Examination of design strategies for inverter-driven induction machines

Considerations for the design of inverter-driven induction machines are presented. Decades of innovation and evolution within the realm of fixed frequency and voltage excitation has allowed the induction machine to become a mature and widely used electromechanical system. Well-defined and accepted performance criteria for conventional line-fed induction machines are used to adequately reduce the machine design space to manageable proportions. Due to the altered operational conditions that exist for inverter-driven systems with power electronics-based converters, generalized constraining conditions are not so well defined, and thus the design space has not been clearly determined. This work explores many of the geometrical design variables and conventions that are commonly employed, the motivation behind their existence, and how/if they are affected by the introduction of high-fidelity power electronics-based machine excitations. An electric traction system requiring a broad constant-power region is used to establish how application-specific constraints heavily determine overall design objectives, allowing for design flexibility in slot count, skewing, and rotor bar geometries to be noted.