skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Demystifying Capacitor Voltages and Inductor Currents in Hybrid Converters
This paper presents a modeling method to accurately predict DC and ripple values of flying capacitor voltages and inductor currents in hybrid converters by recognizing a key relationship between median and average values of these state variables. The method is demonstrated for the Dual-Phase Multi-Inductor Hybrid (DP-MIH) converter and 3-Level Buck converter. Analytical details and intuitive explanations are presented for the well-known balancing problem of flying capacitor voltages and inductor current fluctuations in hybrid converters. Simulation results for the converters at different operating conditions are provided to verify the method and analytical results.  more » « less
Award ID(s):
1810470
PAR ID:
10151284
Author(s) / Creator(s):
; ; ; ; ;
Date Published:
Journal Name:
2019 20th Workshop on Control and Modeling for Power Electronics (COMPEL)
Page Range / eLocation ID:
1 to 8
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; (, 2019 IEEE Applied Power Electronics Conference and Exposition (APEC))
    This paper describes the topology, fundamental operations, and key characteristics of a Dual-Phase Multi-Inductor Hybrid (DP-MIH) Converter for Point of Load (POL) telecommunication and data center applications. The circuit topology employs a unique configuration of switched-inductor and capacitor pairs to achieve complete soft charging and native voltage balancing of flying capacitors regardless of mismatches and variations in capacitor and inductor values. The converter topology and its operation are verified by a five-level DP-MIH converter prototype capable of delivering maximum load of 100A at 1V-5V regulated output voltages from a 48V input supply. It achieves 90.9% peak efficiency and 440 w/in3 power density for 48V-to-1V conversion and 95.3% and 2200W/in3 for a 48V-to-5V conversion. 
    more » « less
  2. ; ; (, IEEE Journal of Emerging and Selected Topics in Power Electronics)
    This paper presents a dual-inductor hybrid (DIH) converter that is capable of efficient non-isolated DC-DC con- versions with extremely large voltage conversion ratios. The converter topology combines a switched-capacitor network and two interleaved inductors, that supports simple duty-cycle control for output regulation. In order to achieve complete soft charging for all flying capacitors, a method to optimally size the capacitors has been proposed and verified. A detailed analysis on the two inductor currents revealing a new and simple method to modulate them and its impacts on output regulation and efficiency are also provided and demonstrated in experiments. Employing the converter topology and design methods, a DIH converter prototype is implemented and measured for a wide range of operating voltages, providing a 1V-2V output from a 48-V input and a 1V-5V output from a 150V input with output currents up to 20A. The converter achieves 94.3% peak efficiency at 48V- to-2V/7A conversion and 93.7% at 150V-to-5V/18A conversion. 
    more » « less
  3. ; (, IEEE International Solid- State Circuits Conference (ISSCC))
    null (Ed.)
    Efficient high-conversion-ratio power delivery is needed for many portable computing applications which require sub-volt supply rails but operate from batteries or USB power sources. In such applications, the power management unit should have a small volume, area, and height while providing fast transient response. Past work has shown favorable performance of hybrid switched-capacitor (SC) converters to reduce the size of needed inductor(s), which can soft-charge high-density SC networks while supporting efficient voltage regulation [1-5]. However, the hybrid approach has its own challenges including balancing the voltage of the flying capacitor and achieving safe but fast startup. Rapid supply transients, including startup, can cause voltage stress on power switches if flying capacitors are not quickly regulated. Past approaches such as precharge networks [3] or fast balancing control [5] have startup times that are on the order of milliseconds. This paper presents a two-stage cascaded hybrid SC converter that features a fast transient response with automatic flying capacitor balancing for low-voltage applications (i.e., 5V:0.4 to 1.2V from a USB interface). The converter is nearly standalone and all gate drive supplies are generated internally. Measured results show a peak efficiency of 96.9%, <; 36mV under/overshoot for 1A/μs load transients, and self-startup time on the order of 10μs (over 100× faster than previous works). 
    more » « less
  4. ; ; (, 2018 IEEE Energy Conversion Congress and Exposition (ECCE))
    This paper presents a new dual inductor hybrid converter (DIHC) that is capable of efficient direct non-isolated DC-DC conversions with extremely large voltage conversion ratios. The converter employs two interleaved inductors and a switched-capacitor (SC) network to bring several significant topological benefits. Capacitance of the flying capacitors of this new topology can be optimally sized to achieve natural, complete soft-charging for all capacitors. This novel capacitor soft-charging feature is a key contribution of this work and can be exploited to overcome the limitations of conventional SC converters suffering from capacitor hard charging losses. The converter topology and its operation are verified in an 36-W converter prototype for 40-120V input to 0.9V-1.8V output up to 20A of current load that achieves peak efficiencies of 91.5% for 120V-to-1.8V and 87.3% for 120V-to-0.9V conversion. Its advantages and performance at extreme conversion ratios push the limit of point-of-load converters, reducing complexity and cost for bus voltage distributions, as well as enabling fewer conversion stages and thus higher efficiency for data centers and high-performance digital systems. 
    more » « less
  5. ; ; ; (, IEEE Transactions on Power Electronics)
    This article investigates the modeling, analysis, and design methods for passively balancing flying capacitor multilevel (FCML) converters using coupled inductors. Coupled inductors synergize with FCML converters by reducing inductor current ripple, reducing switch stress, and, as proven in this article, by providing flying capacitor voltage balancing. This enables FCML topologies to be scaled well to larger systems. This article proves that coupled inductors can solve the unbalancing problem in many FCML converters. Moreover, tools are developed to thoroughly explain and quantify coupled inductor balancing, allowing general design guidelines to be offered for robust coupled inductor FCML converters. Finally, this article derives the limitations of coupled inductor balancing with respect to the number of phases, levels, and the required coupling ratio. The key principles of coupled inductor FCML balancing in steady state are demonstrated with a systematic theoretical framework and extensive experimental and simulation results. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email