The discontinuous conduction mode Sepic and Cuk power factor preregulators: analysis and design

Abstract

Sepic andĆuk converters working as power factor preregulators (PFP) in discontinuous conduction mode (DCM) present the following desirable characteristics for a PFP: 1) the converter works as a voltage follower (no current loop is needed); 2) 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 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. Index Terms-AC-DC power conversion, filtering, power supplies. NOMENCLATUREFreewheeling current. and currents. Conduction parameter; critical conduction parameter. Output-to-peak-input ratio; transformer turn ratio. ON time of the output diode ( ); ON time of the switch ( ). OFF time of both switch and output diode. Switching period. Input voltage and current; rectified input voltage and current. Ouput voltage and current.

Adaptive and Nonlinear Control Techniques Applied to SEPIC Converter in DC-DC, PFC, CCM and DCM Modes Using HIL Simulation

“…According to [16], the average output current of the SEPIC converter in DCM for a half cycle of the AC line and the AC current grid can be written, respectively, as follows:…”

“…In this work, an initial comparison is made between two of them: the traditional approach, using a Proportional-Integral (PI) controller and the nonlinear technique based on FLC (Feedback Linearization Control). A generalized procedure for both linear and non-linear control is shown in Figure 6 When considering the classic control system of the PFC converters, there are two main methods: the multiplicative and the follower voltage, portrayed in [16]. In the case of SEPIC PFC in DCM mode operation, there is an inherent characteristic that simplifies and establishes the control system, explained in the following subsection.…”

Efficiency and Power Factor improvement of Bridgeless Softswitched PWM Cuk Converter using Multiplier control approach

“…The phase shift fixed PWM control is provided for auxiliary switch. The operation and design procedure for the main converter elements are provided in the [2,14].So the design guidelines for designing the auxiliary circuit are discussed. …”

Design of Soft Switching Sepic Converter Fed DC Drive Applications

“…In mode 2, the input current iin is given by (3). From (15) and (16), the ripple component of iin can be removed by satisfying the following condition (19) Under the condition of (19), the input current iin is constant as ILm2 + nILa1 .…”