Algebraic observer design for PEM fuel cell system

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, the concept of the algebraic observer is applied to Proton Exchange Membrane Fuel Cell (PEMFC) system. The aim of the proposed observer is to reconstruct the oxygen excess ratio through estimation of their relevant states in real time from the measurement of the supply manifold air pressure. A robust differentiation method is adopted to estimate in finite-time the time derivative of the supply manifold air pressure. Then, the relevant states are reconstructed based on the output-state inversion model. The objective is to minimize the use of extra sensors in order to reduce the costs and enhance the system accuracy. The performance of the proposed observer is analyzed through simulations considering measurement noise and different stack-current variations. The results show that the algebraic observer estimates in finite time and robustly the oxygen-excess ratio.Peer ReviewedPostprint (author's final draft

Computer algebra and operators

The symbolic computation of operator expansions is discussed. Some of the capabilities that prove useful when performing computer algebra computations involving operators are considered. These capabilities may be broadly divided into three areas: the algebraic manipulation of expressions from the algebra generated by operators; the algebraic manipulation of the actions of the operators upon other mathematical objects; and the development of appropriate normal forms and simplification algorithms for operators and their actions. Brief descriptions are given of the computer algebra computations that arise when working with various operators and their actions

Stability analysis of a grid-connected VSC controlled by SPC

In the near future a large part of traditional generation based on conventional synchronous machines (SM) will be replaced by renewable generation based on voltage source converters (VSC). In this sense, power system operators have begun to demand VSC-based power plants be able to participate in the frequency and voltage regulation, and are also interested in services like inertia emulation and damping of power oscillation, functions that today are carried out by large synchronous generators. Therefore, several studies have suggested new ways to control voltage source converters, that try to emulate the behavior of synchronous generators and are known generically as Virtual Synchronous Machines. The synchronous power controller (SPC) is a flexible solution that emulates the classical swing equation of a synchronous machine and improves its response. The SPC inherits the advantages of conventional synchronous generators, while it fixes many of its drawbacks. In this work, a sensitivity analysis of a VSC connected to the grid and controlled by SPC is performed. In this sense, a non-linear mathematical model of the system is first developed. This non-linear model is then linearized, obtaining a linear model from which the eigenvalues and sensitivities of the system to some relevant parameters are calculated. Finally, time-domain simulations are performed to confirm the results of the sensitivity analysis.Postprint (author's final draft

Stationary Cycling Induced by Switched Functional Electrical Stimulation Control

Functional electrical stimulation (FES) is used to activate the dysfunctional lower limb muscles of individuals with neuromuscular disorders to produce cycling as a means of exercise and rehabilitation. However, FES-cycling is still metabolically inefficient and yields low power output at the cycle crank compared to able-bodied cycling. Previous literature suggests that these problems are symptomatic of poor muscle control and non-physiological muscle fiber recruitment. The latter is a known problem with FES in general, and the former motivates investigation of better control methods for FES-cycling.In this paper, a stimulation pattern for quadriceps femoris-only FES-cycling is derived based on the effectiveness of knee joint torque in producing forward pedaling. In addition, a switched sliding-mode controller is designed for the uncertain, nonlinear cycle-rider system with autonomous state-dependent switching. The switched controller yields ultimately bounded tracking of a desired trajectory in the presence of an unknown, time-varying, bounded disturbance, provided a reverse dwell-time condition is satisfied by appropriate choice of the control gains and a sufficient desired cadence. Stability is derived through Lyapunov methods for switched systems, and experimental results demonstrate the performance of the switched control system under typical cycling conditions.Comment: 8 pages, 3 figures, submitted to ACC 201

An Analysis of Publication Venues for Automatic Differentiation Research

We present the results of our analysis of publication venues for papers on automatic differentiation (AD), covering academic journals and conference proceedings. Our data are collected from the AD publications database maintained by the autodiff.org community website. The database is purpose-built for the AD field and is expanding via submissions by AD researchers. Therefore, it provides a relatively noise-free list of publications relating to the field. However, it does include noise in the form of variant spellings of journal and conference names. We handle this by manually correcting and merging these variants under the official names of corresponding venues. We also share the raw data we get after these corrections.Comment: 6 pages, 3 figure

Geometric Scattering in Robotic Telemanipulation

In this paper, we study the interconnection of two robots, which are modeled as port-controlled Hamiltonian systems through a transmission line with time delay. There will be no analysis of the time delay, but its presence justifies the use of scattering variables to preserve passivity. The contributions of the paper are twofold: first, a geometrical, multidimensional, power-consistent exposition of telemanipulation of intrinsically passive controlled physical systems, with a clarification on impedance matching, and second, a system theoretic condition for the adaptation of a general port-controlled Hamiltonian system with dissipation (port-Hamiltonian system) to a transmission line

A liénard oscillator resonant tunnelling diode-laser diode hybrid integrated circuit: model and experiment

We report on a hybrid optoelectronic integrated circuit based on a resonant tunnelling diode driving an optical communications laser diode. This circuit can act as a voltage controlled oscillator with optical and electrical outputs. We show that the oscillator operation can be described by Liénard's equation, a second order nonlinear differential equation, which is a generalization of the Van der Pol equation. This treatment gives considerable insight into the potential of a monolithic version of the circuit for optical communication functions including clock recovery and chaotic source applications

Network Representation and Passivity of Delayed Teleoperation Systems

The paper proposes a general network based analysis and design guidelines for teleoperation systems. The electrical domain is appealing because it enjoys proficient analysis and design tools and allows a one step higher abstraction element, the network. Thus, in order to analyze the system by means of network elements the mechanical system must be first modeled as an electric circuit. Only then power ports become apparent and networks can be defined. This kind of analysis has been previously performed in systems with well defined causalities, specially in the communication channel. Indeed, a communication channel exchanging flow-like and effort-like signals, as for instance velocity and computed force, has a well defined causality and can thus be directly mapped as a two-port electrical network. However, this is only one of the many possible system architectures. This paper investigates how other architectures, including those with ambiguous causalities, can be modeled by means of networks, even in the lack of flow or effort being transmitted, and how they can be made passive for any communication channel characteristic (delay, package-loss and jitter). The methods are exposed in the form of design guidelines sustained with an example and validated with experimental results