Examining the impacts of DM filters to PFC isolated Ćuk converter for DCM operation by comparing Si and SiC MOSFET

Abstract

Examining impacts of differential mode (DM) filter topologies covering pi, LC with damping, LC, LCL filter through isolated Ćuk single phase PFC converter is realized in this paper regarding to power factor, THD and efficiency. Application of PFC isolated Ćuk converter is conducted with 42 kHz switching frequency and 50 W power. Each filter is modeled, designed, and applied experimentally via isolated PFC Ćuk converter. Average model derivation based on state-space, for DCM operation of input side inductor of isolated PFC Ćuk converter that is not introduced in literature is the main contribution of the paper. Second main contribution is to analyze filter types by linear methods for the transfer functions cascading the converter and filter transfer functions, which is not presented for PFC converters. It is also presented that solely LCL filter which is not analyzed for PFC converters in detail in literature, does not give desired results. So, increasing the effectivity of LCL filter, new filter structure LCL with parallel C filter is proposed and modeled in this paper. Thanks to the applications, presented results of LCL with parallel C filter is better than others with 4.9% current THD and ‘1’ power factor. Proposed LCL filter ensures 45% reduction of total inductor value, comparing to LC filter. Besides, LCL with C filter provides better control characteristics with maximum allowable gain for stability as 0.7585 higher than other topologies. Moreover, practical design methodology of filter types avoiding complex mathematical procedure is given in this paper. Applications with each filters provide THD requirements, obtained 4.9% as a best value, lower than IEC61000-3-2 standard. Maximum percentage improvement comparing to the IEC61000-3-2 is 27.5% for third harmonic. Furthermore, SiC and Si Mosfets are employed separately in the converter and compared by using each DM filters regarding to power factor, THD, efficiency through applications. As a result, better efficiency with SiC Mosfet as 83% and better THD with Si Mosfet as 4.9% are conducted.

LCL Trap Filter Analysis with a PFC Isolated Ćuk Converter Using SiC MOSFET for DCM

“…The transformer is a high-frequency transformer and provides galvanic isolation. Converter parameters can be selected using ( 6)- (11) as in [2,10,16]. In the equations d is the duty cycle, n is the turns ratio, Vin is the input voltage, Vo is the output voltage, L and L2 are the inductances, C1 and C2 are the intermediate capacitors, Co is the outpu capacitor, and RL is the load.…”

“…It is seen that there are three different operation dura tions; these durations are identified as d duty cycle, δ, and 1-d-δ, matching the equivalen circuit in Figure 4 as in [24]. Converter parameters can be selected using ( 6)- (11) as in [2,10,16]. In the equations, d is the duty cycle, n is the turns ratio, V in is the input voltage, V o is the output voltage, L 1 and L 2 are the inductances, C 1 and C 2 are the intermediate capacitors, C o is the output capacitor, and R L is the load.…”

“…A mathematical model of the converter can be derived using the Kirchhoff voltage and current laws regarding switch on and off conditions. Because of the DCM operation, the converter has three different equivalent circuits as in [10]. The equivalent circuits are given in Figure 4 as in [10].…”

“…Because of the DCM operation, the converter has three different equivalent circuits as in [10]. The equivalent circuits are given in Figure 4 as in [10]. While deriving the model of the converter, it is assumed that the high-frequency transformer has ideal characteristics.…”

“…[9] realizes the small-signal modeling of a two-phase boost converter having a coupled inductor for DCM. Modeling of the isolated Ćuk converter is given for DCM mode operation in [10,11]. Ref.…”