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IEEE 2016 POWER ELECTRONICS ABSTRACT A ZV-ZCS ELECTROLYTIC CAPACITOR LESSAC/DC ISOLATED LED DRIVER WITH CONTINOUS ENERGY REGULATION ABSTRACT: Light Emitting Diode (LED) lighting becomes the most environmental friendly and popular light source due to its superior features: 1) Long life time up to 100, 000 hours of operation. 2) Low wattage light source with high luminous efficacy. 3) It can emit different kind of colors depending on the kind of semiconductor material. Based on the ENERGY STAR requirements for solid-state lighting, the luminaires power factor should be greater than 0.9 for commercial usage and 0.7 for residential usage. Power supplies that utilize switch-mode operation are essentially nonlinear loads, which cause harmonics and distortion to the input current. A phase shift between the line current and voltage can also be resulted due to the reactive component in the circuit. LED drivers are classified into passive and switched mode driver. The passive type uses only passive circuit components, which suffers from heavy weight, bulky size and poor efficiency. Switched mode drivers, on the other hand, are widely used currently due to the fact that the passive components can be significantly reduced by increasing the switching frequency of the driver. EXISTING SYSTEM: Conventional AC/DC LED drivers require a large energy storage capacitor at the output to provide a constant current to the LEDs. LED drivers are classified into passive and switched mode driver. The passive type uses only passive circuit components, which suffers from heavy weight, bulky size and poor efficiency. Switched mode drivers, on the other hand, are widely used currently due to the fact that the passive components can be significantly reduced by increasing the switching frequency of the driver. Switched mode driver can be classified into: (1) single stage, (2) two stage circuit. By employing the two-stage solution, a high power factor LED driver with precisely regulated output current and the possibility of eliminating the electrolytic capacitor can be resulted. However, increasing the number of power processing stages means that more components are required in the overall circuit, which will result in a large size and high cost system. Another drawback with the existing LED drivers is the presence of the switching power losses. In order to design a compact and small size LED driver, the switching power losses should be minimized. PROPOSED SYSTEM: AC/DC LED driver requires power factor correction (PFC) circuit to comply with the ENERGY STAR power factor requirements. The driver shall also consist of a DC current regulator to provide constant DC output current. The proposed circuit is a single stage power conversion unit that integrates the discontinuous conduction mode (DCM) boost converter as a power factor correction (PFC) circuit, and the asymmetrical pulse width modulated (APWM) series resonant converter as DC output regulation as shown Figure. The APWM series resonant converter was used to achieve soft switching operation so that high frequency switching operation can be realized without affecting the driver efficiency. By operating the proposed driver circuit at high switching frequency, the reactive components size and cost can be substantially reduced. ADVANTAGES: • Very high power efficiency using energy regulation across the DC-link capacitor • The reactive components size and cost can be substantially reduced. APPLICATIONS: • Illumination applications • Mobile products and backlighting of lcd panels
VLSI PROJECTS ABSTRACT 2016 -2017 LOW-POWER SYSTEMS FOR DETECTION OF SYMPTOMATIC PATTERNS IN AUDIO BIOLOGICAL SIGNALS ABSTRACT: In this paper, we present a low-power, efficacious, and scalable system for the detection of symptomatic patterns in biological audio signals. The digital audio recordings of various symptoms, such as cough, sneeze, and so on, are spectrally analyzed using a discrete wavelet transform. Subsequently, we use simple mathematical metrics, such as energy, quasi-average, and coastline parameter for various wavelet coefficients of interest depending on the type of pattern to be detected. Furthermore, a mel-frequency cepstrum-based analysis is applied to distinguish between signals, such as cough and sneeze, which have a similar frequency response and, hence, occur in common wavelet coefficients. Algorithm-circuit codesign methodology is utilized in order to optimize the system at algorithm and circuit levels of design abstraction. This helps in implementing a low-power system as well as maintaining the efficacy of detection. The system is scalable in terms of user specificity as well as the type of signal to be analyzed for an audio symptomatic pattern. We utilize multiplierless implementation circuit strategies and the algorithmic modification of mel cepstrum computation to implement low power system in the 65-nm bulk Si technology. It is observed that the pattern detection system achieves about 90% correct classification of five types of audio health symptoms. We also scale the supply voltage due to lower frequency of operation and report a total power consumption of ~184 µW at 700 mV supply.
VLSI PROJECTS ABSTRACT 2016-2017 LOW-POWER SYSTEM FOR DETECTION OF SYMPTOMATIC PATTERNS IN AUDIO BIOLOGICAL SIGNALS ABSTRACT: In this paper, we present a low-power, efficacious, and scalable system for the detection of symptomatic patterns in biological audio signals. The digital audio recordings of various symptoms, such as cough, sneeze, and so on, are spectrally analyzed using a discrete wavelet transform. Subsequently, we use simple mathematical metrics, such as energy, quasi-average, and coastline parameter for various wavelet coefficients of interest depending on the type of pattern to be detected. Furthermore, a multi-frequency spectrum-based analysis is applied to distinguish between signals, such as cough and sneeze, which have a similar frequency response and, hence, occur in common wavelet coefficients. Algorithm-circuit codesign methodology is utilized in order to optimize the system at algorithm and circuit levels of design abstraction. This helps in implementing a low-power system as well as maintaining the efficacy of detection. The system is scalable in terms of user specificity as well as the type of signal to be analyzed for an audio symptomatic pattern. We utilize multiplierless implementation circuit strategies and the algorithmic modification of multi spectrum computation to implement low power system in the 65-nm bulk Si technology. It is observed that the pattern detection system achieves about 90% correct classification of five types of audio health symptoms. We also scale the supply voltage due to lower frequency of operation and report a total power consumption of ∼184 µW at 700 mV supply. The proposed architecture of this paper analysis the logic size, area and power consumption using Xilinx 14.2. EXISTING SYSTEM: In the past decade, rapid advancements in the development of low-power design methodologies have resulted in feasible designs for various wearable and implantable medical systems. Numerous wearable health monitoring systems have been proposed in order to deliver early warning of an impending health condition. These systems monitor various internal as well as external parameters related to the human health, such as temperature, heart rate, and so on. Apart from these parameters, it is well known that acoustic symptoms, such as cough, sneeze, belching, and so on, are early markers of serious health issues, such as influenza, diarrhea, and whooping cough, especially among children. If repetitive occurrence of these symptoms is detected in advance, it is possible for the patient or the healthcare personnel to commence remedial action prior to aggravation of the problem. In the literature, most of the developed systems detect a single acoustic symptom (cough or sneeze). The Kids Health Monitoring System (KiMS) proposed in uses wearable sensors and acoustic signal processing in order to provide health monitoring in children. Using the neural network-based processing, the KiMS classifies various symptoms and activities and, subsequently, transmits the record to a parent or doctor for further analysis. PROPOSED SYSTEM: We describe the proposed algorithm and the methodology used to modify the various computational tools in order to make it implementable into low-power hardware. In Section II, we had described the basics and justified the basis for selecting specific computational techniques used in developing this algorithm. The application of these computations is dependent on the characteristic property of the symptom to be detected. The algorithm methodology is shown in Fig. 1. We also describe the details along with the mapping of algorithm to specific signals as follows. ADVANTAGES: • efficient low-power health monitoring system DISADVANTAGES • High power for monitoring system. SOFTWARE IMPLEMENTATION: • Modelsim • Xilinx ISE
IEEE 2016 POWER ELECTRONICS ABSTRACT BIDIRECTIONAL RESONANT DC-DC STEP-UP CONVERTERS FOR DRIVING HIGH-VOLTAGE ACTUATORS IN MOBILE MICRO ROBORTS ABSTRACT: Autonomous micro robots will potentially provide unprecedented opportunities to access the unreachable spaces due to their high makeover ability and ultra compact size. Significant effort has been made toward fabricating micro robot mechanisms for both micro electromechanical systems (MEMS) and non-MEMS applications. Unlike conventional robots, which are mostly driven by electromagnetic motors and solenoids, micro robots are driven through various dielectric electro active polymer (EAP) actuation schemes, including electrostatic, piezoelectric, electrostrictive, and dielectric elastomeric actuators . Each type of actuation scheme has its unique advantages in terms of size, actuation strain, work density, power density, and efficiency. A common inherent characteristic of EAP actuators is their capacitive nature. Depending on the applied voltage across these actuators, their capacitance changes and they compress or expand. Such deformation of actuators is used to create mechanisms like movement of artificial legs or wings in micro robots. EXISTING SYSTEM: Conventional bulky power supplies and electronics used to drive EAP actuators are not practical as on-board energy sources for micro robots. Miniaturized and efficient power electronic interfaces (PEI) are of critical importance to enable autonomous operation of micro robots. One of the challenges of PEI design for such applications stems from the fact that most of the EAP actuators need to be excited with high voltage levels or efficient operation. However, the output voltage of suitable on-board energy sources including chemical battery cells, super-capacitors, fuel cells, and solar cells is generally less than 5 V. In fact, the typical driving voltage of the EAP actuators is at least an order of magnitude higher than 5 V. Therefore, a tiny PEI with high-step-up voltage gain is required to be interfaced between the energy source and the actuators to both step up the voltage and also satisfy the drive requirements of the actuator. Miniature power electronic converters suffer from low efficiencies particularly in light loads. In addition, due to the capacitive nature of the EAP actuators, majority of the transferred energy for excitation is unused and would be lost, if not retrieved [18]. Therefore, a bidirectional PEI could substantially enhance the actuator efficiency through recovering the unused energy during each cycle. Among prior research work on PEI topologies for driving high-voltage capacitive loads, researchers have studied utilizing a boost converter in series with a cascaded charge pump circuit. The large number of capacitor–diode stages makes it impractical for miniaturization and efficient energy. a single-stage ac–dc power electronic converter is proposed to efficiently manage the energy harvested from electromagnetic micro scale and mesoscale generators with low output voltage. The proposed topology combines a boost converter and a buck-boost converter to condition the positive and negative half cycles of the input ac voltage. Only one inductor and capacitor are used in both circuitries to reduce the size of the converter. PROPOSED SYSTEM: This project introduces a single-stage bidirectional resonant dc–dc converter to satisfy the drive requirements of capacitive actuators. It will potentially enable on-board power conversion due to its unique advantages in terms of milligram weight, high power density, and high efficiency. The proposed converter provides high-step-up voltage gain as well as energy recovery capability to meet the stringent driving requirement of EAP actuators, while enhancing the efficiency of the power conversion and actuator system. The resonant topology provides reasonably high efficiency from light load to full load, due to the elimination of switching losses. High-frequency operation (up to 1.5 MHz) of the converter allows miniaturization through using substantially smaller capacitive and inductive passive components. Furthermore, the topology has advantages such as reduced voltage stresses on power transistors. The work highlights the operation analyses, energy recovery control scheme, and capability of creating different driving strategies for EAP actuators. Although the prototype is specified in the work for driving electrostatic actuators, the topology concept can be adapted to other EAP actuators ADVANTAGES: • Milligram weight, • High power density • High efficiency from light load to full load, due to the elimination of switching losses : APPLICATIONS: • MicroElectroMechanical Systems (MEMS) and non-MEMS applications • Power electronic interface applications
IEEE 2016 POWER ELECTRONICS ABSTRACT LCL FILTER DESIGN FOR THREE-PHASE TWO-LEVEL POWER FACTOR CORRECTION USING LINE IMPEDANCE STABILIZATION NETWORK ABSTRACT: These days, three-phase grid-connected PWM voltage source converters (VSCs) like two-level or multilevel converters are widely used in many applications. Trying to improve the power quality and attenuating the current harmonics generated by these converters leads to different approaches such as filter design and harmonic elimination/mitigation methods. To attenuate the harmonic contents at high frequencies one possible solution is relying on the inductor of three-phase boost VSC as a filter. Nevertheless, this solution leads to a bulky inductor with high power inductor losses. Besides, the large inductance value degrades the performance of the controller. Employing high order filters such as LCL, LLCL filters to fulfil the grid regulations are highly attractive solution and have been studied in many researches EXISTING SYSTEM: The DC side of the rectifier consists of the DC capacitor and is connected to a load. Here, two LCL-filter configurations with different resonance frequencies are used. Choosing a higher filter capacitor yields to higher damping of the switching harmonics, but reduces the resonance frequency of the filter as it can be seen in the Bode diagram in Fig. 2.For the purpose of feedback the DC link voltage as well as the converter and line currents are measured. The line voltage is measured for synchronizing the control with the grid frequency. Here the space vector notation is used. The three-phase values are transformed into stationary reference frame and further, using the line voltage vector, into rotating dq coordinates in order to perform the voltage-oriented-control. From control point of view it is advantageous to control DC values since PI controllers can achieve reference tracking without steady state errors. As disadvantage the coordinate transformation leads to current dynamics coupling. PROPOSED SYSTEM: A method for designing an LCL filter for two-level PFCs using LISN. Using the equivalent circuit of the converter, the effect of LISN on measurement is studied. Filter parameters are, then, calculated by analyzing the equivalent circuit. In this paper, a passive damping method also is employed for improving the dynamic performance of the converter. Finally, a 5 kW three-phase PFC setup is used to verify the performance of the designed filter. The single-phase equivalent circuit not only simplifies designing the filter, but also helps to investigate the effect of LISN on circuit. To do that, the noise source must be defined. For an SPWM grid-connected VSC, using double Fourier analysis, the amplitude of ac link voltage at multiples of switching frequency (carrier frequency). ADVANTAGES: • Improved dynamic performance. • Low impedance network for the high frequency harmonics. APPLICATIONS: • High and low power applications. • Silicon-carbides (SiCs).
POWER ELECTRONICS ABSTRACT 2016-2017 A NEW SINGLE-SWITCH ISOLATED HIGH-GAIN HYBRID BOOSTING CONVERTER ABSTRACT: A new single-switch isolated Hybrid Boosting Converter (HBC) featuring low component stress, simple control, high efficiency, high power density and flexible gain extension is proposed in this paper. At the primary side, a new design of energy regenerative snubber is proposed to provide soft switching condition, suppress voltage spike and recycle leakage energy. At secondary side, a Bipolar Voltage Multiplier (BVM) structure which enhances the gain boosting capacity, reduces the output ripple and facilitates fly-back-forward operation of transformer is proposed. Based on this structure, the transformer can deliver energy to the output at both magnetizing and magnetic resetting stages. In addition, the bulky high voltage-rated output filter capacitor can be eliminated due to the cascaded and auto-balanced capacitors in BVM structure. A 200 W 35 V to 400 V prototype is built to demonstrate the feasibility of proposed topology. The peak efficiency of 93.8% is reached and 91.2% is achieved at rated power.
IEEE 2016 POWER ELECTRONICS ABSTRACT: DESIGN AND IMPLEMENTATION OF A HIGH EFFICIENCY MULTIPLE OUTPUT CHARGER BASED ON THE TIME DIVISION MULTIPLE CONTROL TECHNIQUE. ABSTRACT: One of the more promising applications of MOCs would be multiple battery chargers due to its advantages in terms of cost, volume, efficiency and space for installation. However, most of the conventional MOCs are not able to regulate all of the outputs accurately and independently without the help of complex hardware and controllers, which makes them unable to satisfy the strict ripple specifications of charge applications. In order to overcome the above mentioned disadvantages, several methods have been suggested. One method is to apply pre and post regulators to control the multiple outputs. However, accurate control in each slave output can barely be achieved since it is difficult to exactly match the magnetic coupling at each output. Furthermore, this makes it difficult to analyze the circuit. As a result, the design of the controller becomes difficult due to the complicated regulation between the outputs. EXISTING SYSTEMS: A controlled current source in the form of a fairly big inductor connected to each output through a switch on a time shared basis during one switching cycle. However, since it requires a large inductor as a current source, the converter becomes bulky and expensive. In addition, the method is extremely difficult to implement and complex in terms of small signal modeling on account of the differences in time sharing at each output during the freewheeling period of the inductor current. As a result, cross regulation problem is an inherent disadvantage of this method. PROPOSED SYSTEMS: The proposed converter can be used for the higher power applications since it has been developed based on the full bridge topology and exhibit a high efficiency. The proposed multiple battery charger is able to charge a number of batteries at different state of charges (SOCs) by using constant current and constant voltage (CC/CV) charge modes, which is considered to be an efficient method to charge batteries. Since the TDMC method can control each output independently, the battery at each output can be charged independently by either the CC mode or the CV mode. As a result, three batteries can be charged simultaneously. In addition, it is possible to satisfy the strict ripple specifications of the batteries since the cross regulation problem between the outputs does not exist. ADVANTAGES: • It offers an even degree of tight and independent regulation for each output, which is essential for multiple output charge applications. • It is simple in design and analysis, and easy to model the circuit. • No cross regulation problem exists among the outputs. • Only one secondary winding of the transformer is required to regulate the multiple outputs if no isolation between the outputs is required. • Zero voltage switching (ZVS) turn-on can be achieved at all primary switches during the entire charge process. • Zero current switching (ZCS) turn-on and ZVS turn-off can be achieved at all the secondary switches with no additional circuit. APPLICATIONS: • Switching mode power supplies (SMPSs) of personal computers. • Portable electronics. • Household equipment. • Multiple voltage power supplies. • Telecommunication systems.
IEEE 2016 POWER ELECTRONICS ABSTRACT A LOW-VOLUME HYBRID STEP-DOWN DC-DC CONVERTER BASED ON THE DUAL USE OF FLYING CAPACITOR ABSTRACT: In modern battery powered portable applications, such as laptops, tablet computers, smart phones etc., many dc-dc switch mode power supplies (SMPS) are utilized to provide multiple voltage levels for various functional blocks. One of the main challenges with the implementation of the conventional SMPS is their size. In numerous portable devices SMPS are among the largest contributors to the overall size and weight of the entire device and large consumers of printed circuit board (PCB) space. This is primarily due to the bulky and costly reactive components of the SMPS output filters, where the inductors are the largest and heaviest components of the filters. The ever increasing demand for lower volume dc-dc converters for battery powered portable electronics has primarily been met by switching at higher frequencies, up to tens of MHz, allowing smaller filter size. However, higher switching frequency comes with a penalty of increased switching losses negatively affecting the battery life. EXISTING SYSTEMS: A buck converter (step-down converter) is a DC-to-DC power converter which steps down voltage (while stepping up current) from its input (supply) to its output (load). It is a class of switched-mode power supply (SMPS) typically containing at least two semiconductors (a diode and a transistor, although modern buck converters frequently replace the diode with a second transistor used for synchronous rectification) and at least one energy storage element, a capacitor, inductor, or the two in combination. To reduce voltage ripple, filters made of capacitors (sometimes in combination with inductors) are normally added to such a converter's output (load-side filter) and input (supply-side filter). PROPOSED SYSTEMS: A wide-input hybrid dc-dc converter architecture for battery-powered applications that allows volume reduction of the reactive components and efficiency improvement is proposed. In this architecture, the first portion is identical to switched-capacitor voltage divider (SW1- 4, Cin1, Cin2, and Cfly). However, the second portion is a 2- input buck converter (SW5, 6, L, Cout) connected across flying capacitor, Cfly. In this topology the flying capacitor has dual use. It provides a mean for balancing of the capacitor divider, and at the same time reduces voltage stress/swing of the components to a ½ of Vin. ADVANTAGES: • Flying capacitor reduce the voltage stress/swing of the components. • Reducing the size of the filer inductor by 4 times and the output capacitor by 2 times. APPLICATIONS: • Switch mode power supplies (SMPS).
IEEE 2016 POWER ELECTRONICS ABSTRACT: HYBRID MODULATION SCHEME FOR A HIGH-FREQUENCY AC-LINK INVERTER ABSTRACT: Si-device-based high-power inverters usually operate at low switching frequencies owing to higher switching loss and thermal limitations of Si. Low switching frequency yields bulky and expensive magnetic and capacitive filter elements or complex topological structure (for a given device breakdown voltage) to attain higher commutation frequency for the same device switching frequency. If isolation is required, conventional transformer core materials also yield heavier, costlier and high-footprint space device. Recently, developed Si CMOSFETs (with 100–400X lower on resistance) and SiC Schottky diodes (with superior reverse recovery) with high thermal conductivity and thermal sustenance, and high permeability and efficient nano crystalline-core-based transformers overcome some of these limitations. EXISTING SYSTEM: The LLC resonant topology has become attractive due to its desirable characteristics such as high efficiency and natural zero voltage switching (ZVS)/zero current switching (ZCS) commutation. Therefore, a full- bridge LLC resonant converter is employed in the first stage to achieve high efficiency and track the maximum power point of each PV panel. For the three-phase dc/ac converter in the second stage, a variety of active soft-switching topologies have been proposed in last three decades. Most of them can be divided into three groups: auxiliary resonant commutated pole (ARCP) group , resonant dc-link inverter (RDCLI) group , and resonant ac-link converter (RACLC) , The ARCP can be applied broadly for the voltage-source type single -phase or three-phase inverters but it requires a large number of auxiliary components. Compared to the ARCP, the RDCLI has the advantages of fewer auxiliary switches and a simpler circuit. Several soft-switching topologies in were proposed to achieve the minimum number of extra components. However, the driving signals of the auxiliary switches are very sensitive to the noise from the main circuit. Since the RACLC can achieve voltage boosting and electrical isolation at the same time, it is highly preferred for renewable energy power generation. Unfortunately, the control circuit for the RACLC is complex and bidirectional switches are required. PROPOSED SYSTEM: Hybrid converters are conjugation of two types of converters that are based on two different types of devices: one that supports higher power and switches at slow frequency and the other operates at high frequency and supports lower harmonic power. The pulsating-dc/ac converter is a single converter. The term hybrid modulation scheme simply is chosen because at any given time, only one leg of the pulsating-dc/ac converter carries out forced switching while the switches in the other two legs do not change their switching states. This effectively yields a two-third reduction in the switching loss of the pulsating-dc/ac converter simply by modulation and without requiring any complex circuitry. ADVANTAGES: • Reduced switching losses. • Better efficiency. • Low total harmonic distortion (THD). APPLICATIONS: • renewable and alternative energy-based systems, • fuel cell and energy storage applications, • active filters, • traction drives
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