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In this paper, a novel single-switch DC-DC converter is proposed for dimmable MR16 light-emitting diode (LED) drivers. The proposed driver can achieve very low output voltage ripple without using MHz switching frequency; therefore, small non-electrolytic capacitors can be used to achieve longer lifetime and higher efficiency. Also, because of special merit of the proposed converter, it can be designed so that much wider duty ratio operating range can be achieved for LEDs. Hence, better digital dimming level resolution can be attained. Finally, a prototype driver for MR16 LED lamps is constructed to demonstrate the effectiveness of the converter. Experimental results show that a maximum efficiency of 92% can be achieved. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In order to solve the problems caused by the pulsating current ripple of switching-mode power converters, a passive pulsating ripple canceling circuit (PPRCC) is proposed in this paper. The features of the proposed PPRCC include simple, modular structure, and high degree of design flexibility. By integrating the proposed PPRCC, an input current ripple-free flyback-type converter is adopted and analyzed as an example because of its comprehensive utilization in small power rating commercial products. In addition, the switch voltage spike of flyback converter can be suppressed by integrating the proposed PPRCC without using snubbers, it turns out that the efficiency can be further improved. The corresponding operating principle, steady-state analysis, and zero ripple design criteria of the proposed PPRCC are provided. Finally, a 100 W laboratory prototype is constructed to verify the effectiveness of the proposed principle. Experimental results show that the resulting peak-to-peak input current ripple is reduced by 96% and nearly 0.5% and 1.7% improvement in efficiency can be achieved by the proposed PPRCC, at 80 W and 100 W load conditions, respectively. [ABSTRACT FROM PUBLISHER]

In this paper, a novel single stage passive ac to dc converter is first proposed for LED drivers. No controlled active switch, electrolytic capacitors and auxiliary power supply are required in the proposed LED driver. The advantages of the proposed driver include long lifetime, high efficiency and recyclability. In addition, application of the proposed quasi-resonant circuit enables one to use much smaller capacitance and inductance for the capacitors and inductor to achieve high power factor and compact size. Theoretical analysis of the proposed LED driver is made, and some design guidelines are provided. Finally, a prototype system of 50-W rating is constructed. Experimental results confirm the validity of the proposed LED driver. It can be seen that the proposed driver is robust to variations of input voltage, frequency and output load. The features of low cost, long lifetime, robustness and without EMI problem render the proposed driver a very attractive alternative for outdoor applications. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel transformer-less direct current (dc) converter that features low switch voltage stress and automatic uniform current sharing. An interleaved four-phase voltage divider operating from a 400 V dc bus is used to achieve a high step-down conversion ratio with a moderate duty ratio. Based on the capacitive voltage division, the proposed converter achieves two major objectives, i.e., increased voltage conversion ratio, due to energy storage in the blocking capacitors, and reduced voltage stress of active switches and diodes. As a result, the proposed converter permits the use of lower voltage rating MOSFETs to reduce both switching and conduction losses, thereby improving the overall efficiency. In addition, due to the charge balance of the capacitors, the proposed converter enables automatic uniform current sharing of the interleaved phases without adding extra circuitry or complex control methods. The operation principles and performance analyses of the proposed converter are presented, and its effectiveness is verified by a 500 W output power prototype circuit that converts 400 V input voltage into 24 V output voltage. [ABSTRACT FROM AUTHOR]

In this paper, a passive ripple canceling circuit (PRCC) is proposed to eliminate the output power reduction effect of photovoltaic (PV) systems caused by the current ripple of the PV converters. Special features of the proposed PRCC include having low-cost simple modular structure and being independent of the duty ratio control of the main power circuit. Hence, it can be easily integrated to the main power circuit to achieve zero input current ripple, yielding less filter size, loss, and fast response. Meanwhile, the linear line maximum power point tracking (MPPT) control is also integrated with the proposed module integrated converter (MIC) to achieve instantaneous tracking response. Finally, a 90-W laboratory prototype is constructed to verify the effectiveness of the proposed principle. It is seen that the resulting peak-to-peak input current ripple is reduced to about 2% of the original dc converter input ripple. In other words, the input current ripple is almost zero. As a result, the harvested power of the proposed MIC can be increased by 7% as compared with that of the MIC without the proposed PRCC. [ABSTRACT FROM AUTHOR]

In this paper, a novel transformerless interleaved high step-down conversion ratio dc–dc converter with low switch voltage stress is proposed. In the proposed converter, two input capacitors are series-charged by the input voltage and parallel-discharged by a new two-phase interleaved buck converter for providing a much higher step-down conversion ratio without adopting an extreme short duty cycle. Based on the capacitive voltage division, the main objectives of the new voltage-divider circuit in the converter are for both storing energy in the blocking capacitors for increasing the step-down conversion ratio and reducing voltage stresses of active switches. As a result, the proposed converter topology possesses the low switch voltage stress characteristic. This will allow one to choose lower voltage rating MOSFETs to reduce both switching and conduction losses, and the overall efficiency is consequently improved. Moreover, due to the charge balance of the blocking capacitor, the converter features automatic uniform current sharing characteristic of the interleaved phases without adding extra circuitry or complex control methods. The operation principles and relevant analysis of the proposed converter are presented in this paper. Finally, a 400-V input voltage, 25-V output voltage, and 400-W output power prototype circuit is implemented in the laboratory to verify the performance. [ABSTRACT FROM PUBLISHER]

In this paper, a modular interleaved boost converter is first proposed by integrating a forward energy-delivering circuit with a voltage-doubler to achieve high step-up ratio and high efficiency for dc-microgrid applications. Then, steady-state analyses are made to show the merits of the proposed converter module. For closed-loop control design, the corresponding small-signal model is also derived. It is seen that, for higher power applications, more modules can be paralleled to increase the power rating and the dynamic performance. As an illustration, closed-loop control of a 450-W rating converter consisting of two paralleled modules with 24-V input and 200-V output is implemented for demonstration. Experimental results show that the modular high step-up boost converter can achieve an efficiency of 95.8% approximately. [ABSTRACT FROM AUTHOR]

In this paper, a linear torque control strategy is first proposed for interior permanent magnet synchronous motor drives to fully utilize the reluctance torque and simplify the controller design. The proposed linear torque control strategy also extends the existing maximum torque per ampere control In the constant torque limit region up to the entire field'weakenlng region. It is found that in an intermediate speed region, called partial field-weakening region, the existing maximum torque per ampere control can still be applied under lighter load condition. In addition, the proposed control can also achieve the objective of minimum copper loss (i.e., maximum torque per ampere) for the entire speed range. Sound theoretical basis is given in the context. Moreover, an adaptive limiter is proposed for efficiently hnple. menting the proposed control strategy over the entire speed range. Finally, a prototype is also constructed by using a fixed-point DSP TMS32OFZ4O and some experimental results are given to verify the validity of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Derives a closed-form duty cycle control law based on the linear combination of two sets of continuous duty cycle control laws. Description of the circuit of the three-phase boost rectifier; Output voltage bounds for different control laws.

Presents information on a closed-form duty cycle control law proposed for ac/dc converters. Information on the circuit configuration of the proposed ac/dc converter; Derivation of the closed-form control laws for the converter; Details on a basic sinusoidal pulsewidth modulation scheme.

Presents information on a study which proposed a single-stage three-phase pulsewidth modulation boost-buck alternating current/direct current converter based on a set of generalized zero-space vectors. Circuit configuration and operation principle of the proposed converter; Operation range of the proposed converter; Experimental results; Conclusions.

Proposes an algorithm to calculate the smallest singular value of a Jacobian matrix of the load flow equation by employing the non-iterative characteristics of an Incremental Condition Estimation (ICE) method and large scale power networks. Theoretical basis of the proposed method; Two steps of the proposed method; Numerical example; Conclusions.

A new PWM solid-state synchronous condenser (SSSC) is designed and implemented in this paper. The power circuit of this SSSC is simple as only four power semiconductor switches are used. The SSSC allows leading or lagging reactive power compensation, and continuous control of reactive power. It has a rapid response, which allows an almost instantaneous reactive current control, with low harmonic distortion in the line current. Because it uses a current control, instantaneous overcurrent protection is provided naturally, thereby increasing the reliability. The capability of the proposed synchronous condenser is estimated. To ensure a clean line current waveform is obtained, the current-tracking mechanism is analysed with a graphical aid and a critical condition is presented. The performance of the SSSC is demonstrated with some simulation and experimental results. [ABSTRACT FROM AUTHOR]

The conventional step-down dc–dc converters under the single pulsewidth modulation (PWM) control scheme may not provide enough step-down voltage conversion capabilities with considering the minimum on-time and the switching frequency of the power switch. In order to overcome this difficulty, a dual PWM control scheme for designing the high step-down dc–dc converter is proposed in this article. Both high-frequency and low-frequency PWM waveform generators are utilized in synthesizing the dual PWM control of buck converters. The resulting PWM waveform will lead to various switching cycles, and five operating modes of the buck converter, which can be defined accordingly. The operation principle of the proposed converter and its small-signal switched model are presented in detail. One salient feature of the proposed design is that if the duty cycle of the high-frequency PWM is exactly equal to that of the low-frequency PWM, by exploring the volt–second balance condition, the voltage gain can be expressed as the quadratic formula of the duty cycle of the PWM signal when power switches are operated under the continuous conduction mode. Thus, a high step-down conversion ratio and significant reductions of the inductor current ripple can be ensured simultaneously. Since no modifications of the conventional circuit topology are made, the proposed scheme is very cost-effective. Simulation studies and hardware prototype circuit implementations are conducted to validate the proposed design with satisfactory performance. [ABSTRACT FROM AUTHOR]