The first stage: 2-10-2006 1-12-2006

Studies and researches about Fuzzy - Sensorless technologies applicable in electrical transportation drive systems.

ABSTACT
The development of engine vehicles is one of the greatest achievements of modern technology. The increasing number of vehicles caused negative effects mostly regarding the environment. Declining air quality, global warming and petroleum resources mitigation have become the main issues for the modern society. All this aspects have become the reason for developing a secure and clean transportation system with high efficiency. As a consequence, the development of manufacturing technologies for electrical vehicles, hybrid electrical vehicles and fuel cell electrical vehicles represents the most promising alternative solution for ground transportation. Today trends involve the need for engineers to have strong knowledge in this area, in order to be able to implement the new command and control strategies, to find new ways to improve the efficiency, the autonomy and the operating safety of electrical vehicles. The first stage of the project has as objective to present the trends and the current development of the electrical driving systems applied in electrical traction. Different types of electronic power converters, electrical motors associated with the driving system, control strategies, characteristic features for every control method, models for several electrical motors, comparisons between different control systems and also experimental results regarding the use of artificial intelligence in electrical motors control are presented. Nevertheless, for the different types of propulsion motors several sensor-less (no transducers) control methods (for AC motors) and vector control methods (induction motors) have been presented. The analysis has been performed taking into account the peculiarities of the electrical vehicle (specific loads, dynamic performances, construction types). The study has been organized in five chapters. The first chapter presents a short history regarding the electrical vehicles development beginning with the first manufacturing trial, in order to establish the research level in this domain and also to emphasize the trends. Within the presentation the analysis of several factors that have delayed the researches in electrical vehicles, hybrid vehicles and fuel cell vehicles is made. The second chapter shows the types of electrical vehicles, the characteristics of the vehicle's propulsion system and the driving system characteristics. Taking into account that the combustion engine and the electrical motor are the usual mover units it was necessary to present the characteristics that influence the vehicle's performances and in consequence represent the bases of the vehicle's and driving electrical system designing procedure. The third chapter analyses the main electrical propulsion systems of the electrical vehicle, including the electrical driving systems containing DC motors, induction motors, brushless permanent magnet DC motors and electrical commutation with variable reluctance motors - SRM. These are presented from the electrical transportation point of view highlighting the manufacturing characteristics, the operating characteristics, the models used for the analyzed control strategies and the specific control techniques and methods (including vector control of the induction motor and sensorless estimation techniques of the induction motor's parameters, of the brushless DC motor and of the electrical commutation with variable reluctance motor). Thus, the electrical driving systems applied in electrical transportation must reckon with: frequent starts and brakes of the driving motors, increased accelerations and decelerations, important torque at low speed, operating with low torque and high speed and enhanced speed range at constant power. DC motor electrical driving systems for electrical transportation are based on choppers that feed the electrical motor. Therefore, the present study regarding the DC machine contains the operating and control principles of the DC motor - chopper system. The driving systems and the speed/torque adjustment methods for the induction machine have been analyzed considering the specific features of the implied sources, the machine's mathematical model complexity and the load's type. Consequently two main categories of control solutions for electrical vehicles have been presented (scalar and vectorial). In order to reduce the number of imposed values a first solution is to find a steady-state regime relation between two quantities (stator voltage - static frequency or static current - rotor frequency) in order to indirectly control the static flux and the electromagnetic torque. This type of control is named scalar control. The second solution uses the vector features of the operating quantities bringing forth to the vector control methods of the induction machine. Because the majority of electrical traction applications comprising induction motors are based on the so-called vector control or field-oriented control, the detailed induction motor model using the spatial-vector theory is presented. Within vector control systems an important place is taken by "Direct torque vector control". This control technique is presented in detail. Another interesting electrical propulsion solution is based on brushless permanent magnet DC motors due to increased power density (if high magnetic energy magnets are used), high efficiency and high operating speed. Besides the usual control techniques, estimation and sensorless control techniques have been analyzed. Last but not least, SRM systems have an increasing importance. The SRM (Switched Reluctance Motor) is used more often in variable speed applications due to reduced cost, robust construction, the inverter's safety operation, high efficiency for a large speed range and relative simplicity of the control. A few sensorless control methods and parameters and speed estimation methods have been also detailed in this case, canceling the need of a position transducer. The power convert's operation has been highlighted due to its specific features for this type of motor. The forth chapter shows studies and features comparisons regarding the electrical vehicles that have been manufactured since the sixty's. A comparison between the combustion engine vehicles and the electrical vehicles has also been presented. The fifth chapter contains aspects regarding the use of Artificial Intelligence in electrical drive systems. Comparisons between intelligent control and so called classic control have been performed taking into account the fuzzy-logic control techniques which is one of the sixth Artificial Intelligence technologies. The fuzzy-logic control method for the induction motor's control system with "Direct torque vector control" (system analyzed in detail in the third chapter) has been presented. The applied induction machine's torque control algorithm has been also presented in detail along with the choosing procedure for the control linguistic variables. The comparative experimental results (classic control system and fuzzy-logic control system) have proved that the fuzzy-logic control systems have better dynamic responses and so an increased potential to be also suitable for electrical drives applications based on Artificial Intelligence.

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Last Update: April 19 2007