Power Converter Technique
FEKT-MTVMAcad. year: 2017/2018
Thermal phenomena in the power electronics. Active power, its computing and measurement. Computing of the power losses in the converter. DC/DC pulse converters. DC/AC pulse converters. Analysis of the step-down converter. Pulse width modulation – PWM. Power switching transistors. Drivers for the power switching transistors. Analysis of the switch-on and switch-off phenomena in the transistor.
Learning outcomes of the course unit
It is proved by written test, and oral exam that student is able:
- To analyse and to calculate the dynamic thermal phenomena. To calculate and to construct the air, and liquid heat-sink. To describe the principle of the thermal tube.
- To define the active power. To calculate and to measure it in the typical cases occurring in the power electronics.
- To define the EMC criteria in LF. and HF. region. To define the quality of the electrical loads according to EMC regulations.
- To list and to demonstrate the transistor pulse DC converters (DC/DC): Converters working in 1Q, 2Q, 1+2Q, 1+4Q, 1 up to 4Q, converter with the common choke, converters of the type Cuk, SEPIC, Zeta.
- To analyse the converter working in the 1Q in the regime of continual and interrupt current. To design and to calculate output LC-filter for this converter.
- To analyse converters of DC/AC type, 1-phase, 3-phase. To define all voltages in the system consists of 3-phase converter - motor.
- To describe and to analyse PWM system for control of DC/DC, and DC/AC converters.
- To list and to define boundary, static, and dynamic parameters of power switching devices (D, Tyr., Tr., BJT, MOS-FET, IGBT, GTO).
- To analyse turn-on, and turn-off process in the transistor. To define RBSOA. To calculate switching losses in the transistor.
- To describe the circuit solution and all functions of the driver of the switching transistors.
In the laboratory practices the student measures and analyses signals in different power converters with help of oscilloscope. Student trains following skills:
- To handle and to use basic measure instruments in the power electronics laboratory: oscilloscope, voltmeter, ampermeter, DC and AC laboratory supplies.
- To measure and to analyse the net DC suppliers.
- To set and to connect the work place for the measuring of the power transistor switches.
- To catch the oscillograph and to analyse the turn-on, and turn-off process in the IGBT transistor.
- To measure the oscillographs of the impulse currents with the help of the non-inductive coaxial shunt.
- To measure the loss energies at the turn-on, and turn-off process in the IGBT transistor.
- To analyse the function of the snubber circuits, and to compare its influence on turn-off process in the transistor.
- To catch the oscillographs in the DC converter working in 1Q., and to analyse these oscillographs.
- To catch the oscillographs in the 1-phase DC/AC converter working in the sinusoidal PWM regime, and to analyse these oscillographs.
In the numerical lectures the student learns following skills:
- To design the power switching transistors from the current and voltage point of view.
- To calculate the power losses caused by the current conducting.
- To calculate and to construct the air, and the liquid heat sink with the demanded thermal resistance.
- To calculate the active power in the different nodes of the DC/DC pulse converters.
Student must have the previous knowledge from the applied mathematics:
- To use and to apply the mathematical operations above complex numbers in the component and polar representation (summation, subtraction, multiplication, division, and rectification of the complex fraction).
- To apply the basic principles of the integral and differential calculus of one variable: description of the inductor work, i.e. induction law in the differential and integral form, similarly the dif. and integr. relation between instant values of the current and voltage at the capacitor. Calculus of the mean and RMS values of the periodical function.
Student must have the previous general knowledge and ability:
- To describe basic properties of the discrete electronic devices (diode, bipolar and unipolar transistor).
- To attend the course BREB (Control Electronics).
- To be able practically to use and to apply the following tools for the analysis and synthesis of the electric circuits: 1st and 2nd Kirchhoff laws, Ohm law, induction law in the differential and integral form.
Recommended optional programme components
Recommended or required reading
Chee-Mun Ong: Dynamic Simulation of Electric Machinery. Prentice-Hall, 1998. (EN)
Patočka M.: Vybrané statě z výkonové elektroniky, sv.I. (CS)
Patočka M.: Vybrané statě z výkonové elektroniky, sv.II. (CS)
Bose, B.K.: Power electronics and AC Drives. Prentice Hall 1986 (EN)
Planned learning activities and teaching methods
Lectures are lead with the massive support of Power-Point. The Power-Point file is available for students.
In laboratories, students measure and analyse 4 exercises (transistor power converters) with the help of oscillograph.
In numerical exercises, the typical tasks are solved (design of active and passive elements of power converters).
Assesment methods and criteria linked to learning outcomes
Requirements for completion of a course are specified by a regulation issued by the lecturer responsible for the course and updated for every.
Language of instruction
1. Dynamic thermal phenomena. Thermal-electrical-mechanical analogy.
2. Thermal systems with one or several time constants. Thermal model of the power device.
3. Liquid heat-sinks, cooling of the cabinets. Thermal pipes.
4. Active power, its computing and measurement in the power electronics.
5. EMC in LF region. Power factor. Total harmonic distortion of the phase current.
6. DC/DC pulse converters – the principle, overview.
7. Analysis of the DC/DC buck converter. Design of the output LC-filter.
8. DC/AC pulse converters – the principle, overview.
9. Overview of the power switching devices. Boundary, static, and dynamic parameters. Switching losses.
10. Drivers for the power switching transistors. Smart devices.
11. Snubber circuits. Soft-switching. Resonant and quasiresonant converters.
12. Pulse width modulation – PWM for the DC/DC and DC/AC converters.
13. Power, voltage, and current relations in the system of converter-AC motor.
Construction and electric design of the power convrters.
Specification of controlled education, way of implementation and compensation for absences
The attendance at the all numerical and laboratory exercises is required.