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.

The viability of electrified aircraft propulsion (EAP) architectures, from small urban air mobility vehicles to large single-aisle transport aircraft, depends almost exclusively on their energy storage requirements. Because energy storage increases with specific energy and power density, these metrics strongly influence the adoption of EAP architectures. This chapter provides an overview of electrochemical energy storage and conversion systems for EAP, including batteries, fuel cells, supercapacitors, and multifunctional structures with energy storage capability. An overview of today’s state-of-the-art battery technology and related EAP concepts is followed by a review of energy storage requirements for various classes of electrified aircraft. Recent battery technology advances are then reviewed along with their applicability and limitations for expanding the electrified aircraft market. Alternative electrochemical energy storage and conversion systems (e.g., fuel cells, flow batteries, supercapacitors, etc.) are also addressed. The chapter concludes with a review of multifunctional structures with energy storage capability and their potential application to EAP.