D2 Advanced Power Electronics

Topic

Industrial electric power distribution—ranging from kilowatts to megawatts—almost always utilizes three-phase systems because they allow the same amount of power to be transmitted with lower current per conductor compared to an equivalent single-phase system; the voltage measured between two lines in a three-phase system is always higher than the voltage measured between a line and the neutral, following a well-known, fixed ratio.

Variable-frequency drives control the speed of induction motors by simultaneously varying the frequency and voltage supplied to them—employing the pulse-width modulation technique described in the power electronics model in Part II—rather than allowing them to run constantly at the fixed speed dictated by the grid frequency; this technique enables significant energy savings in applications such as industrial pumps, fans, and compressors, which account for a massive share of total industrial electricity consumption.

Resonant converters operate precisely at the resonant frequency described in the reactive components model—a point where switching losses are drastically minimized; this topology is currently the standard for modern portable device chargers. Fast chargers for electric vehicles, which handle hundreds of kilowatts, utilize the wide-bandgap semiconductors described in the power electronics model—operating at high frequencies—to keep the equipment's size and weight within reasonable limits.

Thus, this module—which begins by distributing power across three lines rather than one—concludes with an electric vehicle's battery management system, which individually monitors the charging and discharging of each cell; the core logic of the entire module—converting and controlling energy on a large scale without waste or equipment damage—is replicated here at the much smaller scale of a single cell within a pack containing thousands.

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