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It is well-known that the ripple control technique benefits from fast load transient response and small cross regulation for single-inductor dual-output (SIDO) dc–dc converter. However, existing capacitor current ripple (CCR) controlled SIDO buck converter suffers from incomplete operation state and single switching path. Thus, it has a limited stable load range. In order to extend the stable load range and suppress cross regulation of SIDO buck converter in continuous conduction mode (CCM), a novel ripple control technique, called as capacitor current and capacitor voltage ripple (CCVR) control, is proposed in this article. The operation principle of the proposed CCVR controlled SIDO CCM buck converter is presented, and its discrete iterative map model is established. Furthermore, the stability and stable load range have been discussed by using bifurcation diagrams. Based on the established small signal model, Bode plots are given to show the performance in suppressing cross regulation. Finally, simulation and experiment results are provided to verify the theoretical analysis. It shows that the proposed CCVR control technique can be applied to SIDO CCM buck converter to extend its stable load range and suppress its cross regulation. [ABSTRACT FROM AUTHOR]

Two-stage power conversion of class-D amplifier with front-end switching mode power supply affects the power conversion efficiency of audio amplifier system. Single-stage inverter (SSI) developed from cycloconverter can be used as audio amplifier to improve efficiency. However, current commutation of cycloconverter switches challenges for high efficiency and low total harmonic distortion (THD). In this article, a bipolar phase shift modulation (BPSM) SSI is proposed for high efficiency low distortion audio amplification. Full bridge active clamp (FBAC) circuit is used to clamp the voltage across cycloconverter switches and recycle the energy of filter inductor and leakage inductance. By using active clamp, utilization of magnetizing inductance current and optimization of driving sequence of clamp switches, zero voltage switching of the proposed BPSM FBAC-SSI is achieved over wide range. With BPSM and voltage clamp across cycloconverter switches, low THD of output voltage is also achieved. A 200 kHz prototype with 250 W output power is presented to verify the analysis results of the proposed BPSM FBAC-SSI. [ABSTRACT FROM AUTHOR]

In this article, the sector update delay (SUD) of the digital control three-phase six-switch (3 ph–6 s) buck power factor correction (PFC) converter is analyzed. SUD of 3 ph–6 s buck PFC converter results in the increase of switching loss and input current distortion at the transition from even sector to odd sector. For applications when ac input frequency is 47–63 Hz, the effect of SUD is relatively small, and SUD is usually ignored. However, for applications of high ac input frequency, e.g., 360–800 Hz, the SUD of 3 ph–6 s buck PFC converter seriously affects its efficiency and input current total harmonics distortion (THD). In order to suppress the effect of SUD and to improve the input current THD and efficiency of 3 ph–6 s buck PFC converter over a wide ac input frequency, a time delay compensation method has been proposed in this article. The effect of SUD is verified by a 1.5-kW prototype with a low-cost microcontroller. Experimental results show that lower input current THD and higher efficiency over a wide ac input frequency have been achieved by the proposed compensation method. [ABSTRACT FROM AUTHOR]

A phase-shift pulse-frequency modulation (PS-PFM) for a full-bridge LCC resonant converter is proposed in this paper to reduce both switching frequency variation range and reactive power of a traditional PFM LCC resonant converter. Like the PFM LCC resonant converter, a PS-PFM LCC resonant converter has a wider zero voltage switching operation range than a phase-shift modulated LCC resonant converter. By integrating a voltage-controlled carrier generator, the proposed PS-PFM modulator can adjust phase-shift angle and switching frequency simultaneously, resulting in one more degree of control freedom to optimize the steady-state performance of an LCC resonant converter. A detailed analysis of the proposed PS-PFM LCC resonant converter is performed and a step-by-step parameter design procedure is given. A 500-W/48-V prototype with 100–200 V input voltage is built to verify the theoretical analysis. The maximum efficiency of the prototype reaches 95.3%. [ABSTRACT FROM AUTHOR]

MR16 lighting system with a high-frequency step-down electronic transformer is widely used in commercial lighting. In this paper, a single-switch quadratic boost light emitting diode (LED) driver compatible with electronic transformers for the MR16 lighting system is proposed and analyzed. It combines a prestage boost power factor correction (PFC) converter and a second-stage boost dc–dc converter with a single switch. The effect of the dc link voltage ripple of the prestage boost PFC converter on the output of the second-stage boost dc–dc converter is eliminated by a fast voltage mode control loop of a second-stage circuit. Therefore, flicker-free low ripple LED current is achieved. With a small dc link voltage ripple of prestage, the turn-on time of the active switch is almost constant in a half-line cycle. Therefore, PFC can be achieved with inductor current of prestage operating in a discontinuous conduction mode. With small input capacitance, the proposed LED driver presents a good compatibility performance with different kinds of electronic transformers. Furthermore, the proposed LED driver needs only one active switch and one control loop, which makes circuit volume small and low cost. Finally, a 4 W LED driver for a small-size MR16 lighting system is provided to verify the studied results. [ABSTRACT FROM AUTHOR]

Peak current mode (PCM) control has been widely used for the control of switching dc–dc converters due to its excellent transient performance. With the development of single-inductor dual-output (SIDO) dc–dc converters, PCM control technique is introduced to the control of SIDO dc–dc converters. Conventional PCM buck converter has only one reference current, with two inductor current borderlines are used to divide the operation modes of inductor current. However, PCM SIDO buck converter has more inductor current borderlines as it has one more reference current than that of PCM buck converter. In this paper, inductor current borderlines of PCM SIDO buck converter are investigated, and unified discrete iterative model of PCM SIDO buck converter is established. The effect of the difference of reference currents, initial inductor current and input voltage on the stability of PCM SIDO buck converter has been discussed by using bifurcation diagrams. The study results show that the stability of PCM SIDO buck converter is sensitive to the difference of reference currents, initial inductor current and input voltage. The stability boundary of the difference of reference currents, stability region of initial inductor current, and stability boundary of input voltage are derived. Lyapunov exponent and experimental results are carried out to verify the theoretical analysis results. [ABSTRACT FROM PUBLISHER]

It is known that the ripple-based control of a switching dc–dc converter benefits from a faster transient response than a conventional pulse width modulation (PWM) control switching dc–dc converter. However, ripple-based control switching dc–dc converters may suffer from fast-scale oscillation. In order to achieve fast transient response and ensure the stable operation of a switching dc–dc converter over a wide load range, based on a conventional pulse train (PT) control technique, a peak capacitor current PT (PCC-PT) control technique is proposed in this paper. With a buck converter as an example, the operating modes, steady-state performance, and transient respond performance of a PCC-PT controlled buck converter are presented and assessed. To eliminate fast-scale oscillation, circuit and control parameter design considerations are given. An accurate discrete iteration model of a PCC-PT controlled buck converter is established, based on which the effects of circuit parameters on the stability of the converter operating in a discontinuous current mode (DCM), mixed DCM-continuous conduction mode (CCM), and CCM are studied. Simulation and experimental results are presented to verify the analysis results. [ABSTRACT FROM PUBLISHER]

This paper describes a systematic procedure using power flow graphs for generating all possible double-input single-output (DISO) dc/dc converters. To maximize the generality of applications, the input ports can possibly be connected with voltage source(s) or current source(s), and the output port can be connected with a voltage load or current load. The control methods are described in this paper. A DISO converter with two voltage sources and one voltage load is taken as an example to analyze a few key properties of practical relevance, including input voltage range, efficiency, power distribution, and switching stress. A popular application of DISO converters involves the use of a battery as storage element, and for this specific case, possible choices for the converters, the control method, and the attainable efficiency are discussed. Finally, experimental results are presented to verify the analytical results. [ABSTRACT FROM PUBLISHER]

The pulse-train (PT) control technique for switching dc–dc converters is simple to design and benefits from excellent control performance. Up to now, almost all of the works on PT control are focused on switching dc–dc converters operating in discontinuous conduction mode, with few works reported on PT control of switching dc–dc converters operating in continuous conduction mode (CCM). In this paper, a PT-controlled CCM buck converter is studied and a unique low-frequency oscillation phenomenon is revealed, which results in large undesired inductor-current and output-voltage variations. The effect of equivalent series resistance (ESR) output-capacitor on the low-frequency oscillation is examined. The results indicate that such oscillation occurs when the ESR output-capacitor is relatively small and disappears when it is relatively large. However, a larger ESR will result in a large output-voltage ripple. In order to avoid the low-frequency oscillation and, at the same time, to ensure a small output-voltage ripple, the ICRIF circuit is applied. In this way, a small ESR output-capacitor can be used to decrease the output-voltage ripple. Simulation and experimental results are provided to verify the theoretical analysis. [ABSTRACT FROM PUBLISHER]

Peak Current-Mode (PCM) and Valley Current-Mode (VCM) controlled switching dc-dc converters have symmetrical dynamical behaviors within a wide circuit parameter variation range. To investigate the symmetrical dynamical behaviors between PCM and VCM controlled switching dc-dc converters, the iterative map models and inductor current borderlines that exist in the bifurcation diagrams of both PCM and VCM controlled buck, boost, and buck-boost converters are established. The research results of bifurcation behaviors indicate that the bifurcation diagrams of PCM and VCM controlled switching dc-dc converters have symmetrical dynamical behaviors corresponding to a symmetrical point (SP). The simulation results show that time-domain waveforms of PCM and VCM controlled switching dc-dc converters working in periodic orbits have symmetrical axis and SP, and the SP also exists in corresponding phase portraits. Experimental results are given to verify the analysis and simulation results in this paper. [ABSTRACT FROM AUTHOR]

With the variation of circuit parameters, the operation-state regions of current-mode-controlled switching dc–dc converters can shift among stable period region, robust chaos region in continuous conduction mode, and intermittent chaos region in discontinuous conduction mode. This paper presents a unified approach to the operation-states analysis of switching dc–dc converters with ramp compensation. The piecewise map model of the converters is first derived. With the bifurcation analyses, two boundary classification equations of the orbit state shifting are then obtained. Finally, the operation-state regions are well classified. To verify the theoretical analysis results, 2-D bifurcation diagrams are simulated and experimentations with current-mode-controlled buck converter are conducted. It is revealed that regular and irregular (chaotic or intermittent) operation states can be generated depending on circuit parameters or control of ramp-compensation current. [ABSTRACT FROM AUTHOR]