Battery Charge Applications Based on Wide Output Voltage Range

In this study, high efficiency design procedure of a phase shifted full bridge (PSFB) converter is presented for on-board electrical vehicle (EV) battery charger. Presented design methodology used lithium-ion battery cells because of their high voltage and current rates compared to a lead-acid battery cells. In this case, PSFB converter can be regulated wide range output voltage with while its soft switching operation is maintained. The basic operation principles of PSFB converter is defined and its soft switching operation requirements are given. To evaluate the performance of the converter over wide output voltage range, zero voltage switching (ZVS) operation of converter is discussed based on dead time requirement. To improve efficiency, the snubber inductance effects on soft switching over wide output voltage range are evaluated. Finally, operation of the PSFB converter is validated experimentally with a prototype which has 42-54 V/15 A output range at 200 kHz switching frequency

Soft-Switching DC-DC Converters

Power electronics converters are implemented with switching devices that turn on and off while power is being converted from one form to another. They operate with high switching frequencies to reduce the size of the converters\u27 inductors, transformers and capacitors. Such high switching frequency operation, however, increases the amount of power that is lost due to switching losses and thus reduces power converter efficiency. Switching losses are caused by the overlap of switch voltage and switch current during a switching transition. If, however, either the voltage across or the current flowing through a switch is zero during a switching transition, then there is no overlap of switch voltage and switch current so in theory, there are no switching losses. Techniques that ensure that this happens are referred to as soft-switching techniques in the power electronics literature and there are two types: zero-voltage switching (ZVS) and zero-current switching (ZCS). For pulse-width modulated (PWM) Dc-Dc converters, both ZVS and ZCS are typically implemented with auxiliary circuits that help the main power switches operate with soft-switching. Although these auxiliary circuits do help improve the efficiency of the converters, they increase their cost. There is, therefore, motivation to try to make these auxiliary circuits as simple and as inexpensive as possible. Three new soft-switching Dc-Dc PWM converters are proposed in this thesis. For each converter, a very simple auxiliary circuit that consists of only a single active switching device and a few passive components is used to reduce the switching losses in the main power switches. The outstanding feature of each converter is the simplicity of its auxiliary circuit, which unlike most other previously proposed converters of similar type, avoids the use of multiple active auxiliary switches. In this thesis, the operation of each proposed converter is explained, analyzed, and the results of the analysis are used to develop a design procedure to select key component values. This design procedure is demonstrated with an example that was used in the implementation of an experimental prototype. The feasibility of each proposed converter is confirmed with experimental result obtained from a prototype converter

High power high frequency DC-DC converter topologies for use in off-line power supplies

The development of a DC-DC converter for use in a proposed range of one to ten kilowatt off-line power supplies is presented. The converter makes good use of established design practices and recent technical advances. The thesis begins with a review of traditional design practices, which are used in the design of a 3kW, 48V output DC-DC converter, as a bench-mark for evaluation of recent technical advances. Advances evaluated include new converter circuits, control techniques, components, and magnetic component designs. Converter circuits using zero voltage switching (ZVS) transitions offer significant advantages for this application. Of the published converters which have ZVS transitions the phase shift controlled full bridge converter is the most suitable, and assessments of variations on this circuit are presented. During the course of the research it was realised that the ZVS range of one leg of the phase shift controlled full bridge converter could be extended by altering the switching pattern, and this new switching pattern is proposed. A detailed analysis of phase shift controlled full bridge converter operation uncovers a number of operational findings which give a better and more complete understanding of converter operation than hitherto published. Converter design equations and guidelines are presented and the effects of the new improvement are investigated by an approximate analysis. Computer simulations using PSPICE2 are carried out to predict converter performance. A prototype converter design, construction details and test results are given. The results obtained compare well to the predicted performance and confirm the advantages of the new switching pattern

Unmanned aerial vehicles enabled IoT platform for disaster management

© 2019 by the authors. Efficient and reliable systems are required to detect and monitor disasters such as wildfires as well as to notify the people in the disaster-affected areas. Internet of Things (IoT) is the key paradigm that can address the multitude problems related to disaster management. In addition, an unmanned aerial vehicles (UAVs)-enabled IoT platform connected via cellular network can further enhance the robustness of the disaster management system. The UAV-enabled IoT platform is based on three main research areas: (i) ground IoT network; (ii) communication technologies for ground and aerial connectivity; and (iii) data analytics. In this paper, we provide a holistic view of a UAVs-enabled IoT platform which can provide ubiquitous connectivity to both aerial and ground users in challenging environments such as wildfire management. We then highlight key challenges for the design of an efficient and reliable IoT platform. We detail a case study targeting the design of an efficient ground IoT network that can detect and monitor fire and send notifications to people using named data networking (NDN) architecture. The use of NDN architecture in a sensor network for IoT integrates pull-based communication to enable reliable and efficient message dissemination in the network and to notify the users as soon as possible in case of disastrous situations. The results of the case study show the enormous impact on the performance of IoT platform for wildfire management. Lastly, we draw the conclusion and outline future research directions in this field

Optimal design methodology of zero-voltage-switching full-bridge pulse width modulated converter for server power supplies based on self-driven synchronous rectifier performance

In this paper, high-efficiency design methodology of a zero-voltage-switching full-bridge (ZVS-FB) pulse width modulation (PWM) converter for server-computer power supply is discussed based on self-driven synchronous rectifier (SR) performance. The design approach focuses on rectifier conduction loss on the secondary side because of high output current application. Various-number parallel-connected SRs are evaluated to reduce high conduction loss. For this approach, the reliability of gate control signals produced from a self-driver is analyzed in detail to determine whether the converter achieves high efficiency. A laboratory prototype that operates at 80 kHz and rated 1 kW/12 V is built for various-number parallel combination of SRs to verify the proposed theoretical analysis and evaluations. Measurement results show that the best efficiency of the converter is 95.16%. © 2016 KIPE

A novel ZVS full-bridge converter

Conventional soft switching techniques are promising for improvement of efficiency in full bridge converters. However, efficiency of converters with employing such techniques is restricted due to narrow range of zero voltage switching (ZVS). In such situation, several methods have been proposed in the literature to cope with wide range of ZVS from no load to maximum load. The extra circuitry added to achieve a wide range of ZVS generates more conduction losses in a converter and increase cost of converter. In this paper, a novel ZVS full bridge converter is proposed to eliminate limitations of narrow range ZVS, improved efficiency and reduced cost. The circuit diagram, operation principle of proposed converter is explained and analyzed theoretically in detail. In addition, the proposed converter is built and experimental results are provided to verify the novel ZVS full bridge converter

A New Zcs-Pwm Full-Bridge Dc–Dc Converter With Simple Auxiliary Circuits

In this paper design & analysis of pv system based full bridge dc-dc converter with auxiliary circuits with soft-switching pulse width modulated (PWM) converter is proposed. The advantage of this converter is that it allows its main power switches to operate with zero current switching (ZCS) and with fewer conduction losses than conventional full-bridge converters. This conventional approach will gathered importance towards solar system. This solar system is also designed by using two simple active auxiliary circuits one is active, and the other is passive. The paper presents the PV based converter system and then discusses its operation, steady-state characteristics. Simulation results will be obtained from MATLAB/SIMULINK software to validate the converter’s performance of the PV system  based full bridge dc-dc converter

A Three-Phase Single-Stage AC-DC ZVZCS PWM Full-Bridge Converter

It is standard practice to use two separate power converters to convert an ac input voltage to a desired and isolated dc output voltage. A front-end ac-dc converter is used to convert the input ac voltage into an intermediate dc voltage which is then fed into a dc-dc converter with transformer isolation. The front-end converter also performs input power factor correction (PFC) to shape the input currents to be sinusoidal and in phase with the input voltages to maximize the use of the available source power. Conventional two-stage power conversion, however, requires two power con­ verters and there has been considerable interest to try to integrate the PFC and dc-dc conversion functions in a single power converter to reduce cost and complexity. Although many of these single-stage converters have been proposed for low power, single-phase applications, there have been relatively few higher power three-phase converters that have been proposed. This is due to the challenges faced when trying to perform PFC and dc-dc conversion for a wider load range. A new three-phase, single-stage ac-dc full-bridge converter is proposed in this thesis. The outstanding features of the new converter are that it is relatively simple and it can perform PFC using standard phase-shift pulse width modulation (PWM). In the thesis, derivation of the converter is discussed and its general operation is re­ viewed. The modes of operation of the converter are explained in detail and analyzed and the results of the analysis are used to develop guidelines for its design. The feasibility of the proposed converter is confirmed with experimental results that were obtained from a prototype and are presented in this thesis

A Three-Phase Single-Stage AC-DC ZVZCS PWM Full-Bridge Converter

It is standard practice to use two separate power converters to convert an ac input voltage to a desired and isolated dc output voltage. A front-end ac-dc converter is used to convert the input ac voltage into an intermediate dc voltage which is then fed into a dc-dc converter with transformer isolation. The front-end converter also performs input power factor correction (PFC) to shape the input currents to be sinusoidal and in phase with the input voltages to maximize the use of the available source power. Conventional two-stage power conversion, however, requires two power con­ verters and there has been considerable interest to try to integrate the PFC and dc-dc conversion functions in a single power converter to reduce cost and complexity. Although many of these single-stage converters have been proposed for low power, single-phase applications, there have been relatively few higher power three-phase converters that have been proposed. This is due to the challenges faced when trying to perform PFC and dc-dc conversion for a wider load range. A new three-phase, single-stage ac-dc full-bridge converter is proposed in this thesis. The outstanding features of the new converter are that it is relatively simple and it can perform PFC using standard phase-shift pulse width modulation (PWM). In the thesis, derivation of the converter is discussed and its general operation is re­ viewed. The modes of operation of the converter are explained in detail and analyzed and the results of the analysis are used to develop guidelines for its design. The feasibility of the proposed converter is confirmed with experimental results that were obtained from a prototype and are presented in this thesis