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Pulsewidth modulation (PWM) strategies, including continuous PWM (CPWM) and discontinuous PWM (DPWM), have been efficiently applied in the three-phase voltage source converters (VSCs). In the three-phase VSCs, dead-time distortion is inevitable. The characteristics of the dead-time distortion of three-phase VSCs with CPWM strategies have been studied extensively, whereas those of DPWM strategies have not been studied in detail. In this article, a comparative analysis of the dead-time distortion of CPWM strategies and DPWM strategies is conducted. Furthermore, the improvement of the PWM strategies to mitigate dead-time distortion is presented. The improved PWM strategies inject the compensation signals to the modulation signals to reconstruct the dead-time voltage error, which can significantly reduce the dead-time distortion of various PWM strategies. Experimental tests are conducted and the experimental results are provided to verify the analysis results of the dead-time distortion of DPWM strategies and the improved PWM strategies. [ABSTRACT FROM AUTHOR]

Due to the input current dead zones, the buck power factor correction converter has to set a fixed output voltage for a tradeoff between the total harmonic distortion (THD ${_\mathit{i}}$) and efficiency. Thus, many converter-cell integrated buck-type converters have been proposed to eliminate the dead zones, which unfortunately deteriorate efficiency due to the extra components.This article proposes a group of bridgeless buck-type integrated topologies. Then, a dead-zone-free bridgeless buck-type topology with a wide output voltage range is targeted for further study. The studied converter operates in the buck+flyback mode and can automatically change to flyback mode when the dead zones occur, which only requires a simple control. Moreover, an integrated transformer based on an E-E core is investigated to reduce cost and volume. The bridgeless operation modes are introduced, followed by the PF and THD ${_\mathit{i}}$ analysis to optimize its performance. Prototypes are built and tested, which confirm the effectiveness of the converter and the integrated magnetic. [ABSTRACT FROM AUTHOR]

Given the telecom base transceiver station (BTS) load mission profiles, a mixed conduction mode (MCM) control for a bridgeless boost PFC converter (IPOS boost) is proposed to mainly improve its power factor and reduce the input current total harmonic distortion (THD ${_{\mathit{i}}}$) in the light-load conditions. The principle of the MCM control and the efficiency analysis are introduced. Then, the experimental verification is performed to show the control effectiveness and performance improvements. Furthermore, a mission profile-based reliability assessment for the PFC converter is presented to analyze the IPOS boost under the classical average current (AVC) control and the proposed MCM control, along with its conventional boost counterpart under the AVC control. Considering the measured efficiency data and BTS typical mission profiles in a rural area, the analysis results indicate that given 20 years of operation, the accumulated failure of the IPOS boost under the AVC controls is 0.27%, and is further decreased to 0.24% by just the software update with the proposed MCM control. By contrast, the accumulated failure of the conventional boost counterpart under the AVC control is 2.06%, much higher than the IPOS boost. [ABSTRACT FROM AUTHOR]

In this article, a half-bridge class-D audio amplifier (HB-CDAA) system with embedded bidirectional buck–boost converter is proposed. The proposed HB-CDAA system consists of a front-end symmetric bipolar output converter, a bidirectional buck–boost converter, and an HB-CDAA. With the help of the embedded bidirectional buck–boost converter, bus voltage pumping on the output of the front-end symmetric bipolar output converter of HB-CDAA can be suppressed. Thus, small ceramic capacitors can be used as bus capacitors to increase power density and to improve audio output quality. Furthermore, ZVS of the embedded bidirectional buck–boost converter can be achieved. The operating principle of the proposed circuit is analyzed and an experimental prototype is built. Experimental results show that ZVS of the embedded bidirectional buck–boost converter is achieved, and bus voltage pumping is successfully suppressed with small bus capacitors. [ABSTRACT FROM AUTHOR]

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]

Based on the current-mode switching cell (CMSC), an inductive power transfer (IPT) system with dual-output is proposed in this letter. In the proposed IPT system, two CMSCs are inversely connected in series at the Rx side. Two CMSCs operate in the positive half-cycle and in the negative half-cycle of the Rx coil current, respectively. The dual output voltages can be regulated independently. The circuit structure of the CMSC is quite simple and helps to make the Rx side more compact. The control scheme is based on Rx-side real-time regulation and thereby wireless communication links are not required. Additionally, zero voltage switching is ensured for all switches. In order to verify the theoretical analysis, an experimental prototype with 20 V/3.3 A and 5 V/3 A outputs is fabricated, and the maximum efficiency can reach 92.8%. [ABSTRACT FROM AUTHOR]

Inductor–capacitor–capacitor-series (LCC-S) compensation topology has been widely used in inductive power transfer (IPT) systems due to its constant coil current regardless of the load and the coupling coefficient. Usually, the inductance of transmitter coil is sensitive to misalignments of the magnetic coupler when the asymmetrical coil structure with a smaller size receiver coil is adopted. The fluctuation of the inductance of transmitter coil will increase the power losses in the primary inverter. To compensate the fluctuation of the transmitter coil inductance, a digital switch-controlled capacitor (D-SCC) for maximum efficiency point tracking (MEPT) of LCC-S compensated IPT system is proposed. Consequently, the proposed LCC-S compensated IPT system can achieve high efficiency against the fluctuation of transmitter coil inductance. In traditional switch-controlled capacitor, high- frequency current sensor is required for the synchronization between the transmitter coil current and the driver signals of the switch-controlled capacitor. Nevertheless, the drive signals of D-SCC can be generated directly by the DSP controller in the primary side without detecting zero-cross points of the transmitter coil current, which can improve the system reliability and reduce the cost. Furthermore, the MEPT based on D-SCC is easy to be implemented because only the input dc current measurement is required. A 3.3-kW prototype is presented to verify the validity of the proposed D-SCC-based MEPT. [ABSTRACT FROM AUTHOR]

To regulate the output voltage of inductor–capacitor–capacitor-series (LCC-S) compensated wireless power transfer (WPT) system, a hybrid control strategy of phase shift modulation (PSM) and a switch-controlled capacitor is presented in this article. In the proposed hybrid control strategy, LCC-S compensated WPT system can realize wide output voltage regulation with zero voltage switching (ZVS), and the reactive current in a resonant tank can be minimized in the whole voltage range. Besides, the current in the primary coil of LCC-S compensated WPT system can be regulated with PSM, which helps to reduce the power loss of the primary coil at light load. Compared with conventional dual-loop hybrid control, the proposed hybrid control can regulate two control variables with one feedback loop simultaneously. To verify the theoretical analysis, a 500-W prototype with 400-V input voltage, 100−250-V output voltage is built. The experimental results show that the inverter can realize ZVS within the whole voltage range and a peak efficiency of 94.7% can be obtained. [ABSTRACT FROM AUTHOR]

Conventional boost power factor correction (PFC) converter is only suitable for two-stage power conversion system due to its high output voltage. Inherent step-up characteristic limits its applications in single-stage low voltage output. In this article, a boost-type single-stage step-down resonant PFC converter, which combines a boost PFC converter and a resonant switched capacitor network by using one active switch, is proposed and analyzed. Similar to conventional boost PFC converter, the proposed converter can achieve unity power factor and low input current ripple in universal-input applications. Moreover, the proposed converter can achieve step-down voltage conversion. Furthermore, high-efficiency is realized due to single-stage power conversion. The proposed converter is studied in terms of operation principle, voltage gain, power factor analysis, and key circuit parameters design. Finally, a 70-W prototype with 96.05% peak efficiency is built to verify the theoretical analysis results. [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]

Pulse train (PT) control strategy for the boost power factor correction (PFC) converter operating in the continuous conduction mode (CCM) is proposed and studied in this article. Average current mode (ACM) control is usually utilized for the CCM boost PFC converter. The ACM-controlled PFC converter suffers from poor dynamic response, because its voltage control loop has to be designed with low bandwidth to minimize the effect of low-frequency output voltage ripple on the current control loop. Different from ACM control, the voltage control loop and current control loop of the PT-controlled PFC converter are decoupled, and thus the effect of low-frequency output voltage ripple on the current control loop is eliminated. Besides, PT modulation is utilized in the proposed controller to regulate the inductor current to follow the current reference. Thus, both high power factor and fast dynamic response can be achieved. The operation principle of the PT-controlled CCM boost PFC converter is analyzed, and a 300-W prototype is built to verify the analysis results. The experimental results show that power factor of the PT-controlled PFC converter is higher than 0.998 and the dynamic response is significantly improved. [ABSTRACT FROM AUTHOR]

A flicker-free single switch multi-string LED driver with high power factor and current balancing is proposed and analyzed. It combines a pre-stage boost PFC converter and multiple second-stage buck dc–dc converters by a single active switch and multiple dc-link capacitors. With the proposed circuit configuration of multiple dc-link capacitors, the output current of each LED string can be balanced. Therefore, by controlling the output current of one LED string, the output currents of other LED strings can be controlled via current balancing of dc-link capacitors. The effect of the ripple of dc-link voltage on each output can be eliminated by fast voltage mode control loop. Therefore, flicker-free low ripple current for each LED string is achieved. With small voltage ripple across dc-link capacitors, the turn on time of active switch is almost constant in a half line cycle. Therefore, power factor correction can be achieved with inductor current of pre-stage operating in discontinuous conduction mode (DCM). Finally, prototypes of dual-string LED driver with 90–135 Vac input and 175–265 Vac input for 47 W output power are built to verify the studied results. [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]

Compared with traditional two-stage class-D audio amplifier, audio amplifier based on cycloconverter-type single-stage inverter (CSSI) has advantages of high efficiency and no bus voltage pumping (BVP). However, CSSI requires complex active clamp circuits for the current commutation of cycloconverter, especially for multichannel amplification. In this letter, a 2.1-channel switching amplifier with dc/high-frequency-ac (HFAC) mixed power supply is proposed, where CSSI is used as low-frequency audio channel amplifier and two class-D amplifiers are used as high-frequency audio channel amplifiers. With dc/HFAC mixed power supply, the proposed 2.1-channel switching amplifier does not require additional active clamp circuits for current commutation of cycloconverter. Besides, wide range soft switching of cycloconverter switches can be achieved. Benefiting from single-stage power conversion of low-frequency audio channel and wide range soft switching of cycloconverter switches, high efficiency of the proposed 2.1-channel amplifier is achieved. Without BVP, low voltage stress of switches and low distortion of low-frequency audio signal are realized in the proposed 2.1-channel amplifier. A 200-W prototype is presented to verify the analysis 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]

A novel high-efficiency resonant light emitting diode (LED) backlight driver with passive current balancing and dimming is proposed and analyzed in this paper. The proposed LED driver achieves uniform brightness of each LED string by the charge balance of the resonant capacitor, which benefits from high efficiency. By controlling the output current of one LED string, the output currents of other LED strings can be controlled via current balancing of resonant capacitors, which makes its control simple. The proposed LED driver uses only one active switch, which decreases circuit volume and simplifies the control. Furthermore, a wide load range can be achieved by controlling the turn-on duty ratio of the single power switch of the LED driver with a fixed frequency. Finally, a prototype of a high-dimming-ratio small-size three-string LED driver is provided to verify the studied results. [ABSTRACT FROM PUBLISHER]

A resonant single-stage single-switch four-output LED driver with high power factor and passive current balancing is proposed. By controlling one output current, the other output currents of four-output LED driver can be controlled via passive current balancing, which makes its control simple. When magnetizing inductor current operates in critical conduction mode, unity power factor is achieved. The proposed LED driver uses only one active switch and one magnetic component, thus it benefits from low cost, small volume, and light weight. Moreover, high-efficiency performance is achieved due to single-stage power conversion and soft-switching characteristics. The characteristics of the proposed LED driver are studied in this paper and experimental results of two 110-W four-output isolated LED drivers are provided to verify the studied results. [ABSTRACT FROM AUTHOR]

Both constant on-time (COT) and fixed off-time (FOT) control techniques are suitable for various applications requiring fast transient response. However, the discrete-time model of COT controlled buck converter only has two switched borderlines, whereas that of FOT controlled buck converter has four switched borderlines. Based on the derivations of these borderlines, an asynchronous-switching map of FOT controlled buck converter is established. With the decrease of equivalent series resistance (ESR) of output capacitor, instability and mode shifting from continuous conduction mode (CCM) to discontinuous conduction mode (DCM) are discussed. Furthermore, with small ESR of output capacitor, stability effects of load resistance and inductance on dynamical behaviors are investigated, and the approximate stability criteria and the corresponding normalized critical conditions are obtained. The theoretical analyses and experimental results show that the converter operates in DCM chaos via period-doubling and border-collision bifurcation routes, and its instability caused by small ESR can be removed by choosing appropriate load resistance, inductance, and voltage transfer ratio, which are very suitable for the circuit design of FOT controlled buck converter. [ABSTRACT FROM AUTHOR]

Compared with constant duty cycle-controlled discontinuous conduction mode (DCM) boost power factor (PF) correction (PFC) converter, constant duty cycle-controlled quadratic DCM–DCM boost PFC converter features with much lower second-order line frequency output voltage ripple, and however, it suffers from low PF. To increase PF of quadratic DCM–DCM boost PFC converter, a variable duty cycle control technique for quadratic DCM–DCM boost PFC converter is presented in this paper. An approximation equivalent for the variable duty cycle is employed to simplify the implementation circuit. The corresponding expressions of PF and output voltage ripple are analyzed. For input voltage range of 100–240 Vac, quadratic DCM–DCM boost PFC converter with variable duty cycle control benefits with very high PF, and tradeoff between PF and output voltage ripple of this converter is analyzed. Experimental results from 100-W prototypes are given to verify the theoretical analysis. [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]

Pulse train (PT) control technique realizes the output voltage regulation of switching dc–dc converters by using preset high power control pulse PH and low power control pulse PL. In steady state, PH and PL in some successive switching cycles constitute a control pulse repetition cycle. The control pulse combination of PH and PL in the control pulse repetition cycle has a significant effect on the performances of PT controlled switching dc–dc converters. In this paper, by taking PT controlled discontinuous conduction mode buck converter as an example, the control pulse combination of PT controlled buck converter is studied. Some lemmas to reveal the control pulse combination are presented, and the combination of PH and PL in a control pulse repetition cycle is obtained. Based on which, the steady-state and transient performances of PT controlled buck converter are investigated. The control pulse combination-based analysis of PT controlled buck converter provides an effective way to understand the PT control technique in detail. [ABSTRACT FROM PUBLISHER]

A variable on-time (VOT) control strategy for a critical conduction mode (CRM) flyback power factor correction (PFC) converter with low total harmonic distortion (THD) and high power factor (PF) is proposed in this paper. By using input voltage and the voltage across the auxiliary winding of the flyback transformer to modulate the turn-on time of the switch of the CRM flyback PFC converter, the PF and THD of the converter can be improved. The operation principles of the traditional constant on-time (COT)-controlled CRM flyback PFC converter and VOT-controlled CRM flyback PFC converter are analyzed. The experimental results show that the PF and THD of the VOT-controlled CRM flyback PFC converter are better than those of the COT-controlled CRM flyback PFC converter. [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]

Improved pulse regulation (IPR) control, a novel control technique for switching dc–dc converters, is proposed and studied in this paper. According to the output voltage and load current of the switching dc–dc converter, IPR control technique achieves output voltage regulation by generating control pulse train made up of some preset control pulses with different duty ratios. IPR control needs only comparators, triggers, and some simple logic devices, without error amplifier and the corresponding compensation circuit of pulse width modulation control scheme, thus IPR control scheme is easy to realize, benefits with excellent transient performance and stability. The principle and operation of IPR control scheme are introduced and illustrated with buck converter operating in discontinuous conduction mode as an example. Simulation and experimental results are presented to show that IPR-controlled converter has much lower output voltage ripple and more accurate output voltage regulation than PR converter. [ABSTRACT FROM PUBLISHER]

Equivalent series resistance (ESR) of output capacitor has a significant effect on the control performance of constant on-time (COT) controlled switching dc-dc converters. In this paper, a discrete-time model of COT-controlled buck converter, with variable sampling frequency, is established. Based upon which, the dynamical effects of the ESR of output capacitor on COT-controlled buck converter are revealed and analyzed. The time-domain numerical simulations of the exact switched state equations, the bifurcation diagrams, and maximal Lyapunov exponents of the discrete-time model are obtained. These results verified by experimental circuit indicate that the ESR of output capacitor is a critical factor for COT-controlled buck converter, which can eliminate the unique pulse bursting phenomenon and shift operation mode from discontinuous conduction mode to continuous conduction mode, as well as control stability. [ABSTRACT FROM PUBLISHER]

A novel pseudo-continuous conduction mode (PCCM) boost power-factor-correction (PFC) converter and its corresponding control strategy are proposed in this paper. Connecting a power switch in parallel with the inductor makes the boost converter operate in PCCM, which provides an additional degree of control freedom to realize PFC control. Therefore, a simple and fast voltage control loop of the PCCM boost PFC converter can be designed to realize output-voltage regulation. The additional degree of control freedom introduced by inductor current freewheeling operation of the PCCM boost PFC converter has been exploited through the dead-zone control technique, which can be dynamically adjusted in accordance with the output-voltage ripple. Compared with continuous conduction mode (CCM) boost PFC converter, the controller of the proposed PCCM boost PFC converter is much simpler. Moreover, the PCCM boost PFC converter benefits with reduced inductor-current ripple and improved power factor compared with boost PFC converter operating in discontinuous conduction mode (DCM). Analysis, simulation, and a 400-W prototype of the PCCM boost PFC converter have been presented and compared with those of boost PFC converters operating in conventional CCM and DCM. The results show that the dynamic response of the PCCM boost PFC converter is significantly faster than the existing boost PFC converter. [ABSTRACT FROM AUTHOR]

A novel control technique, called bifrequency pulse-train (BF-PT) control technique, for switching dc–dc converters is proposed. In contrast to the conventional pulsewidth-modulation-based control technique of switching dc–dc converters, which realizes the output voltage regulation by adjusting the duty ratio of the control pulse cycle by cycle, the BF-PT control technique realizes the output voltage regulation of switching dc–dc converters based on the presence and absence of preset high- and low-frequency control pulses. In BF-PT control, the output voltage of switching dc–dc converter is sampled at the beginning of each switching cycle and compared with a reference voltage to determine whether a high- or low-frequency control pulse should be selected as the control pulse. The BF-PT control technique is simple and cost effective and enjoys fast transient response. In addition, two types of control pulses with different switching frequencies spread the emission spectrum over discrete frequencies, resulting in lower electromagnetic interference (EMI) noise and easier EMI filter design. Furthermore, more low-frequency control pulses at lighter load improve the light-load power conversion efficiency. A buck converter operating in discontinuous conduction mode is taken as an example to illustrate the application and benefits of BF-PT control technique. Simulation and experimental results are presented to verify the analytical results. [ABSTRACT FROM PUBLISHER]

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]