The determination of the boundaries between continuous and discontinuous conduction modes in PWM DC-to-DC converters used as power factor preregulators
29 Jun 1992-Vol. 10, Iss: 5, pp 574-582
TL;DR: In this article, the boundaries between continuous and discontinuous conduction modes in PWM DC-to-DC switching power converters used as power factor preregulators are determined.
Abstract: The determination of the boundaries between both modes of conduction (continuous and discontinuous) in PWM DC-to-DC switching power converters used as power factor preregulators (PFP) is presented in this paper. When a DC-to-DC switching power converter works as a power factor preregulator, its operating point is constantly changing due to the fact that both the DC voltage conversion ratio and the load "seen" by the power converter are constantly changing in each half-sinusoid of the line voltage (input voltage of the converter). In these conditions, the conduction mode cannot be directly determined. In this paper, the boundaries between both conduction modes in each angle of the half-sinusoidal input voltage have been determined. The conditions to always operate in continuous or in discontinuous conduction modes have been determined as well. Finally, these results have been verified by simulations and experimental results. >
Citations
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TL;DR: This paper analyzes the operation of both power converters as DCM-PFP using a small-signal model to aid the control loop design and results are presented that are in agreement with the theoretical analysis and complement the work.
Abstract: Sepic and Cuk power converters working as power factor preregulators (PFP) in the discontinuous conduction mode (DCM) present the following desirable characteristics for a PFP: (1) the power converter works as a voltage follower (no current loop is needed); (2) the theoretical power factor is unity; and (3) the input current ripple is defined at the design stage. Besides, input-output galvanic isolation is easily obtained. This paper analyzes the operation of both power converters as DCM-PFP. Design equations are derived, as well as a small-signal model to aid the control loop design. Both simulation and experimental results are presented that are in agreement with the theoretical analysis and complement the work.
371 citations
TL;DR: This paper presents a comprehensive study on state of art of power factor corrected single-phase AC-DC converters configurations, control strategies, selection of components and design considerations, performance evaluation, power quality considerations, selection criteria and potential applications, latest trends, and future developments.
Abstract: Solid-state switch mode AC-DC converters having high-frequency transformer isolation are developed in buck, boost, and buck-boost configurations with improved power quality in terms of reduced total harmonic distortion (THD) of input current, power-factor correction (PFC) at AC mains and precisely regulated and isolated DC output voltage feeding to loads from few Watts to several kW. This paper presents a comprehensive study on state of art of power factor corrected single-phase AC-DC converters configurations, control strategies, selection of components and design considerations, performance evaluation, power quality considerations, selection criteria and potential applications, latest trends, and future developments. Simulation results as well as comparative performance are presented and discussed for most of the proposed topologies.
368 citations
Cites background from "The determination of the boundaries..."
...of control strategies [5], [6], magnetic [3], [4], [7], circuit integration [6], [7], ASIC developments [7], configurations [10], [12], [14]–[17], current conduction modes [13], electronic ballast and DC regulator applications [14], circuit and compo-...
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TL;DR: The reduction of the harmonic distortion of the input current and the increase of the power factor are demonstrated by experiments on a 1-kW boost PFC converter.
Abstract: Whereas power-factor-correction (PFC) converters for low-power ranges (less than 250 W) are commonly designed for operation in the discontinuous conduction mode, converters for higher power levels are operated in the continuous conduction mode. Nevertheless, when these converters are operated at reduced power, discontinuous conduction mode will appear during parts of the line period, yielding input current distortion. This distortion can be eliminated by employing a dedicated control algorithm, consisting of sample correction and duty-ratio feedforward. The reduction of the harmonic distortion of the input current and the increase of the power factor are demonstrated by experiments on a 1-kW boost PFC converter.
183 citations
Cites background or methods from "The determination of the boundaries..."
...In [18], the boundaries of the mixed conduction mode were determined for several converter types, used as power-factor preregulators....
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...However, at reduced load, DCM will appear close to the crossover of the line voltage [18], [19], causing the converter to switch between CCM and DCM within a grid period [this mode of operation will be referred to as mixed conduction mode (MCM)]....
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TL;DR: This source of input-current distortion is analyzed, and a solution is proposed to solve the problem.
Abstract: When power-factor correction (PFC) converters designed for operation in continuous-conduction mode (CCM) at full power are operated at reduced load, operation in discontinuous-conduction mode (DCM) occurs in a zone that is close to the crossover of the line voltage. This zone will gradually expand with decreasing load to finally encompass the entire line cycle. Whereas, in CCM, the parasitic capacitances of the switches only cause switching losses, in DCM, they are a source of converter instability, resulting in significant input-current distortion. In this paper, this source of input-current distortion is analyzed, and a solution is proposed. Experimental results are obtained using a digitally controlled boost PFC converter, which is designed to operate in CCM for 1 kW
168 citations
Cites background from "The determination of the boundaries..."
...An important cause for this distortion is the change in converter dynamics when switching between CCM and DCM [10]–[15] since the gain of the CCM controller is too low to ensure good input-current tracking in DCM....
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...[11] K. De Gussemé, D. M. Van de Sype, A. P. Van den Bossche, and J. A. Melkebeek, “Sample correction for digitally controlled boost PFC converters operating in both CCM and DCM,” in Proc....
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...a zone that is close to the crossover of the line voltage [10]–[12]....
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TL;DR: In this paper, a systematic analysis of line-current distortions of the discontinuous-conduction-mode and the continuousconductionmode boundary boost power factor correction converter due to valley switching (VS) and switching-frequency limitation, where VS is either maintained or lost after the onset of switching frequency limitation, is provided.
Abstract: A systematic analysis of line-current distortions of the discontinuous-conduction-mode and the continuous-conduction-mode boundary boost power factor correction converter due to valley switching (VS) and switching-frequency limitation, where VS is either maintained or lost after the onset of switching-frequency limitation, is provided. Closed-form expressions for the line current are derived. It is shown that if the switching frequency is limited and VS is not maintained, the line current is more distorted with voltage-mode control than with current-mode control. The effects of line-current distortions are demonstrated with both simulation and experimental results.
161 citations
References
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14 Jun 1977
TL;DR: A method for modelling switching converters in the discontinuous conucction mode is developed, whose starting point is the unified state-space representation, and whose end results is a complete linear circuit model which correctly represents all essential features, namly, the input, output, and transfer properties.
Abstract: A method for modelling switching converters in the discontinuous conucction mode is developed, whose starting point is the unified state-space representation, and whose end results is a complete linear circuit model which correctly represents all essential features, namly, the input, output, and transfer properties (static dc as well as dynamic ac small signal). While the method is generally applicable to any switching converter operating in the discontinuous conduction mode, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The outlined method lends itself easily to investigation of the discontinuous conduction mode in more complex structures (cascade connection of buck and boost converters, for example), in which more thean one inductor current may become discontinuous. As opposed to other modelling techniques, the new method considers the discontinuous conduction mode as a special case of the continuous conduction mode.
429 citations
26 Jun 1989
TL;DR: In this paper, the authors derived the waveform distortion and the maximum power factor achievable in a graph form as functions of the ratio of the line voltage to output voltage for active power factor correction circuits.
Abstract: For active power factor correction circuits employing discontinuous-mode boost converters, the line current will automatically follow the sinusoidal line-voltage waveform. However, due to the modulation of the input inductor current discharging time, there is certain distortion in the AC line-current waveform. It is found that the modulation of inductor current discharging time is a function of the line voltage and the output voltage of the boost converter. For practical design considerations, the waveform distortion and the maximum power factor achievable are derived and presented in a graph form as functions of the ratio of line voltage to output voltage. >
376 citations
TL;DR: In this paper, an ac-to-dc converter which draws sinusoidal and inphase current waveforms from the ac power source is described, and a stability analysis and design methodology are given.
Abstract: An ac-to-dc converter which draws sinusoidal and inphase current waveforms from the ac power source is described. Harmonic and power factor measurements obtained from a field- effect transistor (FET) converter operating at 45 kHz for a single- phase and a three-phase connection are presented. A stability analysis and design methodology are given.
251 citations
09 Nov 1992
TL;DR: In this paper, the authors proposed SEPIC and Cuk converters for power factor preregulators in discontinuous conduction mode (DCM) with a fixed operation frequency.
Abstract: SEPIC and Cuk converters present a great advantage over boost and fly-back topologies in discontinuous conduction mode (DCM): an input current with low harmonic content can be obtained by correctly choosing the inductors L/sub 1/ and L/sub 2/ of the converter with a fixed operation frequency, as is demonstrated here. The authors also discuss the intermedium capacitor C/sub 1/ as well as some advantages and disadvantages of the application. Simulation and experimental results support the approach. It is concluded that SEPIC and Cuk converters in DCM seem to be good choices for use as power factor preregulators. >
156 citations
29 Jun 1992
TL;DR: In this article, a simple and accurate small-signal model for the high-power-factor converter with constant switching frequency is developed and verified, which is applicable to all frequencies below half the switching frequency.
Abstract: A simple and accurate small-signal model for the high-power-factor converter with constant switching frequency is developed and verified. The model is applicable to all frequencies below half the switching frequency. The model is useful in the design and analysis of the voltage and current loops, and of the input and the output impedances of the converter. The use of the model is demonstrated in the analysis and design of a power factor boost converter with average current control. >
122 citations