A. Power electronics (converters, IBR, VFDs)
Rectifiers, DC-DC converters, inverters (PWM, grid-forming), VFDs, HVDC, FACTS, EV charging, microgrid architecture.
Lessons
Rectifier waveforms — half-wave, full-wave, 3-φ 6-pulse, SCR control
V_dc equations, ripple factor, firing-angle control, and 6-pulse line-current harmonics (5th, 7th, 11th, 13th).
DC-DC converters — buck, boost, buck-boost
Three classical non-isolated topologies with their CCM transfer functions, CCM vs DCM operation, and L/C sizing for target ripple.
Inverter PWM — sinusoidal PWM, modulation index, SVPWM
How comparing a sine with a triangle generates a clean AC sine at the output; m_a / m_f, over-modulation, and the 3-φ third-harmonic injection that boosts V_LL by 15 %.
Photovoltaic I-V curves and MPPT
PV cell I-V shape, MPP location, irradiance + temperature effects, and Perturb-and-Observe / Incremental-Conductance MPPT algorithms.
V/f speed control (VFD principle)
Keep V/f constant → keep flux constant → full torque at any speed. The trick that turned the IM into a variable-speed drive.
HVDC fundamentals — LCC vs VSC, configurations
When HVDC beats HVAC (long OHL, async tie, subsea cable). LCC (thyristor, ±800 kV / 8 GW) vs VSC (IGBT MMC, black-start, 4-quadrant). Configurations and notable installations.
Grid-forming inverters — IEEE 2800 / P2800.2, FERC 901
High-IBR grids lose synchronous inertia (H_sys 4-5 → 1-2 s) + stiffness (SCR < 3 destabilises GFL). GFL: PLL current source. GFM: voltage source, sets own V/f, synthetic H_eff 1-5 s + damping + voltage stiffness + black-start + fault current 2-4 pu. Three approaches: droop, VSM, VOC. IEEE 2800-2022 + P2800.2 (in dev) + FERC 901 (2024). AEMO mandates >30 MW. Hornsdale 100 MW, Kapolei 185 MW pilots.
EV charging — Level 1, Level 2, DC fast charging
Three levels by power: L1 (120 V, 1.4 kW), L2 (208-240 V, 3-19 kW), DCFC (DC, 50-400 kW with 1 MW emerging). Connectors: J1772 (universal AC), CCS (combined AC+DC), NACS / SAE J3400 (Tesla, adopted by all majors 2023-25), CHAdeMO (declining). Vehicle: OBC + battery + BMS. Protocols: pilot PWM + ISO 15118 + OCPP. NEC 625 (80% continuous, 40 A min L2, CCID GFCI). Grid impact: DCFC plaza = MV service + storage. V2H/V2G future.
FACTS devices — SVC / STATCOM / TCSC / UPFC
Flexible AC Transmission Systems: SVC (TCR + TSC, harmonics, Q ∝ V²), STATCOM (VSC MMC, fast, constant I at low V), TCSC (series cap + TCR for power-flow control + SSR damping), UPFC (full P+Q+V independent control via shunt + series VSC pair).
Microgrid architecture — grid-connected vs islanded, IEEE 2030.7
DOE/IEEE 2030.7 definition: bounded local DERs + loads + PCC, with islanding capability. Components: PV/battery/gas-gen/fuel-cell + tiered loads + PCC + static transfer switch + MEMS controller. Two modes: grid-connected (utility V/f) vs islanded (grid-forming DER self-regulates). Hierarchical control: primary droop / secondary MEMS / tertiary economic. AC vs DC vs hybrid architectures. IEEE 2030.7/2030.8/1547; FERC 2222. Examples: Princeton, Borrego Springs, DoD bases.