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In this paper, a nonisolated two-phase interleaved LED driver with capacitive current sharing is presented. In the proposed LED driver, the current sharing capacitor can be used to balance the input inductor currents and the LED currents. Furthermore, only one grounded LED string current is sensed and controlled. Moreover, under the interleaved control, the input current ripple can be reduced. Finally, the operating principles, analyses, and experimental results are provided to verify the effectiveness of the proposed LED driver. [ABSTRACT FROM PUBLISHER]

In the high step-down voltage applications, the dc–dc converter with a high step-down voltage conversion ratio is usually used. Recently, a high step-down converter, named ultrahigh step-down converter, has been presented. As compared with the nonisolated tapped-inductor buck converter, the ultrahigh step-down converter has not only a higher voltage step-down gain but also a lower voltage spike. On the other hand, in the high-current applications, a multiple phase structure is preferable. Therefore, in this paper, a novel expandable two-phase interleaved ultrahigh step-down converter with automatic current balance is presented, which is derived from the existing single-phase ultrahigh step-down converter. There are four main advantages of the proposed converter. First, the step-down voltage gain is improved. Therefore, the turns ratio of each phase can be decreased. Second, due to the charge balance of the energy-transferring capacitor, the proposed two-phase ultrahigh step-down converter possesses an automatic current balance. Third, as compared with a single-phase ultrahigh step-down converter, the output current ripple can be reduced. Fourth, the phase number of the proposed converter can be expanded. Finally, the basic operating principle of the proposed converter is analyzed, and a prototype is constructed to verify its effectiveness by some experimental results. [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 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]

In this paper, a novel four-phase interleaved high step-down converter is presented. The proposed converter can provide an extremely high step-down voltage conversion ratio within a moderate duty cycle. There are four main advantages of the proposed converter. First, the blocking capacitors can store energy as usual. Therefore, they are used as voltage sources to reduce the input voltage as well as to reduce the switch voltage stresses. Second, due to the charge balance of the dc blocking capacitors, the converter possesses an automatic uniform current sharing characteristic of the interleaved phases without adopting any extra circuitry. Third, due to the phase shift between the interleaved phases, the architecture provides a low output current ripple. Fourth, the number of phases can be expanded or reduced to any even phases; therefore, the converter has a wide range of applications. Finally, the operating principles and analysis of this architecture are given, and an experimental prototype is also provided to verify the effectiveness of the proposed converter. [ABSTRACT FROM PUBLISHER]

In this paper, a four-channel lighting-emitting diode (LED) driver is presented, which combines a twin-bus converter and three differential-mode transformers. In this LED driver, the twin-bus converter can achieve reduction of the voltage stress of the switch, and the differential-mode transformers can achieve current sharing. Furthermore, the twin-bus converter can provide demagnetizing paths for the differential-mode transformers. Above all, the LED strings can be easily expanded. Moreover, the LED currents can be regulated by the dimming control switch. Finally, theoretical deductions and experimental results are provided to demonstrate the effectiveness of the proposed topology. [ABSTRACT FROM PUBLISHER]

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]

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]

In this paper, a full-digital ac–dc converter with power factor correction (PFC)-based on counting is presented. As for the digital output voltage information, it is obtained by injecting the positive and negative triangular wave into the sensed output voltage, comparing this resultant signal with the output voltage reference, and counting the low level of the resulting signal based on one counter in the field programmable gate array (FPGA). As for the digital inductor current information, it is obtained by comparing the positive sawtoothed wave with the sensed inductor current after filtering and counting the low level of the resulting signal based on another counter in the FPGA. On the other hand, the sinusoidal reference command for the current controller is obtained by triggering the sinusoidal table in the FPGA via the zero crossing detecting circuit. This sinusoidal reference command, together with the traditional average current control method, generates a suitable control effort to drive the power switch such that the output voltage is controlled at a desired value and at the same time the input current follows the input voltage as tightly as possible. Above all, the proposed sampling method can be applied to the continuous conduction mode (CCM), the discontinuous conduction mode (DCM), or both. Finally, some experimental results are offered to verify the effectiveness of the proposed sampling method. [ABSTRACT FROM PUBLISHER]

As generally acknowledged, the high step-up dc-dc converter is widely used in the sustainable energy system as the front-end stage of the dc-ac converter. Therefore, a high step-up converter combining one coupling inductor and two bootstrap capacitors, together with the active voltage-clamping circuit which pumps portion of the leakage inductance energy to the output, is presented herein. By doing so, the efficiency at light load can be upgraded greatly, and hence tends to be flat between the minimum load and the rated load. In this letter, the basic operating principles of this converter are first illustrated in detail, and second some experimental results are provided to demonstrate the effectiveness of the proposed high step-up converter topology. [ABSTRACT FROM AUTHOR]

In this paper, novel high voltage-boosting converters are presented. By changing the connection position of the anode of the diode and by using different pulse-width-modulation control strategies, different voltage conversion ratios can be obtained. These converters are constructed based on bootstrap capacitors and boost inductors. Above all, two boost inductors with different values, connected in series, can still make the proposed converters work appropriately. Furthermore, although there are three switches in each converter, only one half-bridge gate driver and one low-side gate driver are needed, but no isolated gate driver would be needed. After some mathematical deductions, some experimental results are provided to verify the effectiveness of the proposed converters. [ABSTRACT FROM PUBLISHER]

In this letter, a buck-boost converter, i.e., 2D converter with a positive output voltage, is presented, which combines the KY converter and the traditional synchronously rectified (SR) buck converter. By doing so, the problem in voltage bucking of the KY converter can be solved, thereby increasing the application capability of the KY converter. Since such a converter operates in continuous conduction mode inherently, it possesses the nonpulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Above all, both the KY converter and the SR buck converter, combined into a buck-boost converter with no right-half plane zero, use the same power switches, thereby causing the required circuit to be compact and the corresponding cost to be down. Furthermore, during the magnetization period, the input voltage of the KY converter comes from the input voltage source, whereas during the demagnetization period, the input voltage of the KY converter comes from the output voltage of the SR buck converter. [ABSTRACT FROM AUTHOR]

In this paper, a novel step-up converter is presented, where the charge pump concept, combined with the traditional boost converter structure, is utilized. Although two inductors are used in such a converter, the difference in value between the two inductors affects the regulation performance of this converter slightly. Furthermore, the behavior of this converter is similar to the traditional boost converter, and hence, the control of this converter can be realized easily. Above all, the energy stored in the two inductors, connected in series with the energy stored in the charge pump capacitor and the input voltage, is released to the load during the demagnetization period. In this paper, the basic operating principles of the proposed converter are presented along with some experimental results to demonstrate the effectiveness of this converter. [ABSTRACT FROM AUTHOR]

A simple current sharing control technique for the switching power supply is presented herein, whose basic concept is that the control effort created from the voltage loop is finely tuned by the control effort created from the current sharing loop based on the proposed phase link so as not only to obtain the desired output voltage but also to make the load current distributed among phases as evenly as possible. Such a control method is not only without any current sharing bus as compared with the traditional current sharing methods, but also suitable for multiple phases under the condition that any one phase among multiple phases fails. Moreover, based on phase link, there is no divider used, as compared with the traditional average current method, and hence, the number of logic elements in the field-programmable gate array (FPGA) can be reduced. In this paper, the detailed basic operating principles, together with new mathematical deductions based on the superposition concept, are firstly described, and secondly some experimental results, based on the FPGA to realize the fully digitalized control of the overall system using one-comparator counter-based sampling without any analog-to-digital converter (ADC), are provided to verify the effectiveness of proposed control strategy. [ABSTRACT FROM PUBLISHER]

In this paper, a fully digitalized current sharing strategy without any analog-to-digital converter (ADC) is presented and applied to light-emitting diode (LED) lighting. By doing so, the cost for digital control is reduced significantly due to no ADC used. Aside from this, LED dimming is easy to realize. Above all, the proposed current sharing method has the capability of resisting variations in input voltage and component parameter. Such a control topology is demonstrated by some experiments and hence is very suitable for LED street lighting. [ABSTRACT FROM AUTHOR]

A simple current-sharing control technique for the switching power supply is presented herein, which is based on the concept of the differential-mode transformer and which makes the load current evenly shared well among phases all over the line voltage and load current ranges. This current-sharing structure is very simple, and it makes the efficiency relatively high at light load, which is quite suitable for industrial applications with standby power considered. In this circuit, a synchronously rectified switch is used to further upgrade the efficiency, and the coupling output inductors in copolarity are utilized to decrease the phase current ripples. In this paper, the detailed basic operating principles, together with mathematical deductions, are first described, and second, some simulated and experimental results are provided to demonstrate the proposed control strategy. [ABSTRACT FROM AUTHOR]

In this letter, a KY boost converter is presented, which is the KY converter combined with the traditional synchronously rectified (SR) boost converter. Such a converter has continuous input and output inductor currents, different from the traditional SR boost converter, and has a larger voltage conversion ratio than the traditional SR boost converter does, and hence, this converter is very suitable for low-ripple applications. A detailed description of the proposed converter is presented herein along with a mathematical deduction and some experimental results. [ABSTRACT FROM PUBLISHER]