Optimization Design of a Five-Phase IPMSM Designed for Third-Harmonic Injection

Multiphase motors offer distinct advantages over traditional three-phase motors in terms of power density, fault tolerance, and torque performance. Consequently, they have progressively emerged as a prominent research focus in propulsion applications such as ships and new energy vehicles. Taking the five-phase permanent magnet synchronous motor (PMSM) as an example, its fundamental plane and third harmonic plane exhibit relative independence. When a third harmonic component is present in the air-gap flux density, the injection of a third harmonic current can enhance electromagnetic torque. Compared to surface-mounted permanent magnet synchronous motors (SPMSMs), interior permanent magnet synchronous motors (IPMSMs) possess a higher saliency ratio, which contributes to improved power density and extended speed range; however, they are characterized by higher harmonic content and associated losses. This study aims to enhance motor efficiency and torque density by synergistically combining a five-phase configuration with an IPMSM topology. This is achieved through an optimized slot-pole combination and the implementation of an uneven air-gap rotor design. The inherent limitations of the interior permanent magnet motor structure are strategically transformed into exploitable features. Subsequently, a third-harmonic current-injection five-phase interior permanent magnet synchronous motor was designed and manufactured. Finally, the motor’s performance was rigorously validated through comprehensive simulation and experimental testing.