A Constant-Power Battery Charger with Inherent Soft Switching and Power Factor Correction

N. K. Poon, Bryan M H Pong, Chi Kong Tse

Research output: Journal article publicationJournal articleAcademic researchpeer-review

27 Citations (Scopus)


A battery charging circuit, which operates as a constant power source, is proposed in this paper. By maintaining a constant output power throughout the charging process, the circuit reduces the size of thermal installation which would normally be required in the cases of constant-voltage or constant-current charging. The proposed circuit takes the form of a half-bridge converter with an additional small inductor and two extra diodes connected in parallel to two dividing capacitors. Constant power delivery is achieved by the discontinuous-voltage-mode operation of the two dividing capacitors, each of which is connected in parallel with a diode. The circuit enjoys low voltage and current stresses, and achieves soft switching with no extra components. When used off-line, the converter maintains a high input power factor and a low level of input current harmonic distortion that meets international regulations. All the above characteristics are determined only by the values of the circuit parameters, the control mechanism being noncritical. A 12 V 65 W prototype was built to demonstrate the merits of this circuit.
Original languageEnglish
Pages (from-to)1262-1269
Number of pages8
JournalIEEE Transactions on Power Electronics
Issue number6
Publication statusPublished - 1 Nov 2003


  • Battery charger
  • Power factor correction
  • Switching converters
  • Zero-voltage-switching

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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