A Synchronous Look at the Simulink Standard Library

International audienceHybrid systems modelers like Simulink come with a rich collection of discrete-time and continuous-time blocks. Most blocks are not defined in terms of more elementary ones—and some cannot be—but are instead written in imperative code and explained informally in a reference manual. This raises the question of defining a minimal set of orthogonal programming constructs such that most blocks can be programmed directly and thereby given a specification that is mathematically precise, and whose compiled version performs comparably to handwritten code. In this paper, we show that a fairly large set of blocks of a standard library like the one provided by Simulink can be programmed in a precise, purely functional language using stream equations, hierarchical automata, Ordinary Differential Equations (ODEs), and deterministic synchronous parallel composition. Some blocks cannot be expressed in our setting as they mix discrete-time and continuous-time signals in unprincipled ways that are statically forbidden by the type checker. The experiment is conducted in Zélus, a synchronous language that conservatively extends Lustre with ODEs to program systems that mix discrete-time and continuous-time signals

Improved direct torque control using Kalman filter: application to a doubly-fed machine

Direct Torque Control (DTC) has been extensively researched and applied during the last two decades. However, it has only first been applied to the Brushless Doubly Fed Reluctance Machine (BDFRM) a few years ago in its basic form inheriting its intrinsic flux estimation problems that propagate throughout the algorithm and hence compromise the DTC performance. In this paper, we propose the use of Kalman Filter (KF) as an alternative to improve the estimation and consequently the control performance of the DTC. The KF is designed around a nominal model, but is shown to be reliable over the whole operating range of the BDFRM. Moreover, we use a modified robust exact differentiator based on Sliding Mode (SM) techniques to calculate the angular velocity from an angular position encoder. Computer simulations are meticulously designed to take into account real-world physical constraints and thus show illustrative supporting results as expected from an experimental setup

Evaluating Energy Storage Methods for the Stabilization of Rural Microgrids

Microgrids are a hot topic in industry at the moment due to their ability to help integrate renewables into the national grid. However, they are mainly used in urban settings, despite the stability benefits they could provide to rural communities. This research aims to help expand microgrids into a rural context by building a streamlined, phasor-domain model of a microgrid in MATLAB-Simulink’s toolbox Simscape Electrical and using it to evaluate three energy storage options: a national grid connection, battery, and flywheel. My capstone involved testing models of these three solutions by subjecting my overall microgrid to faults typical of a rural setting. The design requirements for this project were split into two parts. First were the simulation specifications for the overall model, which had to accurately simulate the critical components of a microgrid: traditional diesel generation, wind and solar generation, a connection to the national grid, electrical load, and of course some form of energy storage. Second were the performance requirements for power service and quality, which were evaluated for a variety of fault scenarios and at each important element of the microgrid model. These included measures of power factor and microgrid voltage, voltage angle, and frequency. Both simulation and performance metrics were evaluated through direct observation of simulation output through scopes. It was found that my model was an accurate portrayal of the phasor-domain, power-flow behavior of all three types of energy storage and a general microgrid. In this same domain, all three types of energy storage performed similarly and were superior to having no energy storage at all. There were some issues with the phasor domain limiting the scope of my simulation, especially with the flywheel model. These limitations did not prevent me from reaching meaningful results, and they also provide ample opportunities for future work on real-time simulation and additional energy storage types

Modelling, dynamics and control of a permanent magnet generator for wind power applications.

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN014115 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Object-oriented shipboard electric power system library

The objective of this thesis is to explore the powerful capabilities of using an object-oriented modeling language to model and simulate an all electric Naval Shipboard Power System. Modelica has been used to model and simulate the shipboard power system which acts as an alternative simulation tool. The shipboard system is developed using the concept of packages. Different components like the buck converter, inverter, and AC machines have been modeled as a part of the library to develop the power system. The shipboard system has been simulated as two decoupled systems, the AC and DC systems. This research further focuses on developing a networked protection system to detect and clear faults and protect the shipboard power system from complete breakdown. A discrete supervisory controller has been designed using Petri nets as part of the protection system to control the converters and clear faults. A communication network has also been modeled for communication. Two different case studies, the open circuit test, and short circuit test were performed to test the effectiveness of the protection system and the simulation results are presented. This thesis also gives an overview of different properties of Modelica along with its advantages over other simulation tools, a detailed survey of different types of object-oriented simulation tools available, a comparison of different power electronics simulation tools, and some of the previous work done in Modelica

High performance position control for permanent magnet synchronous drives

In the design and test of electric drive control systems, computer simulations provide a useful way to verify the correctness and efficiency of various schemes and control algorithms before the final system is actually constructed, therefore, development time and associated costs are reduced. Nevertheless, the transition from the simulation stage to the actual implementation has to be as straightforward as possible. This document presents the design and implementation of a position control system for permanent magnet synchronous drives, including a review and comparison of various related works about non-linear control systems applied to this type of machine. The overall electric drive control system is simulated and tested in Proteus VSM software which is able to simulate the interaction between the firmware running on a microcontroller and analogue circuits connected to it. The dsPIC33FJ32MC204 is used as the target processor to implement the control algorithms. The electric drive model is developed using elements existing in the Proteus VSM library. As in any high performance electric drive system, field oriented control is applied to achieve accurate torque control. The complete control system is distributed in three control loops, namely torque, speed and position. A standard PID control system, and a hybrid control system based on fuzzy logic are implemented and tested. The natural variation of motor parameters, such as winding resistance and magnetic flux are also simulated. Comparisons between the two control schemes are carried out for speed and position using different error measurements, such as, integral square error, integral absolute error and root mean squared error. Comparison results show a superior performance of the hybrid fuzzy-logic-based controller when coping with parameter variations, and by reducing torque ripple, but the results are reversed when periodical torque disturbances are present. Finally, the speed controllers are implemented and evaluated physically in a testbed based on a brushless DC motor, with the control algorithms implemented on a dsPIC30F2010. The comparisons carried out for the speed controllers are consistent for both simulation and physical implementation

Control strategies for Brushless DC motors

Tato diplomová práce se zabývá strategiemi řízení, které jsou dostupné pro bezkartáčové DC motory, a které mohou být použity pro řízení rychlosti pohonů elektrických vozidel. Úkolem práce je studium rozličných řídicích algoritmů, nalezení způsobů, jak optimalizovat jejich výkon, a zároveň simulovat jejich chování pro ověření jejich vlastností. Závěrečná etapa práce spočívá v přípravě implementovatelného řídicího algoritmu, který je poté spuštěn na laboratorním stanovišti s aktivním řídicím systémem založeným na zpětné vazbě PID regulátoru a uživatelského rozhraní (HMI) pro snadnou interakci v průběhu testu.Master's Thesis researching the various control strategies available for BLDC motor control that can then be employed in the speed control of electric vehicle drive systems. The task involved studying the various control algorithms, finding ways to optimize their performance and simulate them as a proof of concept. The final stage of the thesis involved the preparation of an implementable control algorithm that was then run on a test bench with an active PID feedback-based control system and HMI for easy interaction in runtime