Control Elements in Electrical Drives
FEKT-MREPAcad. year: 2017/2018
Galvanically separated sensors of electric values (voltage, current), sensors of non-electric values (position, speed, acceleration, temperature, pressure,...). Analogue memories. Sampling of analogue signals in electrical drives. A/D converters. D/A converters. Phase-controlling of controlled rectifiers. Pulse-width modulators (PWM) for DC/DC converters and DC/AC converters controlling. Galvanic separation of control signal for a tyristor, triac and power switching transistor. Special circuity.
Learning outcomes of the course unit
- The graduate knows practical and theoretical consequences regarding the application of a current sensing shunt in power circuits of pulse converters.
- The graduate can design and realize a measuring current transformer for single-acting and double-acting pulse converters and also a classical current transformer for sine 50Hz applications. He understands the theoretical analysis of the current transformer in detail. He knows the practical limits in the usage of current transformers.
- The graduate knows the principle and is able to draw the internal connection of current sensors LEM (compensated and uncompensated). He is able to choose and use an appropriate LEM sensor for any defined application. He has the practical knowledge (linearity, bandwidth etc.).
- The graduate knows the principle of Rogowski coil. He is able to deduce the formula for the voltage of the coil. He can draw the connection of the sensor with the Rogowski coil and following impedance separator and integrator. He knows the practical limits of the usage and construction details. He also knows the possibility to use a passive integration for HF purposes. He is able to explain mathematically the practical limits in this case.
- The graduate knows the problems of voltage sensing from a power circuit of a pulse converter (voltage divider with a filter capacitor, voltage sensor LEM – galvanic separation, usage limits of differential amplifiers).
- The graduate is able to describe the most often systems with a power control loop (drives – electric vehicles, arc welding, etc.). He knows the methods of sensing the actual output power of DC/DC converters with PWM based on the sampling of the true current with the duty or based on the sensing of the average value of the input current from the DC link.
- The graduate knows typical circuit realizations used in the analogue part of control circuits (elimination of the influence of variable internal resistance, limiters, protections, dead-time realization, du/dt slope limiters).
- The graduate knows many generators of a rectangle signal (astable flip-flops with transistors, logical gates, various relaxation oscillators, connections with opamps and comparators).
- The graduate is able to explain system requirements on the drivers of power transistors of pulse converters. He understands the operation and requirements on saturation protection.
- The graduate is able to design a driver for MOSFET or IGBT with a transfer of the driving information together with the driving energy by a magnetic way (several circuits). He knows the practical limits of these concrete circuits.
- The graduate is able to construct galvanically separated DC supply sources of a low power for the supplying of the driver secondary side. He knows the requirements on such sources (parasitic capacity etc.).
- The graduate knows the principle and connection of a charge pump (bootstrap capacitor) as a replacement of the galvanically separated supply source for the driver secondary side. He knows the practical problems and disadvantages of this solution, especially if a level shifter is used instead of a galvanical separation of the control signal.
- The graduate knows the parameters of professional drivers SEMIKRON and CONCEPT.
- The graduate can draw a block diagram of PLL. He can explain in detail the operation of all blocks. He understands the problems of control to a zero frequency deviation or zero phase deviation. He knows the basic usage.
- The graduate knows the basic principles of position sensors and proximity switches. He can realize his own sensor based on the principle of HF eddy currents.
- The student should know basic linear and non-linear connections of operational amplifiers (inverting/non-inverting amplifiers, low-pass filters, P, I and PI controllers, comparators without/with hysteresis).
- The student should have knowledge about magnetism (definition and mutual relations of basic quantities, real understanding of coil and voltage transformer operation – not only when operating with harmonic currents and voltages).
- The student should know the principles of DC/DC and DC/AC converters. He should have knowledge about switching semiconductors including practical information (transistor switching times, diode recovery times, typical du/dt slopes etc.). Also he should understand typical parasitic effects of these components and power circuits.
- Before studying this course the student should graduate the course MPEL (Industrial electronics) and especially courses Power electronics 1 and 2.
Recommended optional programme components
Recommended or required reading
Horowitz, Hill,: The Art of Electronics (EN)
Punčochář: Operační zesilovače (CS)
Patočka M., Vorel P.: Řídicí elektronika - pasivní obvody (CS)
Patočka M., Vorel P.: Řídicí elektronika - aktivní obvody (CS)
Planned learning activities and teaching methods
Techning methods include lectures, excercises and practical laboratories. Students have to complete two projects during the course.
Assesment methods and criteria linked to learning outcomes
Final examination - 70points
Test - 15points
Laboratories - 15points
Language of instruction
1. Current sensing in power circuit of a converter - shunt application.
2. Measuring current transformer - substitutional diagram, analysis of consequencies, design. Pulse current transformer for single acting and double-acting applications - detail design.
3. Rogowski coil - detail analysis, design of the coil and circuits, HF applications with a passive integration.
4. Voltage sensing methods, sensing the output power of DC/DC converters, applications.
5. Typical circuit realizations in control circuits of pulse converters.
6. Rectangle signal generators.
7. Drivers for MOSFET and IGBT - system requirements, typical problems and their solution, saturation protection, possibilities of the galvanic separation (detail description of typical solutions).
8. Drivers for MOSFET and IGBT - secondary supppy source realization.
9. Drivers for MOSFET and IGBT - charge pumps usage. variants of circuits, advantages/disadvantages. Analysis of concrete drivers, advantages/disadvantages.
10. PLL - principle, theoretical analysis, applications, view of practical connections.
11. Induction position sensors.
12. Connecting important knowledge and consequences - system DC/AC inverer + IM.
13. Connecting important knowledge and consequences - system DC/AC inverter + PMSM.
Students should learn the operation and the design of some typical analogue ang digital circuits used in the control electronics of electrical drives.
Specification of controlled education, way of implementation and compensation for absences
The content and forms of instruction in the evaluated course are specified by a regulation issued by the lecturer responsible for the course and updated for every academic year.