Contents I. Introduction
A variable and stable DC power supply is important for the most electrical and electronics appliances which can be obtained by AC to DC conversion. Diode bridge rectifier is used to convert an AC signal to DC signal usually. Here input capacitors are used to reduce ripple from output voltage. But it makes the input current to be pulsating in nature that contains a lot of harmonics. The boost, buck-boost, and Cúk converters in discontinuous-induction-current mode (DICM) operation were demonstrated to have inherent power factor correction (PFC) capability [1]–[4]. However, these converters have high current stress thus heavy conduction loss. Furthermore the input current contains much switching ripple. Cúk converters in discontinuous-capacitor-voltage mode (DCVM) operation were reported by Cúk in [5]. Cúk converters in DCVM operation inherently have a good power factor and low switching stress [6]–[9]. But the input current contains a lot of harmonics components. Harmonics create a lot of problems [10]. Combining active and passive filter [11], switch mode regulator [12], Cúk converter in DCVM operation [9] and Cúk converter with variable switching frequency [13]–[16] to reduce the THD is proposed. But in every case, it is found that the value of THD is greater than 2%. The value of THD was obtained 0.65% [17], it can be reduced up to 0.35% by using the converter circuit proposed in this paper. A small LC filter is used in the proposed circuit to reduce the lower order harmonics and smooth out the input current.
Circuit diagram of a typical Cúk regulator
