On the Size and Weight of Passive Components: Scaling Trends for High-Density Power Converter Designs

Abstract

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.

Large Signal Analysis on Variations of the Hybridized Dickson Switched-Capacitor Converter

“…Figure 9. Measured voltage and current waveforms of a 1:7 resonant instantiation of the D-1L-direct split-phase Dickson variant analyzed in Section VI.With V L = 10 V, these results validate the derivation of (63), (64),(65), and (66).Table III COMPARISON: MAXIMUM CAPACITOR UTILIZATIONTheoretical Simulated (ideal) Simulated (w/ Loss) Measured Min (V) Max (V) Min (V) Max (V) Min (V) Max (V) Min (V) Max (V)…”

“…A discrete 1:7 (N =7) D-1L-direct converter prototype, depicted in Fig. 8, was constructed to validate the derivation of ( 63), ( 64), (65), and (66). The primary components of the power stage are listed in Table II, where these values dictate both the resonant switching frequency (64) and q H,max (65).…”

“…8, was constructed to validate the derivation of ( 63), ( 64), (65), and (66). The primary components of the power stage are listed in Table II, where these values dictate both the resonant switching frequency (64) and q H,max (65). Figure 9 plots measured waveforms with a 10 V input, resonant switching frequency of 296 kHz, and a predicted maximum load of 0.41 A.…”

“…Table IV reiterates that indirect or tank-based topologies exhibit switch voltage stress that is largely independent of load-induced flying capacitor voltage ripple, provided switch resistance remains small. Figure 10 plots the three distinct maximum flying capacitor utilization equations (η max [A]-[C] in Table IV) and demonstrates the extent to which each of these groupings can utilize a specified total capacitor energy or size [65]. When confined to direct (non-tank) structures, split-phase approaches are expected to achieve superior flying capacitor utilization at high conversion ratios, leading to smaller capacitor volume/area in practice, with a 43% increase in capacitor utilization observed at N = 15.…”

Characterization and Modeling of Ceramic Capacitor Losses Under Large Signal Operating Conditions

“…Shown in Fig. 5 is the result of a survey of commercially available Class I, Class II and Ceralink ceramic capacitors [23], which illustrates energy density as a function of blocking voltage for the two technologies. Here, energy density is defined as the maximum energy that can be stored on the capacitor (1/2 CV 2 rated ).…”