Course detail

# Power Electronics

FEKT-BKC-VELAcad. year: 2023/2024

Basic classification of power converters: AC/DC, AC/AC, DC/DC, DC/AC. Cascade of few converters. DC-bus. Static thermal phenomena. Cooling of semiconductors. Demanded thermal resistance of the heat sink. Active power; its calculation in special cases. EMC in LF region. Power factor, total harmonic distortion factor. Power switching devices, overview: diode, thyristor, triac, BJT, MOS-FET, IGBT, GTO.

Rectifiers: non-controlled, controlled. Typical loads. Mean value of output voltage. Net rectifiers for supplying of transistor converters. AC/AC converters: 1-phase, 3-phase. Loads of R, L, R-L, R-L-Ui types. Phase control of triacs. DC/DC transistor converters. DC/AC transistor converters (1-phase, 3-phase). Control strategy of DC/DC, and DC/AC converters. PWM, sinusoidal PWM. Magnetic phenomena in the power electronics. Transformer theory. Mathematic models of the voltage transformer. Switch-mode supplies. DC/DC converters with the pulse transformer. Single-end buck converter.

Language of instruction

Number of ECTS credits

Mode of study

Guarantor

Entry knowledge

Rules for evaluation and completion of the course

1+1+1+1 points = 4 points for 4 laboratory tasks.

6 points for second semestral test.

70 points for exam.

100 points total.

The attendance at the all numerical and laboratory exercises is required.

Aims

It is proved by written test, that student is able:

- To define power converter. To define ideal switching element. To list four basic types of converters: AC/DC, AC/AC, DC/DC, DC/AC. To describe the cascade of more converters with the voltage/current DC-bus.

- To describe static thermal phenomena. To explain the cooling of semiconductors. To calculate the demanded thermal resistance of the heat-sink.

- To define the active power. To calculate the conducting losses of a switching device.

- To define EMC in LF area. To define the power factor. To define the total distortion factor of a phase current.

- To list power switching devices: uncontrollable (D), semi-controllable (Ty, Tri), controllable (BJT, MOS-FET, IGBT, GTO). To name its usable parameters.

- To list all types of the rectifiers (AC/DC): uncontrolled, controlled, semi-controlled, node/bridge, m-phase, q-pulse, with/without flywheel diode. To list typical loads: DC-motor, LC-filter, accumulator, welding arc. To justify, why the mean value of the output voltage is useable. To describe hte rectifier from the cybernetics point of view: control char., transport delay, dynamics.

- To represent the current rippling in the rectifier load. To analyse the shapes of the input phase currents.

- To describe and analyse the net DC sources for transistor converters: 2-pulse uncontrolled rectifier with pick-up capacitor, 6-pulse uncontrolled rectifier with pick-up capacitor or LC-filter.

- To list and to describe AC/AC type converters: 1-phase, 3-phase. To analyse its work into the R-load. To deduce the control characteristics for R-load, and justify why the RMS value of the output voltage is useful.

- To list the transistor pulse DC converters (DC/DC). To divide it with regard to the ability to work in the different quadrants of the VA-characteristics of the load. To analyse the converter working in I.Q.

- To analyse the DC/AC converters, 1-phase, 3-phase.

- To describe the PWM system for the control of DC/DC and DC/AC converters.

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 operational properties of different uncontrolled diode rectifiers. To describe measured oscillographs of currents and voltages. To measure the rippling of the output voltage and current.

- To measure pulse converter working in the 1.Q. To describe measured oscillographs of currents and voltages. To analyse the voltage and current rippling on the load.

- To measure 1-phase converter of the AC voltage (AC/AC). To describe the measured oscillographs of currents and voltages.

- To analyse the diagrams of voltages in the 1-phase DC/AC converter working in the sinusoidal PWM regime.

In the numerical lectures the student learns following skills:

- To calculate the mean and RMS value of typical signals.

- To design the current and voltage capability of the power switching devices.

- To calculate the power conducting loss of the power switching device.

- To calculate demanded thermal resistance of the heat-sink in the steady-state.

- To calculate the active power in the different nodes of DC/DC power converters.

- To design controlled rectifier. To calculate in it the voltage, current, and power rates.

- Navrhnout a dimenzovat střídavý měnič napětí. Spočítat v něm napěťové, proudové a výkonové poměry.

- To design AC/AC converter. To calculate in it the voltage, current, and power rates.

Study aids

Prerequisites and corequisites

Basic literature

Patočka M.: Vybrané statě z výkonové elektroniky, sv. 2, skriptum FEKT, VUT Brno (CS)

Patočka M.: Výkonová elektronika, 1. část - usměrňovače, střídavé měniče napětí, skriptum FEKT, Brno, 2010 (CS)

Patočka M.: Magnetické obvody Elektronický učební text, FEKT, VUT Brno (CS)

Recommended reading

Z.Čeřovský,J.Pavelka : Výkonová elektronika 1, skripta ČVUT (CS)

Bose, B.K.: Power electronics and AC Drives. Prentice Hall 1986 (EN)

Classification of course in study plans

- Programme BKC-SEE Bachelor's, 2. year of study, winter semester, compulsory

#### Type of course unit

Lecture

Teacher / Lecturer

Syllabus

2. Static thermal phenomena. Cooling of semiconductors. Demanded thermal resistance of the heat sink.

3. Active power; its calculation in special cases.

4. EMC in LF region. Power factor, total harmonic distortion factor.

5. Power switching devices, overview: diode, thyristor, triac, BJT, MOS-FET, IGBT, GTO.

6. Special chapters from the semiconductor theory. Chip structure of following power devices: fast diode, slow diode, symmetric thyristor, asymmetric thyristor, bipolar transistor, MOS-FET, IGBT, GTO. Detail analyse of the switch-on, and switch-off processes in the transistors. Switching loss calculation.

7. Rectifiers: non-controlled, controlled. Typical loads. Mean value of output voltage.

8. Rippling of the load current. Demanded inductance of the choke. Type power of transformer.

9. Main rectifiers for supplying of transistor converters. Two-pulse, and six-pulse rectifier with the capacitor.

10. AC/AC converters: 1-phase, 3-phase. Loads of R, L, R-L, R-L-Ui types. Phase control of triacs.

11. DC/DC transistor converters. DC/AC transistor converters (1-phase, 3-phase).

12. Control strategy of DC/DC, and DC/AC converters. PWM, sinusoidal PWM.

13. Magnetic phenomena in the power electronics. Transformer theory. Mathematic models of the voltage transformer and current transformer. Switch-mode supplies. DC/DC converters with the pulse transformer. Single-end, and double-end buck converters.

9. AC/AC converters: 1-phase, 3-phase. Loads of R, L, R-L, R-L-Ui types. Phase control of triacs.

10. DC/DC transistor converters. DC/AC transistor converters (1-phase, 3-phase).

11. Control strategy of DC/DC, and DC/AC converters. PWM, sinusoidal PWM.

12. Magnetic phenomena in the power electronics. Transformer theory. Mathematic models of the voltage transformer and current transformer.

13. Switch-mode supplies. DC/DC converters with the pulse transformer. Single-end, and double-end buck converters.

Fundamentals seminar

Teacher / Lecturer

Syllabus

2. Active power; its calculation in special cases.

3. Controlled rectifiers. Design. Rippling of the load current. Demanded inductance of the choke. Type power of transformer.

4. Main rectifiers for supplying of transistor converters. Design. Two-pulse, and six-pulse rectifiers.

5. DC/DC transistor converters. Design.

6. DC/AC transistor converters. Design.

7. Magnetic phenomena in the power electronics. Choke design.Transformer design.

Laboratory exercise

Teacher / Lecturer

Syllabus

2. Uncontrolled rectifiers. Basic features.

3. AC voltage inverter. Control characteristics. Analysis of output values.

4. DC/DC converter. Control and load characteristics. Analysis of output values.

5. DC/AC converter. Analysis of output values. Basic characteristics.