Matz Lenells

Possibilities of obtaining small-signal models of DC-to-DC power converters by means of system identification

This paper presents some existing system identification methods and the results obtained when applying these methods to a forward DC-to-DC power converter. Some of the advantages and disadvantages of the methods are presented. With system identification, measured data from a systems input and output can be processed to results in a model of the system.

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.

Efficient voltage feed-forward algorithms for switched mode power supplies

We present a number of approximation algorithms for voltage feedforward compensation of Switch Mode Power Supplies. The complexity of the algorithms differs, as well as their ability to suppress input voltage transients. The compensation is attained by manipulating the integral part of the feedback control law reducing the computation requirements and makes it suitable for firmware realization in standard Digital Pulse Width Modulation Integrated Circuits or as resource and power efficient implementations in ASICs.

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.

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.

Analysis of a capacitive loaded buck converter

In this paper we study how the capacitive load influences the system dynamics in switched DC/DC converters. A study is made about how the system dynamics depend on the values of the capacitance and ESR. Parallel coupling of capacitors to achieve larger capacitance is studied from a control loop stability point of view. We define a capacitor with a given minimum capacitance and a certain ESR range, which can be paralleled up to a given total maximum capacitance, where the control loop stability margins are guarantied. This result is also extended for a mix of different capacitor types used in parallel.

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.

A load capacitance identification algorithm for switched Mode Power Supplies

We present an algorithm for identification of the load capacitance for Switch Mode Power Supplies. The algorithm does not inject any disturbance that can cause additional noise on the output voltage of the power supply. The algorithm is computationally effective and is suitable for implementation in hardware or software. Experiments show an uncertainty of σ<inf>c</inf> = 100μF for the capacitance estimate using a current measurement with an uncertainty of σ<inf>I</inf> = 1A.