Investigation of Inter-turn Voltage Stress in Fractional Slot Concentrated Winding of Inverter-fed Permanent Magnet Synchronous Machines

Under the high-frequency and high-voltage inverter-fed conditions, fractional-slot concentrated winding (FSCW) may experience localized maximum inter-turn voltage stress (ITVS), which can easily lead to premature partial discharge and threaten the operational safety of the motor. One of the key reasons for this issue lies in the insufficient understanding the ITVS in motor winding, making it difficult to balance the conflicting demands of motor performance and reliability during the design stage. To bridge this gap, this paper focuses on studying the ITVS of FSCW. Firstly, a high-frequency equivalent circuit model for FSCW permanent magnet motors is proposed, which simultaneously considers the coupling effects of in slot- and the end-winding. Then, an experimental platform is built to measure the ITVS in FSCW under the rated load. The error between simulation and experimental results for the maximum ITVS is about 3.46%, validating the accuracy of the calculation models and methods. Finally, the ITVS of different winding connection scheme is analyzed, and a novel low ITVS FSCW structure is proposed. Compared to the original scheme, the maximum ITVS of proposed FSCW is reduced by 43.3%.