Papers by Sébastien Mariéthoz
Series Resonant Converter for DC fast-charging electric vehicles with wide output voltage range
2019 21st European Conference on Power Electronics and Applications (EPE '19 ECCE Europe)
The paper presents an investigation of the operating range achievable with a series resonant conv... more The paper presents an investigation of the operating range achievable with a series resonant converter. In its fully resonant mode, the series resonant converter is an attractive topology due to the switching at zero current, which results in high efficiency. The question that is addressed by this paper is if the topology is applicable for fast DC charging of electric vehicles, that is if it can cover the required operating range and what effective efficiency is achieved over this operating range.
Application of model predictive control and analysis of switched systems to the direct voltage control of AC-DC converters
2009 European Control Conference (ECC), 2009
ABSTRACT
Minimising conversion losses in isolated multisource DC-DC converters with non-negligible resistive components
2015 IEEE Energy Conversion Congress and Exposition (ECCE), 2015
This paper presents a control approach for minimising conversion losses in isolated multisource D... more This paper presents a control approach for minimising conversion losses in isolated multisource DC-DC power converters. As opposed to approaches found in literature, it accounts for the impact of the resistances on the current waveforms. This impact is non-negligible at low switching frequencies or if the converter inductance is low. The approach is based on systematic modelling of the system dynamics and losses. These models allow for mathematical optimisation of the waveforms to minimise conversion losses. For real-time implementation, the optimal modulation patterns are precomputed and stored in a look-up table. The effectiveness of the scheme is demonstrated on a twosource lab setup.
Introduction générale TABLE DES MATIÈRES v C Modélisation du convertisseur d'alimentation C.1 Mod... more Introduction générale TABLE DES MATIÈRES v C Modélisation du convertisseur d'alimentation C.1 Modélisation d'un convertisseur réversible .
High-speed online MPC based on a fast gradient method applied to power converter control
Proceedings of the 2010 American Control Conference, 2010
Bounding the computational complexity of an online optimization method in a real-time environment... more Bounding the computational complexity of an online optimization method in a real-time environment with hard time constraints is a challenging problem. This paper investigates a new solution approach based on a fast gradient method in the context of model predictive control (MPC) of power converters. Different from other solution methods that either provide bounds that are far off from the practically observed ones or do not allow for bounding the computational effort at all this method enables easy to compute and meaningful bounds that can further be decreased by means of a pre-conditioning technique.We report an implementation of the fast gradient method on an industrial-type digital signal processor with integer arithmetics and show that worst case runtimes are in the order of tens of μs using less than one kByte of memory while being numerically robust. Moreover, this method also improves the control performance compared to explicit MPC.
A market mechanism for solving multi-period optimal power flow exactly on AC networks with mixed participants
2012 American Control Conference (ACC), 2012
ABSTRACT The difficult problem of optimal power flow on AC networks has recently been tackled via... more ABSTRACT The difficult problem of optimal power flow on AC networks has recently been tackled via reformulation as a semidefinite program. New work in the field suggests that a globally optimal solution is attainable in this way. Here, the problem is extended to multiple time periods in order to accommodate the time-coupled nature of power system entities' costs and constraints. A market mechanism is then developed for the clearing of nodal prices for both real and reactive power, and it is shown that these prices are optimal under standard convexity assumptions. The mechanism is motivated by the separable structure of the Lagrangian associated with the relaxed SDP formulation, allowing the application of a dual subgradient method. Physical insights into the electrical network are then used to make improvements over the standard method that dramatically speed up convergence. The advantage of considering multiple time periods in parallel is that dynamic costs and constraints, e.g. generator ramping and wear, as well as the important price smoothing role of storage, can be accommodated naturally - something existing multi-period auctions do not allow. The mechanism is demonstrated on a 39 bus network populated with a variety of market participant types.
IEEJ Transactions on Industry Applications, 2008
Matrix converters have no boost capabilities. Their output voltage amplitude is therefore reduced... more Matrix converters have no boost capabilities. Their output voltage amplitude is therefore reduced compared to back-to-back inverter topologies. Moreover, as the input and output power of matrix converters are equal all the time, they are sensitive to grid voltage fluctuations and disturbances and the voltage transfer ratio is further reduced under such grid perturbations. Two-stage matrix converters have a DC-link with no energy storage and their behaviour and control is very similar to single-stage direct matrix converters. One advantage of such converters is that this intermediate DC-link voltage can be increased or decreased by the means of an additional circuitry, so called compensator. The goal of this compensator is to provide a higher voltage transfer ratio and a higher robustness to the grid unbalances, using some storage devices in the compensator circuitry. The two-stage matrix converters investigated in this paper use two different principles: ( 1 ) adding a voltage in series with the rectifier DC voltage in order to increase it to provide the required voltage to the load (Fig. ), ( 2 ) modulating the rectifier DC-voltage with a higher voltage source connected in parallel, as required to obtained a satisfactory DC-voltage for the load. This auxiliary voltage sources are balanced by the means of a DC-DC converter that draw its power from the rectifier stage. Undistorted grid current and load voltage is usually obtained for matrix converters applying a simple control scheme for the conventional two-stage matrix converter. As the DC-DC converters of these hybrid structures draw their power from the grid through the rectifier stage, a current is superimposed to the inverter stage DC current. This current affects the waveform of the load voltages and grid currents, which are modified consequently. The conventional modulation pattern can no more be used and the new control scheme has to be adapted to keep grid current and load voltage undistorted. The operation of all switches has to be synchronised in order to inject even charges on the phases and to apply the right voltage on the
IEEE Transactions on Power Electronics, 2002
This paper proposes two frequency based methods for parallel active filtering of current harmonic... more This paper proposes two frequency based methods for parallel active filtering of current harmonics in utility grids. Active filter (AF) reference prediction and AF current control are the two key-points to obtain high performances. This paper deals with the AF reference prediction. The two proposed methods are based on the Fourier Series and its implementation on DSP. They belong to two prediction structures: 1) the open-loop structure which predicts the reference currents from the load currents; 2) the closed-loop structure which predicts the reference currents from the grid currents. Fourier Series based methods are very flexible and have several interesting properties. These two methods have been successfully implemented and tested. The latter method cancels permanent errors and results in better performances. Both methods are very flexible.
Explicit Model Predictive Control of DC–DC Switched-Mode Power Supplies With Extended Kalman Filtering
IEEE Transactions on Industrial Electronics, 2009
... Index TermsExplicit Model Predictive Control, MPC, Ex-tended Kalman Filter, EKF, DC-DC, SMPS... more ... Index TermsExplicit Model Predictive Control, MPC, Ex-tended Kalman Filter, EKF, DC-DC, SMPS, Boost Converter I. INTRODUCTION DC-DC switched power supplies are widely used in a broad variety of applications. Most of these DC-DC converters are regulated by ...
Comparison of Hybrid Control Techniques for Buck and Boost DC-DC Converters
IEEE Transactions on Control Systems Technology, 2010
AbstractFive recent techniques from hybrid and optimal con-trol are evaluated on two power elect... more AbstractFive recent techniques from hybrid and optimal con-trol are evaluated on two power electronics benchmark problems. The benchmarks involve a number of practically interesting oper-ating scenarios for fixed-frequency synchronous dc-dc converters. The ...
IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society, 2012
The paper introduces a hierarchical structure for the finite time constrained optimal control of ... more The paper introduces a hierarchical structure for the finite time constrained optimal control of a system with a fuel cell and a supercapacitor storage unit. The supercapacitor storage unit is employed to improve life time, reduce hydrogen consumption of the fuel cell, increase peak power and allow for some regeneration from the load. The three control layers regulate the supercapacitor storage unit charge, the DC bus voltage level and the currents of the fuel cell and supercapacitor storage unit. They are all based on explicit linear offset-free model predictive control, where the optimal control law is computed off-line and stored in a look-up table.
Lagrangian duality in mixed integer optimization is a useful framework for problems decomposition... more Lagrangian duality in mixed integer optimization is a useful framework for problems decomposition and for producing tight lower bounds to the optimal objective, but in contrast to the convex counterpart, it is generally unable to produce optimal solutions directly. In fact, solutions recovered from the dual may be not only suboptimal, but even infeasible. In this paper we concentrate on large scale mixed-integer programs with a specific structure that is of practical interest, as it appears in a variety of application domains such as power systems or supply chain management. We propose a solution method for these structures, in which the primal problem is modified in a certain way, guaranteeing that the solutions produced by the corresponding dual are feasible for the original unmodified primal problem. The modification is simple to implement and the method is amenable to distributed computations. We also demonstrate that the quality of the solutions recovered using our procedure improves as the problem size increases, making it particularly useful for large scale instances for which commercial solvers are inadequate. We illustrate the efficacy of our method with extensive experimentations on a problem stemming from power systems. RV, PME, and MM are with the
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Papers by Sébastien Mariéthoz