Digital Voltage Sampling Scheme for Primary-Side Regulation Flyback Converter in CCM and DCM Modes

Primary-side regulation (PSR) flyback topology with discontinuous conduction modulation (DCM) mode has been widely used in low-power application due to its high stability, wide input voltage range, low cost, and low standby power. To improve the output power, continuous conduction modulation (CCM) m...

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Bibliographic Details
Published in:IEEE transactions on circuits and systems. I, Regular papers Regular papers, 2022-08, Vol.69 (8), p.3438-3449
Main Authors: Wang, Chong, Sun, Daying, Gu, Wenhua, Gui, Sang
Format: Article
Language:English
Subjects:
Comparators
continuous conduction modulation (CCM)
Digital to analog converters
Electric potential
flyback converter
Low speed
Modulation
primary-side regulation (PSR)
Regulation
Resistance
Sampling methods
Topology
Voltage
Voltage control
Voltage sampling method
Windings
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Summary:Primary-side regulation (PSR) flyback topology with discontinuous conduction modulation (DCM) mode has been widely used in low-power application due to its high stability, wide input voltage range, low cost, and low standby power. To improve the output power, continuous conduction modulation (CCM) mode is always introduced. However, in CCM mode, conventional PSR voltage-sampling method cannot realize high precision of output voltage or the voltage sampling method requires complex control of high cost. In this paper, a simple digital voltage sampling scheme with two reference voltages outputted from a digital-to-analog converter (DAC) is put forward to trace the "accurate-point" voltage for DCM and CCM modes. In CCM mode, the sampling voltage error of the "knee-point" voltage can be compensated just by inserting DCM switching cycle to obtain the "accurate-point" voltage. Voltage difference between DCM mode and CCM mode will be eliminated, and high precision is easily realized. The proposed method is verified in a 20V, 65W PSR flyback converter. The sampling method only requires a low speed DAC, three comparators and a digital controller. The output voltage precision is within 0.6% with universal input voltage.
ISSN:1549-8328
1558-0806
DOI:10.1109/TCSI.2022.3167428