| Abstract [eng] |
One of the most efficient investigations of variable speed drives is computer modelling. Development and optimization of frequency converters take place under disturbances that result from inaccurate measurements of system parameters, change of object properties or for any other reason. Therefore, development of specific drives used for fan or pump application requires performing a research of a variety controllers working under load conditions. In the doctoral thesis problems related to the variable frequency drive operating by the different types of controllers and loads are solved and analyzed. Synergy of induction motor drive model created in a transformed coordinate system together with a variable frequency drive is analyzed. Development of frequency drive model, synthesis of controllers and approval of created models adequacy are problems, solved in this work. Recently the induction motors are replacing the DC motors in the industry because of their reliability and the price. For example USA in 1995 have installed about 100 million of induction motors, in 2004 USA have sold about 2–3 million of pieces of frequency converters. Around 75 % of produced electric energy is consumed by electric motors used for ventilation or pump drives because of this, most popular are frequency converters with scalar control induction drive methods. Vector control frequency converters are mostly used with drive with more than 10 kW. The development of frequency converters requires large infrastructure, materials, power and other recourses therefore during the last time, scientists problems related with control or design of the drives solved by means of computer modelling of variable frequency drives. One of the most popular simulation programs is MathWorks Matlab® Simulink®. It operates under finite element methods and can solve different types of electrical tasks. Therefore it is used for analysis and development of variable frequency drive prototype; however models of worldwide drive producers are confidential. The purpose of this work is to create motor control models for variable frequency drive simulation. It will provide new knowledge to the scientists in one of the world's scientific priority areas – analysis of variable frequency electrical drives. |
