Design and Load Test of High Speed Slotless Permanent Magnet Synchronous Motor with Round-Wire Air-Core Distributed Winding

This study presents a design method for high-torque-density air-core distributed windings with round wires applied to slotless permanent magnet synchronous motors (SL-PMSMs). The authors extend the conventional method to the case of applying round wires and Halbach-array magnets and clarify the optimization method considering interference with adjacent coils. As a result of the calculation, the objective function, which is the torque constant per square root of the copper loss, is limited to 0.86 times or less relative to the optimal solution. The actual test of a prototype SL-PMSM was conducted to validate the optimization method, and the experimental resistance of one coil is 6% larger than that of calculation, and the objective function measured from the current-torque characteristic at 60 kr/min decreased by 30% to that of the calculation.