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

Linearized large signal modeling, analysis, and control design of phase-controlled series-parallel resonant converters using state feedback

This paper proposes a linearized large signal state-space model for the fixed-frequency phase-controlled series-parallel resonant converter. The proposed model utilizes state feedback of the output filter inductor current to perform linearization. The model combines multiple-frequency and average state-space modeling techniques to generate an aggregate model with dc state variables that are relatively easier to control and slower than the fast resonant tank dynamics. The main objective of the linearized model is to provide a linear representation of the converter behavior under large signal variation which is suitable for faster simulation and large signal estimation/calculation of the converter state variables. The model also provides insight into converter dynamics as well as a simplified reduced order transfer function for PI closed-loop design. Experimental and simulation results from a detailed switched converter model are compared with the proposed state-space model output to verify its accuracy and robustness

Optimization study of high power static inverters and converters Final report

Optimization study and basic performance characteristics for conceptual designs for high power static inverter

High Power and High Frequency Class-DE Inverters

This thesis investigates the various aspects of the theory. design and construction of a Class-DE type inverter and how these affect the power and frequency limits over which a Class-DE inverter can feasibly be used to produce AC (or RF) power. To this extent. an analysis of Class-DE operation in a half-bridge inverter is performed. A similar approach to Hamill [61 is adopted but a different time reference was used. This allows the concept of a conduction angle to b1: introduced and hence enables a more intuitive understanding of the. equations thereafter. Equations to calculate circuit element values LCR ne1wor'k are developed. The amount above the resonant frequency of the LCR network that the switching frequency must be in order to obtain the correct phase lag of the load current is shown. The effect of a non-linear output capacitance is studied, and equations are modified lo take this effect into account. It was found that a Class-DE topology offers a theoretical power advantage over a Clalls-E topology. However, this power advantage decreases with increasing frequency and is dependent on the output capacitance of the active switching devices. Using currently available MOSFETs, a Class-OE topology has a theoretical power advantage over a Class-E topology up to approximately 10MHz. However, the prac1ical problems of implementing a Class-DE invener lO work into the HF band are formidable. These practical problems and the extent to which they ltml! !he operating frequency and power of a Class-DE type inverter are investigated Guidelines to solving these practical problems are discussed and some novel soluuons are developed that considerably extend the feasible operating frequency and power of a Class-DE inverter. These solutions enabled a brc,adband design of the control circuitry. communication-link and gate-drive to be developed. Using these des[gns, a prototype broadband half-bridge inverter was developed which was capable of switching from 50k.Hz through to 6MHz. When operated in the Class-DE mode, the inverter was found to be capable of delivering a power output of over J kW from SOk.l-lz to 5Mllz with an efficiency of over 91 %. The waveforms obtained from the inverter clearly show Class-OE operation. The results of this thesis prove that a Class-DE series resonant inverter can produce. RF power up to a frequency of 5MHz with a higher combination of power and efficiency than any other present topology. The pracucal problems of even higher operaun& frequencies are discussed and some possible solutions suggested. The mismatched load tolerance of a Class-DE type inverter is briefly investigated. A Class-DE Lype inverter could be used for any applications requiring RF power in the HF band, such as AM or SW rransmirters, induction neating and plasma generators. The information presented in this thesis will be useful 10 designers wishing lo implement such an impeller. In add1non a Class-DE inverter could form the first stage of a highly efficient and high frequency DC-DC converter and the 1nformat1on presented here is directly applicable to such an applicatio

Control of power electronic interfaces in distributed generation.

Renewable energy has gained popularity as an alternative resource for electric power generation. As such, Distributed Generation (DG) is expected to open new horizons to electric power generation. Most renewable energy sources cannot be connected to the load directly. Integration of the renewable energy sources with the load has brought new challenges in terms of the system’s stability, voltage regulation and power quality issues. For example, the output power, voltage and frequency of an example wind turbine depend on the wind speed, which fluctuate over time and cannot be forecasted accurately. At the same time, the nonlinearity of residential electrical load is steadily increasing with the growing use of devices with rectifiers at their front end. This nonlinearity of the load deviates both current and voltage waveforms in the distribution feeder from their sinusoidal shape, hence increasing the Total Harmonics Distortions (THD) and polluting the grid. Advances in Power Electronic Interfaces (PEI) have increased the viability of DG systems and enhanced controllability and power transfer capability. Power electronic converter as an interface between energy sources and the grid/load has a higher degree of controllability compared to electrical machine used as the generator. This controllability can be used to not only overcome the aforementioned shortfalls of integration of renewable energy with the grid/load but also to reduce THD and improve the power quality. As a consequence, design of a sophisticated controller that can take advantage of this controllability provided by PEIs to facilitate the integration of DG with the load and generate high quality power has become of great interest. In this study a set of nonlinear controllers and observers are proposed for the control of PEIs with different DG technologies. Lyapunov stability analysis, simulation and experimental results are used to validate the effectiveness of the proposed control solution in terms of tracking objective and meeting the THD requirements of IEEE 519 and EN 50160 standards for US and European power systems, respectively

High power density AC to DC conversion with reduced input current harmonics

PhD ThesisThis thesis investigates the bene ts and challenges arising from the use of minimal capacitance in AC to DC converters. The purpose of the research is to ultimately improve the power density and power factor of electrical systems connected to the grid. This is carried out in the con- text of a low cost brushless DC drive system operating from an o ine power supply. The work begins with a review of existing applications where it is prac- tical to use a limited amount of DC link capacitance. The vast majority of these have a load which is insensitive to supply power variations at twice the line frequency. Low performance motor drives are found to be the most prevalent, with the inertia of the rotor mitigating the e ect of torque ripple. Further research is carried out on active power factor cor- rection techniques suitable for this application, leading to the conclusion that no appropriate systems exist. A power supply is developed to enable a 24V, 200W brushless motor drive to operate from the mains. The system runs successfully using only 1µF of DC link capacitance, which causes the motor supply volt- age to have 100% ripple. It is noted that whilst this drastically reduces the low frequency input current harmonics, those occurring at the load switching frequency are greatly increased. To combat this, a novel active power factor correction system is proposed using a notch lter to detect the input current error. The common problem of voltage feedback ripple is avoided by eliminating the voltage control loop altogether. The main limitations are identi ed as a high sensitivity to load step changes and variations in line frequency. Despite this, a high power factor is maintained in all operating conditions, as well as compliance with the relevant harmonic standards.Dyson Technology Ltd and Newcastle Univer- sit

Power Converters in Power Electronics

In recent years, power converters have played an important role in power electronics technology for different applications, such as renewable energy systems, electric vehicles, pulsed power generation, and biomedical sciences. Power converters, in the realm of power electronics, are becoming essential for generating electrical power energy in various ways. This Special Issue focuses on the development of novel power converter topologies in power electronics. The topics of interest include, but are not limited to: Z-source converters; multilevel power converter topologies; switched-capacitor-based power converters; power converters for battery management systems; power converters in wireless power transfer techniques; the reliability of power conversion systems; and modulation techniques for advanced power converters