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Summary: A 2‐channel LED driver is presented herein, which possesses non‐pulsating input current and automatic current sharing. There are 4 features in the proposed LED driver. First, due to an input inductor, the input current is non‐pulsating, which makes the life of the renewable energy module or input capacitor longer. Second, each coupled inductor winding has a capacitor connected in series. Therefore, the dc magnetizing bias current is zero, and this can improve the iron core utilization, making the core loss and size reduced. Third, the number of LED channels can be extended by increasing windings. Fourth, the LED currents can be almost identical even if there are different LED numbers in LED strings. Eventually, the proposed LED driver is verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

Summary: In this study, an extensible 2‐phase interleaved high step‐up converter with automatic current balance is presented. This converter uses coupled inductors and energy‐transferring capacitors to improve the voltage gain of the traditional 2‐phase interleaved boost converter as well as employs these energy transferring capacitors to do automatic current balance. Furthermore, the voltage gain can be enhanced not only by adjusting the turns ratio but also by increasing the numbers of phases, diodes, and energy‐transferring capacitors. Therefore, it can be used in high input current and high step‐up voltage applications. In this paper, the basic operating principles of the proposed converter are described and analyzed, and finally, its effectiveness is demonstrated by experiment. In addition, the field‐programmable gate array, named EP13T100C8N and manufactured by Altera Co, is used as a control kernel, and an experimental prototype, with input voltage of 12 V, output voltage of 200 V, and rated output power of 200 W, is given to provide the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

In this paper, a single-switch coupled-inductor-based two-channel light-emitting diode (LED) driver with a passive regenerative snubber is presented. In the proposed LED driver, the energy-transferring capacitor is not only used to step up the voltage gain but also to achieve the current balance among LED strings. Moreover, a passive regenerative snubber is added not only to recycle the leakage inductance energy but also to improve the voltage gain. As compared with the prior work, only one switch is required. Thus, the configuration of the proposed LED driver is simpler. Since the proposed LED driver has a higher voltage gain than the prior work, the turns ratio of the proposed LED driver can be lower. Thus, the magnetic core size can be reduced. In addition, both LED drivers have the same component count. Finally, the operating principle, analysis, and experimental results are provided to verify the effectiveness of the proposed LED driver. [ABSTRACT FROM AUTHOR]

In this paper, a nonisolated two-channel light-emitting diode (LED) driver with automatic current balance and zero-voltage switching (ZVS) is presented. In this LED driver, a dc-blocking capacitor is connected with one side of the coupled inductor. Therefore, based on the ampere–second balance, a current source is generated with the average value of the positive current identical to the absolute average value of the negative current. Accordingly, the LED currents can be balanced naturally without extra active components or current sharing transformer. Consequently, the circuit components can keep at a low count. In addition, the proposed LED driver can achieve ZVS turn-on. Thus, the switching loss can be decreased. Above all, the proposed two-channel LED driver can be extended to a multichannel LED driver. In this paper, detailed theoretical analyses and experimental results are provided to verify the feasibility and effectiveness of the proposed LED driver. [ABSTRACT FROM AUTHOR]

A nonisolated coupled-inductor-based high step-down converter with zero dc magnetizing inductance current and nonpulsating output current is presented. Since the dc magnetizing inductance current is zero, the magnetizing current can be positive and negative. Therefore, the entire core B–H loop can be used, ranging from the first quadrant to the third quadrant. That is, the utilization of the coupled inductor can be improved and, hence, the core loss can also be reduced. Moreover, due to a discrete output inductor, the proposed converter also features a nonpulsating output current, which makes the output current ripple smaller. In this paper, detailed theoretical analyses and experimental results are provided to verify the feasibility and effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

A novel isolated high voltage-boosting converter, derived from the traditional forward converter, is presented in this paper. As compared with the traditional forward converter, the demagnetizing winding of the transformer in the proposed converter is used not only to demagnetize but also to improve the voltage conversion ratio. Therefore, the duty cycle is not limited, and the utilization of the transformer, also called coupled inductor, can be increased also. Furthermore, the proposed converter maintains the advantage of possessing a non-pulsating output current, leading to a small output voltage ripple. Moreover, by applying one additional voltage-boosting winding to the transformer, the voltage conversion ratio can be significantly improved. In addition, an active clamp circuit is employed in the proposed converter to reduce the voltage stress of the main switch, caused by the leakage inductance in the transformer, and the switches can achieve zero-voltage switching. Finally, the analysis of operating principles, choice of the turns, turns ratio, core size, and each wire size of the coupled inductor are described in detail, and the experimental results with a prototype with 12-V input voltage, 100-V output voltage, and 100-W output power are provided to verify the feasibility and effectiveness of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, an ultrahigh step-down converter is presented, which combines one coupled inductor and one energytransferring capacitor. The corresponding voltage conversion ratio is much lower than that of the traditional synchronously rectified (SR) buck converter, and the proposed converter can achieve extremely low output voltage with an appropriate duty ratio. Moreover, there are three major merits in the proposed converter. One merit is that the voltage conversion ratio of the proposed converter is linear, thereby making control quite easy. Another merit is that if one of the switches fails or is abnormally controlled, a high voltage does not appear in the output terminal, so the output load can be protected. The other merit is that the proposed converter can be driven using the existing SR buck pulse-width modulation control integrated circuit. In this study, brief theoretical deductions and some experimental results are given to verify the feasibility and effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

In this paper, a novel voltage-boosting converter is presented, which combines one charge pump and one coupled inductor with the turns ratio. The corresponding voltage gain is greater than that of the existing step-up converter combining KY and buck-boost converters. Since the proposed converter possesses an output inductor, the output current is nonpulsating. After some mathematical deductions, an experimental setup with 12-V input voltage, 72-V output voltage, and 60-W output power is used to verify the effectiveness of the proposed converter. [ABSTRACT FROM PUBLISHER]

To overcome the traditional buck converter, which is difficult to achieve a high step-down gain with an appropriate duty cycle, a coupled-inductor-based step-down converter, named ultrahigh step-down converter, is proposed by Hwu et al. [11]. As compared with the buck converter, the ultrahigh step-down converter can achieve a much higher step-down gain, which can be determined by not only the duty cycle but also the turns ratio of the coupled inductor. However, the ultrahigh step-down converter is designed at a fixed input voltage of 48 V. In the telecommunication applications, the high dc bus voltage varies in a wide range, not kept at a fixed nominal voltage of 48 V. The experimental results show that as the input voltage increases, the efficiency of the ultrahigh step-down converter decreases. Therefore, in this paper, an improved ultrahigh step-down converter with a wide input voltage range is presented. According to the topology exchange, the voltage gain can be changed to a suitable one when the input voltage changes. By doing so, as compared with the ultrahigh step-down converter [11], the duty cycle of the proposed converter can be extended, and hence the efficiencies of the proposed converter can be improved. The proposed converter is verified by a wide input voltage (18–54 V), with an output voltage of 1.2 V and a rated output current of 10 A. [ABSTRACT FROM AUTHOR]

In this paper, a high step-down bidirectional converter, utilizing one coupled inductor and two energy-transferring capacitors, is presented. In the step-down mode, the capacitor is connected between input voltage and coupled inductor, which plays a role to step down the input voltage. Therefore, the corresponding voltage conversion ratio is much lower than that of the traditional buck converter and also can be lower than that of the tapped-inductor buck converter. Moreover, the output voltage varies with the duty cycle linearly, making control easier. In the step-up mode, one capacitor is first charged by the coupled inductor, and then releases the energy along with the coupled inductor and the other capacitor connected in series. Therefore, a higher voltage gain can be obtained. Furthermore, the leakage inductance energy can be recycled. Therefore, the switching losses can be reduced and the efficiency can be improved. In this study, the operating principles and experimental results are provided to verify the effectiveness and performance of the proposed converter. [ABSTRACT FROM AUTHOR]