Module 2 — Sources, switching, and power electronics

Module status: outline

Module 1 is the fully written core. This page is the detailed outline for Module 2 — the topics, the hands-on circuits, and the practice themes — so you can see where the course is heading and start exploring the relevant samples now. The full chapter prose is in development.

Module 1 handled smooth, linear elements. Real power systems are full of switching: breakers, diodes, thyristors, and transistors that change the network's topology mid-run. This module extends the per-step solver to handle them, and applies it to the converters that dominate modern grids.

What you will learn

• How independent and controlled sources and control signals are represented in the time domain.
• How an ideal switch is modeled (two-state conductance) and what its operation costs the solver (re-stamping and re-factorization, from Chapter 3).
• How diodes, thyristors, and IGBTs decide their own state, and why that requires iterating within a step.
• The numerical hazards of switching — chatter (spurious oscillation) and switching-instant error — and the interpolation / damping techniques that tame them.
• How rectifiers and DC-DC / DC-AC converters are assembled and analyzed.

Planned chapters

• 4. Sources and control signals. DC and AC sources, source impedance (Thévenin), ramps and soft-starts; control-domain blocks (gain, sum, integrator, signal generators) and how a control signal drives an electrical device.
• 5. Switches and self-commutating devices. The ideal switch as a conductance that flips between "on" and "off"; diodes (state from terminal voltage), thyristors (gated turn-on), IGBTs (gated, forced commutation); in-step iteration for state consistency.
• 6. Numerical issues of switching. Switching-instant placement, trapezoidal chatter after current interruption, and the standard remedies (critical-damping adjustment, interpolation to the switching instant).
• 7. Rectifiers and converters. Half- and full-wave rectifiers, the buck converter, and PWM-controlled power conversion; reading ripple, conduction intervals, and average vs instantaneous quantities.

Hands-on circuits

Existing samples you can open and run today:

• Half-bridge rectifier
• Full-bridge rectifier
• Buck converter
• PWM power control

These will be supplemented with course-specific worked examples (for instance, a single diode + R-L circuit to isolate the diode's state logic, and a controlled half-bridge to study chatter and its remedy). The Scope panel concept page is useful background for reading switching waveforms.

Practice themes

Expect problems on: predicting conduction intervals and average output of a rectifier; computing why an inductive current interruption triggers chatter and how interpolation fixes it; and relating a converter's duty cycle to its average output.

References

• H. W. Dommel, Electromagnetic Transients Program (EMTP) Theory Book, Bonneville Power Administration — switches and the in-step solution.
• J. Arrillaga and N. R. Watson, Power Systems Electromagnetic Transients Simulation, IET Power and Energy Series 39 — power-electronic systems, switching instants, and chatter removal.

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Previous: Chapter 3 — Building and solving the network each step · Next: Module 3 — Transmission lines and cables.