Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

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A review of single-phase improved power quality AC-DC converters

An apparatus and method is characterized by providing an optical transfer function between a predetermined illuminated surface pattern, such as a street light pattern, and a predetermined energy distribution pattern of a light source, such as that from an LED. A lens is formed having a shape defined by the optical transfer function. The optical transfer function is derived by generating an energy distribution pattern using the predetermined energy distribution pattern of the light source. Then the projection of the energy distribution pattern onto the illuminated surface is generated. The projection is then compared to the predetermined illuminated surface pattern to determine if it acceptably matches. The process continues reiteratively until an acceptable match is achieved. Alternatively, the lens shape is numerically or analytically determined by a functional relationship between the shape and the predetermined illuminated surface pattern and predetermined energy distribution pattern of a light source as inputs.

LED Device for Wide Beam Generation

In this paper, three-phase PFC rectifier topologies with sinusoidal input currents and controlled output voltage are derived from known single-phase PFC rectifier systems and/or passive three-phase diode rectifiers. The systems are classified into hybrid and fully active PWM boost-type or buck-type rectifiers, and their functionality and basic control concepts are briefly described. This facilitates the understanding of the operating principle of three-phase PFC rectifiers starting from single-phase systems, and organizes and completes the knowledge base with a new hybrid three-phase buck-type PFC rectifier topology denominated as Swiss Rectifier. In addition, analytical formulas for calculating the current stresses on the power semiconductors of selected topologies are provided, and rectifier systems offering a high potential for industrial applications are comparatively evaluated concerning the semiconductor stresses, the loading and volume of the main passive components, and the DM and CM EMI noise level. Finally, core topics of future research on three-phase PFC rectifier systems are discussed, such as the analysis of novel hybrid bucktype PFC rectifier topologies, the direct input current control of bucktype systems, the multi-objective optimization of PFC rectifier systems concerning efficiency and power density, and the investigation of the system performance sensitivity to semiconductor and passive components technology.

The essence of three-phase PFC rectifier systems

This paper focuses on the development of multilevel hysteresis current regulation strategies. Two such strategies have been discussed and some modifications in their control tasks have been proposed to achieve more reliable and improved performance. In general, the multiband concept has been used while making the proposals. The hysteresis band size considerations have also been presented by taking into account the desired and existing system conditions. The proposed modulation schemes have been applied to a five-level flying-capacitor inverter, whose operation under hysteresis current control mode is much less established. A new method of flying-capacitor voltage balancing is proposed which ensures balanced flying-capacitor voltages and, at the same time, maintains the desired current profile. It uses a time-based approach for controlling the capacitor voltages and achieves appreciable voltage spectrum under wide range of load power factor conditions. The performance of the proposed strategies is confirmed through both simulation and experimental investigations.

Improved Multilevel Hysteresis Current Regulation and Capacitor Voltage Balancing Schemes for Flying Capacitor Multilevel Inverter

This paper presents a new average d- q model and a control approach with a carrier-based pulsewidth modulation (PWM) implementation for nonregenerative three-phase three-level boost (VIENNA-type) rectifiers. State-space analysis and an averaging technique are used to derive the relationship between the controlled duty cycle and the dc-link neutral-point voltage, based on which an optimal zero-sequence component is found for dc-link voltage balance. By utilizing this zero-sequence component, the behavior of the dc-link voltage unbalance can be modeled in d-q coordinates using averaging over a switching cycle. Therefore, the proposed model is valid for up to half of the switching frequency. With the proposed model, a new control algorithm is developed with carrier-based PWM implementation, which features great simplicity and good dc-link neutral-point regulation. Space vector representation is also utilized to analyze the voltage balancing mechanism and the region of feasible operation. Simulation and experimental results validated the proposed model and control approach.

Average Modeling and Control Design for VIENNA-Type Rectifiers Considering the DC-Link Voltage Balance

An assembly of light emitting diodes for a streetlight or the likes comprises a first board having a first matrix of light emitting diodes (LEDs) mounted thereon defining a first light projection plane and at least another board having a second matrix of LEDs mounted thereon defining a second light projection plane. The other boards are mounted to the first board so as to define an angle therebetween. The LEDs can be mounted to the boards so as to independently define and angle therewith. They can also be oriented towards privileged directions. The present assembly allows providing a more uniform light distribution.

Assembly of light emitting diodes for lighting applications

A system and method for controlling a matrix of light emitting diodes (LED) connected to an input line comprises a power converter for connecting to the matrix of LEDs and to the input line therebetween and for receiving from the input line an input current and an input voltage characterized by a shape and a frequency and for providing a direct current (D.C.) output for powering up the LEDs, yielding an operating current through the LEDs. The power converter includes a first current sensor for sensing the input current and a second current sensor for sensing the operating current. The system further comprises a controller for connecting to both the input line and to the power converter. The controller includes a voltage sensor for sensing the input voltage and a pre-regulator i) for receiving the operating current, the input current and the input voltage, ii) for biasing the operating current towards a target current value, and iii) for regulating the power converter to cause the input current to follow the shape and frequency of the input voltage, yielding a unity power factor and minimizing the input current harmonic distortion. The present method and system allows maximizing the energy savings, controlling current flowing in the diodes so as to obtain the maximum flux of light with the minimum energy and also allows meeting all safety, EMI, reliability and robustness requirements.

System And Method For Controlling A Matrix Of Light Emitting Diodes And Light Provided Therewith

In this paper, two control laws based respectively on hysteresis and pulse-width-modulation (PWM) techniques are applied on a unity-power-factor current-injection-based three-phase rectifier. A theoretical analysis is carried out in order to evaluate the performance of each technique, in terms of the line current ripple and the switching frequency. The control detuning problem, which contributes mainly to the line current distortion, is also considered. In order to highlight the comparative study, numerical simulation is accomplished using the Power System Blockset tool of Matlab/Simulink.

A comparative study of hysteresis and PWM control techniques applied to an injection-current-based three-phase rectifier

This paper presents a new dynamic model of a three-phase, three-switch, three-level, fixed-frequency Pulse-Width-Modulated (PWM) rectifier. The modeling approach uses the state-space averaging technique in continuous current mode. The averaging process is applied on two time intervals: the switching period for average current evaluation, and the mains period for average voltage computation. A basic mathematical model of the converter is first established. A simplified time-invariant model is then deduced using rotating Park transformation. The steady-state regime is analyzed on the basis of the obtained model, and converter design criteria are consequently discussed. Numerical simulations are carried out in order to demonstrate the effectiveness of the proposed modeling approach.

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A new low-frequency state model of a three-phase three-switch three-level fixed-frequency PWM rectifier

In this paper, a new control strategy based on the pulse-width-modulation (PWM) control technique and using a single feedback current loop is proposed. The control scheme is applied to a particular three-phase unity power factor (UPF) current injection AC-DC converter. For this purpose, a dynamical model of the converter is developed using the state-space averaging method. Simulation results are used to validate the theoretical approach carried out through the paper.

L. Duguay

Papers

Assembly of light emitting diodes for lighting applications

System And Method For Controlling A Matrix Of Light Emitting Diodes And Light Provided Therewith

A comparative study of hysteresis and PWM control techniques applied to an injection-current-based three-phase rectifier

A new low-frequency state model of a three-phase three-switch three-level fixed-frequency PWM rectifier

Modeling and analysis of a three-phase unity power factor current injection rectifier using one loop control strategy