Recent Advances in Additive Manufacturing for High-Power-Density Electrical Machines: A Topical Review of Winding Architectures, Integrated Cooling, and System-Level Technology Readiness

Additive manufacturing (AM) is increasingly examined as a manufacturing route for high-power-density electrical machines (EMs), particularly when continuous loading is limited by winding congestion, indirect cooling paths, and assembly constraints. This topical review synthesizes recent AM literature within a 2021-2026 evidence window, with older work retained only when it defines baseline architectures, terminology, or qualification context. The review evaluates AM-enabled windings, integrated cooling, magnetic and thermal subassemblies, and hybrid implementations through four filters: evidence maturity, boundary-condition completeness, net machine-level benefit, and application-specific qualification burden. A compact five-level evidence-maturity framework is used to distinguish simulation concepts and coupons from subsystem, complete EM, and qualification-oriented demonstrations, and the framework is explicitly compared with Technology Readiness Level logic. The synthesis indicates that shaped or hybrid windings, direct-conductor cooling, slot-level heat exchangers, and compact thermal hardware currently show the clearest near-term value, provided that conductivity degradation, AC-loss behavior, insulation reliability, hydraulic power, leakage risk, repeatability, and cost-throughput penalties are reported. Magnetic core AM and fully additively manufactured EMs remain less mature because of core-loss control, anisotropy, repeatability, and limited inverter-fed validation. The review concludes that AM should be adopted selectively at dominant thermal, electromagnetic, or packaging bottlenecks and benchmarked against strong conventional baselines by net machine-level benefit rather than geometric novelty.