Power Electronics
Every converter in this subject is built from devices that are never allowed to sit half-on, because that is the only way to move kilowatts without dissipating them. These topics animate the switching and the waveform it produces.
Start from the beginning →8 topics you can watch now, 12 still to come.
Why switching
The argument that decides the shape of every circuit that follows.
- Why Switching, Not DissipatingStart here. Drop 100 W across a linear regulator, then do the same job with a switch and find the missing heat.
- Power SwitchesVoltage, current and speed pull the physics in different directions — which is why five device families are still in production, and why SiC broke the trade rather than moving along it.
- Power diode reverse recovery
- Snubber design
- Gate driver circuits
AC to DC: rectifiers
Taking a sinusoid and getting a usable DC level out of it.
- Three-phase rectifier waveforms in detail
- Effect of source inductance and overlap
DC to DC: choppers
Changing a DC voltage by chopping it and averaging the result.
- SEPIC and Ćuk converters
- Small-signal modelling and compensator design
DC to AC: inverters
Manufacturing a sinusoid out of a battery and four switches.
- Selective harmonic elimination
- Multilevel topologies in detail
Applications
Where all of this actually ends up.
- Motor DrivesFan power goes as the cube of speed, so a 20% reduction halves the energy. Then vector control made the better motor the easier one to command.
- Switched-Mode Power SuppliesRectify first, then switch fast — one reordering, and the transformer shrinks a thousandfold. Everything awkward about an SMPS follows from that same decision.
- Grid-Connected ConvertersA grid-tied inverter controls current, not voltage — and anti-islanding, ride-through and synthetic inertia are all consequences of that one fact.
- AC voltage controllers and cycloconverters
- UPS topologies
- Battery chargers and bidirectional converters
About Power Electronics
Power electronics is what happens when you use semiconductors purely as switches, and do it fast. The reason is efficiency: a device that is either fully on or fully off dissipates very little, while one held in between turns the difference into heat. Every converter here is an arrangement of switches and energy storage exploiting that fact.
From there the topologies follow a logic rather than a list. Choppers change DC voltage levels. Inverters synthesise AC from DC by switching in a pattern. Rectifiers go the other way. Switched-mode supplies combine these with feedback to hold an output steady.
The waveforms are the subject. Currents and voltages here are deliberately not sinusoidal, and their shapes — the ripple, the switching instants, the discontinuities — carry the design intent, so they are shown changing rather than drawn once.
What to know first
- Analog Electronics, particularly diodes and transistors as switches
- Electric Circuit Analysis for the transient behaviour
Where it gets used
- Understanding what is inside a phone charger or a laptop adapter
- Sizing an inductor and capacitor for an acceptable output ripple
- Working with motor drives and variable-frequency control