EE3-14 Power Electronics
Lecturer(s): Prof Tim Green; Dr Paul MitchesonAims:
To demonstrate the opportunities provided by power semiconductors to improve the efficiency and controllability of electrical energy conversion as part of power supply systems, motor controls and grid interfaces.
Learning Outcomes:
A generally quantitative approach is taken and the student should be able to analyse the operation of the circuits given and choose suitable circuits and components for given applications. There are three broad areas of learning with details as follows.
• Appreciate the properties of semiconductor devices useful in power applications
o Be able describe how diodes and MOSFETs are designed to provide high voltage and current ratings and the compromises that are faced
o To understand why a 4-layer power structure such as an IGBTs is beneficial
o Be able to calculate power losses, in devices and choose heat sinks
o Be able to design loss reduction circuits such as snubbers and quasi resonant circuits.
• Be able to describe the operating principal and be able to design power converters for a variety of application areas including:
o dc/dc converters including derivation of input/output relations, component choices for low voltage ripple, operation of HF transformers for isolation
o dc/ac converters including qualitative assessment of frequency spectra
o controlled and uncontrolled ac/dc converters including electromagnetic interference issues and regulations
• Be able to apply power converter designs to application areas including
o assessment of various options for variable speed operation of induction machines
o general performance limits on drive systems
o comparison of various approaches to uninterruptable power supplies
Syllabus:
Improvements to basic switch-mode power supply circuits to provide isolation, negative polarity and low ripple; inversion of DC to AC and rectification with sinusoidal current; principles of power (c.f. signal) semiconductors; analysis of power losses and loss reduction techniques; control of induction machines with an inverter; use of inverters as grid interfaces for real and reactive power control
Assessment:
80% coursework, 20% class test in Spring Term
Coursework contribution: 80%
Term: Spring
Closed or Open Book (end of year exam): Closed
Coursework Requirement
Laboratory Experiment
Non-assessed problem sheets
Oral Exam Required (as final assessment): no
Prerequisite: None required
Course Homepage: http://learn.imperial.ac.uk
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