EE 6904 Lecture 3 Microprocessor applications in Power

EE 6904 Lecture 3 Microprocessor applications in Power Electronics & Non-isolated and Isolated DC/DC Converters Book reference: Power Electronics Handbook, Fourth Edition------ by M. H. Rashid Part of the lecture is taken from the link: https: //www. ee. iitb. ac. in/student/~cmouli/index_files/ee 675_slides_20%20 OCT%2008. pdf

Learning Outcome At the end of this course, students will be able to LO 1: familiar with the advanced semiconductor devices applied in power electronics and also their using technique in power electronics LO 2: design isolated and non-isolated dc-dc converters 2/25/2021 Department of EEE, KUET 2

Typical Control Structure of a Power Electronic System 2/25/2021 Department of EEE, KUET 3

Microcontrollers 2/25/2021 Department of EEE, KUET 4

Microprocessors 2/25/2021 Department of EEE, KUET 5

Digital Signal Processors 2/25/2021 Department of EEE, KUET 6

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Non-isolated and Isolated DC/DC Converters: transformer less and transformer based converters 2/25/2021 Department of EEE, KUET 9

Design consideration • High quality • Small in size • Light-weight • Reliable • Energy efficient 2/25/2021 Department of EEE, KUET 10

Functions of dc/dc converters 2/25/2021 Department of EEE, KUET 11

Types of dc/dc converters • Pulse-width-modulated (PWM) converters • Resonant and soft-switching converters Advantages of PWM converters: • Low component count • High efficiency • Constant frequency operation • Relatively simple control and commercial availability of IC controllers • ability to achieve high conversion ratio 2/25/2021 Department of EEE, KUET 12

Applications of dc-dc converters • High performance dc drives: electric traction, electric vehicles and machine tools • Power supply: x-ray lamp (tens of kilowatts), 3. 3 V for modern microprocessor, 5 V and 12 V logic circuits, 48 V for telecommunication equipment, and 270 V for main dc bus on airplanes. • Distributed power supply system • Utility ac grid--- for UPS, battery chargers etc. • Power factor correction (PFC) 2/25/2021 Department of EEE, KUET 13

DC Choppers Fig. 1 DC chopper with resistive load, (A) circuit diagram and (B) output voltage waveform 2/25/2021 Department of EEE, KUET 14

DC Choppers Fig. DC chopper with RLE load, (A) circuit diagram and (B) output voltage waveform 2/25/2021 Department of EEE, KUET 15

DC Choppers Fig. The dc step-up chopper 2/25/2021 Department of EEE, KUET 16

Step-down (buck converter) Fig. Buck converter, (A) circuit diagram and (B) waveforms 2/25/2021 Department of EEE, KUET 17

Forward Converter • In the forward converter, the energy-transfer current flows through the transformer in one direction • This converter is popular for low power application • for medium power levels, converters with bidirectional transformer excitation are preferred due to better utilization of magnetic components 2/25/2021 Department of EEE, KUET 18

Push-Pull Converter Transformer is excited with bidirectional current, hence core saturation is not a problem. 2/25/2021 Department of EEE, KUET 19

Half-Bridge Converter D<=0. 5 In comparison with the push-pull converter, the primary of the transformer is simplified at the expense of two voltage-sharing input capacitors 2/25/2021 Department of EEE, KUET 20

Full-Bridge Converter D<=0. 5 • This is a versatile converter • It is very popular in dc-ac conversion and four-quadrant dc drives 2/25/2021 Department of EEE, KUET 21

Step-Up (Boost) Converter Fig. Boost converter, (A) circuit diagram and (B) waveforms 2/25/2021 Department of EEE, KUET 22

Buck-Boost Converter Fig. Buck-boost converter, (A) circuit diagram and (B) waveforms 2/25/2021 Department of EEE, KUET 23

Flyback Converter Fig. Buck-boost converter, (A) circuit diagram and (B) circuit with a transformer model showing the magnetizing inductance 2/25/2021 Department of EEE, KUET 24

Ćuk Converter (A) Fig. Ćuk converter, (A) circuit diagram and (B) waveforms 2/25/2021 Department of EEE, KUET (B) 25

Lecture 4 SEPIC, Zeta, power factor correction at ac mains in these converters, their application in SMPS, UPS, welding and lighting. 2/25/2021 Department of EEE, KUET 26