29 research outputs found
Convergence Rate of Nonlinear Switched Systems
This paper is concerned with the convergence rate of the solutions of
nonlinear switched systems. We first consider a switched system which is
asymptotically stable for a class of inputs but not for all inputs. We show
that solutions corresponding to that class of inputs converge arbitrarily
slowly to the origin. Then we consider analytic switched systems for which a
common weak quadratic Lyapunov function exists. Under two different sets of
assumptions we provide explicit exponential convergence rates for inputs with a
fixed dwell-time
Large-signal stability conditions for semi-quasi-Z-source inverters: switched and averaged models
The recently introduced semi-quasi-Z-source in- verter can be interpreted as
a DC-DC converter whose input- output voltage gain may take any value between
minus infinity and 1 depending on the applied duty cycle. In order to generate
a sinusoidal voltage waveform at the output of this converter, a time-varying
duty cycle needs to be applied. Application of a time-varying duty cycle that
produces large-signal behavior requires careful consideration of stability
issues. This paper provides stability results for both the large-signal
averaged and the switched models of the semi-quasi-Z-source inverter operating
in continuous conduction mode. We show that if the load is linear and purely
resistive then the boundedness and ultimate boundedness of the state
trajectories is guaranteed provided some reasonable operation conditions are
ensured. These conditions amount to keeping the duty cycle away from the
extreme values 0 or 1 (averaged and switched models), and limiting the maximum
PWM switching period (switched model). The results obtained can be used to give
theoretical justification to the inverter operation strategy recently proposed
by Cao et al. in [1].Comment: Submitted to the IEEE Conf. on Decision and Control, Florence, Italy,
201
Stability of uniformly bounded switched systems and Observability
This paper mainly deals with switched linear systems defined by a pair of
Hurwitz matrices that share a common but not strict quadratic Lyapunov
function. Its aim is to give sufficient conditions for such a system to be
GUAS.We show that this property of being GUAS is equivalent to the uniform
observability on of a bilinear system defined on a subspace whose
dimension is in most cases much smaller than the dimension of the switched
system.Some sufficient conditions of uniform asymptotic stability are then
deduced from the equivalence theorem, and illustrated by examples.The results
are partially extended to nonlinear analytic systems
Asymptotic Behavior of a Class of Evolution Variational Inequalities
We establish a new LaSalle's invariance principle and discuss the asymptotic behavior of a class of first-order evolution variational inequalities
On reduction of differential inclusions and Lyapunov stability
In this paper, locally Lipschitz, regular functions are utilized to identify
and remove infeasible directions from set-valued maps that define differential
inclusions. The resulting reduced set-valued map is point-wise smaller (in the
sense of set containment) than the original set-valued map. The corresponding
reduced differential inclusion, defined by the reduced set-valued map, is
utilized to develop a generalized notion of a derivative for locally Lipschitz
candidate Lyapunov functions in the direction(s) of a set-valued map. The
developed generalized derivative yields less conservative statements of
Lyapunov stability theorems, invariance theorems, invariance-like results, and
Matrosov theorems for differential inclusions. Included illustrative examples
demonstrate the utility of the developed theory
Switched systems with multiple invariant sets
This paper explores dwell time constraints on switched systems with multiple, possibly disparate invariant limit sets. We show that, under suitable conditions, trajectories globally converge to a superset of the limit sets and then remain in a second, larger superset. We show the effectiveness of the dwell-time conditions by using examples of switching limit cycles commonly found in robotic locomotion and flapping flight