Chien-Hsuan Chang

A High-Efficiency Solar Array Simulator Implemented by an LLC Resonant DC–DC Converter

In this paper, a high-efficiency solar array simulator (SAS) implemented by an LLC resonant dc-dc converter is proposed to save the cost and energy of photovoltaic (PV) system testing. The proposed converter has zero-voltage switching (ZVS) operation of the primary switches and zero-current switczero-current switching (ZCS) operation of the rectifier diodes. By frequency modulation control, the outputhing (ZCS) operation of the rectifier diodes. By frequency modulation control, the output impedance of an LLC resonant converter can be regulated from zero to infinite without shunt or serial resistors. Therefore, the efficiency of the proposed SAS can be significantly increased. The circuit operations are analyzed in detail to derive the theoretical equations. Circuit parameters are designed based on the practical considerations. Finally, an illustrative example is implemented to demonstrate the feasibility of the proposed SAS.

Design and Implementation of a Single-Stage Driver for Supplying an LED Street-Lighting Module With Power Factor Corrections

This paper proposes a novel single-stage light-emitting diode (LED) driver for street-lighting applications with power factor corrections (PFC). The presented driver integrates a modified bridgeless PFC ac-dc converter with a half-bridge-type LLC dc-dc resonant converter into a single-stage conversion circuit topology. The proposed ac-dc resonant driver provides input current shaping, and it offers attributes of lowered switching losses to the soft-switching functions obtained on two power switches and two output-rectifier diodes. The proposed driver features cost-effectiveness, high circuit efficiency (>92%), high power factor (>0.99) and low input current total harmonics distortion (<;8%). A prototype driver is developed for supplying a 144-W-rated LED street-lighting module with utility-line input voltages ranging from 100 to 120 V, and experimental results demonstrate the functionalities of the proposed LED driver.

A high efficiency solar array simulator implemented by an LLC resonant DC/DC converter

In order to save the cost and energy for PV system testing, a high efficiency solar array simulator (SAS) implemented by an LLC resonant DC/DC converter is proposed. This converter has zero voltage switching (ZVS) operation of the primary switches and zero current switching (ZCS) operation of the rectifier diodes. By frequency modulation control, the output impedance of an LLC converter can be regulated from zero to infinite without shunt or series resistor; hence, the efficiency of the proposed SAS can be significantly increased. According to the provided operation principles and design considerations of an LLC converter, a prototype is implemented to demonstrate the feasibility of the proposed SAS.

An Integrated High-Power-Factor Converter With ZVS Transition

This paper proposes a single-phase high-power-factor ac/dc converter with soft-switching characteristic. The circuit topology is derived by integrating a boost converter and a buck converter. The boost converter performs the function of power-factor correction to obtain high power factor and low current harmonics at the input line. The buck converter further regulates the dc-link voltage to provide a stable dc output voltage. Without using any active-clamp circuit or snubber circuit, the active switches of the proposed converter can achieve zero-voltage switching-on transition together with high power factor that satisfies the IEC 61000-3-2 standards over a wide load range from 30% to 100% rated power. The steady-state analysis is developed and a design example is provided. A prototype circuit of 60 W was built and tested. Experimental results verify the feasibility of the proposed circuit with satisfactory performance.

Modeling and Design of the LLC Resonant Converter Used as a Solar-Array Simulator

The LLC resonant converter has been used to implement a solar-array simulator with high-efficiency and fast-response features. In this paper, its small-signal model is derived based on the extended describing function concept. The corresponding frequency response can be easily obtained from IsSPICE simulation of the equivalent circuit model. The derived model is matching with the measured results very well. Furthermore, a solar-array simulator with closed-loop control is designed according to the derived small-signal model. The experimental measurements have really proved that high-efficiency and fast-transient responses can be achieved in the system. The output voltage and output current can be adjusted simultaneously to match the electrical characteristics of photovoltaic output.

A single-stage LED driver for street-lighting applications with interleaving PFC feature

This paper proposes a single-stage light-emitting diode (LED) driver with interleaving power-factor-correction (PFC) feature for street-lighting applications. The presented circuit integrates an interleaved boost PFC converter with a half-bridge-type LLC resonant converter into a single-stage power converter. The presented AC-DC resonant converter uses interleaving methods to achieve input-current shaping, and possesses soft-switching functions on two active power switches to reduce their switching losses in order to increase the circuit efficiency. The proposed LED driver features low levels of input-current ripple, reduced switching losses, high power factor, low total harmonics distortion (THD) of input current, and a reduced components count. Finally, a prototype driver is successfully implemented and tested to provide a 144W-rated LED street-lighting module with a 110V utility-line input voltage. Experimental results demonstrate the feasibility of the proposed circuit.

A novel single-stage high-power-factor LED driver for street-lighting applications

This paper proposes a novel single-stage LED driver for street-lighting applications with high levels of power factor. The presented driver integrates a modified bridgeless power-factor-correction (PFC) AC-DC converter with a half-bridge-type LLC DC-DC resonant converter into a single-stage conversion circuit topology. The proposed AC-DC resonant driver provides input current shaping, and its offers attributes of lowered switching losses to the soft-switching functions obtained on two power switches and two output rectifier diodes. The proposed driver features cost-effectiveness, high circuit efficiency, high power factor, low input current ripples and a reduced components count. A prototype driver is developed to supply a 144W LED street-lighting module with a 110V utility-line input voltage. Experimental results demonstrate the functionalities of the proposed circuit.

A novel single-stage LLC resonant AC-DC converter with power factor correction feature

This paper proposes a novel single-stage LLC resonant ac-dc converter with power factor correction feature. The proposed circuit is the integration of a buck-boost type power factor corrector and an LLC resonant dc-dc converter. The proposed single-stage converter which has power factor correction and output voltage regulation features can simplify circuit complexity, reduce cost, and increase system reliability over conventional two-stage systems. Experimental results of a 100W prototype are used to verify the feasibility and validity of the theoretical predictions.

A novel single-stage LED driver with coupled inductors and interleaved PFC

This paper proposes a novel single-stage light-emitting diode (LED) driver with coupled inductors and interleaved power-factor correction (PFC), suitable for streetlight applications. The presented LED driver integrates an interleaved boost PFC converter with coupled inductors and a half-bridge-type series-resonant converter cascaded with a full-bridge rectifier into a single-stage power-conversion circuit. Coupled inductors inside the interleaved boost PFC converter sub-circuit are designed to operate in discontinuous-conduction mode (DCM) for achieving input-current shaping, and the half-bridge-type series-resonant converter cascaded with a full-bridge rectifier is designed for obtaining zero-voltage switching (ZVS) on two power switches to reduce their switching losses. Analysis of operational modes and design equations for the presented LED driver are described and included. In addition, the proposed driver features high power factor, low total-harmonic distortion (THD) of input current and soft-switching. Finally, a prototype 165W-rated LED driver is developed and tested with a utility-line input voltage of 110V. Satisfactory outcomes from experimental results demonstrate the feasibility of the proposed circuit.

Analysis and design of a novel interleaved single-stage LLC resonant AC-DC converter

This paper proposes a novel interleaved single-stage LLC resonant ac-dc converter. Two derivative buck-boost typed power-factor-correctors (PFCs) with interleaved operation are integrated with an LLC resonant converter to form the presented circuit. The proposed single-stage converter has the features of simple circuit structure, balance switch currents, low dc-bus voltage, low input current harmonics, and high system reliability. Both the active switches can turn on with zero voltage switching (ZVS), and both the output rectifier diodes can turn off with zero current switching (ZCS), which results in lower switching losses. Circuit derivations, operation principles, and circuit analysis of the proposed converter are addressed. Finally, a laboratory prototype with an 110Vrms utility-line voltage is implemented correspondingly. The experimental results have verified the validity of the theoretical predictions and the feasibility of the proposed circuit.