The Symmetric Dual Inductor Hybrid Converter for Direct 48V-to-PoL Conversion

This work introduces the symmetric dual inductor hybrid (SDIH) dc–dc converter topology, which is suitable for large conversion ratios where regulation is required, such as direct 48 V to point-of-load (PoL) applications. A Dickson-type switched capacitor network is used to effectively produce two interleaved pulsewidth-modulated (PWM) outputs with a greatly reduced voltage amplitude relative to the input voltage, allowing the subsequent magnetic volume to be reduced while retaining modest switching frequencies. Distinct from related variations, part count is significantly reduced while both even and odd order switched capacitor networks can be used with straightforward split-phase control; allowing either network type to achieve complete soft-charging of all flying capacitors. Additionally, charge flow is uniformly distributed through all elements, with equal capacitor and inductor values being preferred. Subsequently, this topology is expected to simplify component selection, improve electrical and thermal performance, and reduce cost. Furthermore, analysis is presented that calculates precise phase durations without making small ripple assumptions, revealing up to a 75% timing error in cases where either inductor or capacitor ripple is ignored. Finally, a discrete prototype validates this analysis and demonstrates very high measured power densities of 1029, 754, and 663 W/in
$^{3}$
for 48 V input and regulated output voltages of 3, 2, and 1 V, respectively, while switching at a frequency of 750 kHz.