Anders Hultgren

A Limit Cycle Of A Resonant Converter

Abstract We study a piecewise linear system approximating the behavior of a switched DC/DC-converter. We give conditions for a unique limit cycle. The stability of a state space trajectory controlled converter is addressed. The discontinuity curves have been carefully examined with respect to uniqueness of intersecting solutions.

An in-situ real time impulse response auto-test of resistance temperature sensors

A new method for achieving an automated in-situ impulse response test of resistance temperature sensors is described in this paper. An implementation of the automated in-situ test and some experimental results are also given. The experimental setup is based on a signal processor board programmable directly from Matlab and Simulink. The suggested test can be built into the sensor system giving an intelligent or smart sensor.

Switched Kalman filter in a high frequency series loaded resonant converter

A switched power converter is a hybrid system and can be modelled by a switched linear model consisting of a set of linear differential equations and connected logic conditions. If the time instants of the switching are known the system can be viewed as a linear time varying system. A switched Kalman filter is developed to meet the switched property and enable a state feedback control. The filter is tested in a high frequency resonant power converter. The filter is developed in a system for rapid prototyping of filter and control algorithms.

CONVERGENCE OF A SWITCHED HAMILTONIAN OBSERVER APPLIED TO AN SLR CONVERTER

Abstract A design method for switched observers is presented. Global convergence of the switched observer is addressed in the case of a persistently exciting control signal. Hamiltonian modelling is used in the observer design. The observer is applied to a Series Loaded Resonant converter. A global model of the converter is given. Simulation is performed for illustration of the convergence properties.

Asymmetric Limit Cycles in an Industrially Applied Controlled Resonant Converter

An industrially applied LCC power converter is modelled as a hybrid system. It is found that the hybrid system given a parameter set up and different initial conditions has three different limit cycles, one unstable and two asymmetric stable limit cycles. Effects of the asymmetric limit cycles are considered.

Stability of a nonlinear Hamiltonian observer applied to a general electrical network

A nonlinear Hamiltonian observer is defined and applied to a general switched electrical network. A design and analysis method is suggested. A proof is given for the stability of the observer error process. As an example, the observer is applied to a switched resonant power converter. Simulations indicate convergence properties.

Operator Interface for a Water Tank Process - A Java Programming Project

Abstract Operator interface for a controlled water tank process has been developed in Java. The task of the system is to control the water level in a tank, to give the user an opportunity to interact with the controller, and to present data in a lucid way. The P-, I- and D-part of the control signal are shown in a graph and thereby give a clear insight in the function of the controller. Taking use of the Java standard libraries has made the program small but at the same time powerful.

Limit cycle control of an industrially applied resonant converter modelled as a hybrid system

Limit cycle control of an industrially applied high power, high voltage resonant power converter is modelled as a hybrid system. It is found that the hybrid system with three continuous states and one logic state given a parameter set up and different initial conditions has a rich solution set indicating possible problems in the industrial application. The solution set are one central closed trajectory and two asymmetric types of limit cycles.

Limit cycles in an industrially applied hybrid system

An industrially applied LCC power converter is modelled as a hybrid system. It is found that the hybrid system with three continuous states and one logic state given a parameter set up and different initial conditions has among other solutions one central closed trajectory and two types of limit cycles, on the left and the right side. The other solutions are indicated.

Fault tolerant high voltage resonant power converter application

A high voltage and high power fault tolerant application of a resonant converter is presented. The resonant converter load shows frequent short circuits making the load voltage drop to zero within some us, implying high stress on the main circuit components. A load voltage short circuit fault tolerant system is suggested by including a novel way of augmenting the controller with a load voltage estimator. The estimator can detect load voltage short circuit and will then be a part of a fault tolerant high voltage resonant converter.