Totem-pole bridgeless boost PFC rectifier using series-parallel resonant network

A new series-parallel resonant bridgeless boost (SPBBR) power factor correction (PFC) rectifier is proposed in this paper. It is based on a totem-pole bridgeless boost (TPBLB) configuration which allows bi-directional current to flow during resonance to provide soft-switching for all semiconductor devices. Therefore, no additional active switch is needed. The resonant is produced by a resonant network which is placed before the output capacitor. A detailed analysis of the converter operation and control is presented. Design considerations and parameter values determination are also given. Simulation results is used to verify the theoretical analysis of the SPBBR

A Novel Two-Stage AC-DC Power Converter with Partial Power Processing

A two-stage power converter with an AC-DC boost converter and a soft-switched DC-DC full-bridge converter is proposed in this thesis. The first stage has two interleaved modules that perform power factor correction; the second stage converts the output of the first stage to the desired output. An auxiliary circuit with a switch, a small transformer, and passive components is used to turn off the AC-DC converter switches with soft-switching; the auxiliary switch can also be turned on and off softly. The secondary of the auxiliary transformer is connected to the output of the overall converter so that some power can be transferred from the front-end converter to the output. This power is processed only once, thus reducing conversion losses. The thesis explains the operation of the converter and presents steady-state analysis and a design procedure. Results obtained from an experimental prototype are presented to confirm the converter’s feasibility

A Novel AC-DC Interleaved ZCS-PWM Boost Converter

AC-DC converters with input power factor correction (PFC) that consist of two or more interleaved boost converter modules are popular in industry. PFC is a must in today’s AC-DC converters as their input current must meet harmonic standards set by regulatory agencies. With interleaving, the input current of each module can make to be discontinuous and the size of their input inductors since interleaving can reduce the high ripple in each module and produce a net input current with a ripple that is comparable to that achieved with a single boost converter module with a large input inductor. In high- frequency converters, so as to achieve low harmonic, fast dynamic response, low size, and high-power density the frequency should be increased. The drawback of increasing the switching frequency is increasing the switching losses. This is reason that why soft-switching methods should be used. The focus of the thesis is on zero current switching (ZCS) methods for IGBT converters. The auxiliary switch in the proposed converter is activated whenever a main converter switch is about to be turned off, gradually diverting current away from the switch so that it can turn off with ZCS and eliminate the switching losses. In addition, the auxiliary circuit is designed in a way that it can be activated only when the converter is operating with heavier loads and not used when the converter is operating with light load to maximize the overall efficiency. The operation of the novel converter will then be explained and the mathematical analysis in steady-state will be derived. Based on the results of the analysis, general design guidelines will be provided. Finally, the design procedure will be confirmed by experimental results obtained from the proof of concept prototype

Totem-Pole Bridgeless Boost PFC Rectifier Using Series-Parallel Resonant Network

A new series-parallel resonant bridgeless boost (SPBBR) power factor correction (PFC) rectifier is proposed in this paper. It is based on a totem-pole bridgeless boost (TPBLB) configuration which allows bi-directional current to flow during resonance to provide soft-switching for all semiconductor devices. Therefore, no additional active switch is needed. The resonant is produced by a resonant network which is placed before the output capacitor. A detailed analysis of the converter operation and control is presented. Design considerations and parameter values determination are also given. Simulation results is used to verify the theoretical analysis of the SPBBR

Bridgeless High Power Factor Buck-Converter Operating In Discontinuous Capacitor Voltage Mode

High power factor AC-DC rectifiers have gained a lot of attention due to demanding international regulations. The international harmonics’ standards, i.e. IEC 61000-3-2 and EN 61000-3-2 require low harmonic content of the main line current, or in other words, high power factor. Also, new market initiatives such as the 80 PLUS initiative, require high efficiency of the power supply. These standards specify the AC line current harmonics’ limits depending on load and application. In this research, a new converter, with high power factor and high efficiency, operating in discontinuous capacitor voltage mode (DCVM) – is investigated targeting personal computers (PC) and server applications. To the best of our knowledge, this is the first publish bridgeless topology operating in DCVM. To ensure high efficiency, the bridgeless rectifier topology is modified by eliminating two diodes and replacing them with two unidirectional switches. On the other hand, the DCVM has the advantages of no need for high frequency input filter, soft turn-off switching, low switch current stress and high efficiency at low loads. A comparison between full bridge DCVM buck power factor correction (PFC) converter and the proposed topology is presented. The present topology found to have higher efficiency than that of the full bridge DCVM buck PFC converter, and less THD. Hence, the power factor has been significantly improved. The comparison is summarized and tabulated in chapter five Design procedure, simulation and measurements are in chapter five. Simulation results are presented to demonstrate the topology’s performance. Orcad PSpice software has been used to simulate the proposed topology. Measurements are presented to verify the theoretical analysis and the simulation findings. The harmonics at the input current are also compared with the IEC 61000-3-2 harmonic standard values. A step by step design procedure for the converter has been developed at any operating point over universal line input voltage (90-265Vrms). Small signal analysis and bode plots for the proposed topology were developed for the line-to-output and control-to-output transfer functions

Soft-Switching Techniques of Power Conversion System in Automotive Chargers

abstract: This thesis investigates different unidirectional topologies for the on-board charger in an electric vehicle and proposes soft-switching solutions in both the AC/DC and DC/DC stage of the converter with a power rating of 3.3 kW. With an overview on different charger topologies and their applicability with respect to the target specification a soft-switching technique to reduce the switching losses of a single phase boost-type PFC is proposed. This work is followed by a modification to the popular soft-switching topology, the dual active bridge (DAB) converter for application requiring unidirectional power flow. The topology named as the semi-dual active bridge (S-DAB) is obtained by replacing the fully active (four switches) bridge on the load side of a DAB by a semi-active (two switches and two diodes) bridge. The operating principles, waveforms in different intervals and expression for power transfer, which differ significantly from the basic DAB topology, are presented in detail. The zero-voltage switching (ZVS) characteristics and requirements are analyzed in detail and compared to those of DAB. A small-signal model of the new configuration is also derived. The analysis and performance of S-DAB are validated through extensive simulation and experimental results from a hardware prototype. Secondly, a low-loss auxiliary circuit for a power factor correction (PFC) circuit to achieve zero voltage transition is also proposed to improve the efficiency and operating frequency of the converter. The high dynamic energy generated in the switching node during turn-on is diverted by providing a parallel path through an auxiliary inductor and a transistor placed across the main inductor. The paper discusses the operating principles, design, and merits of the proposed scheme with hardware validation on a 3.3 kW/ 500 kHz PFC prototype. Modifications to the proposed zero voltage transition (ZVT) circuit is also investigated by implementing two topological variations. Firstly, an integrated magnetic structure is built combining the main inductor and auxiliary inductor in a single core reducing the total footprint of the circuit board. This improvement also reduces the size of the auxiliary capacitor required in the ZVT operation. The second modification redirects the ZVT energy from the input end to the DC link through additional half-bridge circuit and inductor. The half-bridge operating at constant 50% duty cycle simulates a switching leg of the following DC/DC stage of the converter. A hardware prototype of the above-mentioned PFC and DC/DC stage was developed and the operating principles were verified using the same.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

A Bidirectional Soft-Switched DAB-Based Single-Stage Three-Phase AC–DC Converter for V2G Application

In vehicle-to-grid applications, the battery charger of the electric vehicle (EV) needs to have a bidirectional power flow capability. Galvanic isolation is necessary for safety. An ac-dc bidirectional power converter with high-frequency isolation results in high power density, a key requirement for an on-board charger of an EV. Dual-active-bridge (DAB) converters are preferred in medium power and high voltage isolated dc-dc converters due to high power density and better efficiency. This paper presents a DAB-based three-phase ac-dc isolated converter with a novel modulation strategy that results in: 1) single-stage power conversion with no electrolytic capacitor, improving the reliability and power density; 2) open-loop power factor correction; 3) soft-switching of all semiconductor devices; and 4) a simple linear relationship between the control variable and the transferred active power. This paper presents a detailed analysis of the proposed operation, along with simulation results and experimental verification

A Single-Stage LED Driver Based on ZCDS Class-E Current-Driven Rectifier as a PFC for Street-Lighting Applications

This paper presents a light-emitting diode (LED) driver for street-lighting applications that uses a resonant rectifier as a power-factor corrector (PFC). The PFC semistage is based on a zero-current and zero-derivative-switching (ZCDS) Class-E current-driven rectifier, and the LED driver semistage is based on a zero-voltage-switching (ZVS) Class-D LLC resonant converter that is integrated into a single-stage topology. To increase the conduction angle of the bridge-rectifier diodes current and to decrease the current harmonics that are injected in the utility line, the ZCDS Class-E rectifier is placed between the bridge-rectifier and a dc-link capacitor. The ZCDS Class-E rectifieris driven by a high-frequency current source, which is obtained from a square-wave output voltage of the ZVS Class-D LLC resonant converter using a matching network. Additionally, the proposed converter has a soft-switching characteristic that reduces switching losses and switching noise. A prototype for a 150-W LED street light has been developed and tested to evaluate the performance of the proposed approach. The proposed LED driver had a high efficiency (>91%), a high PF (>0.99), and a low total harmonic distortion (THD i <; 8%) under variation of the utility-line input voltage from 180 to 250 V rms . These experimental results demonstrate the feasibility of the proposed LED scheme

Design of a Feedback-Controlled Wireless Converter for Electric Vehicle Wireless Charging Applications

Electric vehicles (EVs) have played an important role in the modern transporta-tion system in recent years. However, current generations of EVs face unsolved drawbacks such as short driving range, long charging time, and high cost due to expensive battery systems. Wireless Power Transfer (WPT) is a promising technology that is able to mitigate the drawbacks EVs are facing. This paper focuses on investigating and building a complete high-efficiency WPT system that is capable of efficiently charging electric vehicles. The goal is to design and ap-ply two different configurations of compensation networks to the WPT system. In this paper, the two compensation network configurations studied are LLC and LCC. After comparing their operational characteristics and efficiencies, the most suitable configuration is proposed. Moreover, a phase-shifted controller is applied in order to regulate the power transferred through the WPT system

Resonant UPS topologies for the emerging hybrid fiber coaxial networks

Uninterruptible power supply (UPS) systems have been extensively applied to feed critical loads in many areas. Typical examples of critical loads include life-support equipment, computers and telecommunication systems. Although all UPS systems have a common purpose to provide continuous power-to critical loads, the emerging hybrid fiber-coaxial networks have created the need for specific types of UPS topologies. For example, galvanic isolation for the load and the battery, small size, high input power factor, and trapezoidal output voltage waveforms are among the required features of UPS topologies for hybrid fiber-coaxial networks. None of the conventional UPS topologies meet all these requirements. Consequently. this thesis is directed towards the design and analysis of UPS topologies for this new application. Novel UPS topologies are proposed and control techniques are developed to allow operation at high switching frequencies without penalizing the converter efficiency. By the use of resonant converters in the proposed UPS topologies. a high input power factor is achieved without requiring a dedicated power factor correction stage. In addition, a self-sustained oscillation control method is proposed to ensure soft switching under all operating conditions. A detailed analytical treatment of the resonant converters in the proposed UPS topologies is presented and design procedures illustrated. Simulation and experimental results are presented to validate the analyses and to demonstrate the feasibility of the proposed schemes