This paper proposes a novel high step-up interleaved boost converter suitable for distributed generation using renewable and alternative power sources. The proposed interleaved boost converter not only lengthens the lifetime of the renewable power source by reducing the input-current ripple but also achieves high step-up conversion. In addition, the voltage stress of the main switches is lowered due to the lossless passive-clamp circuit. Hence, large voltage spikes across the main switches are alleviated and the efficiency is improved. Finally, a prototype circuit with an input voltage of 48 V, an output voltage of 380 V and an output rated power of 3.5 kW is implemented and tested to demonstrate the functionality of the proposed converter. Moreover, satisfying experimental results are obtained and discussed in this paper; the measured full-load efficiency is 94.7%, and the highest measured efficiency of the proposed converter is 97.3%.

In this paper, a high-efficiency isolated bidirectional interleaved converter (IBIC) is proposed for high step-up and high step-down conversion systems. Two inductors are used in the low-voltage side to reduce the current ripple. The IBIC incorporates an ideal transformer to achieve energy transformation and galvanic isolation; the voltage-doubler circuit in the high-voltage side not only improves the voltage gain but also minimizes the voltage stress of power switches. Clamp capacitors achieve active clamping, and the energy stored in the leakage inductance is recycled. Moreover, all switches are operated with soft-switching and slightly reduced switching losses. The prototype circuit, with low-side voltage VL of 48 V, high-side voltage VH of 380 V, and rated power of 1.5 kW, is implemented to demonstrate the functionality of the proposed IBIC. The peak efficiency levels of the proposed converter in the high step-up and high step-down stages are 95.3% and 95.8%, respectively.

The conventional two-stage non-isolated driver for high-power light-emitting diodes (LEDs) is composed of a power-factor-correction (PFC) converter with a non-isolated flyback converter for regulating the output voltage/current for supplying LEDs. However, large numbers of circuit components are required and the total efficiency is limited because of two-stage power conversion. This study proposes a high-power LEDs driver based on a single-stage topology. The presented driver combines a buck-boost PFC converter with a non-isolated flyback converter with two output windings connected in series into a single-stage power-conversion circuit. The proposed driver offers high power factor, high efficiency, low total-harmonics-distortion (THD) of input utility-line current, cost-effectiveness and a constant-output voltage along with limited-output-current control scheme. Finally, a prototype driver is developed and tested in order to supply a 100 W LED light bar module with universal utility-line input voltages for indoor or outdoor general lighting applications. Operational analysis, design equations, a design example and experimental results provided by examining three LED light bar modules demonstrate the feasibility of the proposed circuit.

This paper proposes a novel ac/dc light-emitting diode driver. The circuit configuration consists of a low-pass filter, a diode rectifier, and two flyback converters which are interleaved operated with 180° phase shift. Although both flyback converters lose the capability of galvanic isolation in this proposed circuit, the active switch of each converter can achieve zero-voltage switching without needing to use the additional active clamping circuit or snubber circuit. Also, the energy stored in the leakage inductance of the coupled inductor can be either recycled or supplied to the output load, resulting in high circuit efficiency and low product cost. Besides, high power factor and low total current harmonic distortion are obtained by operating the flyback converters in discontinuous current mode. The steady-state analyses of different operation modes and the design criteria for circuit parameters are provided. Finally, a 200-W prototype circuit was implemented. Satisfactory performances are obtained from the experimental results.

This paper presents a single-stage alternating current (AC)/direct current (DC) light-emitting diode (LED) tube lamp driver for energy-saving indoor lighting applications; this driver features power-factor corrections and soft switching, and also integrates a dual buck-boost converter with coupled inductors and a half-bridge series resonant converter cascaded with a bridge rectifier into a single-stage power-conversion topology. The features of the presented driver are high efficiency (>91%), satisfying power factor (PF > 0.96), low input-current total-harmonic distortion (THD < 10%), low output voltage ripple factor (<7.5%), low output current ripple factor (<8%), and zero-voltage switching (ZVS) obtained on both power switches. Operational principles are described in detail, and experimental results obtained from an 18 W-rated LED tube lamp for T8/T10 fluorescent lamp replacements with input utility-line voltages ranging from 100 V to 120 V have demonstrated the functionality of the presented driver suitable for indoor lighting applications.