Power electronic circuits enable electrified aircraft propulsion (EAP) – from the More-Electric Aircraft (MEA) (an aircraft where the propulsion systems are still traditional, but some or all of the secondary non-propulsion-related subsystems are electrified) to the All-Electric Aircraft (AEA) (an aircraft with fully electrified propulsion and secondary subsystems) – and their importance cannot be understated. This chapter provides general power conversion concepts while fostering a solid high-level understanding of power electronic circuits, focusing on those circuits and devices that are crucial for EAP. Power system metrics, including power density and voltage, and integration techniques are presented. This is followed by a description of relevant converter topologies, including two- and multi-level inverters, direct and indirect matrix converters, rectifiers, circuits for open winding and multi-phase electric machines, and fault-tolerant topologies. A discussion of semiconductor devices and materials, including a brief discussion of silicon-carbide (SiC) devices, concludes the chapter.

Cryogenic power electronics enable the highly efficient ultra-dense power conversion systems that are critical for electrified aircraft propulsion (EAP) and have the potential to transform aircraft powertrain design. Much like superconducting electric machines, cryogenic power electronics offer benefits achieved through improved power device performance, reduced conductor electrical resistivity, and increased heat transfer temperature differential. In this chapter, key steps in the development of cryogenic power electronics are presented, from the component to the converter level. First, the characterization of critical components – including power devices and magnetics – at cryogenic temperature is introduced to establish the basic knowledge necessary for cryogenic design and optimization. Second, special considerations specific to cryogenic design, and trade and design studies for the cryogenic power stage and filter electronics are detailed. Finally, an example of a high-power cryogenically-cooled inverter system for an EAP application is illustrated, with safety considerations and the protection scheme highlighted.