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: Notions and a passivity tool for switched DAE systems
This paper proposes notions and a tool for passivity properties of non-homogeneous switched Differential Algebraic Equation (DAE) systems and their relationships with stability and control design. Motivated by the lack of results on input-output analysis (such as passivity) for switched DAE systems and their interconnections, we propose to model non-homogeneous switched DAE systems as a class of hybrid systems, modeled here as hybrid DAE systems with linear flows. Passivity and its variations are defined for switched DAE systems and methods relying on storage functions are proposed. The main contributions of this paper are: 1) passivity and detectability concepts for switched DAE systems, 2) links of the aforementioned passivity and detectability properties to stabilization via static output-feedback. Our results are illustrated in a power system, namely, the DC-DC boost converter, whose model involves DAEs and requires feedback control.  more » « less
Award ID(s):
1710621
PAR ID:
10066596
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Proceedings of 2017 IEEE 56th Annual Conference on Decision and Control (CDC 2017)
Page Range / eLocation ID:
3612 to 3617
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Hybrid Systems: Computation and Control (part of CPS Week 2022), HSCC'22)
    Bartocci, Ezio; Putot, Sylvie (Ed.)
    Switched systems are known to exhibit subtle (in)stability behaviors requiring system designers to carefully analyze the stability of closed-loop systems that arise from their proposed switching control laws. This paper presents a formal approach for verifying switched system stability that blends classical ideas from the controls and verification literature using differential dynamic logic (dL), a logic for deductive verification of hybrid systems. From controls, we use standard stability notions for various classes of switching mechanisms and their corresponding Lyapunov function-based analysis techniques. From verification, we use dL's ability to verify quantified properties of hybrid systems and dL models of switched systems as looping hybrid programs whose stability can be formally specified and proven by finding appropriate loop invariants, i.e., properties that are preserved across each loop iteration. This blend of ideas enables a trustworthy implementation of switched system stability verification in the KeYmaera X prover based on dL. For standard classes of switching mechanisms, the implementation provides fully automated stability proofs, including searching for suitable Lyapunov functions. Moreover, the generality of the deductive approach also enables verification of switching control laws that require non-standard stability arguments through the design of loop invariants that suitably express specific intuitions behind those control laws. This flexibility is demonstrated on three case studies: a model for longitudinal flight control by Branicky, an automatic cruise controller, and Brockett's nonholonomic integrator. 
    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. ; ; (, 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
  4. ; ; ; (, 2018 IEEE 61st International Midwest Symposium on Circuits and Systems (MWSCAS))
    This paper proposes a complementary topology for Switched-Capacitor (SC) DC-DC converter to enhance the dynamic response. For battery charging unit with faster charging time requirement, one of the major restrictions comes from the equivalent output resistance of the SC DC-DC converter. By connecting one completely symmetric SC converter as complementary topology with the original single converter, the proposed SC DC-DC converter topology decreases the equivalent output resistance down to half. Simulated in 0.13-μm standard CMOS process, the simulation results show that this complementary SC converter gains faster dynamic response, shorter charging time, and higher energy-conversion efficiency. 
    more » « less
  5. ; ; ; (, IEEE Conference on Decision and Control)
    Task-invariant feedback control laws for powered exoskeletons are preferred to assist human users across varying locomotor activities. This goal can be achieved with energy shaping methods, where certain nonlinear partial differential equations, i.e., matching conditions, must be satisfied to find the achievable dynamics. Based on the energy shaping methods, open-loop systems can be mapped to closed-loop systems with a desired analytical expression of energy. In this paper, the desired energy consists of modified potential energy that is well-defined and unified across different contact conditions along with the energy of virtual springs and dampers that improve energy recycling during walking. The human-exoskeleton system achieves the input-output passivity and Lyapunov stability during the whole walking period with the proposed method. The corresponding controller provides assistive torques that closely match the human torques of a simulated biped model and able-bodied human subjects’ data. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email