Recent demonstrations of merged inductorcapacitor (LC) switching converters have resulted in record power densities being achieved at high voltage conversion ratios. To do so, sophisticated switch control schemes may be required. This work demonstrates N-phase and Split-phase switching techniques applied to a resonant Cockcroft-Walton converter. For the same hardware, the lower resonant switching frequency of the N-phase scheme significantly improves light-load efficiency relative to the Split-phase scheme. However, the N-phase approach suffers reverse body diode turn-on at large voltage ripple contributing to the Split-phase scheme obtaining the highest power density. Converter performance combining both switching techniques is analyzed using a discrete 1:5 Cockcroft-Walton converter implemented using gallium nitride FETs, multi-layer ceramic chip (MLCC) capacitors, and a 68 nH inductor. The resulting converter achieves a peak efficiency of 94.9% and 94% for the Nphase and Split-phase schemes respectively with the N-phase scheme seeing a 30% reduction in losses at light-load. The converter achieves a maximum output power of 190W, resulting in a record power density of 483.3 kW/liter (7,920 W/inch 3 ) and specific power of 243 kW/kg.

Hybrid LC switched-capacitor converter architectures have demonstrated high power density while retaining efficiency at high conversion ratios. This work presents a resonant Cockcroft-Walton (CW) converter that achieves full zero-current switching (ZCS) on all switches using a single inductor and requiring only one current sensor. To do so, an Nphase clocking scheme is employed, eliminating the parallel paths that typically introduce transient shorting losses in a conventional 2-phase CW converter. The reduced voltage stress on the CW's fly capacitors results in a dramatic reduction in volume when using common MLCC capacitors. A discrete 1:5 CW prototype using silicon FETs and a spiral trace inductor was assembled on two commonly available PCB processes: 0.8 mm FR4 with 2 oz. Cu, and 0.127 mm polyimide film with 0.75 oz. Cu. The latter achieved a peak efficiency of 95% and a maximum power density of 0.686 W/mm 3 (11.2 kW/inch 3 ) in a volume of 44.5 mm 3 (0.00271 inch 3 ), excluding level-shifting and clock generation circuits.

This work introduces a new Symmetric Dual-Inductor Hybrid (SDIH) Dickson DC-DC converter topology that 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 PWM drives with a greatly reduced voltage amplitude relative to the input line voltage, in turn allowing magnetic volume to be reduced while retaining modest switching frequencies. Both even and odd order switchedcapacitor networks can be used with straight-forward split-phase switching allowing either network type to achieve complete softcharging of all fly capacitors. Additionally, charge flow is well balanced 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. A discrete prototype measuring 0.176 inch 3 demonstrates very high measured power densities of 768 W/in 3 , 751 W/in 3 , and 598 W/in 3 for regulated output voltages of 3 V, 2 V, and 1 V respectively while switching at a frequency of 750 kHz.

The flying capacitor multilevel (FCML) converter has shown promise for high step-up/down conversion ratio applications due to its relatively low switch stress and small inductor volume. For higher level-count (N ≥ 3) variations of this topology, there is limited research on resonant mode operation, despite its potential to yield considerable performance benefits for fixed conversion ratio applications. When operating resonantly, the decreased inductance requirement compared to regulated operation can further reduce the magnetic volume and improve transient response, while also allowing for zero-voltage/zerocurrent switching (ZCS/ZVS). This work presents and analyzes a clocking scheme required to operate an N :1 FCML converter both at-resonance and above-resonance, while maintaining minimum current ripple for reduced losses. A complete derivation is presented, enabling the calculation of precise phase durations as a function of switching frequency. Moreover, a 5:1 FCML hardware prototype is demonstrated, verifying intended operation both atand above-resonance, in addition to highlighting the achievable loss reduction with the proposed switching scheme.

With increasing calls of electrification for transportation (e.g., electric vehicles, hybrid or electric aircraft), the need for systematic guidelines that gauge passive component specific energy density for weight-optimized converter design has become apparent. Observing a lack of data sets and corresponding modeling process for passive components that usually dominate a converter's weight, this work proposes a transformation that estimates the specific energy density of passive components from comprehensively surveyed volumetric energy density data and empirical specific density models, and thus forms a convenient guideline for converter weight optimization. The proposed model is then applied to a converter designed for electric aircraft applications to showcase the component mass estimation and selection process along with estimation accuracy.