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.


This content will become publicly available on January 1, 2026

Title: Balancing Flying Capacitor Multilevel Converters With Coupled Inductors: Multi-Resonant Dynamics
This paper investigates dynamic balancing of flying capacitor multilevel (FCML) converters with coupled inductors. Coupled inductors help to reduce the ripple current, accelerate transient response, and balance the flying capacitors of FCML converters at steady-state. However, coupled inductors also change the dynamic balancing properties compared to uncoupled inductors, and these principles must be understood for robust design. As an extension of a previously developed feedback mechanism for understanding the steady-state behaviors of coupled inductors in FCML converters, this paper derives models of coupled inductor FCML converters in dynamic operation, revealing several key insights: (i) the multi-resonant behavior of large-order FCML converters and their dependence on the initial conditions, (ii) how power dissipation relates to balancing speed, and (iii) the relation between multiphase and multilevel FCML balancing. The insights uncovered by this paper can provide useful guidelines for designing multi-phase self-balanced FCML converters with coupled inductors.  more » « less
Award ID(s):
1847365
PAR ID:
10565068
Author(s) / Creator(s):
;
Publisher / Repository:
IEEE
Date Published:
Journal Name:
IEEE Transactions on Power Electronics
ISSN:
0885-8993
Page Range / eLocation ID:
1 to 15
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, 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
  2. ; ; (, 2019 20th Workshop on Control and Modeling for Power Electronics (COMPEL))
    This work explores the mechanisms and limitations of natural voltage balancing in flying capacitor multilevel (FCML) DC-DC converters. A simple discrete-time state space model is used to explore the fundamental conditions that will lead to (or prevent) natural balance of flying capacitor voltages, along with the balancing dynamics. The treatment is used to highlight straightforward ways to alleviate problems with natural imbalance by adjusting the switching scheme. The model is compared against circuit simulations and the proposed switching scheme is verified in a hardware prototype. 
    more » « less
  3. ; (, 2022 IEEE 7th Southern Power Electronics Conference (SPEC))
    The size, weight, power density, cost, and efficiency are crucial factors that should be considered when designing or employing power electronics converters for a specific application. Therefore, comparing different converters to investigate which converter provides better figures of merit at the same application and operating condition is essential. This paper uses theoretical, simulation and experimental comparisons between the two-level and multilevel converters. The DC-DC two-level buck and the flying capacitor multilevel (FCML) buck converters are chosen to carry out the theoretical, simulation and experimental prototypes when both employ Gallium Nitride (GaN) power semiconductor switches. It was found that the FCML converter inherently provides superior performance and figures of merit over both the two-level and multilevel converters. Simulation and experimental results that validate each other are provided in this paper. 
    more » « less
  4. ; (, IEEE Open Journal of Power Electronics)
    In this article, a high-efficiency and high-density 2.5 kW four-level interleaved flying capacitor multilevel (FCML) totem-pole bridgeless power-factor-correction (PFC) rectifier with 200 V GaN devices is analyzed, designed, and tested. This 2.5 kW four-level continuous conduction mode (CCM) GaN totem pole PFC operates with three times inductor current ripple frequency than that of the switching frequency which significantly reduces the size of the inductors while also supporting switching loss reduction. This article compares the loss of the two-level CCM GaN totem-pole PFC, four-level non-interleaved FCML PFC and interleaved four-level FCML PFC with the same ripple frequency (300 kHz) and shows that the interleaved four-level CCM GaN PFC has much less device loss. In addition, this article discusses the detailed EMI spectrum analysis and derivation of the mathematical model for determining the attenuation requirement of the four-level interleaved FCML PFC converter followed by volumetric co-optimization of AC-side passives i.e., the boost inductor and differential mode (DM) EMI filter. A 2.5 kW four-level interleaved FCML GaN totem-pole PFC prototype with an optimized 94 kHz switching frequency is developed and tested in this article. The converter exhibits a peak efficiency of 99.14% with system power density reaching 89.47 W/inch3. 
    more » « less
  5. ; ; ; ; ; (, 2019 20th Workshop on Control and Modeling for Power Electronics (COMPEL))
    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
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email