Groupe de recherche en électronique de puissance et commande industrielle

In this paper, a new nonlinear control strategy is proposed for a permanent-magnet salient-pole synchronous motor. This control strategy simultaneously achieves accurate torque control and copper losses minimization without recurring to an internal current loop nor to any feedforward compensation. It takes advantage of the rotor saliency by allowing the current (i/sub d/) to have nonzero values. This, in turn, allows us to increase the power factor of the machine and to raise the maximum admissible torque. We apply input-output linearization techniques where the inputs are the stator voltages and the outputs are the torque and a judiciously chosen new output. This new output insures a well-defined relative degree and is linked to the copper losses in such a way that, when forced to zero, it leads to maximum machine efficiency. The performance of our nonlinear controller is demonstrated by a real-time implementation using a digital signal processor (DSP) chip on a permanent-magnet salient-pole synchronous motor with sinusoidal flux distribution. The results are compared to the ones obtained with a scheme which forces the i/sub d/ current to zero.

This paper presents a novel approach to fuel cell modeling. The model is developed with the objective to facilitate the simulation of fuel cell power systems and requires only few variables from manufacturer datasheets. The user would need to extract data from the datasheet in order to perform the simulation and does not need to perform experimental tests on a real stack. Based on the amount of information available on a given stack, a simplified model or, alternatively, the detailed model can be used. These models are generic models and able to emulate the behavior of any fuel cell types fed with hydrogen and air. The procedure to extract data from fuel cells datasheet is described along with the method to approximate cell's parameters. The models are validated through comparison with real datasheet performance and with experimental data from an actual fuel cell stack. The simulations results obtained are close to the expected results with an error in the range of plusmn 1%, that for both steady and transient states and at any condition of operation, provided a controlled stack internal humidity. Finally, the models are included in SimPowerSystems (SPS) and used in the simulation of a Fuel Cell Backup Power System (FCBPS). The FCBPS is used as a rescue to a three-phase to ground fault on a 25 kV system feeding an asynchronous motor. The performance obtained from the FCPBS model is as expected, the fault is totally unseen by the connected load.

Abstract A comparative study evaluates the problem of determining the control that must be exerted on manipulator joints. Two different techniques are studied: (i) direct and indirect adaptive controls and (ii) neural adaptive control. In the direct adaptive technique the Lyapunov stability‐based approach is used with the objective of minimizing the tracking errors of the joints in the adaptation process. In the indirect adaptive technique the regulator parameters are updated via the estimation of the process model. This step, using a recursive least squares algorithm, is based on the error at the input and on the filtered dynamic model in order to avoid acceleration measurements. Neural adaptive control is based on learning from input‐output measurements and not on parametricmodel‐based dynamics. It is important to note that adaptive control requires a real‐time estimation of the system parameters and a well‐defined dynamic model, whereas neural adaptive control does not require any of these conditions. All the above‐mentioned techniques are applied to the trajectory‐tracking control of a two‐degree‐of‐freedom (2DOF) manipulator. the experimental results show the effectiveness of the neural adaptive techniques for the trajectory‐tracking errors.

The main hurdle in achieving real-time performance for the simulation of power-electronic circuits is the large calculation effort required to update the model after a discontinuous change in switch impedance. The method presented here suggests that by separating the switch model from the rest of the circuit, only a much smaller equation set needs updating. Thus, it reduces the update effort to a level where it is no longer the bottleneck of the overall simulation loop. Unlike previous works on this issue, the method is independent on both the simulation approach and the circuit topology. The method has been tested on a variety of circuits with impressive results, two of which are presented here. First, there is a complete HVdc system, representing the higher limit in size and complexity. Second, a pulse-width-modulated motor drive with an external controller in a hardware-in-the-loop configuration represents a higher limit in performance requirements. Both test circuits are simulated in real time on a low-cost off-the-shelf personal computer, using the xPC technology from Simulink and automatic generation of optimized code, and are compared to a very precise variable step offline simulation.

The purpose of this paper is to investigate the "input-output linearization" technique for speed regulation of a permanent magnet synchronous motor (PMSM) fed by a PWM voltage-source inverter. The nonlinear controller is compared to a classical linear controller based on an approximate linear model of PMSM equations. The input-output linearization technique is tested for different operation regions. In particular, the flux-weakening region where the saturation phenomenon takes place is considered.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In this paper, a new technique for shaping the line current and reducing the total harmonic distortion in a three-phase bridge rectifier, feeding a capacitive load, is presented. Using the topology proposed by Ewaldo et al. (1995), a new control technique has been implemented. The main objective here is to minimise the THD of the line current under different load conditions (20% to 100% of full load). A review of the problems inherent in a bridge rectifier feeding a capacitive load and the possible solutions are first presented. Subsequently, the analysis of the new circuit, and the control technique used are described along with simulation results. Finally the experimental results on a 1.6 kW prototype are presented.

In this paper, the authors present a direct torque control scheme for a permanent-magnet (PM) AC motor. For this purpose, state feedback input-output linearization techniques are used with a systematic way of selecting outputs in such a way that not only the torque-voltage (or speed-voltage and position-voltage if necessary) relationship is linearized but a physical criterion is optimized (the minimization of copper losses for example). This strategy can be applied to various types of motors, such as brushless DC motors and PM stepper motors, and can also be seen as method to extend the Park's transformation. Simulations show the high performances of the proposed direct torque control scheme.

Recently, technological advances have been focused on the cockpit of modern unmanned aerial vehicles (UAVs) in order to reduce pilot requirements and workload to operate them. First person view (FPV) flight represents a key point when UAVs perform tasks beyond the line of sight. This paper presents the design and implementation of a cockpit for a remotely operated quadrotor. We have developed an intuitive graphical user interface (GUI) for piloting the quadrotor encompassing the most relevant flight instruments as an altimeter, attitude, heading, and ground speed indicators. The GUI is developed using the programming development environment LabVIEW®.

Network components are nonlinear devices and their impedance values vary with frequency, voltage and power variations. Tracking of these parameters and subsequent update tasks are mainly CPU intensive. Accuracy expected from modern digital simulators imposes frequent updates of the various admittance values. Real-time digital simulators impose the new challenge of performing these updates on large matrix at best in HRT (hard real-time) (every step) and at worst in near real-time (every few steps). HRT is achieved when the computations are performed as fast as the phenomena unfolds, in this case 60 Hz. The authors have focused on this problem and more specifically on the frequency dependency. They have examined various algorithms and developed an implementation strategy that allows real-time frequency compensation of large network admittance matrices. Their algorithm consists in representing each circuit element by its frequency dependent quadrupole model and the corresponding q-matrix. These q-matrices are combined to produce the network elements equivalent c-matrices. Finally, the c-matrices are used to compute the updated admittance matrix elements and update the network nodal matrix. Their strategy consists in isolating the q-matrix and c-matrix formation from the admittance matrix update. In this fashion, the algorithm can be easily implemented on a parallel architecture and thus achieve HRT. The algorithm, the models and the strategy have been implemented on a two serial and one parallel computers using the C programming language. In this paper, the authors present their results as applied to a single-phase balanced power network.

The authors reconstitute a dynamic model of a real-time compensator for electrical networks using Simulink under the MATLAB environment. Study of a unified control system for network power flow necessitates modelling of each element according to the function attributed in this application. The control is based on a vector analysis of the network parameters by the symmetrical component method. This reconstitution has made possible a series of tests and measurements to validate the topology.

The Modular Multilevel Converter (MMC) is a promising topology for STATCOM applications due to its key features, such as modularity, scalability, and reduced harmonic content. Increasing the number of voltage levels in MMC reduces harmonics but simultaneously increases the number of submodules (SMs) per arm, leading to larger sizes and higher costs, which presents a challenge. To address this, this article introduces a novel 17-level MMC-STATCOM based on the Z Packed U-Cell (ZPUC) converter as its SM, which enables the generation of more voltage levels with fewer components and reduced harmonic content, offering significant advantages in terms of size and cost. Given the complex structure of the proposed converter and the associated challenges in building a physical prototype, real-time (RT) simulation using FPGA technology is employed for validation. The key contributions include integrating the ZPUC-SM into a three-phase STATCOM for the first time and adapting the converter model and its control system to RT tools, including RT-LAB with an electric hardware solver for FPGA execution. In addition, capacitor voltage balancing and energy sorting algorithms are integrated within Phase-Shift Pulse Width Modulation, eliminating the need for an additional controller while maintaining the floating capacitors of ZPUC-SMs balanced and regulated. The specifications of the proposed converter are defined, the mathematical model and control system are derived, and a real-time implementation based on CPU and FPGA execution is built to verify the scheme. The obtained RT simulation results provide practical evidence confirming the effective operation of the proposed scheme in VAR compensation mode.

A real-time implementation of nonlinear control based on the technique of input-output linearisation is applied with the aid of a Texas Instruments C31 digital signal processor working at 16 MHz. Some results of simulation and practical results are presented. This article is limited to the results of regulation of the internal currents of the motor.

The main objective of this work is a comparison of three nonpollutant AC-DC convertor topologies with unity power factor and high efficiency, in order to derive maximum benefit from the assembly utilised while ensuring AC/DC conversion. Discussion of the principle of comparison is followed by a detailed analysis and tables showing the advantages and disadvantages of each convertor. The results of simulation of the three proposed convertors are presented.

The authors present a detailed study of a series-resonant convertor topology functioning in quasi-resonant mode. This is used in a photovoltaic to electrical power conversion application. A general method of dimensioning is given which allows quantification of the various stresses borne by the components of the convertor. A performance analysis, based upon theoretical and experimental results, bears upon the harmonic content of the output signals from the convertor feeding three types of loads.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>