28-12-2012, 05:33 PM
Interleaved Buck Converter Having Low Switching Losses and Improved Step-Down Conversion Ratio
Interleaved Buck Converter.pptx (Size: 3.38 MB / Downloads: 96)
ABSTRACT
This project proposes a new interleaved buck converter (IBC) having low switching losses and improved step-down conversion ratio, which is suitable for the applications where the input voltage is high and the operating duty is below 50%.
It is similar to the conventional IBC, but two active switches are connected in series and a coupling capacitor is employed in the power path, such as C´uk, Sepic, and Zeta converters.
CIRCUIT OPERATIONS
The Fig. 2 structure is similar to a conventional IBC except two active switches in series and a coupling capacitor employed in the power path.
Figs. 3 and 6 show the key operating waveforms of the proposed IBC in the steady state.
Referring to the figures, it can be seen that switches Q1 and Q2 are driven with the phase shift angle of 180◦.
This is the same as that for a conventional IBC. Each switching period is divided into four modes, whose operating circuits are shown in Figs. 4 and 5.
The maximum voltage of Q2 is the input voltage, but the voltage before turn-on or after turn-off is equal to VCB.
As these results, the capacitive discharging and switching losses on Q1 and Q2 can be reduced considerably.
In addition, since diodes with good characteristics such as schottky can be used for D1 and D2 , the reverse-recovery and conduction losses can be also improved.
RELEVANT ANALYSIS RESULTS
The following relevant analyses are conducted over the entire duty cycle range for a detail design guide.
A. DC Conversion Ratio:-
The dc conversion ratio of the proposed IBC can be derived using the principle of inductor volt-second-balance (VSB).
In the case ofD≤0.5, the following equations can be obtained from the VSB of L1 and L2 , respectively