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The use of light-emitting diodes (LEDs) in street lighting applications has been greatly welcomed with the current trends of energy saving, environmental protection, carbon reduction, and sustainable development. This paper presents a novel AC-DC LED integrated streetlight driver that combines an interleaved buck converter with a coupled inductor and a half-bridge series resonant converter with a full-bridge rectifier into a single-stage power conversion topology with power factor correction (PFC) and soft switching capabilities. The PFC is achieved by designing the coupling inductor in the interleaved buck converter sub-circuit in discontinuous conduction mode. In addition, the resonant tank in the half-bridge series resonant converter sub-circuit is designed to be similar to an inductive load, thus giving the power switch a zero-voltage switching (ZVS) function, decreasing switching losses and increasing the overall efficiency of the proposed circuit. A prototype circuit of the proposed LED integrated streetlight driver with a power rating of 165 W (235 V/0.7 A) and 110 V input utility voltage has been developed and tested. According to the measurement results, a power factor greater than 0.98, a total harmonic distortion coefficient of the input current less than 3%, and an efficiency greater than 89% were obtained in the AC-DC LED integrated streetlight driver. Therefore, the experimental results are satisfactory and demonstrate the functionality of the proposed AC-DC LED integrated streetlight driver.

Many transformer-less pseudo dc-link inverters with step-up/down feature have been proposed to simplify circuit complexity and improve efficiency. Among them, the traditional boost converter is usually used to step up output voltage. In actuality, however, voltage gain will be limited by both the parasitic resistance of the power components and the reverse-recovery problems exhibited by the power diodes under a high duty ratio. Therefore, in order to develop grid-tied photovoltaic (PV) power systems with 220- $\text{V}_{\mathrm {rms}}$ voltage, this article proposes a transformer-less high-gain step-up/down inverter. The proposed inverter is composed of a high-gain boost converter and a full-bridge unfolder. The input current is equally shared by the two boost inductors, so the conduction losses can be reduced to improve efficiency. A partial sinusoidal pulsewidth modulation (P-SPWM) controls the full-bridge unfolder to implement the step-down function. The proposed inverter requires only a single stage of energy processing to generate 220- $\text{V}_{\mathrm {rms}}$ sinusoidal output voltage. Finally, a 1-kW laboratory prototype is built using careful analysis and design procedures. The experimental results are provided to verify the validity and feasibility of the proposed inverter.

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.

To improve the efficiency of photovoltaic (PV) grid-tied systems and simplify the circuit structure, many pseudo DC-link inverters have been proposed by combining a sinusoidal pulse-width modulation (SPWM) controlled buck-boost converter and a low-frequency polarity unfolder. However, due to the non-ideal characteristics of power diodes, the voltage-gain of a buck-boost converter is limited. To meet the needs of grid-connected systems with low input voltage and 220 Vrms utility, this paper uses two two-switch buck-boost converters with coupled inductors to develop a transformer-less buck-boost grid-tied inverter with low leakage-current and high voltage-gain. The proposed inverter is charging on the primary side of the coupled inductor and discharging in series on the primary side and the secondary side so that the voltage-gain can be greatly increased. Furthermore, the utility line can be connected to the negative end of the PV array to suppress leakage current, and the unfolding circuit can be simplified to reduce the conduction losses. High-frequency switching is only performed in one metal-oxide-semiconductor field-effect transistor (MOSFET) in each mode, which can effectively improve conversion efficiency. A prototype was implemented to obtain experimental results and to prove the validity of the proposed circuit structure.

Light-emitting diode (LED) has the characteristics of environmental protection and energy saving, having become the lighting source of a new generation of street-light lamps. The traditional two-stage power supply for providing an LED street-light lamp is composed of an AC-DC converter with a power-factor-correction (PFC) function at the front stage and a DC-DC converter at the rear stage. The two-stage power supply for an LED street-light lamp has a large number of electronic components and costs, and the circuit efficiency is not high. Therefore, this paper presents a novel single-stage high power factor AC-DC power supply for providing an LED street-light lamp featuring soft-switching and Bluetooth wireless dimming capability through using smart tablets or smartphones to remote control the output power of the LED street-light lamp for achieving energy-saving benefits. The proposed AC-DC LED power supply integrates an interleaved buck converter circuit with coupled inductors and a half-bridge LLC resonant converter circuit into a single-stage power conversion circuit. Moreover, the coupled inductor of the interleaved buck converter circuit is designed to operate in the discontinuous conduction mode, which can naturally achieve PFC. In addition, the two power switches in the novel LED power supply have zero-voltage switching (ZVS) characteristics, which can reduce the switching losses of the power switches. The two output diodes have the characteristics of zero-current switching (ZCS), which can reduce the conduction losses of the power diodes. This paper developed a single-stage prototype circuit for providing an 144 W (36 V/4 A)-rated LED street-light lamp. According to the experimental results of the prototype circuit with an AC input voltage of 110 volts, the presented single-stage LED power supply offers high power factor (PF > 0.99), low input-current total harmonic distortion factor (THD < 3%), and high efficiency (>89%). In addition, this paper used the built-in Bluetooth wireless communication function of a smart tablet or smart phone to fulfill remote dimming control. By changing the duty ratio of the control signal, we could realize remote dimming control of 20% to 100% of the output LED street-light lamp power.

This paper presents a single-switch AC-DC LED tube light drier with coupled-inductor and power-factor-correction (PFC) for indoor lighting applications. The presented LED tube light driver including input-current shaping feature integrates an inverse buck-boost converter with coupled-inductor and a lossless snubber. A prototype circuit has been successfully developed and implemented for supplying an 18W(60V/0.3A)-rated LED tube light with an input utility-line voltage of 110 V. Satisfactory results have demonstrated the functionality of the presented AC-DC LED tube light driver and its suitability for indoor lighting applications.

This paper presents a novel single-stage LED power supply with soft-switching feature suitable for streetlight applications. The proposed AC-DC LED power supply integrates an interleaved buck converter with coupled inductors and a half-bridge LLC resonant converter into a single-stage power-conversion circuit with reduced voltage stress on the DC-bus capacitor and power switches. Furthermore, coupled inductors in the interleaved buck converter are designed to be operated in discontinuous-conduction mode (DCM) for carrying on power-factor-correction, and the half-bridge LLC resonant converter features zero-voltage switching (ZVS) to reduce switching losses of power switches, and zero-current switching (ZCS) to decrease conduction losses of power diodes. A 144 W (36V14A)-rated LED prototype circuit is successfully developed and implemented for supplying an LED streetlight module and operating with a utility-line input voltage of 110 V. High power factor and satisfying efficiency are achieved in the proposed LED power supply for streetlight applications.

Traditional photovoltaic (PV) grid-connection inverters with sinusoidal pulse-width modulation (SPWM) control suffer the problem of buck-typed conversion. Additional line-frequency transformers or boost converters are required to step-up output voltage, leading to low system efficiency and high circuit complexity. Therefore, many flyback inverters with electrical isolation have been proposed by adopting a flyback converter to generate a rectified sine wave, and then connecting with a bridge unfolder to control polarity. However, all energy of a flyback inverter must be temporarily stored in the magnetizing inductor of transformer so that the efficiency and the out power are limited. This paper presents a high-efficiency active-clamp forward inverter with the features of zero-voltage switching (ZVS) and electrical isolation. The proposed inverter circuit is formed by adopting a forward converter to generate a rectified sine wave, and combining with the active-clamp circuit to reset the residual magnetic flux of the transformer. Due to the boost capability of the transformer, this inverter is suitable for the PV grid-connection power systems with wide input-voltage variation. The operation principles at steady-state are analyzed, and the mathematical equations for circuit design are conducted. Finally, a laboratory prototype is built as an illustration example according to proper analysis and design. Based on the experimental results, the feasibility and satisfactory performance of the proposed inverter circuit are verified.

In this paper, the study of various sliding modes has suggested that integral terminal attractor (ITA) performs satisfactorily in regulating the output during load perturbations. Though all sliding modes are insensitive to system uncertainties, their unique properties are greatly different. The sliding mode control (SMC) and terminal attractor (TA) inherently have steady-state error, but TA assures the good transient response. Though both integral sliding mode control (ISMC) and ITA possess less steady-state error, better transient response is ITA. Experimental results in this study show that the ITA can be regarded as a viable controller for pulse-width modulated (PWM) inverter applications, such as photovoltaic inverter, wind power inverter and fuel cell inverter.

This study presents a dc/dc converter featuring soft-switching characteristic, high conversion efficiency, and high step-up ratio. The proposed circuit is composed of two parallel-connected boost converters. Only one coupled inductor is used to replace inductors of the boost converters which are interleaved operated at discontinuous-conduction mode (DCM). The current ripples at the input and the output terminals are reduced due to the interleaved operation. By freewheeling the current of the coupled inductor to discharge the stored electric charges in the parasitic capacitors of the active switches, both active switches can fulfill zero-voltage switching on (ZVS). Owing to DCM operation, the freewheeling diodes can fulfill zero-current switching off (ZCS). Therefore, the power conversion efficiency is improved. The operation principle for each operation mode is analyzed in detail and design equations for the component parameters are provided in this report. Finally, a prototype 200 W 48&ndash, 400 V converter was implemented and measured to demonstrate the effectiveness of the proposed circuit.

This paper puts forward an optimal quick-response variable structure control with a single-phase sine-wave inverter application, which keeps harmonic distortion as low as possible under various conditions of loading. Our proposed solution gives an improvement in architecture in which a quick-response variable structure control (QRVSC) is combined with a brain storm optimization (BSO) algorithm. Notwithstanding the intrinsic resilience of a typical VSC with respect to changes in plant parameters and loading disruptions, the system state convergence towards zero normally proceeds at an infinitely long-time asymptotically, and chattering behavior frequently takes place. The QRVSC for ensuring speedy limited-time convergence with the system state to the balancing point is devised, whilst the BSO will be employed to appropriately regulate the parametric gains in the QRVSC for the elimination of chattering phenomena. From the mix of both a QRVSC together with a BSO, a low total harmonic distortion (THD) as well as a high dynamic response across different types of loading is generated by a closed-loop inverter. The proposed solution is implemented on a practicable single-phase sine-wave inverter under the control of a TI DSP (Texas Instruments Digital Signal Processor). It has experimentally shown the simulation findings as well as the mathematical theoretical analysis, displaying that both quick transient reaction as well as stable performance could be obtained. The proposed solution successfully inhibits voltage harmonics in compliance with IEEE 519-2014’s stringent standard of limiting THD values to less than 5%.

Purpose A typical photovoltaic grid-connection power system usually consists of multi-stage converters to perform multiple functions simultaneously. To simplify system configuration, reduce cost and improve conversion efficiency, this paper aims to develop a buck–boost-type inverter. The proposed inverter has both step-up and step-down functions, so that it is suitable for applications with wide voltage variation. As only one power switch operates with high frequency at one time, switching losses can significantly be reduced. Design/methodology/approach A step-up/down inverter is developed by adopting a buck-interleaved buck–boost (BuIBB) DC-DC converter and connecting with an H-bridge unfolding circuit with line-commutated operation. Finding The proposed circuit can work functionally as either a buck-type or boost-type inverter, so that partial energy can be directly delivered to output to improve efficiency. The input current is shared by two inductors, leading to the reduction of current stresses. Research limitations/implications To apply the proposed inverter to micro-inverter applications in the future, developing a step-up/down inverter with a higher conversion ratio will be considered. Practical implications A laboratory prototype is built accordingly to verify the feasibility of the proposed inverter. The experimental results are presented to show the effectiveness. Originality/value This paper proposes a step-up/down inverter by using the BuIBB converter, which is innovatively studied.

This paper presents a single-stage driver with soft-switching and interleaved power-factor correction (PFC) features suitable for light-emitting diode (LED) energy-saving streetlight applications. The proposed LED streetlight driver integrates an interleaved buck-boost PFC converter with coupled inductors and a half-bridge LLC resonant converter into a single-stage power-conversion circuit with reduced voltage stress on the DC-linked capacitor and power switches, and it is suitable for operating at high utility-line voltages. Furthermore, coupled inductors in the interleaved buck-boost PFC converter are operated in discontinuous-conduction mode (DCM) for accomplishing PFC, and the half-bridge LLC resonant converter features zero-voltage switching (ZVS) to reduce switching losses of power switches, and zero-current switching (ZCS) to decrease conduction losses of power diodes. Operational modes and design considerations for the proposed LED streetlight driver are introduced. Finally, a 144 W (36V/4A)-rated LED prototype driver is successfully developed and implemented for supplying a streetlight module and operating with a utility-line input voltage of 220 V. High power factor, low output-voltage ripple factor, low output-current ripple factor, and high efficiency are achieved in the proposed LED streetlight driver.

A novel dimmable light-emitting diode (LED) driver is proposed in this study. The circuit topology uses two active switches. One active switch shared by a buck–boost converter and a buck converter is operated at high-switching frequency while the other one is low-frequency pulse-width modulated to dim high-power LEDs. The buck–boost converter plays the role of a power-factor corrector. It operates at discontinuous-conduction mode to waveshape the line current to be sinusoidal and in phase with the input-line voltage. The buck converter regulates the dc-link voltage to output a low-frequency pulse-width modulation (PWM) voltage to drive high-brightness LEDs. Since only one power-conversion process is required, and the buck converter works only when the low-frequency PWM voltage is at a high level, the proposed LED driver has the advantage of high efficiency. Besides, it achieves unity power factor and low total current harmonic distortion.

This study proposes a single-stage light-emitting diode (LED) tube lamp driver with input-current shaping for T8/T10-type fluorescent lamp replacements. The proposed AC–DC LED driver integrates a dual-boost converter with coupled inductors and a half-bridge series-resonant converter with a bridge rectifier into a single-stage power conversion topology. This paper presents the operational principles and design considerations for one T8-type 18 W-rated LED tube lamp with line input voltages ranging from 100 V rms to 120 V rms. Experimental results for the prototype driver show that the highest power factor (PF = 0.988), lowest input current total harmonic distortion (THD = 7.22%), and highest circuit efficiency (η = 92.42%) are obtained at an input voltage of 120 V. Hence, the proposed driver is feasible for use in energy-efficient indoor lighting applications.

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.

This paper proposes a dc/dc converter that mainly consists of two interleaved boost converters. Both boost converters are designed to operate at discontinuous current mode (DCM). Both boost converters share one coupled inductor which consists of a magnetic core with two windings. Based on the principle of magnetic flux balance, the magnetic exciting current can be diverted between two windings of the coupled inductor. This leakage current is used to discharge the parasitic capacitors of the active switches. By this way, the active switches can be turned on at zero voltage. It helps to reduce the switching losses and hence, achieve high circuit efficiency. A 200W prototype circuit was built and tested. Based on the experimental results, both active switches are operated at ZVS. The circuit efficiency is 90%. The satisfactory performance has verified the feasibility of the proposed circuit.

To simplify circuit configuration and increase system efficiency, a two-switch buck-boost (TSBB) inverter has been proposed by connecting a buck-cascaded buck-boost (BuCBB) converter in series with a line-frequency unfolding circuit. In accordance with the level of input voltage and sinusoidal output voltage, this inverter can work with buck or boost operation principle. Wherefore, efficiency can be increased by delivering partial energy directly to output. This inverter is suitable for developing photovoltaic grid-connection systems with wide voltage-variation of input. In order to further increase its output power, this paper proposes to develop a high-efficiency inverter by connecting two BuCBB converters in interleaving parallel. Due to the cancelation of inductor ripple-currents, size and cost of input and output filters can be significantly reduced. Since the output power is shared equally by two parallel dc-dc converters, the overall conduction losses of power switches and inductors can also be reduced to improve efficiency. Finally, an experimental prototype is implemented with proper analysis and design. The experimental results are measured to verify the feasibility and correctness of the proposed inverter.

This paper develops an enhanced grey variable structure controlled DC-AC inverter in parallel, and is suitable for the application of ultra-precision machining (UPM). The enhanced grey variable structure control methodology consists of a nonlinear sliding function (NSF) and a grey model, GM(2,1). The NSF has finite system-state convergence time, and thus the AC output voltage regulation and balanced current-sharing among the parallel modules can be achieved. However, once the loading of the UPM is a highly nonlinear condition, the chatter still exists in NSF. The chatter may cause heat losses and high voltage harmonics in parallel-connected DC-AC inverter output, and thus deteriorates the stability and reliability of the UPM. To eliminate the chatter, the control gains of the NSF can be adjusted by the use of the GM(2,1) under system uncertainty bounds are overestimated. With the enhanced methodology, the parallel-connected DC-AC inverter yields a high-quality AC output voltage with low voltage harmonics and fast dynamic response under highly nonlinear loading, thus achieving the stability and reliability of the UPM. Experimental results are performed to demonstrate the enhanced methodology.

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 (

Recently, many high-efficiency buck-boost typed inverters for the photovoltaic (PV) grid-connection applications have been proposed. However, the PV grid-connection inverters are in idle state at nighttime or low insolation. Based on green energy demand, the presented work proposes a high-efficiency bidirectional buck-cascaded buck-boost (BuCBB) inverter. It is developed via the connection of a bidirectional BuCBB converter and an H-bridge unfolding circuit with line-commutated. At nighttime, the proposed inverter can function as an active power filter (APF) for compensating reactive power and suppressing current harmonic distortions. The proposed circuit can work functionally as either a step-down or step-up inverter, resulting in low dc-bus voltage. Electrolytic capacitors with lower voltage-rating can be adopted for improving system life-time and reducing costs. A laboratory prototype with 110 V rms /60 Hz utility-line voltage is implemented accordingly to verify the feasibility of the proposed inverter.

In order to simplify the configuration of photovoltaic (PV) grid-connection system, this paper proposes to adopt a buck-boost dc-dc converter, and then develops a single-phase inverter via the connection with an H-bridge unfolding circuit with line-commutated. Depending on the conditions of dc input-voltage and ac output-voltage, the proposed circuit can work functionally as either a step-down or step-up inverter. It is suitable for the applications with wide voltage-variation range. Since only one switch is operated with high-frequency, the switching loss can be significantly reduced to improve the efficiency. Finally, a laboratory prototype with 110 V rms / 60 Hz output voltage is then simulated and implemented accordingly to verify the feasibility of the proposed inverter.

This paper proposes a novel LED driver, which consists of an isolated single-switch AC-DC converter with power factor correction (PFC) suitable for streetlight applications. Theoretical analysis of operational modes for the presented LED driver is included. In addition, a 65W-rated prototype circuit of the proposed LED driver with an input utility-line voltage of 110 V has been implemented and tested. Satisfying outcomes obtained from experimental results demonstrate the functionality of the proposed LED driver.

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.

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.

Light emitting diodes (LEDs) have substituted for incandescent bulbs and fluorescent lamps gradually in the residential, industrial and commercial lighting applications. This paper proposes an active clamp forward converter with the sequential color display (SCD) control to drive red, green and blue (RGB) LED arrays. Both of the main switch and the auxiliary switch can turn on under zero voltage switching (ZVS), resulting in high system efficiency. RGB LED arrays are sequentially driven by the same converter, which can save components and reduce cost significantly. Besides, the pulse-width modulation (PWM) control is applied to achieve a large chromaticity variation. The operation principles of the proposed LED driver are addressed. Experimental results of a 100W laboratory prototype are used to verify the feasibility and validity of the theoretical predictions.

This paper proposes a novel high-step-up DC-DC power converter for high output-voltage applications from a low level of input voltage. The presented power converter is composed of a integrated boost-flyback converter with two output windings plus cascaded voltage doublers to boost up the 12 V input voltage to a high DC voltage level of 400 V. Description of the presented DC-DC power conversion circuit, and experimental results of a prototype converter for providing 40W output power with a 12V input DC voltage are demonstrated.

This paper proposed a single-stage single-switch ac-to-dc converter which is derived by integrating a boost converter and a flyback converter. Only one active switch and simple control are required. The boost converter performs as a power-factor corrector (PFC) which is designed to operate at discontinue-conduction mode (DCM) to makes the input current be a sinusoidal waveform and in phase with the input voltage. High power factor and low total current harmonic distortion (THD) are ensured. The flyback converter further regulates the output voltage of the boost converter to provide an isolated dc voltage with low voltage ripple. The flyback converter is designed to operate at continue-conduction mode (CCM) to have the transformer current of a low peak value. It will be effectively reduce the switching stress and the switching losses of semiconductor components. The paper conducts the mathematical equations for the converter circuits, and then designing the circuit parameters. A prototype circuit designed for a 100 W output power was built and tested. Satisfactory results are obtained experimentally.

In this paper, a variable structure controller based on dynamic game theory is proposed to reduce the effects of parameter variations, and external disturbances caused by uncertain systems. The variable structure controller (VSC) is a popular method for tracking control, since it can offer robustness to parameter variations, and external disturbances. However, the chattering problem occurs. The chattering may cause the degraded system performance and poor tracking control. Thus, the dynamic game theory is applied in VSC, to quickly, and precisely enforce the system states to the sliding surface, thus reducing the chattering. The stability and the convergence of the overall system are confirmed by the Hamiltonian function. The control algorithm has been realized for the actual power conditioning system (PCS) controlled by a TMS320F2812 DSP. With this proposed controller, an example that the controlled PCS under nonlinear loads yields the better robustness in performance. Experimental results validate the theoretical analysis.