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A novel, zero-voltage switched (ZVS) PWM boost converter that combines soft-switching with constant frequency operation is proposed in this paper. This converter can be operated with PWM control at a fixed frequency because ZVS operation is achieved with a simple auxiliary resonant circuit that is activated for only a small fraction of the switching period and handles much less power than the main power circuit. In the paper, the modes of operation of the converter are explained and analyzed, and a set of design guidelines is developed. The feasibility of the converter is shown with results obtained from an experimental prototype. >

This paper presents a zero-voltage-transition (ZVT) boost converter using a soft switching auxiliary circuit. The improvement over existing topologies lies in the structure and position of the auxiliary circuit capacitors and the subsequent reduction in the main switch resonant current. This converter has the following features: (1) soft switching of the main switch and boost diode under all operating conditions; (2) reduced auxiliary circuit losses due to soft switching of the auxiliary switch; (3) feedforward of a part of the auxiliary circuit energy to the output. The operation of this converter is analyzed and characteristic curves are presented, which help in the design process. Experimental results from a 250 W, 127 Volt input laboratory prototype switching at 100 kHz are shown which verify the advantages of this topology.

This paper presents a full bridge AC-AC inverter for high frequency power distribution system with power factor correction stage controlled by a unified controller. The proposed inverter has the following features: (1) load independent output voltage with constant frequency and very low total harmonic distortion; (2) soft switching of the full bridge switches for a wide range of input voltage and load conditions; (3) simple control and cost effectiveness for the power factor correction stage; (4) minimum DC bus voltage in the worst case. Operating principles and performance characteristics are presented, and guidance to design the converter is given. Experimental results of a 90-265 V/sub AC/ input, 30 V/sub AC/ output at 100 kHz, 250 W prototype are given to verify the thoretical analysis and computer simulations.

This paper presents an AC-AC inverter for a high frequency power distribution architecture. The inverter includes a high frequency resonant inverter and a buck-boost power factor correction stage. A unified controller controls both the resonant inverter and power factor correction stages. Unlike other single stage power factor corrected inverter topologies, the proposed inverter system has reduced DC bus voltage stress for the universal input line voltage. The proposed inverter is found attractive in low power applications.

This paper presents two approaches for power factor corrected (PFC), low frequency to high frequency power supplies for high frequency power distribution architecture. Boost and buck-boost topologies are applied to the PFC stage respectively. In both approaches, a unified controller controls the PFC stage and the inversion stage. Performance characteristics of the two approaches are presented and a detailed comparison is given. Laboratory prototypes are also built to support the comparison.

This paper presents a modulation method for single phase online three-leg uninterruptible power supplies. The proposed modulation method brings the flexibility of the well-known space vector modulation for the single-phase UPS considered and it can be easily implemented in digital controllers. Three switching sequences are presented and evaluated in terms of total harmonic distortion and the location of the harmonics in the frequency spectrum of the input current and output voltage. It is found out that first switching sequence would require simpler soft switching auxiliary circuit since one of the converter's legs is commutated at low frequency. The second switching sequence is the best suited for hard switched implementation since it has the smallest switching losses, and third switching sequence has moderate switching losses while producing harmonics in well defined frequency for all operating conditions. Experiments of a DSP controlled 1 kW UPS are presented to validate the proposed method.

This paper presents a new modulation method for single phase on-line three-leg uninterruptible power supplies. The proposed modulation method brings the flexibility of the well-known space vector modulation for the single-phase UPS considered and it can be easily implemented in a digital controller. Three switching sequences are presented and evaluated in terms of total harmonic distortion and the location of the harmonics in the frequency spectrum of the input current and output voltage. Simulation and experimental results have been presented to demonstrate the feasibility of the proposed modulation method. A performance indicative is obtained by the comparison of distortion factors of the input current and output voltage and switching losses to each switching sequence. It is found out that first switching sequence would require simpler soft switching auxiliary circuit since one of the converter legs is commutated at low frequency. The second switching sequence is the best suited for hard switched implementation since it has the smallest switching losses. Finally, the third switching sequence has moderate switching losses while producing harmonics in well defined frequency for all operating conditions. Experimental results using the DSP controller TMS320F243 are presented to validate the proposed method.

This paper deals with analysis of a new topology for an interleaved converter with application to telecommunication systems, typically 3-phase, 220 V ac input and 10 kW and 48 V DC output. The interleaved converter consists of two unidirectional four-leg semi-converters with four active switches in each of the semi-converters. A fourth wire (an artificial neutral point) is formed up locally using an L-C network to eliminate the need of a neutral conductor and this also prevents the flow of triplen harmonics through the phase wires. The fourth leg of each of the semi-converters is connected to this artificial neutral conductor. The interleaved converter has several advantages including shoot through free leg structure, a reduced number of active switches, reduced cost, increased reliability, improved performance and the elimination of triplen and even harmonics. The typical steady state and transient performance results confirm the feasibility of the structure.

The zero-voltage switched (ZVS) pulsewidth modulated (PWM) full-bridge (FB) converter is widely used in industry because it can operate with soft-switching and fixed frequency control. This converter, however, loses its ZVS capability under light load conditions, and some auxiliary circuitry is usually added to extend its ZVS range. This paper examines several auxiliary circuits, explaining how they operate, and comparing their respective advantages and disadvantages. Guidelines for the selection of auxiliary circuits for various operating conditions are given.

This paper deals with a detailed analysis of a unidirectional interleaved power converter for telecommunication systems typically with 3-phase, 220 V AC input and 10 kVA and 48 V DC output. To simplify the control system and to minimize the number of active switches used in the standard three-phase-three-pole and three-phase-four-pole topologies of PWM converter a new topology with 4 active switches is introduced. Along with the proposed topology some other available topologies with a reduced number of active switches are given. To improve the performance of the proposed topology and to eliminate the content of even harmonics in the supply current /spl pi//2 symmetry is introduced by interleaving basic units of a four switch converter. The interleaved converter consists of two diametrically opposite four-leg semi-converters. To eliminate the need of neutral conductor and to prevent the flow of triplen harmonics through the phase wires, a fourth wire (an artificial neutral point) is formed up locally using an R-L network. The fourth leg of each of the semi-converters is connected to this artificial neutral conductor. The interleaved converter has reduced cost, increased reliability, shoot though fault free legs and it is free from the problems of triplen and even harmonics. The proposed converter is tested for different steady state and transient operating conditions of the load.

Although considerable research has been done on the use of synchronous rectification in PWM converters as a means of reducing conduction losses, relatively little research has been done on its use in resonant converters. This is in spite of the fact that resonant converters have several advantages over PWM converters such as lower switching losses and EMI. In the paper, the implementation of synchronous rectification in a PWM controlled, series-resonant converter with a capacitive output filter is investigated. The operation of the converter is discussed, and issues concerning the use of synchronous rectifiers in this particular converter are examined. The feasibility of using synchronous rectifiers is verified by computer simulation.

A precisely regulated multiple output forward converter topology is presented in this paper. In this topology, each output voltage is directly and independently regulated by its own feedback control circuit that controls the appropriate synchronous rectifiers in the pertinent output stage, while the main switch is feedforward controlled. Thus, there is no cross regulation between the outputs, and design of each output becomes straightforward. Steady state analysis is performed to understand the topology and to provide design guidance. A prototype circuit with two outputs is built, and experiment are carried out on this prototype and the results verify the concepts and design.

The current sense schemes for zero-voltage switching, phase-shift bridge power converter are discussed. A new current sense scheme is proposed that can reliably and accurately sense the output inductor current and at the same time prevent the power transformer and current sense transformer from saturating in both steady state and transient conditions. The operation of the circuit is discussed. Computer simulation and experimental results are presented to confirm the analysis.

Although the zero-voltage switched (ZVS) pulsewidth modulated (PWM) full-bridge (FB) converter can operate with soft-switching and fixed frequency control it loses its ZVS capability under light-load conditions. This paper examines the use of auxiliary circuits attached to the bottom switches of the standard ZVS-PWM-FB converter as a means of extending the ZVS range. The auxiliary circuits, each consisting of an active switch and passive components, operate for only a small portion of the switching cycle, and handle very little power. The basic operating principles of these type of modified ZVS-PWM-FB converters are explained in detail in the paper, and general guidelines for their design are given. A design procedure is derived and demonstrated on an example converter. The feasibility of this converter is shown with results obtained from an experimental prototype.

This paper deals with the analysis of three-phase PWM voltage source rectifiers with reduced number of active switches. The main contribution of this paper is to simplify the control system and to minimize the number of active switches used in the standard three-phase-three-pole and three-phase-four-pole topologies of a PWM rectifier. The popular topologies with reduced number of switches are given. A new topology of three-phase-four-pole PWM voltage source rectifier is proposed. The proposed topology uses only four active switches (IGBTs). The new rectifier topology is analyzed and its performance is compared with a standard topology of the PWM rectifier. To improve the performance of the proposed new topology and to minimize the content of even harmonics in the supply current /spl pi//2 symmetry is introduced in its carrier based PWM current controller (used for generation of switching signals). The new rectifier topology is tested for different steady state and transient operating conditions of the load to establish performance and design criteria. Key results are given.

This paper deals with a comparative evaluation of AC-DC power supplies with 220 V, three-phase AC input and 48 V DC output in 10 kVA power range. These are widely used AC-DC converters in many applications, particularly telecommunication systems. These converters can be categorized into three groups, first topologies based on single-phase switched mode rectifier and PWM semi-boost rectifier, second, topologies based on PWM current source rectifier and third, topologies based on PWM voltage source rectifier. Comparative evaluation includes number of active and passive components, number of control loops and complexity of control system, number of sensors, requirement of output stage isolation and performance of all the converters at input/output ports. Standard software for simulation for power electronics circuits provides steady state and transient performance of these converters. The size of all the active and passive components is set to meet the standard criteria for performance. The experimental verification of simulated results is carried out.

This paper presents a Zero-Voltage-Transition (ZVT) boost converter using a soft switching auxiliary circuit. This converter has the following features: (1) soft switching of the main switch and boost diode under all operating conditions; (2) reduced auxiliary circuit losses due to soft switching of the auxiliary switch; (3) feed-forward of a part of the auxiliary circuit energy to the output thereby reducing the conduction losses of the main and auxiliary switches. The principle of operation and design of the proposed converter is given in the paper. Experimental results, from a 250 W, 127 Volt input laboratory prototype switching at 100 kHz, are given to verify 'proof-of-concept' of the proposed topology.

A simple PWM full-bridge converter that integrates input power factor correction (PFC) with DC-DC conversion is examined in the paper. The converter's operation is analyzed, and the results of the analysis are used to determine its steady-state characteristics. A design procedure for the selection of components is derived and demonstrated with an example. The feasibility of the converter and its ability to satisfy the IEC 1000-3-2 Class D requirements for electrical equipment are shown with results obtained from an experimental prototype.

Four distinct high frequency transformer uninterruptible power supplies for powering fiber-coaxial networks topologies are presented and compared in this paper. All the considered UPS topologies have isolation between the input, the output and the battery, therefore, providing safety and flexibility in the selection of the battery voltage and grounding. It has been found that the series-parallel resonant based UPS with capacitive output filter is a strong candidate since it requires just one isolation transformer and it presents high efficiency in both the line operating mode and backup mode.

A high frequency ac power distribution systems for the drop segment of a hybrid fiber/coax architecture is presented. It is shown in the paper that the high frequency distribution system provides self current limiting against a short circuit fault and no voltage glitch across the other converters. A prototype system which distributes 30 Vrms at 128 kHz over coax cable is built and experimental results are given which support the high frequency distribution as an attractive and viable option.

The quality of air of Bhopal city is assessed for common pollutants present in the air. These pollutants causes harmful effects on the environment as well as human beings. Ambient air monitoring is carried out at various places to control the strategy for increasing pollution of Bhopal. The analytical work is carried out on calorimeter. High volume air sampler was used for air monitoring studies.

This paper presents a comparative performance of resonant, soft-switched and hard-switched single phase power factor corrected rectifier circuits for telecommunication power supply applications. Three practical rectifiers employing a boost pre-regulator and a resonant, soft-switched and hard-switched DC/DC power converter topologies respectively are built in the laboratory for the same set of requirements. It is shown that the resonant rectifier has higher efficiency than other two rectifiers. All the three rectifiers with forced air cooling are found to have the same size. >

This study introduces a technique that combines passive and active electromagnetic interference (EMI) filtering methods to attenuate the common mode conducted noise in the input bus of the DC/DC converter and to minimise the size and the cost of the existing passive EMI filters. The technique presented can be implemented in all DC/DC converters topologies to provide a level of compliance with the electromagnetic directives. The circuit analysis and the attenuation curves showing the performance and the viability of this technique is provided. The filter input/output impedance criterion is verified to ensure the stability of the converter, by measuring the gain and the phase margins of the open-loop frequency response of the converter. The proposed technique provides a valuable design solution for compliance engineers where the Printed Circuit Board real-estate is an issue. Experimental results reveal more than 30 dB attenuation across the electromagnetic compatibility spectrum. This method contributes to the reduction of the size and weight of the input passive EMI filter. The proportion of the passive filter as compared to the DC/DC converter device can vary from 5 to 3%, depending on the converter specifications. Experimental results to demonstrate the performance and the effectiveness of the input active EMI filter in DC/DC converters are presented.

The authors present a generalized model and analysis of the fixed frequency phase-shift modulated DC/DC resonant power converter with a tuned parallel resonant circuit on the tertiary winding of the high-frequency transformer. A harmonic equivalent circuit model and frequency-domain analysis, which incorporate the effect of the leakage inductance of the high-frequency transformer, are used to develop generalized equations. Steady-state characteristics curves are presented to describe the effect of the leakage inductance and resonant circuit parameters on the performance of the converter. It is shown that, with a tuned parallel resonant circuit on the tertiary winding, the converter can be operated at higher frequency with efficiency higher than 80%. This resonant convertor also provides greater flexibility in selecting the resonant capacitor and an opportunity to integrate the series and parallel inductors with the output transformer. The tuned parallel resonant branch also results in low total harmonic distortion and improved regulation of the converter output voltage. >

Realisation of a digital control system, which implements a complete state feedback control strategy for the voltage-source inverter-fed induction motor (IM) drive, is reported. The controller design is based on the application of the linear quadratic regulator (LQR) theory to a linearised state-space model for the machine in the synchronous frame. The control objective is to achieve rotor speed control and orientation of the stator flux vector at constant magnitude by adjusting the stator voltage and frequency. To overcome the detrimental effects of inevitable modelling errors and disturbances, the structure of the feedback controller used here resembles that of the classical proportional-integral controller but is more versatile. The control system design considers the inverter's output limits and proposes an anti-windup scheme to avoid instability risk under integral windup. A supplementary feedforward control loop is provided to enhance transient response of the controlled drive by utilising few future values of the speed reference and load torque signals in advance. The hardware implementation of a controller is discussed and experimental tests are presented, along with computer simulation results, to verify the validity of the method.

A description and analysis of a clamped series inverter are presented. A generalized Fourier series method is developed to describe the steady-state behavior of the inverter in both discontinuous and continuous modes of operation. A transient analysis is also presented to describe its behaviour in both modes. The maximum flux requirement of the matching transformer is determined, and a starting method for the inverter is presented in order to obtain the reduced flux level of the transformer. The performance curves of the inverter under a wide range of operating conditions are presented. All the theoretical results obtained have been experimentally verified. >

A hybrid resonant inverter system is presented that satisfies the steady-state operating requirements of a power source for the proposed International Space Station mobile servicing system. The steady-state behavior of the inverter was analyzed and a method is described for optimizing the design of the resonant network. The performance characteristics such as the total harmonic distortion of the output voltage, RMS output voltage, and the inverter efficiency are presented. The hybrid resonant inverter system maintains an excellent efficiency over varying output-load demand. >

Presents the design of a clamped series inverter for induction heating. Possible faults in the inverter system are investigated, and it is shown how the inverter system can be designed to be self-protecting against these faults. A design criterion to select the inverter input filter is given. The requirements of the logic circuit are discussed, and a control philosophy is presented to meet the requirements. A design procedure is illustrated to select the system components for a 100 kW static power supply for induction heating applications.

The voltage-source series inverter with a transformer-coupled high-Q induction heating load is found to have latching and commutation problems at starting due to insufficient output current. This is because a high-Q load requires a number of cycles before sufficient energy, and therefore current is built up in the series load. A novel starting inverter is presented which establishes sufficient current in the load at starting. The operation of the inverter is described, and the modes of operation are identified. The behavior of the inverter in each mode is analyzed, and an optimum mode is selected which results in the minimum rating of the starting inverter. The selection and the rating of the components to design the starting inverter are presented. A prototype inverter system has been built and all theoretical results have been verified experimentally. >

The voltage source series inverter with a transformer-coupled induction heating load suffers from either latching or commutation failure when starting under certain load conditions. The load conditions that cause starting failure are determined. The commutating and latching current capabilities of the inverter are obtained by a transient analysis of the invertor for the first half cycle. The requirements for successful operation of the inverter are discussed, and the regions for successful and unsuccessful commutation and latching of the inverter are given. >

This paper determines the transient flux level of a matching transformer in a series resonant inverter. At starting, the transformer will saturate if it is not designed corresponding to the transient flux level. The saturation of the transformer will short circuit the output of the inverter and will result in the failure of inverter operation. A transient analysis of the inverter is, therefore, presented to obtain the transient flux level of the transformer. All the theoretical results obtained have been verified experimentally.

The authors present solutions to startup problems of a voltage-source series inverter with a transformer-coupled induction heating load. Two new inverter configurations are introduced, and their operating characteristics and design criteria described. The type-A inverter uses an auxiliary starting inverter to latch and commutate the switches of the main inverter and is suitable for any load-Q/sub 0/. The type-B inverter has a simple circuit configuration and a self-starting capability; however, it is only suitable for Q/sub 0/ >

Substituted/unsubstituted-(2,8-bis-trifluoromethyl-quinolin-4-yloxy)-acetic acid derivatives of cephalosporin have been synthesized by condensation of acid chlorides of substituted/unsubstituted - (2,8-bis-trifluoromethyl-quinolin-4-yloxy)-acetic acid with various silylated (6R,7R)-7-amino-3-substituted cephalosporanic acids. The products have been tested for their antibacterial activity.

A novel auxiliary circuit to guarantee zero-voltage switching (ZVS) of full bridge converters is presented. A generalized time-domain analysis for steady-state behavior of the auxiliary circuit and a complete comparison with a single-inductor auxiliary are provided. For the same auxiliary peak current, a minimum of 20 percent less rms current is achieved to minimize conduction losses. Also in presence of adaptive peak current adjustment via switching frequency variation scheme 65 percent reduction in frequency variation range is obtained, reducing the need for a wide range of switching frequencies and extra gate driver losses. The theoretical results are experimentally verified.

This paper addresses the source localization problem of an acoustic fish-tag using the Time-of-Arrival measurement of an acoustic signal, transmitted by the fish-tag. The Time-of-Arrival measurements denote the pseudo-range information between the acoustic receiver and the fish-tag, except that the Time-of-Transmission of the acoustic signal is unknown. Starting with the pseudo-range measurement equation, a globally valid quasi-linear time-varying measurement model is presented that is independent of the Time-of-Transmission of the acoustic signal. Using this measurement model, an Uniformly Globally Asymptotically Stable (UGAS), three stage estimation strategy (eXogenous Kalman Filter) is designed to estimate the position of an acoustic fish-tag and evaluated against a benchmark Extended Kalman Filter based estimator. The efficacy of the developed estimation method is demonstrated experimentally, in presence of intermittent observations using an array of receivers mounted on three Unmanned Surface Vessels (USVs). © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.