion In A Flying Capacitor Multilevel Inverter

  

Author Name : S.SHANMUGA PRIYAN, K.RAMANI 

Synopsis :  

This paper concentrates on the closed loop control scheme, focusing on the reduction of total harmonic distortion (THD) in a proposed seven level flying capacitor multilevel inverter (FCMLI). Among the various multilevel inverter (MLI) topologies, FCMLI provides more advantages. The development of closed loop model for seven level FCMLI dramatically reduces the low-order harmonics and THD. Extensive simulation has been applied to compare the performance of the proposed system in closed loop control scheme with that of the open loop control scheme. In order to justify the merits of the proposed system, it is interfaced with the single phase lamp load and analysed through simulation investigations.

Fuzzy Flatness Based Control Of Three Phase Inverter Fed Induction Motor

Vol. 1 No. 1

Year: 2013

 
Issue: Jan-Mar

Title : Fuzzy Flatness Based Control Of Three Phase Inverter Fed Induction Motor 

Author Name : SASIKUMAR C, C. Muniraj 

Synopsis :  

Induction motor plays a vital role in engineering and industry. Induction motor offer a convenient means for controlling the operation of different equipment used in industry. Induction motor input supply will give from the voltage source inverter for its speed control purpose. If we connect induction motor directly to the AC supply its speed control will not applicable, so that we go inverter fed induction motor speed control. Vector control can controls the independent control of flux and torque in the induction motor. By adjusting gate pulse through vector control for vary speed of induction motor. fuzzy flatness based control is applied in the speed controller of induction motor. This method gives better efficiency of induction motor speed control. Fuzzy flatness controller method for induction motor gives better performance and reduces tracking error and reduces the torque ripple.

Comparison of Various Variable Amplitude Carrier Overlapping PWM Methods for Three Phase Five Level Cascaded Inverter

Vol. 1 No. 1

Year: 2013

 
Issue: Jan-Mar

Title : Comparison of Various Variable Amplitude Carrier Overlapping PWM Methods for Three Phase Five Level Cascaded Inverter

  

Author Name : R. Revathy, C.R.Balamurugan , S.P.Natarajan

  

Synopsis :  

This paper presents the comparison of various Carrier Overlapping Pulse Width Modulation (COPWM) Strategies for the three phase Cascaded Multi Level Inverter (CMLI). Various new schemes adopting the constant switching frequency and also variable switching frequency multicarrier control freedom degree combination concepts are developed and simulated for the chosen three phase CMLI. A three phase CMLI is controlled in this paper with Sinusoidal PWM (SPWM) reference along with Carrier Overlapping (CO) techniques and simulation is performed using MATLAB-SIMULINK. The variation of fundamental RMS output voltage and total harmonic distortion is observed for various carrier overlapping techniques. Among the various equal amplitude carrier overlapping techniques such as COPDPWM, COPODPWM, COAPODPWM, COVFPWM and COPWM-D, it is observed that COAPOD provides less total harmonic distortion (THD) and COPWM-D provides higher RMS voltage. Among the various variable amplitude carrier overlapping techniques, such as VACOPDPWM, VACOPODPWM, VACOAPODPWM, VACOVFPWM and VACOPWM-D, it is recognised that VACOAPOD provides less THD and VACOPOD provides higher RMS voltage. By comparing the equal amplitude carrier overlapping techniques with the variable amplitude carrier overlapping techniques, it is observed that VACOVFPWM provides higher fundamental RMS output voltage with relatively low distortion.

Studies on Triangular Reference with Carrier Overlapping Pulse Width Modulation Methods for Diode Clamped Five Level Inverter

Vol. 1 No. 1

Year: 2013

 
Issue: Jan-Mar

Title : Studies on Triangular Reference with Carrier Overlapping Pulse Width Modulation Methods for Diode Clamped Five Level Inverter

  

Author Name : S.Sumathi, D.Meena , C.R.Balamurugan , S.P.Natarajan

Synopsis :  

This paper presents the comparison of Variable Amplitude Pulse Width Modulation COPWM techniques for the three phase Diode Clamped Multi Level Inverter (DCMLI). A three phase DCMLI is controlled in this paper with Triangular PWM (TPWM) reference for Carrier Overlapping (CO) techniques. The variation of Total Harmonic Distortion (THD) in the inverter output voltage is observed for various modulation indices. Simulation is performed using MATLAB-SIMULINK. By comparing the various carriers overlapping technique such as COPWM-A, COPWM-B, COPWM-C and COPWM-D, it is observed that COPWM-C provide an output with relatively low distortion and COPWM-A and COPWM-D provides relatively higher fundamental RMS output voltage. By comparing the various variable amplitude carriers overlapping technique such as VACOPWM-A, VACOPWM-B, VACOPWM-C and VACOPWM-D, it is observed that VACOPWM-C provide a output with relatively low distortion and VACOPWM-D provides relatively higher fundamental RMS output voltage. Finally by comparison between the various COPWM  and variable amplitude carrier overlapping technique, it is observed that VACOPWM-C provide an output with relatively low distortion and VACOPWM-D provides relatively higher fundamental RMS output voltage.