【目的】港口传输大功率永磁直驱电机通常采用高电压等级设计。然而，这种方案给电磁设计、制造精度和维护可靠性带来了巨大挑战。对于变速驱动系统来说，依靠高成本的电力电子设备进行频率转换大大增加了生产成本。为解决这些问题，本文提出了一种用于永磁直驱电机的低压多支路结构设计。【方法】首先，根据港口传输大功率永磁直驱电机的设计要求，对电机的电磁方案进行设计，采用多个低压变频器供电，由各个支路共同分担整个电机的总电流。然后，对电机的定子绕组进行多支路结构设计，并通过有限元仿真分析不同支路绕组之间的耦合以及不同支路投入运行时电机的电磁性能，从理论上验证多支路电机的可行性。当不同支路投入运行时，会增加气隙磁场不均匀，影响电机的稳定性。最后，通过在转子开设辅助槽对电机的齿槽转矩进行优化。【结果】仿真结果表明，低压多支路结构方案，有效解决了低压方案电流大的问题，根据负载需求投入不同的支路运行，提高了电机整体效率；当某个变频器出现故障时，通过控制其他变频器，增大电流，使电机输出额定转矩，大大提高了电机驱动系统的可靠性；未开槽的电机齿槽转矩峰峰值为2 419.5 N·m，经过开设转子辅助槽优化后齿槽转矩峰峰值降为1 136.7 N·m，降幅为53.02%。【结论】本文所提低压多支路结构优化方案有效解决了港口传输大功率永磁直驱电机的高成本和大电流问题。该方案可根据负载要求来决定投入运行的支路数，提高了电机效率，为大功率电机设计提供了一定的参考。

[Objective] High-power permanent magnet direct-drive motors for port transmissions are usually designed with high voltage ratings. However, this solution poses significant challenges in terms of electromagnetic design, manufacturing precision and maintenance reliability. For variable-speed drive systems, relying on high-cost power electronics for frequency conversion greatly increases the production cost. To address these problems, a low-voltage multi-branch structure design for permanent magnet direct-drive motors is proposed in this paper. [Methods] Firstly, according to the design requirements of high-power permanent magnet direct-drive motor for port transmissions, the electromagnetic scheme of the motor was designed to use multiple low-voltage inverters to supply power, and the total current of the whole motor was shared by each branch circuit. Then, the stator winding of the motor was designed with multi-branch structure, and the coupling between different branch windings and the electromagnetic performance of the motor when different branches were put into operation were analyzed by finite element simulation to theoretically verify the feasibility of the multi-branch motor. When different branches were put into operation, it increased the unevenness of the air-gap magnetic field and affected the stability of the motor. Finally, the cogging torque of the motor was optimized by opening an auxiliary slot in the rotor. [Results] Simulation results showed that the low-voltage multi-branch structure scheme, which effectively solved the problem of high current in the low-voltage scheme, put different branches into operation according to the load demand and improved the overall efficiency of the motor. When a certain inverter failed, the reliability of the motor drive system was greatly improved by controlling other inverters and increasing the current so that the motor output the rated torque. The peak-to-peak value of cogging torque of the un-slotted motor was 2 419.5 N·m, and after opening the rotor auxiliary slot optimization, the peak-to-peak value of cogging torque was reduced to 1 136.7 N·m, a reduction of 53.02%. [Conclusion] The low-voltage multi-branch structure optimization scheme proposed in this paper effectively solves the high cost and high current problems of high-power permanent magnet direct-drive motors for port transmission. The scheme can decide the number of branches to be put into operation according to the load requirements, which improves the efficiency of the motor and provides a certain reference for the design of high-power motors.

国家自然科学基金(52207064,52177054);辽宁省应用基础研究计划项目(2023JH2/101600001)