Abstract
By adding a suitable LC filter to the input of a Buck converter, a high-power-factor buck converter is proposed. The converter can operate in the discontinuous-output-current mode operation. A Buck converter in this operation mode features simple control as the constant duty cycle PWM used. The operation condition of the converter is studied. The validity of analysis is verified by Simulation and Experimental results.
Highlights
Intensive research has been carried out to improve the power factor of AC/DC converters [1]-[4]
The simulation results verify the theoretical analysis and show that input current will follow the input voltage automatically when Buck converter with an input LC filter operates in DICM with a constant the duty cycle
The Buck converter with LC input filter operating in DICM can gain a high power factor when the duty ratio maintain constant
Summary
Intensive research has been carried out to improve the power factor of AC/DC converters [1]-[4]. It has been reported that by adding a suitable LC filter to the input of a Buck converter to make the converter operate as power factor correction circuit [5] [6]. The voltage stress across switch(S in Figure 1) and diode (D in Figure 1) imposes major restrictions as the peak value of Vc1 is very high when Vc1 becomes zero for part of the switching cycle. The Buck converter with LC input filter operates in a “discontinuous-output-current” mode. The current of output inductor (L2 in Figure 1) fells to zero for part of the switching cycle and the voltage of the input capacitor (C1) becomes continuous. The peak value of Vc1 is reduced substantially and switch voltage stress will be no longer a restriction. Besides the reverse recovery loss of the freewheeling diode (D) is reduced
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