Servomotors

Subject description

Mathematical tools for description of servomotors, electromechanical analogies and basic electrical and mechanical properties of different types of motors are introduced. Physical foundations of direct current electric motor are presented, followed by transfer functions, calculations of heat losses, heat transfer function, and temperature dependence of motor parameters. The impact of power supply and the resonance in electromechanical system are overviewed. Asynchronous induction servomotors are presented, with physical principles of operation and their main properties. Stepper motors (variable reluctance and hybrid stepper motors) are the third type of motors presented along with their properties, characteristics and types of power supply and control. Physical fundamentals of hydraulic flow of fluid under pressure are overviewed to introduce hydraulic actuators (motors and valves) and electrohydraulic controllers for their application in hydraulic servosystems.

The subject is taught in programs

Objectives and competences

To learn about physical principles and working properties of various servomotor types (electric and hydraulic). To get insight into mathematical modeling and estimation of servomotor transfer function estimation and into application of different servomotor types with respect to their characteristics.

Teaching and learning methods

The next teaching methods will be used: lectures and practical lab work.

Lectures: Formal transfer of fundamental knowledge and data using theoretical and mathematical explanations and supported with graphical tools (images, movies) and computer simulations. Exercises in solving problems concerning servomotor analysis and performance.

Lab vork: practical assignments to support the material covered in lectures, on which the students work in pairs. Some of the lab work may be conducted in a form of larger mini-projects on topics not neccessarily covered in lectures. Practical work consists of measurement and determination of of static and dynamic properties of motors and of performance testing of electromechanical systems. The students are requested to self-study and to prepare for the assignment. Reports must be written for all practical assignments.

Expected study results

After successful completion of the course, students shoud be able to:

Describe physical background of operation of different selected types of motors (actuators) and relationships between the input electrical or hydraulic quantities and the output mechanical quantities.
Explain the effect of different parameters on operation of motors.
Apply transfer functions for mathematical description of relationship between the controlling and the controlled variable in open- and closed loop case.
Use measurement instrumentation in a correct and safe manner.
Apply the selected motor as actuator in a regulated servosystem.
Apply mathematical modelling of electromechanical and electrohydraulic systems for description of operation of these systems.

Basic sources and literature

A. Hughes, B. Drury, Electric motors and drives, 5th ed., Newnes/Elsevier, 2019.
P. Kramar, T. Jarm. Servomotorji : zbirka rešenih nalog. izd. Ljubljana: Založba FE in FRI, 2014.
V. Ambrožič, P. Zajec, Električni servo pogoni. Ljubljana: CIGRE-CIRED, 2016.
N.D. Manring, Hydraulic control systems, Wiley, 2005.
S. Reberšek, Hidravlična krmilja in servosistemi, Založba FER, Ljubljana, 1995
Dodatno neformalno študijsko gradivo na predavanjih in vajah.